Human Anatomy, 9th Edition Elaine N. Marieb Solution Manual

Type:

Solution Manual

Resource:

Human Anatomy

Edition:

9th Edition

Author(s):

Elaine N. Marieb Patrick M. Brady Jon B. Mallatt

INSTRUCTOR’S RESOURCE GUIDE

Justin Shaffer COLORADO SCHOOL OF MINES

Leslie Hendon UNIVERSITY OF ALABAMA AT BIRMINGHAM

Human Anatomy NINTH EDITION GLOBAL EDITION

Elaine N. Marieb Patricia Brady Wilhelm Jon Mallatt

Contents

PREFACE

V

CHAPTER 1

The Human Body: An Orientation

1

CHAPTER 2

Cells: The Living Units

12

CHAPTER 3

Basic Embryology

24

CHAPTER 4

Tissues

33

CHAPTER 5

The Integumentary System

47

CHAPTER 6

Bones and Skeletal Tissues

58

CHAPTER 7

Bones, Part 1: The Axial Skeleton

72

CHAPTER 8

Bones, Part 2: The Appendicular Skeleton

85

CHAPTER 9

Joints

96

CHAPTER 10

Skeletal Muscle Tissue

111

CHAPTER 11

Muscles of the Body

123

CHAPTER 12

Fundamentals of the Nervous System and Nervous Tissue

142

CHAPTER 13

The Central Nervous System

154

CHAPTER 14

The Peripheral Nervous System

169

CHAPTER 15

The Autonomic Nervous System and Visceral Sensory Neurons

181

CHAPTER 16

The Special Senses

195

CHAPTER 17

The Endocrine System

207

CHAPTER 18

Blood

220

CHAPTER 19

The Heart

231

CHAPTER 20

Blood Vessels

246

CHAPTER 21

The Lymphatic and Immune Systems

260

CHAPTER 22

The Respiratory System

271

CHAPTER 23

The Digestive System

286

CHAPTER 24

The Urinary System

302

CHAPTER 25

The Reproductive System

314

APPENDIX A

Key to Audiovidual Distributors

330

Preface This Instructor Resource Guide accompanies the textbook Human Anatomy, Ninth Edition,

by Elaine N. Marieb, Patricia Brady Wilhelm, and Jon Mallatt, and it is devoted solely to supplying teaching suggestions and resources that augment the use of the textbook in the classroom.

Organization and Features The Instructor Resource Guide follows the organization of Human Anatomy, Ninth Edition, chapter for chapter. Within each chapter you will find the following new and revised resources: (1) Lecture and Demonstration, (2) Art Resources, (3) Supplemental Course Materials, (4) Answers to Textbook Questions, and (5) Supplemental Student Materials.

(1) Lecture and Demonstration: The opening section of each chapter in the Instructor Resource Guide is devoted to helping you structure and augment your classroom lectures and activities. Five features are offered: Objectives The objectives focus on the principal themes and topics that should be covered for each chapter, and they match the objectives in the book.

Suggested Lecture Outline The outlines generally correspond to the sequence of headings that appear in each textbook chapter. Key page, figure, and table numbers appear next to most of the entries in each outline.

Lecture Hints This feature is composed of a list of key lecture points, which follows the order of the suggested lecture outline. In addition to calling attention to the main concepts of each chapter, the lecture hints identify ideas or topics that students may have difficulty mastering in their reading or during lecture.

Classroom Discussion Topics and Activities This popular feature consists of activities, demonstrations, and discussion topics that can be used to augment and enliven your anatomy lectures and laboratories.

Clinical Questions This section of each chapter provides additional clinically focused, critical reasoning questions like those that appear at the end of each textbook chapter.

The answers follow each question.

(2) Art Resources: This section is provided to help you utilize the updated illustration program in the Ninth Edition of Human Anatomy in your classroom teaching. This section includes: Instructor Resources This list details which figures in the chapter are available in the “instructor resources” area of Mastering A&P Teaching with Art This section is designed to facilitate your lecture presentations about key figures in each chapter, and it is also aimed at encouraging students to become actively engaged with the textbook illustrations in order to strengthen their understanding of major topics. Each Teaching with Art section consists of a checklist of major discussion points about a figure and a list of concepts that students sometimes find difficult to understand or fail to perceive when they interpret a figure on their own. Finally, this section includes an art-based exercise that is designed to help students to better understand the anatomy depicted in a figure. Teaching with Art concludes with a visual critical reasoning challenge in which students are asked to synthesize a response based on the visual evidence presented in a figure. ..

PREFACE

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(3) Supplemental Course Materials: This section of each chapter consists of materials that you may use to augment your classroom presentations or assign for student completion.

This section consists of the following: Library Research Topics These term paper or report topics can be assigned for extra credit or to help deepen students’ understanding of anatomy.

Media Revised and updated, this section lists videos and software in addition to those offered by Pearson. A key to the abbreviations used to identify the audiovisual and electronic media distributors in each list can be found in Appendix A. Suggested Readings Revised and updated for this edition, this feature lists classic readings, advanced anatomy textbooks, and current journal articles. This bibliography can be used to introduce your students to scientific literature and to the research process in addition to enhancing their knowledge of human anatomy.

(4) Answers to Textbook Questions: This section provides answers to the Short Answer and Essay Questions section and the Critical Reasoning and Clinical Applications Questions section, both located at the end of each textbook chapter. Answers to the new Interpreting Medical Images questions (which are part of selected figures in the text) are also included.

(5) Supplemental Student Materials: This feature consists of a student-oriented introduction to the mission of each chapter and a description of the practical importance of its coverage. An extended series of learning checkpoints follows that students may use to chart their progress while reading the chapter. This feature is formatted to be easily photocopied and distributed to your students.

Guide to Supplements Accompanying the Textbook The suite of supplementary materials developed by Pearson for the Ninth Edition of Human Anatomy is more innovative and thorough than ever before—in print and on the Web—for you and your students alike.

For a complete guide to the student and instructor supplements that accompany the ninth edition, please see the Additional support for Students & Instructors section in the front matter of the book, on page 6.

I thank the whole Pearson team for their exquisite abilities in keeping me on track and organized throughout the revision process.

Leslie Hendon

Justin Shaffer

Biology Department

Chemical and Biological Engineering Department

University of Alabama at Birmingham

Colorado School of Mines

References Chakraborty, T. R., & Cooperstein, D. F. (2018). Exploring anatomy and physiology using iPad applications. Anat Sci Educ, 11(4), 336-345. doi:10.1002/ase.1747 Khot, Z., Quinlan, K., Norman, G. R., & Wainman, B. (2013). The relative effectiveness of computer-based and traditional resources for education in anatomy. Anat Sci Educ, 6(4), 211-215. doi:10.1002/ase.1355 Lewis, T. L., Burnett, B., Tunstall, R. G., & Abrahams, P. H. (2014). Complementing anatomy education using three-dimensional anatomy mobile software applications on tablet computers. Clin Anat, 27(3), 313-320. doi:10.1002/ca.22256 Lombardi, S. A., Hicks, R. E., Thompson, K. V., & Marbach-Ad, G. (2014). Are all hands-on activities equally effective? Effect of using plastic models, organ dissections, and virtual vi

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dissections on student learning and perceptions. Adv Physiol Educ, 38(1), 80-86. doi:10.1152/advan.00154.2012 Meyer, A. J., Stomski, N. J., Innes, S. I., & Armson, A. J. (2016). VARK learning preferences and mobile anatomy software application use in pre-clinical chiropractic students. Anat Sci Educ, 9(3), 247-254. doi:10.1002/ase.1555 Meyer, A. J., Stomski, N. J., Losco, C. D., & Armson, A. J. (2016). The influence of anatomy app use on chiropractic students' learning outcomes: a randomised controlled trial. Chiropr Man Therap, 24, 44. doi:10.1186/s12998-016-0125-8 Moro, C., Stromberga, Z., Raikos, A., & Stirling, A. (2017). The effectiveness of virtual and augmented reality in health sciences and medical anatomy. Anat Sci Educ, 10(6), 549-559. doi:10.1002/ase.1696 Preece, D., Williams, S. B., Lam, R., & Weller, R. (2013). "Let's Get Physical": Advantages of a physical model over 3D computer models and textbooks in learning imaging anatomy.

Anatomical Sciences Education, 6(4), 216-224. doi:10.1002/ase.1345 Pringle, Z., & Rea, P. M. (2018). Do Digital Technologies Enhance Anatomical Education?

Practice and Evidence of Scholarship of Teaching and Learning in Higher Education, 13(1), 2-27.

Raney, M. A. (2016). Dose- and time-dependent benefits of iPad technology in an undergraduate human anatomy course. Anat Sci Educ, 9(4), 367-377. doi:10.1002/ase.1581 Van Nuland, S. E., & Rogers, K. A. (2017). The skeletons in our closet: E-learning tools and what happens when one side does not fit all. Anat Sci Educ, 10(6), 570-588. doi:10.1002/ase.1708 Wainman, B., Wolak, L., Pukas, G., Zheng, E., & Norman, G. R. (2018). The superiority of threedimensional physical models to two-dimensional computer presentations in anatomy learning. Med Educ, 52(11), 1138-1146. doi:10.1111/medu.13683 Yammine, K., & Violato, C. (2015a). The effectiveness of physical models in teaching anatomy: a meta-analysis of comparative studies. Adv Health Sci Educ Theory Pract. doi:10.1007/s10459-015-9644-7 Yammine, K., & Violato, C. (2015b). A meta-analysis of the educational effectiveness of threedimensional visualization technologies in teaching anatomy. Anat Sci Educ, 8(6), 525-538. doi:10.1002/ase.1510

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CHAPTER

1

The Human Body: An Orientation

Lecture and Demonstration Objectives 1. Define anatomy and physiology, and describe the subdisciplines of anatomy.

2. Use the meaning of word roots to aid in understanding anatomical terminology.

3. Identify the levels of structural organization in the human body, and explain the interrelationships between each level.

4. List the organ systems of the body, and briefly state the functions.

5. Use metric units to quantify the dimensions of cells, tissues, and organs.

6. Define the anatomical position.

7. Use anatomical terminology to describe body directions, regions, and planes.

8. Describe the basic structures that humans share with other vertebrates.

9. Locate the major body cavities and their subdivisions.

10. Name the four quadrants of the abdomen, and identify the visceral organs located within each quadrant.

11. Explain how human tissue is prepared and examined for its microscopic structure.

12. Distinguish tissues viewed by light microscopy from those viewed by electron microscopy.

13. Describe the medical imaging techniques that are used to visualize structures inside the body.

Suggested Lecture Outline I. An Overview of Anatomy (pp. 34–38) A. Subdisciplines of Anatomy (p. 34) 1. Gross anatomy studies the human body structures with the naked eye, and dissection is the major technique. In systemic anatomy, organs with related functions are studied together. Professional schools study anatomy by the regional approach: All organs and structures in a single region are studied as a group. The third subdivision is surface anatomy, which studies the landmarks on the surface of the body that reveal underlying organs.

2. Microscopic anatomy (also called histology) uses the microscope to study specially prepared tissue slides. ..

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3. Developmental anatomy explores how body structures form, grow, and mature throughout their life span.

4. Embryology is the study of how the human body structures form and develop before birth.

B. The Hierarchy of Structural Organization (pp. 34–38, Figs. 1.1, 1.2) 1. Structural Organization (pp. 34–38) a. The levels of structural organization, from the simplest to the most complex, are as follows: chemical, cellular, tissue, organ, organ system, and the human organism itself. b. Organ systems are organs working closely together to accomplish a common function. The body’s organ systems are the integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic, immune, respiratory, digestive, urinary, and reproductive systems.

C. Scale: Length, Volume, and Weight (p. 38) 1. The metric system provides precision for measuring the dimensions of cells, tissues, and organs.

D. Anatomical Terminology (p. 38) 1. Ancient Greek and Latin provide the origins for most anatomical terms.

II. Gross Anatomy: An Introduction (pp. 38–45) A. Regional and Directional Terms (pp. 38–39, Fig. 1.3, Table 1.1) 1. Learning the anatomical position is essential because directional terminology used in anatomy refers to the body in this position.

2. Regional terms name the specific body areas.

3. The standardized terms of direction are: superior/inferior; anterior (ventral)/posterior (dorsal); medial/lateral; and superficial/deep.

B. Body Planes and Sections (pp. 39 and 42, Fig. 1.4) 1. The body and/or organs are cut into sections along a flat surface called a plane.

2. Planes are identified as sagittal, frontal (coronal), transverse (horizontal), and oblique.

3. Sagittal planes are midsagittal (median) planes or parasagittal planes.

C. The Human Body Plan (pp. 42–43, Fig. 1.6) 1. Tube-within-a-tube 2. Bilateral symmetry 3. Dorsal hollow nerve cord 4. Notochord and vertebrae 5. Segmentation 6. Pharyngeal pouches D. Body Cavities and Membranes (pp. 43–45, Figs. 1.6, 1.7) 1. The dorsal body cavity is subdivided into the cranial cavity and the vertebral cavity. a. The cranial cavity houses the brain. b. The vertebral cavity runs through the vertebral column and encloses the spinal cord.

2. Three serous cavities are all enclosed body cavities with no openings to the external surface of the body.

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a. The pericardial cavity surrounds the heart. b. The pleural cavity surrounds the lung. c. The peritoneal cavity surrounds the abdominopelvic viscera.

E. Abdominal Quadrants (p. 45, Fig. 1.8) 1. The abdomen is divided into four quadrants: the right upper quadrant, the left upper quadrant, the right lower quadrant, and the left lower quadrant.

F. Anatomical Variability (p. 45) 1. Anatomical structures do not always match the textbook descriptions.

III. Microscopic Anatomy: An Introduction (pp. 45–47, Fig. 1.9) A. Light and Electron Microscopy (pp. 45–46) 1. Microscopy is the examination of the fine structure of organs, tissues, and cells.

2. Specimens for LM or TEM must be fixed (preserved) and then cut into sections (slices) thin enough to transmit light or electrons.

B. Scanning Electron Microscopy (pp. 46–47) 1. Scanning electron microscopy provides three-dimensional pictures of whole, unsectioned surfaces.

C. Artifacts (p. 47) 1. Preserved tissue that has been exposed to many procedures can show minor distortions called artifacts.

IV. Clinical Anatomy: An Introduction to Medical Imaging Techniques (pp. 47–51, Figs. 1.10–1.14) A. X-Ray Imaging (pp. 47–48, Fig. 1.10) 1. Traditional x-ray images continue to play a major role in medical diagnoses involving bone and abnormal dense structures, such as a tumor.

B. Advanced X-Ray Techniques (pp. 48–49, Figs. 1.11, 1.12) 1. Computed tomography (CT) or computed axial tomography (CAT) produces improved x-ray images that are computer enhanced for clarity.

2. Mammography is an imaging technique that uses low-dose radiation to examine the breast for tumors.

3. Angiography is an imaging technique that utilizes a contrast medium injected into a blood vessel to produce clear images of blood vessels. Angiography is important for diagnosing diseases and disorders of blood vessels.

4. Digital subtraction angiography (DSA) provides an unobstructed view of small arteries. Images of vessels are taken before and after injection of the contrast medium.

Computer technology allows for the “before” image to be “subtracted,” yielding clear images of potential blockages in vessels to the heart or brain.

C. Positron emission tomography (PET) tracks radioisotopes in the body, locating areas of high energy consumption and high blood flow. (p. 49, Fig. 1.13) D. Sonography (ultrasound imaging) provides sonar images of developing fetuses and internal body structures, such as an enlarged liver. (p. 50, Fig. 1.14) E. Magnetic resonance imaging (MRI) subjects the body to strong magnetic fields and radio waves, producing high-contrast images of soft body parts. (pp. 50–51, Fig. 1.15) ..

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Lecture Hints 1. Discuss the terms anatomy and physiology. Describe how scientists use these terms and how the terms complement each other.

2. Explain the relationship of structure to function in the study of anatomy.

3. Describe advancements in each of the subdisciplines of anatomy. Offer examples of specific careers among the disciplines.

4. Distinguish systemic anatomy from regional anatomy. Certain professions use one or the other approach when studying the human body. Note that professional texts usually take a regional approach, whereas undergraduate studies usually take a systemic approach to anatomy.

5. Establish the significance of learning anatomical terminology at the beginning of the course. Students must understand that they are learning a “new language” and will be successful academically in anatomy when they master this language.

6. Teach students word origins (Greek and Latin roots) whenever relevant. Use terms with which they are familiar—for example: hand, manus, manual. Encourage online research of terms using reputable websites as well as the glossary and word root origins summary from the back cover of the text.

7. Point out that multiple terms exist for some anatomical structures (e.g., Eustachian tube, auditory tube, pharyngotympanic tube, otopharyngeal tube). Remind students that some anatomical terms are structural designations, whereas others are functional. Finally, explain that some terms are eponyms that denote the discoverer’s name (e.g., Bartholin’s gland and Circle of Willis).

8. Point out that an organ system is an artificial grouping of structures that works toward a common goal. Explain how organs and systems interact together to form the entire organism, the human body.

9. Caution students that there is a difference between the cardiovascular system and the circulatory system. Explain the distinctions and their relationship to the lymphatic system.

10. Explain to students how the terms superior/inferior, anterior/posterior, and dorsal/ventral refer to different body regions for humans and would be different for four-legged animals. Point out that more than one word can be used to correctly describe the position of a structure.

11. Stress to students that most body cavities are potential spaces filled with viscera, tissues, and fluids.

12. In addition to the dorsal and ventral body cavities, cite other cavities, such as the pleural cavity, abdominal cavity, pelvic cavity, and the pericardial cavity.

13. Contrast the types of images obtained with x-ray machines, CT scans, MRI scans, and ultrasonography. Show actual examples of x-ray films, if possible, and keep in mind the potential use of x-ray images to demonstrate anatomy in other chapters.

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Classroom Discussion Topics and Activities 1. Reinforce concepts of structure and function by asking students to explain the relationships between muscle and bone, the circulatory system and respiratory system, and the muscles and nerves.

2. Have students discuss the relative vulnerability of the organs in the dorsal and ventral body cavities by asking, “Why do you think a dog instinctively curls over and protects its abdomen when that body region is threatened by a blow or even during play?”

3. Ask students to write down 12 body parts that consist of three letters (e.g., eye, ear, leg).

Follow up with the anatomical term for each part (e.g., arm = brachium). Additionally, have students use the index in their text and simply search for three-letter words. This exercise will heighten their familiarity with the text.

4. Demonstrate preserved human specimens, if available. A simple statement, “This is a heart (or kidney or brain or bone),” is all that is necessary. Ask the class what characteristics the specimens have in common: Nerves? Blood? Tissues?

5. Stand in the anatomical position, and ask the students how that position differs from the “usual” standing position. Ask students to explain the importance of the anatomical position with regard to their studies.

6. Call out regional terms (e.g., buccal, femoral), and have the students (as a group) point out the named regions on their own bodies.

7. Ask students to describe the purpose of directional terms. Why are these terms used in pairs? Ask students to demonstrate their understanding: “My elbow is _______________ to my shoulder.” Get the students to act these out as a group, or choose a volunteer to demonstrate at the front of the classroom.

8. Place a chair in front of the class, and ask a volunteer to show how the chair would be cut along the sagittal, frontal, and transverse planes.

9. Use a dissectible model of a human torso to point out the dorsal and ventral body cavities and the main organs in each cavity.

10. Remove all the viscera from the ventral body cavity of a model of the human torso. Ask for volunteers or assign students to return the viscera to their proper anatomical locations.

As each organ is properly repositioned, have the rest of the students call out its name and identify its organ system.

11. Demonstrate plastinated sections of the human body, which are available for purchase.

Alternatively, project sections using PowerPoint images to be viewed by the entire class.

12. Thrust your fist into a partially inflated balloon to illustrate the two layers of the serous membrane.

13. Explain to the class how tissues are cut into thin sections for microscopic viewing. You can describe this in a general way, or you might obtain a microtome and demonstrate how a paraffin-embedded rat liver is sectioned. Remind students that their glass slides possess only a small, thin slice of an organ.

14. Obtain slides to show the types of stains used for light microscopy, such as hematoxylin and eosin, Sudan black B, and methylene blue.

15. Show the class transmission electron micrographs, scanning electron micrographs, and light micrographs. Have the students explain how to distinguish among these. ..

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16. Offer examples of medical conditions, and have the students explain which medical imaging technique they would use to diagnose that condition.

17. As a special assignment, have students work in groups to show how a potato (or other inexpensive item) looks different in different sections. Student groups could photograph their potato sections and make a PowerPoint or other presentation to send to the professor by e-mail.

Clinical Questions 1. A surgeon removed a section of tissue along a transverse plane for microscopic examination. What is this section called?

Answer: A cross-section.

2. Which medical imaging technique has been studied most extensively for its effects on human health?

Answer: The traditional x-ray technique because it has been used the longest. MRI and ultrasound are such new techniques that long-term studies of their effects have not yet been possible.

Art Resources Figure 1.1 Figure 1.2 Figure 1.3 Figure 1.4 Figure 1.5 Figure 1.6 Figure 1.7 Figure 1.8 Figure 1.9 Figure 1.10 Figure 1.11 Figure 1.12 Figure 1.13 Figure 1.14 Figure 1.15 Table 1.1

Focus Figure. Levels of Structural Organization.

The body’s organ systems and their major functions.

Anatomic position and regional terms.

Planes of the body with corresponding magnetic resonance imaging (MRI) scans.

Basic human body plan, indicated by structures shared among all vertebrates.

Dorsal and ventral body cavities and their subdivisions.

The serous cavities and their associated membranes.

Abdominal quadrants.

Cells viewed by three types of microscopy.

X-ray images.

Computed tomography (CT).

Digital subtraction angiography (DSA).

Positron emission tomography (PET).

Ultrasound image of a fetus in the uterus.

Magnetic resonance image (MRI).

Orientation and Directional Terms

Teaching with Art Figure 1.7a–d

The serous cavities.

Textbook p. 44

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Checklist of Key Points in the Figure • In each part, indicate that the visceral layer is in direct contact with the surface of an organ and that the parietal layer is in contact with the wall of the body cavity.

• Comment on the function of fluid in the cavities.

• Describe the relationship of the pericardium to the heart, the pleura to the lungs, and the peritoneum to the abdominal organs.

• Explain how the visceral peritoneum and parietal peritoneum form a framework of doublelayer folds called mesenteries.

Display Figure 25.1, Reproductive organs of the male, sagittal view.

• In (d), explain how mesenteries support abdominal organs.

Common Conceptual Difficulties Interpreting the Art • Explain the differences between mucous membranes and serous membranes.

• Explain why the pleural and pericardial cavities are “potential spaces.” Tell students that the art exaggerates the space between the membranes and that, in a healthy body, only a thin layer of fluid separates the two membranes.

• In (d), explain the difference between an intra-abdominal and retroperitoneal organ.

Display Figure 23.3, Focus on the peritoneum, to demonstrate how organs become retroperitoneal. Display Figure 24.2, Position of the kidneys abutting the posterior abdominal wall, for a detailed view of retroperitoneal organs.

Art Exercise To help students understand the continuity of the parietal and visceral peritoneum, ask students to trace a continuous line around the serous membrane in (d).

Critical Reasoning Pleurisy is an inflammation of the pleural layers characterized by the abnormal production of pleural fluid. Referring to Figures 1.6 and 1.7, ask students where they think the excess pleural fluid might collect.

Answer: The pleural fluid collects by gravity in the space between the diaphragm and the rib cage, called the costodiaphragmatic recess. Medical professionals can extract the excess fluid using a syringe.

Supplemental Course Materials Library Research Topics 1. Research the historical development of gross anatomy.

2. Research the historical development of the techniques of microscopy and histology.

3. Explore the modern-day definitions of life and death.

Suggested Readings Clemente, C. D. Anatomy: A Regional Atlas of the Human Body. 5th ed. Baltimore: Lippincott Williams & Wilkins, 2006. ..

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Lester, David S., and James L. Olds. “Biomedical imaging: 2001 and beyond.” The Anatomical Record 265 (2001): 35–36.

Moore, K. L., and Arthur F. Dalley, II. Clinically Oriented Anatomy. 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2009.

Morris, D. The Naked Ape: A Zoologist’s Study of the Human Animal. New York: Dell Publishing Co., 1999.

Raloff, Janet. “Breast screening tool finds many missed cancers.” Science News (Web edition: July 1, 2010).

Roach, Mary. Stiff: The Curious Lives of Human Cadavers. New York: W.W. Norton & Company, Inc., 2003.

Sivitz, Laura B. “Beyond imaging.” Science News 159 (1) (Jan. 2001): 12.

Answers to Textbook Questions Answers for multiple-choice and matching questions 1–11 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 12. In the anatomical position, the body stands erect, the arms hang at the sides, the palms face anteriorly, the thumbs point away from the trunk, and the feet are flat on the ground with toes forward. It is necessary to use this standard position because most directional terms refer to the body in this position, regardless of its actual position. (p. 38) 13. (a) The cardiovascular system pumps and transports blood. (b) The integumentary system covers the body’s external surface. (c) The testes are a part of both the endocrine system and the male reproductive system. (pp. 36–37) 14. (a) Bilateral symmetry means that the structures on the right half of the body are essentially mirror images of those on the left half. (b) Organs of the abdomen that are not bilaterally symmetrical include the stomach, spleen, intestines, liver, and gallbladder. (pp. 42 and 45) 15. (a) Only CT uses x-rays. (b) MRI uses magnetic fields and radio waves. (c) PET uses radioisotopes. (d) CT, PET, sonography, and MRI display body regions in sections; angiography, which is based on traditional x-ray images, does not use sections. (pp. 47–51) 16. (a) appendicular, (b) axial, (c) appendicular, (d) axial, (e) appendicular. (p. 39, Figure 1.3) 17. Light microscopy: Lower resolution and lower magnification allow viewing of structures at the tissue and cellular level, images are in color because light is used to illuminate tissues, and images are sectional views. Electron microscopy: Higher resolution and greater magnification allow viewing of cellular structures and structures within cells; images are in shades of gray because beams of electrons are used. Transmission electron microscopy: Tissue sections are stained with heavy metals. However, using scanning electron microscopy, images are whole unsectioned surfaces. (pp. 45–47) 18. Here are some examples of correct usage of directional terms: a. The cephalic region is superior to the cervical region. b. The cervical region is inferior to the oral region.

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c. The scapulae are dorsal to the breastbone. d. The pubic region is ventral to the gluteal region. e. The nose is medial to the ears. (Or, the nose is intermediate to the ears.) f. The eyes are lateral to the nose. g. The skeletal muscles are superficial to bones. h. The liver is deep to the skin. i. The knee is proximal to the ankle. j. The knee is distal to the femur. (p. 40) 19. The dorsal cavity is subdivided into the cranial cavity and the vertebral cavity.

The ventral cavity is subdivided into the thoracic cavity and the abdominopelvic cavity. (p. 43) 20. In general terms, the lady has hurt her buttock, neck, and wrist. (p. 39) 21. (a) Two serous cavities inside the thoracic cavity are the pleural cavity surrounding

the lungs and the pericardial cavity surrounding the heart. (b) The serous membranes lining these cavities are called pleura, serous pericardium, and peritoneum.

The outer wall of the cavity is known as the parietal serosa, and the inner layer that covers the visceral organs is known as the visceral serosa. (c) The serous cavities contain a thin layer of serous fluid that is produced by both serous membranes. This fluid allows the internal organs to easily move and change shape by reducing friction across the cavity walls. (pp. 43–45).

Critical Reasoning and Clinical Applications Questions 1. Angiography is a procedure in which a contrast medium is injected into blood vessels so that their images can be captured. In this case, images of blood vessels in Samantha’s brain could be recorded using conventional radiography, a CT scan, or an MRI. (pp. 49–50) 2. Using his knowledge of anatomical terminology, Ross would break down the

word ‘hepatitis’ to explain it in layman’s terms. The word hepatitis, made up of ‘hepata’ (liver) and ‘itis’ (inflammation), indicates a viral inflammation of the liver. (p. 38) 3. The inguinal region is the groin, or the most inferior part of the anterior abdomen, just above the thigh. The lumbar region is the loin or back of the abdomen. The perineum is the region around the anus and external genitalia. (p. 39) 4. A sagittal plane shows the division of the body into right and left parts. A coronal

plane shows the division of the body into anterior and posterior parts, while a transverse plane shows the division of the body into superior and inferior parts. (pp. 40–41) 5. The spinal column and spine refer to the same thing (i.e., the bony vertebral column).

The spinal cord, by contrast, is the nerve cord that runs through the vertebral canal.

6. (1) The meanings of the following roots: super- = above/upon; contra- = against; para- = next to, beside, near; ante- = preceding, before; mamm- = breasts; epi- = over, above, on top of; peri- = around; -graph = instrument for recording data or writing; trans- = across, through.

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(2) Examples of terms used in Chapter 1 derived from each root listed: superior or superficial, contralateral, parasagittal, anterior, mammary, epigastric, perineum, micrograph, and transverse.

(3) Definitions of words based on the meaning of the root word: superior = above the point of reference; contralateral = the other side; parasagittal = adjacent to the midsagittal plane; anterior = in front of the point of reference; mammary = pertaining to the breast; epigastric = above the gastric region; perineum = around the anus; micrograph = picture of a small structure; transverse = a plane crossing the body from side to side. (p. 40)

Interpreting Medical Images Questions Answers to Interpreting Medical Images questions are provided in the Instructor Resources area of Mastering A&P. Figure 1.10: (a) The brightness of a structure on an x-ray film indicates the density of the object.

Denser organs—bones and the heart—absorb more x-rays and and produce a white, unexposed area on the x-ray film. Organs that are less dense, such as the air-filled lungs, are easily penetrated by x-rays and produce a dark, exposed area on the x-ray image. (b) First, remember that looking at an image is like looking at a person—meaning that the left side of the image is actually the person's right side. Beginning with the left side of the image (right side of the body) and moving clockwise, the regions of the colon shown in this radiograph are the ascending colon; transverse colon across the top of the image; descending colon beginning in the upper right corner of the image; and sigmoid colon, the dark, S-shaped region in the lower center of the image.

Figure 1.13: PET uses radioactively tagged water or sugar molecules to identify areas of high metabolic activity. The cells in the brain are highly active; therefore, they pick up large amounts of tagged molecules, and the brain “lights up” on the PET scan. Notice that the heart and bladder are also quite opaque because both are metabolically active organs.

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 1: The Human Body: An Orientation To the Student The concepts in this chapter will orient you to the human body and introduce you to the science of anatomy. Mastering the vocabulary in this chapter will help you to understand basic anatomical relationships and help you to communicate effectively with anatomists and those working in the healthcare professions. Making use of the online resource MyA&P.com will be of great benefit to your studying.

Step 1: Learn the organ systems of the human body. __ Name the 12 basic organ systems. __ List several examples of organs in each system. __ Identify which organ systems are located in the head, thorax, abdominal cavity, and lower extremity. __ Do you perceive one system as more important than another? Why or why not?

Step 2: Master the professional vocabulary of the science of anatomy. __ Describe how a man sitting with his hands on his lap moves his body into anatomical position. __ Using the regional terms and names of specific body areas in Figure 1.3, write comparative statements for the following directional terms: superior/inferior, anterior/posterior, ventral/dorsal, medial/lateral, and proximal/distal. (Example: “The phalanges are distal to the shoulders.”) __ Demonstrate the difference between frontal (coronal), transverse, and sagittal planes using your own body. __ Make vocabulary flash cards to help you learn the language of anatomy. __ Make copies of text figures without labels for review and test preparation. (You can also use resources in MyA&P.com for your textbook.)

Note: Your instructor can print any illustration in the text without labels.

Step 3: Differentiate the major and minor body cavities. __ Name two major body cavities. __ List the subdivisions of each cavity. __ Name the organs associated with each subdivision. __ Referring to Figure 1.6, identify the distinctive structure that separates the abdominal cavity from the thoracic cavity. __ Relate serous membranes and fluids to the subdivisions of the ventral body cavity.

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CHAPTER

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Cells: The Living Units

Lecture and Demonstration Objectives 1. Define a cell, its basic activities, and its three major regions.

2. Describe the composition and basic functions of the plasma membrane.

3. Explain the different processes used to move molecules across the plasma membrane.

4. Describe the structure and cellular activity of each organelle: ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, mitochondria, peroxisomes, cytoskeleton, centrosome, and centrioles.

5. Explain the structure of glycosomes and lipid droplets.

6. Describe the role of each of the three parts of the nucleus in the control of cellular activities: the nuclear envelope, the nucleolus, and chromatin.

7. List the phases of the cell life cycle, and describe a key event of each phase.

8. Name specific cell types, and relate their overall shape to their special functions.

9. Compare theories of cell differentiation and aging.

Suggested Lecture Outline I. Overview of Cells (pp. 55–56, Fig. 2.1) A. Revolutionary discoveries in the 1800s overturned the theory of spontaneous generation.

Scientists affirm that organisms are composed of cells that arise from other cells. (p. 55) B. The cell is the basic structural and functional unit of all living things. (pp. 55–56) 1. Major cellular regions are the plasma membrane, cytoplasm, and nucleus.

2. Most cell types contain each of the requisite organelles, but in differing abundances based on the cell’s type and its function.

3. Each organelle functions like a specific division of a manufacturing plant.

II. The Plasma Membrane (pp. 56–60, Figs. 2.2–2.5) A. Structure (p. 58, Fig. 2.2) 1. Double layer, or bilayer, of lipid molecules (phospholipids, cholesterol, and glycolipids) with protein molecules dispersed within it.

B. Functions (pp. 58–59, Fig. 2.2) 1. Separates two major fluid compartments: the intercellular fluid within the cells, and the extracellular fluid, which lies outside and between cells.

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2. Some membrane proteins act as receptors and are part of the body’s cellular communication system.

3. The plasma membrane controls which substances can enter or leave the cell.

C. Membrane Transport (pp. 59–60, Figs. 2.3, 2.4, 2.5) 1. Small uncharged molecules pass through the lipid bilayer by diffusion.

2. Osmosis is the diffusion of water molecules across a selectively permeable membrane.

3. Facilitated diffusion is the movement of molecules down their concentration gradient, diffusing through the plasma membrane by moving through specific integral proteins.

4. Moving molecules across the plasma membrane against their concentration gradient is an energy-requiring process called active transport.

5. Two types of vesicular transport, endocytosis and exocytosis, move the largest macro-molecules.

6. Three types of endocytosis occur in cells: phagocytosis, pinocytosis, and receptor-mediated endocytosis. a. Hormones, low-density lipoproteins (LDLs), viruses, and some toxins enter cells by receptor-mediated endocytosis.

7. Exocytosis is the process by which substances move from the cytoplasm to the outside of a cell.

III. The Cytoplasm (pp. 60–66, Figs. 2.6–2.12) A. Cytosol (p. 60) 1. The three major elements of the cytoplasm are the cytosol, organelles, and inclusions.

2. Cytosol is the jellylike fluid that suspends cytoplasmic elements.

B. Cytoplasmic organelles (pp. 61–65, Figs. 2.6–2.12, Table 2.1) 1. Cytoplasmic organelles perform different cellular survival functions and compartmentalize the cell’s biochemical reactions.

2. Ribosomes are the sites of protein synthesis.

3. Endoplasmic reticulum makes proteins (rough ER) and is the site of lipid and steroid synthesis (smooth ER).

4. Golgi apparatus packages and modifies proteins.

5. Mitochondria synthesize ATP. 6. Lysosomes are the sites of intracellular digestion.

7. Peroxisomes detoxify toxic substances.

8. Cytoskeleton supports cellular structures.

9. Centrioles act in forming cilia and flagella and organize microtubule networks during mitosis.

C. Cytoplasmic inclusions (pp. 65–66) 1. Inclusions are temporary structures in cells; examples are food-storage units for fats and sugars as well as pigments. (pp. 65–66)

IV. The Nucleus (pp. 66–69, Figs. 2.13–2.15) A. The nucleus is the control center of the cell; it contains the DNA that directs the cell’s activities by providing the instructions for protein synthesis.

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B. Nuclear Envelope (p. 66, Fig. 2.13) 1. The nuclear envelope surrounds the nucleus and consists of two parallel membranes separated by a fluid-filled space.

C. Nucleolus (pp. 66–67) 1. Nucleoli contain parts of several chromosomes and assist in assembling ribosomal subunits.

D. Chromatin and Chromosomes (pp. 67–69, Figs. 2.14, 2.15) 1. Chromatin is composed of DNA and histone proteins located in the nucleus.

2. The DNA molecule is a double helix made up of four types of nucleotides with bases of adenine, thymine, guanine, and cytosine.

V. The Cell Life Cycle (pp. 69–72, Figs. 2.16, 2.17) A. Interphase (p. 69, Figure 2.16) 1. The two major divisions of the cell cycle are interphase and cell division (mitotic phase). Cytokinesis occurs at the end of the M (mitotic) phase of the cell life cycle.

2. Interphase is divided into G1, S, and G2 subphases. DNA replication occurrs during the S subphase.

B. Cell Division (pp. 69–72, Figure 2.17) 1. During G1 and G2 of interphase, “checkpoints” evaluate cellular activity. The G1 checkpoint assesses cell size, and the G2/M checkpoint verifies the accuracy of replication.

2. Nuclear material divides during mitosis.

3. During cytokinesis, an entire cell is divided into two daughter cells.

VI. Developmental Aspects of Cells (pp. 72–74, Fig. 2.18) A. Cell Differentiation (pp. 72–73, Fig. 2.18) 1. Cell differentiation is the development of specific and distinctive features among the cell types in human body cells.

B. Aging (pp. 73–74) 1. Evidence supports the theory that aging occurs because mitochondria are damaged by free radicals and/or genetically influenced processes.

Lecture Hints 1. Explain why the cell in Figure 2.1 is described as a “generalized” cell. Emphasize that many body cells have a different structure, and relate shape to function. (Example: Mature red blood cells are anucleate, and skeletal muscle cells are multinucleate. RBCs are biconcave discs that lack organelles and are packed with hemoglobin for oxygen transport.)

2. Display slides of electron micrographs to augment text diagrams. Comment on the preparation of animal tissues for microscopy and on different types of microscopes.

3. Relate the function of the plasma membrane to its location at the interface between the cell’s interior and exterior.

4. Describe the structure and functions of integral and peripheral proteins.

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5. Explain diffusion and osmosis. Comment on how diffusion and osmosis differ from active transport mechanisms such as exocytosis, endocytosis, and phagocytosis.

6. Describe the roles of v-SNARES and t-SNARES in exocytosis. Note that SNARE is an acronym for a group of proteins known as “soluble NSF attachment receptors.”

7. Explain the characteristics and content of cytoplasm, and distinguish it from cytosol.

8. Discuss the specific roles of cytoplasmic organelles and inclusions.

9. Present a summary list of cellular organelles organized as membranous, microtubular, or “other,” and briefly comment on the functions of each organelle.

10. Explain the role of mitochondria as the source of most cellular energy. Refer to Figure 2.10.

11. Relate a molecule of glucose (food energy) to ATP production.

12. Using specific cellular examples, comment on why some cells have larger numbers of mitochondria and some have fewer mitochondria.

13. Discuss protein synthesis within cells.

14. Correlate the role of the nucleus as the source of information for protein synthesis with the ribosome as the site of protein synthesis and the Golgi apparatus as the site of packaging and delivery of proteins within cells.

15. Explain why the rough ER is considered the cell’s “membrane factory” by tracing the flow of membrane components from the rough ER to the plasma membrane.

16. List components of the cytoskeleton.

17. Explain how the various elements of the cell’s skeleton differ from each other in structure and function.

18. Discuss the role of the nucleus as the control center of the cell.

19. Explain the importance of DNA, and describe the design of the double helix. Tell students they will not confuse complementary base pairing if they simply remember “A-T” as the only word possible from the base symbols, G, C, A, and T. 20. Describe the relationship of the nuclear envelope to rough ER. 21. Explain differences between chromatin and chromosomes.

22. Describe the structures and functions of the nucleus and nucleolus. Stress that the two are different entities within the cell.

23. Introduce the concept of cellular diversity by relating the shape of a cell to its function.

Figure 2.18 is excellent for this concept.

24. Emphasize the cell cycle as a continuous process using the stages as discrete events.

25. Contrast cellular changes during interphase with changes during mitosis.

26. Describe the functions of “checkpoints” during interphase of the cell cycle.

27. Ask students why telophase is the reverse of prophase.

28. Explain cytokinesis, and clearly distinguish it from mitosis.

29. Point out that mitosis is possible without cytokinesis, using multinucleated skeletal muscle cells as an example.

30. Make sure students can distinguish genes, chromatin, chromosomes, DNA, and proteins.

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31. Discuss the free-radical and mitochondrial theories of aging in relation to environmental pollution and the current enthusiasm for ingesting antioxidants such as vitamins C and E. 32. Discuss telomeres and telomerase in reference to the genetic theory of aging.

33. Distinguish apoptosis from senescence.

Classroom Discussion Topics and Activities 1. Organize students in groups of three to model the plasma membrane with Plasticine or Play-doh. Using Figure 2.2, p. 56, instruct students to include phospholipids, cholesterol, glycocalyx, and one membrane protein. Then have brief group presentations covering the structure and functions of the chosen proteins.

2. Illustrate a cell by using a hypothetical Jell-O fruit salad. The Jell-O is the cytosol, an orange is the nucleus, and nuts, raisins, and other fruits are the organelles.

3. Ask students to name common examples of diffusion, osmosis, and active transport.

4. Use a model of an animal cell to demonstrate the various organelles and other cell features.

5. Instruct students to list all parts of a generalized cell that are involved in the following functions: respiration, digestion, excretion, transportation, reproduction, food acquirement, energy production, protein formation, and internal support.

6. Instruct the students to construct a chart that lists the membrane-bound organelles in one column and, in another column, the organelles that are not membrane bound.

7. Use a Slinky to demonstrate the helical nature of DNA. Demonstrate the relationship between chromatin and the chromosome states by stretching or tightly coiling the Slinky.

8. Beginning with a typical diploid human body cell containing 46 chromosomes, have students identify the number of chromosomes and chromatids present in each stage of mitosis.

9. Use models of chromosomes with detachable chromatids to illustrate mitotic phases.

(Make simple models using strands of colored yarn with sewn-on snaps or colored pipe cleaners.)

10. Assign the following questions to be answered at the next class meeting: a. Why is damage to the heart or brain more damaging than injury to the liver? b. Why is precise division of the chromosomes during metaphase of mitosis so important? c. Is mitosis without cytokinesis possible? What would be the result?

11. Discuss why certain body cells (e.g., muscle and nerve cells) “lost” their ability to divide.

12. Ask students why they survive even though they lose billions of cells daily.

13. Ask students to consider possibilities of growing organs from “scratch.” What ethical issues of tissue engineering and regenerative medicine are involved?

14. Pique students’ interest by discussing topics such as the cell biology of cancer or theories on aging.

15. Describe telomeres as “pencil erasers”; once the “eraser” is gone, the cell undergoes senescence.

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Clinical Questions 1. A patient receiving treatment for testicular cancer was told that the chemotherapy drug he received inhibits the division of cancer cells. What could the drug be, and how would it stop cell division?

Answer: One chemotherapy drug considered in this chapter, vinblastine, inhibits the formation of microtubules and mitotic spindles required for cell division. Because cancer cells divide rapidly, the drug will preferentially affect these cells. Unfortunately, normal cells that divide rapidly will also be affected.

2. A small boy received a cut on his arm, and his mother applied hydrogen peroxide to the wound. The wound bubbled! Why? Answer: The hydrogen peroxide was degraded to water and oxygen (which bubbled off) by the action of the intracellular enzymes in peroxisomes. (Bacteria in the cut produce a similar enzyme.)

Art Resources Figure 2.1 Figure 2.2 Figure 2.3 Figure 2.4 Figure 2.5 Figure 2.6 Figure 2.7 Figure 2.8 Figure 2.9 Figure 2.10 Figure 2.11 Figure 2.12 Figure 2.13 Figure 2.14 Figure 2.15 Figure 2.16 Figure 2.17 Figure 2.18 Table 2.1

Structure of a generalized cell.

The plasma membrane according to the fluid mosaic model.

Membrane transport mechanisms.

The three types of endocytosis.

Exocytosis.

The endoplasmic reticulum (ER) and ribosomes.

Golgi apparatus.

The sequence of events from protein synthesis on the rough ER to the final distribution of these proteins.

Electron micrograph of a cell containing lysosomes (27,000X), artificially colored.

Mitochondria.

Cytoskeletal elements support the cell and help to generate movement.

Centrosome and centrioles.

The nucleus.

Molecular structure of DNA. Chromatin and chromosome structure.

The cell cycle.

Focus Figure: Focus on Mitosis.

Cellular diversity.

Parts of the Cell: Structure and Function

Teaching with Art Figure 2.2 Figure 2.4 Figure 2.5

The plasma membrane.

The three types of endocytosis.

Exocytosis.

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Checklist of Key Points in the Figure • Explain the “fluid” nature of the fluid mosaic model.

• Explain why the fluid mosaic model is a “mosaic.”

• Define intracellular fluid and extracellular fluid.

• Correlate Figures 2.2–2.5 to differentiate bulk-transport concepts, exocytosis, and endocytosis. Students often do not understand the important point that endocytosis involves taking in the dissolved solutes in the fluid, not just the solvent itself.

• Explain the terms cell-eating and cell-drinking.

• Describe the difference between nonselective pinocytosis and highly selective receptor-mediated endocytosis.

• Illustrate the importance of phagocytosis using white blood cells.

• Illustrate exocytosis with the production of salty protein-containing solution by cells in tear glands when weeping occurs.

Common Conceptual Difficulties Interpreting the Art • Remind students that Figure 2.2 focuses on the molecular level.

• Cellular components are recycled and reused.

• Energy is required. Where does it come from?

• Point out the relationship between the plasma membrane and vesicle formation during endocytosis and exocytosis.

• Point out that because the membrane is “highly selective” in receptor-mediated endocytosis, this does not mean harmful substances such as toxins and viruses are kept out of the cell.

Art Exercise Using Figure 2.4 for reference, instruct students to represent phagocytosis with a simple drawing. Follow a highlighted segment of the plasma membrane to its incorporation into a phagosome. Add lysosomes to the drawing. Ask students where the highlighted membrane finally ends up. A similar demonstration is possible using Figure 2.4 with an overlay and colored marker.

Critical Reasoning Ask students why lymph nodes become swollen and tender when there is an infection in the body.

Answer: Lymphocytes are white blood cells that fight infections in the body. A swollen node means a proliferation of lymphocytes and is evidence of the body’s fight against infection.

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Supplemental Course Materials Library Research Topics 1. Can protein molecules move within the cell membrane? What research supports your findings?

2. Receptor-mediated endocytosis is a highly selective mechanism to ingest molecules.

How can it be used to kill cancer cells?

3. Do chemical carcinogens cause all cancers? What other substances can cause cancer?

4. Review the evidence for and against the theory that mitochondria evolved from bacteria that came to live within primitive eukaryotic cells.

5. Read about the newest research on aging.

6. Research current use of tissue and organ engineering and regenerative medicine.

Suggested Readings Choi, Charles Q. “Organelle Stimulated on Microchip for First Time.” Scientific American (July 31, 2009).

Cormack, D. H. Ham’s Histology. 9th ed. Philadelphia: J. B. Lippincott, 1998.

Finkel, Elizabeth. “The Mitochondrion: Is It Central to Apoptosis?” Science 292 (5516) (April 27, 2001): 624–626.

Galef, Julia. “You Say Embryo, I Say Parthenone: Stem cells from unfertilized eggs may be too tightly regulated.” Scientific American (November 4, 2011). *NOTE: There is a $7.95 charge for downloading this issue of Scientific American.

Graham, Sarah. “Mouse Research Bolsters Controversial Theory of Aging.” Scientific American (May 6, 2005).

Hayflick, L. How and Why We Age. New York: Ballantine Books, 1996.

Hentze, Matthias W. “Believe It or Not—Translation in the Nucleus.” Science 293 (5532) (August 10, 2001): 1058–1059.

Hunot, Stephane, and Richard A. Flavell. “Death of a Monopoly?” Science 292 (5518) (May 2001): 865–866.

Kageyama, Yusuke, Zhongyan Zhang, and Ricarod Roda. “Mitochondrial Division Ensures the Survival of Postmitotic Neurons by Suppressing Oxidative Damage.” Journal of Cell Biology (197) (May 7, 2012): 535–551.

Kaiser, Jocelyn. “Conquering Cancer by Thwarting Tumor’s Immune Shield.” Science NOW (June 2, 2012).

Sinclair, D., and L. Guarente. “Unlocking the Secrets of Longevity Genes.” Scientific American (February 20, 2006).

Sprong, H., et al. “How Proteins Move Lipids and Lipids Move Proteins.” Nature Reviews: Molecular Cell Biology 2 (July 2001): 504–513.

Wasmeier, Christina, and Alistair N. Hume. “Melanosomes at a Glance.” Journal of Cell Science 121 (24) (2008).

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Answers to Textbook Questions Answers for multiple-choice and matching questions 1–12 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 13. Glycoproteins and glycolipids present on the external surface of the plasma membrane form the glycocalyx. The glycocalyx assists cells in recognizing and binding with each other when they come together. (p. 58) 14. A nucleolus is a dark-staining structure within a nucleus, much smaller than the nucleus itself. Whereas the nucleus contains many chromosomes, the nucleolus consists of parts of several of these chromosomes that work together to manufacture the basic subunits of ribosomes. (pp. 66–67) 15. It is believed that mitochondria arose from bacteria, which invaded the ancient ancestors of animal and plant cells. The reason behind this belief is that mitochondria are very similar to a group of bacteria known as the purple bacteria phylum. (p. 64) 16. Inside a cell’s nucleus, the double helix of DNA is packed with protein molecules and is coiled in increasingly thick and structurally complex strands. Each two turns of the DNA helix is packed with eight disc-shaped protein molecules called histones (a cluster, which together is called a nucleosome). Further coiling of the nucleosomes form a tight helical fiber. Known as condensed chromatin, these thick fibers are further packed and later form the shape of chromosomes. This is how DNA is packed inside the nucleus of a cell. (p. 68. Fig. 2.15) 17. Organelles that participate in the specified cell functions are as follows (pp. 61–65): a. Ribosomes are the sites of protein synthesis. b. Endoplasmic reticulum makes proteins (rough ER) and is the site of lipid and steroid synthesis (smooth ER). c. Golgi apparatus packages and modifies proteins. d. Mitochondria synthesize ATP. e. Lysosomes are the sites of intracellular digestion. f. Peroxisomes detoxify toxic substances. g. Cytoskeleton supports cellular structures. h. Centrioles act in forming cilia and flagella and organize microtubule networks during mitosis.

18. (a) Centrioles - In cytoplasm - Organize a microtubule network during mitosis to form the spindle and asters; form the bases of cilia and flagella (b) Microtubules - In cytoplasm - Support the cell and give it shape; involved in intracellular and cellular movements; form centrioles (c) Nuclear envelope - On the nucleus - Separates the nucleoplasm from the cytoplasm and regulates passage of substances to and from the nucleus (d) Chromatin - In nucleus - they are formed by DNA, which constitutes the genetic information. (pp. 57).

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Critical Reasoning and Clinical Applications Questions 1. Telomeres are the repetitive DNA stretches that cap the ends of chromosomes and protect them from deterioration. Additionally, they also regulate the maximum number of times a cell can divide. Telomeres become shorter each time DNA replication occurs. After reaching a certain minimum length, they send cells a signal to stop dividing. Cancer cells have an enzyme, telomerase, which can inhibit telomeres from shortening, causing uncontrolled cell division. (pp. 73–74) 2. Hyperplasia means the cells have proliferated into a thick layer of structurally normal cells; dysplasia means that a few of the cells show abnormal size or shape; lack of neoplasia means that the cells were not proliferating uncontrollably (no tumor or cancer was evident). Therefore, Kareem did not have cancer of the mouth. (See “Related Clinical Terms,” p. 74.)

3. G1, S, G2, and M are all phases of the cell life cycle (Figure 2.16). G1 is a growth phase followed by S, the phase in which DNA is replicated in preparation for cell division.

G2 is when the final preparations for cell division are made, and M is the mitotic phase leading to division of the nucleus. Clearly, the tumor-suppressor genes are halting various phases of the cell life cycle in precancer cells that would otherwise multiply uncontrollably. (p. 69) 4. Lysosomes, which degrade unwanted substances and phagocytize pathogenic organisms, are found abundantly in phagocytic cells. They contain enzymes that help to breakdown such unwanted particles. Any defect in these enzymes would lead to an abnormal accumulation of the particles in the tissues. (p. 63) 5. Receptor-mediated endocytosis. Low-density lipoprotein (LDL) molecules are transported into cells by binding to their own receptors in protein-coated pits on the plasma membrane. Once LDL receptors are saturated, a part of the plasma membrane (invagination) pinches off to form an internal vesicle. When human rhinovirus 2 binds to these LDL receptor proteins, it enters the cell using the same mechanism because the LDL receptors cannot distinguish which ligand is bound to them. (pp. 59–60 and Fig. 2.4c) 6. Vinblastine inhibits the formation of microtubules and mitotic spindles required for cell division. Because cancer cells divide rapidly, the drug will preferentially affect these cells. Unfortunately, normal cells that divide rapidly will also be affected. Without microtubules, the mitotic spindle cannot form, and without the mitotic spindle, mitosis and cell division are impossible. Refer to Figure 2.17. (pp. 69–71) 7. (a) interphase means “between” phases (b) prophase means “before” phase (i.e. start of mitosis) (c) metaphase means “after” phase (i.e. after prophase of mitosis) (d) anaphase means “apart” phase (i.e. pulling chromatids apart in mitosis) (e) telophase means “end” phase (i.e. end of mitosis) (f) cytokinesis means “cell” “movement” (i.e. splitting one cell into two after mitosis)

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 2: Cells: The Living Units To the Student The cell is the structural and functional unit of all living things. The human body has 50 to 60 trillion cells consisting of some 200 different types that are amazingly diverse in size, shape, and function. Mastery of basic knowledge of the cell leads to fuller understanding and comprehension of tissues, organs, organ systems, and ultimately the human organism.

Step 1: Learn basic concepts about cells. __ Define cell. __ List three major regions of a “generalized” animal cell. __ Indicate the general function of each of the three regions of an animal cell.

Step 2: Correlate plasma membrane structure and function. __ Describe the composition of the plasma membrane. __ Describe how the composition of the plasma membrane relates to the movement of substances into and out of the cell. __ Differentiate passive forms of membrane transport from active transport mechanisms. __ Describe transport processes relative to energy source, substances transported, direction of movement, and mechanisms.

Step 3: Summarize basic structural and functional relationships about the cytoplasm. __ Describe the composition of cytosol. __ List 10 organelles, including vaults and inclusions, found in the cytosol. __ Define inclusions, and list several kinds. __ Explain the structure and function of mitochondria. __ Explain the structure, function, and interrelationships of ribosomes, the endoplasmic reticulum, and the Golgi apparatus. __ Compare the functions of lysosomes and peroxisomes. __ Name and describe the structure and function of cytoskeletal elements.

Step 4: Summarize basic structural and functional relationships about the nucleus. __ Describe the structure and function of the nuclear envelope. __ Explain the structure and function of chromatin. __ Explain the structure and function of a nucleolus.

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Step 5: Understand events of cell growth and reproduction. __ List the phases of the cell cycle. __ Describe the specific events of each phase of the cell cycle. __ Explain the significance of interphase.

Step 6: Recognize cell diversity. __ List all the specific cell types described in this chapter. __ Relate the shapes of different cell types to the functions of the cells.

Step 7: Understand the developmental aspect of cells. __ Describe how cell differentiation leads to structural and functional variation. __ Describe how cells differ in function based on specific requirements. __ Explain the current theories of aging.

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CHAPTER

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Basic Embryology

Lecture and Demonstration Objectives 1. List the practical and clinical reasons for studying embryology.

2. Distinguish the embryonic period from the fetal period of development.

3. Sketch the basic structural plan of the adult body, which is established during the embryonic period.

4. Describe the earliest stage of development, from zygote to blastocyst (week 1).

5. Identify the structures that develop as the inner cell mass differentiates into a two-layered disc.

6. Explain gastrulation and the formation of the three germ layers (week 3).

7. Discuss how the body folds from a flat disc into its three-dimensional tubular shape (week 4).

8. In a cross-section of a week 4 embryo, identify the outer tube, the inner tube, and the coelom.

9. List the main derivatives of ectoderm and endoderm.

10. In a cross-section of a week 4 embryo, identify the five regions of mesoderm and list the main derivatives of each region.

11. Describe the main events of the second month of development.

12. List the major events of fetal development.

Suggested Lecture Outline I. Stages of Prenatal Development (pp. 78–79, Fig. 3.1) A. Embryology is the prenatal study of the origin and development of an individual.

B. The two stages of prenatal development are the embryonic period and the fetal period.

II. The Basic Body Plan (pp. 79–80, Fig. 3.2) A. The tube-within-a-tube basic plan is evident by month 2.

B. The basic structures present are precursors for the skin, trunk muscles, vertebral column, spinal cord and brain, digestive and respiratory tubes, serous cavities, heart, kidneys, gonads, and limbs.

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III. The Embryonic Period (pp. 80–91, Figs. 3.3–3.11) A. Week 1: From Zygote to Blastocyst (pp. 80–82, Fig. 3.3) 1. Week 1 is characterized by fertilization, a four-celled stage, the morula, and implantation of the blastocyst.

B. Week 2: The Two-Layered Embryo (p. 82, Fig. 3.4) 1. In week 2, the two-layered embryo completes implantation and forms the bilaminar embryonic; the amnion and yolk sac also form.

C. Week 3: The Three-Layered Embryo (pp. 82–86, Figs. 3.5–3.7) 1. During week 3, the embryo becomes a trilaminar disc.

2. The endoderm, ectoderm, and mesoderm are established.

3. The primitive streak and notochord form.

4. Neurulation begins.

5. The mesoderm begins to differentiate and divides into three regions: somites, intermediate mesoderm, and lateral plate mesoderm.

D. Week 4: The Body Takes Shape (pp. 86–88, Figs. 3.8–3.10) 1. The flat embryo folds into a tadpole shape in week 4, achieving the basic plan of a tube in a tube; limb buds appear.

E. Weeks 5-8: The Second Month of Embryonic Development (pp. 88–90, Fig. 3.11) 1. During weeks 5–8, the major adult structures are derived from the ectoderm, endoderm, and mesoderm.

IV. The Fetal Period (pp. 91–92, Table 3.1) A. Weeks 9 through 38 are a time of maturation and rapid growth of structures that were established during the embryonic period.

B. During the first half of the fetal period, cells continue differentiating into specific cell types.

Lecture Hints 1. Distinguish between the embryonic period and the fetal period of development.

2. Describe the structures of the “inner tube” and structures of the “outer tube.”

3. Define zygote, morula, and blastocyst. Point out that the blastocyst is actually embedded in the endometrial wall.

4. Explain the process of fertilization and implantation.

5. Stress that early cell divisions of the fertilized egg increase the total number of cells but not the overall size of the embryo because cells do not have time to grow between cell divisions.

6. Describe the trophoblast and its role in forming the placenta.

7. Contrast the functions and importance of the yolk sac and amniotic sac. Emphasize structural relationships of the embryonic/fetal membranes because students often do not understand the anatomical orientation.

8. Distinguish between monozygotic (identical) and dizygotic (fraternal) twins. Add a touch of humor by referring to twins as “wombmates.”

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9. Convey to students that the events occurring at the primitive streak form the three primitive germ layers.

10. Correlate the basic adult body plan to the three embryonic germ layers.

11. Give examples of major derivatives of the embryonic germ layers.

12. Emphasize that invaginating mesodermal cells are pinched off into the rod, forming the notochord.

13. Discuss the process of neurulation.

14. Emphasize that the role the notochord plays in forming the neural tube is an example of induction: the influence one group of cells has on the development of other cells.

15. Discuss differentiation of the mesoderm. Encourage students to learn the derivatives of endoderm and ectoderm first and then learn mesodermal derivatives. Stress that learning derivatives of germ layers through “real world” examples will help students remember rather than memorize. Therefore, learning these derivatives will help them understand regional anatomy in later chapters and in professional school.

16. Using Figures 1.5a–c, point out similarities and differences in the basic body plan between animals and humans.

17. Explain programmed cell death (apoptosis) as a natural part of development.

18. Display Figure 25.11 (Internal organs of the female reproductive system, midsagittal section) and Figure 25.27 (Stages of labor) for uterine size comparison. Point out that a nonpregnant human uterus is approximately 3”  2”  1” and increases in size about tenfold during pregnancy.

19. Discuss the structure of the placenta, and discuss which substances readily pass from maternal to fetal blood (e.g., infectious agents, drugs, alcohol, and antibodies).

20. Summarize the human life cycle using the developmental stages of fertilization, cleavage, gastrulation, formation of tissues, organogenesis, and growth, including tissue specialization.

21. Ask students to cite examples of “milestones” in fetal development. (Table 3.1) 22. Ask students to think about which specific birth defects may occur at different embryonic and fetal stages.

Classroom Discussion Topics and Activities 1. Use embryonic fetal–development models to show cleavage, the blastula, and other stages of development.

2. Show preserved specimens of human embryos or fetuses in various stages of development to illustrate the changes that occur during gestation.

3. Exhibit preserved animal fetuses obtained from a biological supply house.

4. Open a raw chicken egg, and point out the small white disc on the yolk as the part of the egg where cleavage occurs. Emphasize that in humans the yolk sac is not a major nutrition source. Rather, it is part of the yolk sac in humans that forms the digestive tract and early blood vessels.

5. To model the embryonic disc, shape clay into three thin discs: blue clay = ectoderm; red clay = mesoderm; yellow clay = endoderm. Bend the flat disc into the shape of a

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cylinder (and a tadpole) to show how the body takes shape during the fourth week of development. (p. 88, Fig. 3.9) 6. Display a sonogram of a fetus for the class.

7. List several features that form early in embryonic development that are later lost in development or converted to new structures (e.g., tail = coccyx).

8. Ask students to compare the similarities and differences of the human life cycle with that of other animals. Include plants as well if you feel adventurous.

9. Use three pieces of differently colored paper to show how the germ layers form.

10. Discuss the necessity for sexually active women of childbearing age, whether practicing contraception or not, to maintain a lifestyle that will enhance, not harm, the developing embryo and fetus should the woman become pregnant. Then list the things a pregnant woman should and should not do.

Clinical Questions 1. Natasha’s mother told a neighbor that Natasha was “pregnant in her tubes.” Explain what she means. Will Natasha give birth at the end of this pregnancy?

Answer: The embryo has implanted in one of her uterine tubes rather than in the wall of the uterus. No placenta can be established, and without treatment the tube will rupture and cause severe internal bleeding. Tubal pregnancies do not come to term.

2. Lamar and Lamont were twin brothers, and Lorinda and Belinda were twin sisters. Each pair of twins looked alike at birth, but as the boys grew older, it became clear that they did not look any more alike than typical siblings; the girls, however, remained so similar that people mixed them up. Explain the differences between the two sets of twins, and explain how each act of twinning occurred during embryonic development.

Answer: The boys are fraternal (dizygotic) twins, meaning that their mother released two eggs that were fertilized by two sperm. The girls are identical (monozygotic) twins, meaning that a single morula or blastocyst split into two during the first week of embryonic development.

Art Resources Figure 3.1 Figure 3.2 Figure 3.3 Figure 3.4 Figure 3.5 Figure 3.6 Figure 3.7 Figure 3.8 Figure 3.9 Figure 3.10 Figure 3.11 Table 3.1 A Closer Look ..

The prenatal period.

The adult human body plan (simplified cross-section).

Fertilization and the events of the first six days of development.

Implantation of the blastocyst during week 2 of development.

The primitive streak stage.

Formation of the mesoderm and the notochord in a 16-day embryo.

Neurulation and mesoderm differentiation, week 3.

Folding of the embryo, lateral views.

The germ layers in week 4 and their adult derivatives.

Flow chart showing the major derivatives of embryonic germ layers.

A 29-day embryo.

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Teaching with Art Figure 3.3

Fertilization and the events of the first six days of development.

Textbook p. 81.

Checklist of Key Points in the Figure • Differentiate the uterus from the ovary.

• Explain the anatomy of the uterine tube.

• Focus on the events of fertilization, cleavage, and implantation.

• Explain fraternal and identical twins.

• Point out the open funnel-shaped infundibulum surrounded by the fimbriae of the uterine tube. Explain that this region is unique because this is the only place in the human body where a serous membrane meets a mucous membrane.

Common Conceptual Difficulties Interpreting the Art • Because the oocyte is released directly into the peritoneal cavity (the uterine tube fimbriae do not touch the ovaries), explain to students how the oocyte is “propelled” into the lumen of the uterine tube.

• Tie in the release of mucus, beating of cilia, and peristaltic contractions to the movement of the egg/embryo within the uterine tube.

• Comment on the pathway that the sperm had to travel to reach this ultimate destination.

• Explain how the embryo is sustained until implantation by nutrients originally stored in the ovum.

• Describe implantation as an inward erosion process that is in part possible because of the release of digestive enzymes by the embryo.

Art Exercise Ask students to label an unlabeled copy of Figure 3.3. Follow up with additional diagrams representing events associated with twinning. (Use the instructor resources area of Mastering A&P to post the figure on your course website so students can print copies without labels or leader lines.)

Critical Reasoning After asking students to recall what they’ve learned in Chapter 2 about the cell cycle, propose the following question: “Why do you think the embryo does not enlarge in size between fertilization and implantation?”

Answer: The cells of an embryo divide so rapidly during the first seven days that they do not have time to grow between cell divisions. Hence, the average cell size diminishes by half following each division, so that the developing embryo remains relatively constant in size.

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Supplemental Course Materials Library Research Topics 1. Explore the use of folic acid to prevent neural tube defects.

2. Research the major birth defects, tabulating them according to the organ systems they affect (e.g., skeletal system, circulatory system).

3. Research the effects of various drugs (illegal and legal) on embryological and fetal development.

4. Research the effects of alcohol on embryological and fetal development.

5. Research the effects of viral and bacterial diseases on embryological and fetal development.

6. Research the types of problems in the fetus and infant that are associated with the mother’s lifestyle (e.g., effects of sexually transmitted diseases, alcoholism, crack addiction, AIDS).

7. Research in vitro fertilization and artificial insemination. Identify any controversial issues surrounding these processes.

8. Research the various methods of contraception currently used, and identify possible future methods.

9. Explore the pros and cons of the following debate topic: When does life begin?

Suggested Websites The Visible Embryo: http://www.visembryo.com/baby/index.html Human Embryology Animations: http://www.indiana.edu/~anat550/embryo_main/ Human Embryo: http://www.med.uc.edu/embryology/contents.htm Life’s Greatest Miracle: http://www.pbs.org/wgbh/nova/miracle/program.html

Suggested Readings Barinaga, Marsha. “Cells Exchanged during Pregnancy Live On.” Science 296 (5576) (June 2002): 2169–2172.

Boldt, Jeffrey, Donald Cline, and David McLaughlin. “Human Oocyte Cryopreservation As an Adjunct to IVF–Embryo Transfer Cycles.” Human Reproduction 18 (6) (June 2003): 1250–1255.

Couzin, Jennifer. “Quirks of Fetal Environment Felt Decades Later.” Science 296 (5576) (June 2002): 2167–2169.

Duesbery, Nicholas S., and George F. Vande Woude. “An Arresting Activity.” Nature 416 (April 2002): 804–805.

Thisse, Christine, and Leonard I. Zon. Organogenesis—Heart and Blood Formation from the Zebrafish Point of View.” Science 295 (5554) (Jan. 2002): 457–462.

Van Keymeulen, Alexandra, and Cedric Blanpain. “Tracing Epithelial Stem Cells during Development, Homeostasis, and Repair.” Journal of Cell Biology 197 (5) (May 28, 2012): 575–584.

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Answers to Textbook Questions Answers for multiple-choice and matching questions 1–16 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 17. At the primitive streak, epiblast cells migrate inward to form the mesoderm and endoderm. As a result of this, the three primary germ layers are present: ectoderm, mesoderm, and endoderm. This occurs during the third week of embryonic development. The primitive node lies at one end of the primitive streak in the third week of embryonic development. At this node, epiblast cells move inward as a rod, pick up some cells from the hypoblast, and thereby form the notochord (primitive version of the backbone). (pp. 83–84) 18. The amniotic sac contains amniotic fluid and surrounds the developing embryo and fetus.

It protects the fetus from shock. The yolk sac contains a small amount of yolk and part of it develops into the digestive tube. In addition, the tissue around the yolk sac gives rise to the earliest blood cells and blood vessels. (p. 82) 19. The notochord is a rod formed of mesodermal cells and a few cells from the underlying endoderm. It defines the body axis, extends the length of the body, and is the site of the future vertebral column. By contrast, the neural tube is formed by the infolding of the neural groove, made of ectoderm in the dorsal midline. It elongates both cranially (to form the brain) and caudally (to form the spinal cord). (pp. 83–84) 20. The flat embryonic disc achieves a cylindrical body shape as its sides fold inward and it lifts up off the yolk sac into the amniotic cavity. At the same time, the head and tail regions fold under. All this folding gives the month-old embryo a tadpole shape. The sequence is illustrated in Figure 3.8 on p. 87.

21. Limb muscles, such as the biceps of the arm, develop from myotomes, not from splanchnic mesoderm. (pp. 86–89) 22. The neural crest gives rise to the sensory nerve cells, pigment cells, and some skeletal structures and vessels of the head and neck. (Here, for greater precision, the instructor may briefly introduce melanocytes, adrenal medulla for “fight or flight,” and the skeleton of the larynx.) (p. 87, Fig. 3.10) 23. Somites and intermediate mesoderm are segmented and form the segmented structures of the outer tube. The lateral plate mesoderm is unsegmented and is associated with the developing inner tube organs. (p. 89) 24. During neurulation, the ectoderm in the dorsal midline thickens to form a neural plate, which then folds inward to form a neural groove. This groove deepens until a hollow neural tube is pinched off. Then, neural crest cells develop from the lateral ridges of the neural plate and lie just outside the neural tube. (pp. 84–85 and Fig. 3.7) 25. The basic human body plan is a tube within a tube. By month 2, the outer tube forming the outer body wall and the inner tube composed of respiratory and digestive structures are evident. Cavities separate the two tubes. In the thoracic cavity, the pleural cavities surround the lungs, and the pericardial cavity surrounds the heart; in the abdominal cavity, the peritoneal cavity surrounds the stomach and intestines. Three structures located in the outer tube are the trunk muscles, vertebral column, and ribs. Three

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examples of structures contained in the inner tube are the stomach, jejunum, and ileum. (pp. 79–80) 26. Delta was not correct. During the first two months, organs are forming and the basic body plan is emerging. By the end of month 2, the embryo is distinctly human in appearance. (pp. 79 and 88, and Fig. 3.1)

Critical Reasoning and Clinical Applications Questions 1. Answer (c) is correct, meaning your friend should be aware of the possibility of birth defects. Many harmful substances do pass from mother to fetus, so choice (b) is wrong.

The period of maximum danger is from week 3 through week 8 of development, which includes the period when the friend was taking drugs. Because she continued her drug use past the eighth week of pregnancy, choices (a) and (d) are not correct. (p. 92) 2. The fetus is suffering from a condition called anencephaly. This is characterized by the neural tube failing to close cranially, resulting in exposed brain tissue at the cranial end.

The condition is associated with poor brain development and is usually fatal. (p. 85) 3. Yes. She is correct. By the eighth week, the limb buds of the embryo would be formed, and the digits would appear webbed, like a duck’s feet. Nonetheless, they would soon be separated by the end of the week. (p. 90) 4. An amniocentesis can be performed from as early as Week 11 of pregnancy to diagnose these types of fetal abnormalities. (p. 93)

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 3: Basic Embryology To the Student Knowledge of basic embryological concepts will enable you to understand the origin of normal adult anatomy and to understand the origin of birth defects. The central challenge of this chapter is to understand how the adultlike body components of a fetus are assembled from a single fertilized ovum.

Step 1: Distinguish between an embryo and a fetus. __ Define embryo. __ Define fetus.

Step 2: Outline early stages of development from zygote to blastocyst. __ Describe the process of fertilization. __ Define zygote. __ Relate the anatomy of the uterine tube to the movement of an embryo within it. __ Describe the process of implantation. Be able to discuss the events depicted in Figures 3.4a–e, and name the embryonic tissue structures that form following implantation.

Step 3: Summarize week 2 through week 8 of embryonic development. __ Describe how the embryo becomes a two-layered disc during week 2. (Fig. 3.6) __ Describe the formation of three germ layers during week 3. (Fig. 3.7) __ Explain the formation of the neural tube, notochord, and neural crest. (Fig. 3.8) __ Explain how the embryo changes shape during week 4. (Fig. 3.9) __ List examples of the main derivatives of the embryonic germ layers. __ Describe the main events of the second month of development.

Step 4: List the major events of fetal development. __ Summarize monthly changes in the fetus until birth. (Table 3.1)

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Tissues

Lecture and Demonstration Objectives 1. List the functional and structural characteristics of epithelial tissue.

2. Identify the different epithelia of the body, and describe the chief function(s) of each.

3. Distinguish exocrine from endocrine glands.

4. Explain how multicellular exocrine glands are classified.

5. Describe apical, lateral, and basal surface features of epithelia and epithelial cells.

6. Describe the features that are common to all connective tissues.

7. Identify the four main classes of connective tissue.

8. Differentiate between the different types of connective tissues in reference to the types of cells located within the tissue, the structure and composition of the extracellular matrix, and the main function of each.

9. Discuss the structure and function of mucous, serous, and cutaneous membranes.

10. Briefly describe the three types of muscle tissue.

11. Distinguish the cell types found in nervous tissue.

12. Describe the inflammatory and repair processes by which tissues recover from injury.

13. Indicate the embryonic derivation of each tissue class.

14. Briefly describe the changes that occur in tissues with age.

Suggested Lecture Outline I. Epithelial Tissue (pp. 97–109, Figs. 4.1–4.8, Table 4.1) A. Epithelial sheets of tissue cover body surfaces and organs and line body cavities; all functions reflect their role as interface tissues and boundary layers. (p. 97) B. Functions include protection, secretion, absorption, diffusion, filtration, and sensory reception. (pp. 97–98) C. Special Characteristics of Epithelia (p. 98, Fig. 4.1) 1. Special characteristics of epithelium differentiate it from the other basic tissue types. a. Cellularity b. Specialized contacts c. Polarity d. Support by connective tissue

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e. Avascular but innervated f. Regeneration D. Classification of Epithelia (pp. 97–104, Figs. 4.2, 4.3, Table 4.1) 1. In classification, each epithelial tissue is identified by two names. The epithelial tissue’s first name indicates the number of cell layers; its second name categorizes by cell shape.

2. In categorizing epithelial cells by shape, cells are recognized in three categories: squamous, cuboidal, and columnar.

3. In classification by cell layers, simple epithelia have a single layer of cells, and stratified epithelia have more than one layer of cells. Describe the functions of each of the listed tissues. a. Simple epithelia i. Simple squamous epithelium ii. Simple cuboidal epithelium iii. Simple columnar epithelium iv. Pseudostratified columnar epithelium b. Stratified epithelia i. Stratified squamous epithelium ii. Stratified cuboidal epithelium iii. Stratified columnar epithelium iv. Transitional epithelium E. Glands (pp. 104–105, Figs. 4.4, 4.5) 1. Certain specialized epithelial cells make and secrete a product and are called glands.

2. Glands are classified as exocrine (with ducts) or endocrine (without ducts) as well as unicellular or multicellular.

3. The only example of a one-celled exocrine gland is the goblet cell; its product is mucin, which combines with water to form mucus.

4. Multicellular exocrine glands have two basic parts: an epithelium-walled duct and a secretory unit. These exocrine glands are classified by the structure of their ducts and further classified by their secretory units.

5. Endocrine glands secrete hormones.

F. Epithelial Surface Features (pp. 106–109, Figs. 4.6–4.8) 1. Cell junctions are lateral surface features that primarily bind adjacent cells to each other. The main types are tight junctions, adhesive belt junctions, desmosomes, and gap junctions.

2. The basal lamina is a noncellular sheet of proteins that acts as a selective filter and separates the epithelium from the underlying connective tissues.

3. Apical surface features of epithelia are microvilli and cilia. a. Microvilli are fingerlike extensions of the plasma membrane containing a core of actin filaments. Microvilli increase the surface area for absorption in the small intestines, aid in ion transport in kidney tubules, and are abundant on epithelia that secrete mucus. b. Cilia are whiplike extensions of apical surface membranes and contain a core of microtubules that are arranged in doublets. The motor protein dynein helps the cilia to 34

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beat in coordinated waves to propel mucus and other substances across the epithelial surface.

II. Connective Tissue (pp. 109–124, Figs. 4.9–4.11, Table 4.2) A. Connective tissue is the most diverse and abundant type of tissue. (p. 109) B. There are four main classes and many subclasses. (p. 109) 1. Connective tissue proper (loose and dense) 2. Cartilage 3. Bone tissue 4. Blood C. Special Characteristics of Connective Tissue (pp. 110–111, Fig. 4.9, Table 4.2) 1. It has relatively few cells with a large amount of extracellular matrix.

2. Matrix is composed of ground substance and fibers.

3. Common embryonic origin is mesenchyme.

D. Structural Elements of Connective Tissue (pp. 110–113, Fig. 4.9, Table 4.2) 1. Usually the primary cell type produces the extracellular matrix. These cells are called fibroblasts in connective tissue proper.

2. Three types of fibers are found in connective tissues: collagen fibers, reticular fibers, and elastic fibers.

3. Ground substance is produced and secreted by the primary cell type of the connective tissue.

E. Classification of Connective Tissue (pp. 113–121, Fig. 4.10) 1. Areolar connective tissue shares characteristics with many other connective tissue types. Thus, areolar connective tissue is used as a connective tissue “model” to describe general functional and structural elements of other connective tissues. (p. 113, Figs. 4.9, 4.10b) a. General functional features of areolar connective tissue: i. Supporting and binding ii. Holding tissue fluid iii. Defending against infection iv. Storing fat 2. Connective tissue proper has two primary subdivisions: loose connective tissue and dense connective tissue. (pp. 113–118, Fig. 4.10b–g, Table 4.2) a. Loose connective tissues: i. Areolar connective tissue (underlies almost all epithelial tissues) ii. Adipose connective tissue (contains fat) iii. Reticular connective tissue (found in bone marrow, the spleen, and lymph nodes) b. Dense connective tissues: i. Dense regular connective tissue (found in tendons, ligaments, and aponeuroses) ii. Dense irregular connective tissue (found in the dermis of skin and joint capsules)

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3. Other connective tissues (pp. 118–121, Fig. 4.10h–l, Table 4.2): a. Cartilage i. Hyaline cartilage ii. Elastic cartilage iii. Fibrocartilage b. Bone c. Blood F. Covering and Lining Membranes (pp. 121–124, Fig. 4.12) 1. The cutaneous membrane is the skin, which is discussed further in Chapter 5.

2. Mucous membranes (mucosae) line the inside of every hollow internal organ system that opens to the exterior of the body.

3. Serosae secrete watery fluid and line the closed pleural, pericardial, and peritoneal cavities.

III. Muscle Tissue (p. 125, Fig. 4.13a–c) A. The three types of muscle tissue are cardiac, smooth, and skeletal.

IV. Nervous Tissue (pp. 125–127, Fig. 4.14) A. Nervous tissue is the main component of the brain, spinal cord, and nerves. The characteristic cells are neurons and supporting cells (neuroglial cells).

V. Tissue Response to Injury (pp. 127–129, Fig. 4.15) A. Inflammation (p. 127, Fig. 4.15) 1. Once the epithelia and connective tissues are penetrated, the body reacts with inflammatory and immune responses.

B. Repair (p. 129) 1. Tissue repair occurs in two major ways: regeneration and fibrosis.

VI. The Tissues Throughout Life (pp. 129–130, Fig. 4.16) A. Most epithelium and nervous tissue are derived from embryonic epithelia, the ectoderm, and endoderm. (p. 129) B. Mesodermal mesenchyme is the origin of endothelium, mesothelium, connective tissue, and muscle tissue. (p. 129) C. Poor nutrition and circulatory deficits contribute to declining tissue function with aging. (p. 130)

Lecture Hints 1. Define tissue, and ask students to begin developing an understanding of the functional relationships among cells, tissues, organs, and organ systems. Strongly encourage students to make use of Practice Anatomy Lab 3.0 (PAL), which they can access from www.myaandp.com.

2. Give specific examples of each of the four main tissue types, and ask students to provide example locations of each tissue and its function.

3. Explain why glands are included with epithelial tissues. A student may not make the connection that liver tissue is of glandular epithelial origin.

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4. List the special characteristics of epithelium, and explain how these features distinguish epithelium from other tissue types. Display Figure 4.1.

5. Referring to Figure 4.2: a. Classify epithelium based on cell shape. b. Classify epithelium based on number of cell layers. c. Relate epithelial functions to the shape of the cell and the number of cell layers. d. Point out that the cell shape of stratified epithelium may vary from layer to layer and that traditionally, the cell shape of stratified epithelium is described according to the apical layer. e. Mention how pathologists use the tissue level of organization when examining organ biopsies, such as the Pap smear examination of cervical stratified squamous epithelium.

6. Provide specific examples of the locations of each type of epithelium as they relate to form and function.

7. Describe apical surface features: microvilli and cilia. Comment on the importance of ciliary movement in the propulsion of mucus.

8. Describe lateral surface features that “glue” epithelial cells together. Discuss specific examples of cell junctions and their typical locations.

9. Compare the function and structure of basal lamina and the basement membrane.

10. Define gland. Explain classification of glands as exocrine or endocrine, and cite examples.

11. Using Figure 4.4, describe the goblet cell as an important unicellular exocrine gland because of its mucin production.

12. Review the roles of the rough ER, Golgi apparatus, and secretory vesicles learned in Chapter 2, and apply them to the goblet cell.

13. Note that all the glands in Figure 4.5 are multicellular exocrine glands, which secrete substances through ducts. Endocrine glands secrete hormones directly into the bloodstream and will be discussed in Chapter 17.

14. Define and explain the basic structures and functions of connective tissues.

15. Using Figure 4.9, comment on the simple, basic structural plan of all connective tissues, pointing out three basic elements of connective tissue. Use Figure 4.10b to describe areolar connective tissue as a prototype for other connective tissues.

16. Distinguish between ground substance and matrix.

17. Explain four main classes of connective tissue using examples from Figure 4.10a–l: a. Describe specific examples of connective tissue cells, including embryonic origin, function, and mobility. b. Describe fibers of connective tissue, including protein structure and mechanical properties. c. Discuss properties of the extracellular matrix. d. Explain the nature of ground substance.

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e. Emphasize that cartilage is avascular and that this quality results in slow repair and healing. f. Remind students that bone is living tissue with its own blood supply. g. Emphasize that the “fibers” in blood are unique because they are composed of a soluble protein that becomes insoluble only during the process of clot formation.

18. Explain fascia, and distinguish deep fascia from superficial fascia.

19. Discuss covering and lining membranes as a combination of epithelial tissue with an underlying layer of connective tissue. Refer to Figure 4.12.

20. Briefly describe the cutaneous membrane (skin) as a combination of epidermis (epithelium) and dermis (connective tissue). Details of the structure and function of the cutaneous membrane are covered in Chapter 5.

21. Describe the serous membrane, introduced in Chapter 1, as a combination of mesothelium and areolar connective tissue.

22. List three types of muscle tissue, and describe each briefly.

23. Using the text, discuss the histological representations in Figure 4.13 and compare each of the three types of muscle tissue according to the following characteristics: a. Description (include cell shape, number of nuclei, cell arrangement, presence or absence of striations, and presence or absence of intercalated discs.) b. Locations c. Functions d. Voluntary or involuntary nervous control 24. Explain inflammation and repair responses to tissue injury, giving examples of tissues that do not regenerate or repair themselves—that is, cardiac muscle and most nervous tissue. Refer to Figure 4.15.

25. Review the embryonic origin of epithelial, connective, muscle, and nervous tissue.

26. Remind students that all connective tissues are derived from mesenchyme.

27. Discuss the significance of stem cells.

28. Summarize the effect of aging on tissues and organs.

Classroom Discussion Topics and Activities 1. Using prepared digital photomicrographs from PAL 3.0, show specific examples of all the basic tissues at different magnifications to help students find the tissues and understand distinguishing characteristics of each tissue when they are using a microscope.

2. Use simple three-dimensional models, such as a cube (for cuboidal cells), a fried egg (for squamous cells), and a drinking glass (for columnar cells), to illustrate the shapes of the cells in the various types of epithelial tissues.

3. Short stories from personal experiences always liven up a lecture. You can reenact bashing your shin on the coffee table (or other incident) to describe the steps of the inflammatory response. Get students involved by having them explain the origin of each symptom of inflammation.

4. Ask the class to consider how acute inflammation differs from chronic inflammation.

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osteoarthritis. Additionally, ask students how inflammation caused by an infection (as in a pimple) differs from inflammation caused by a wound (a cut in the skin)?

5. Ask students to explain how and why nervous and muscle tissues also contain areolar connective tissue.

6. Discuss how the basic structural characteristics of each of the classes of epithelia (thickness and cell shape) relate to the specific functions of these epithelia.

7. Discuss how the features of the extracellular matrix of the various connective tissues (dense, loose, bone, cartilage) account for the mechanical properties of each tissue type.

8. Some deep wounds are sutured closed. Ask students why this is necessary (apart from reducing bleeding and preventing infection).

9. Thrust your hand into a flaccid balloon to demonstrate the relationship between the parietal and visceral layers of serosa.

10. Ask students to design a connective tissue comparison chart. The classification of connective tissues forms the left column. Use the following labels for the comparison columns: • Characteristic types of cells • Types of fibers • Nature of ground substance • Nature of matrix • Functions • Locations 11. Ask students to demonstrate the function of cilia by doing the “wave” as a class.

12. Remind students that additional media resources are available at the www.myaandp.com website, including an interactive multiple-choice quiz and the online histology tutorial.

Clinical Questions 1. The following statements are events that occur during tissue repair. Arrange the events in their sequence of occurrence. The initial event, the injury, is already indicated as 1.

1. The skin receives a cut that penetrates into the dermis; bleeding begins.

2. Epithelial regeneration and scar formation occur.

3. Granulation tissue forms.

4. Blood clotting occurs and stops the blood flow.

5. Macrophages engulf and clean away cellular debris.

Answer: 1, 4, 3, 5, 2.

2. A person gets a cut on her hand. After several days, she notices swelling, pain, heat, and redness. Upon opening the wound to relieve the pressure, she sees yellow pus coming out. What has happened to the wound?

Answer: The wound is infected. The symptoms indicate acute inflammation. Pus indicates the presence of dead or dying neutrophils, broken-down tissue cells, and living and dead bacteria.

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3. When a tendon is torn, it does not heal rapidly. Why? Answer: Tendons consist primarily of dense regular connective tissue, which is poorly vascularized. Poorly vascularized tissues heal slowly.

4. What are the signs of inflammation, and why is the inflammatory response beneficial?

Answer: The four signs of inflammation are swelling, redness, heat, and pain. Swelling, called edema, is beneficial because the increased amount of tissue fluid leaving the capillaries helps to dilute harmful substances that may be present in the connective tissue. It also brings in large quantities of oxygen, nutrients, and white blood cells that are necessary for the repair process.

5. Vitamin C is needed for the proper formation of collagen fibers. Insufficient vitamin C in the diet causes a condition known as scurvy, which is characterized by the general weakening of connective tissues and collagen throughout the body. Keeping in mind that strong connective tissues and collagen are needed to bind body parts together, what might be some of the major symptoms of scurvy?

Answer: Teeth fall out of their sockets, blood vessels rupture, and wounds fail to heal.

(Strong collagen is necessary for holding teeth in their sockets, reinforcing blood vessels, and healing wounds.)

Art Resources Figure 4.1 Figure 4.2 Figure 4.3 Figure 4.4 Figure 4.5 Figure 4.6 Figure 4.7 Figure 4.8 Figure 4.9 Figure 4.10 Figure 4.11 Figure 4.12 Figure 4.13 Figure 4.14 Figure 4.15 Figure 4.16 Table 4.1 Table 4.2 A Closer Look

Special characteristics of epithelium.

Classification of epithelia.

Epithelial tissues.

Goblet cells (unicellular exocrine gland).

Type of multicellular exocrine glands.

Cell junctions.

Microvilli.

Cilia structure and function.

Areolar connective tissue: A model connective tissue.

Connective tissues.

Focus Figure: Identifying Epithelial and Connective Tissue.

Types of membranes.

Muscle tissues.

Nervous tissue.

Tissue repair of a skin wound.

Embryonic germ layers and the primary tissue types they produce.

Function of the Epithelial Tissue Related to Tissue Type Comparison of Classes of Connective Tissues Cancer—The Intimate Enemy

Teaching with Art Figure 4.9

Areolar connective tissue: A model connective tissue.

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Checklist of Key Points in the Figure • Explain why areolar tissue serves as a model or prototype of connective tissue.

• Relate four functions of areolar connective tissue to its structural constituents.

• Explain the origin of tissue fluid and its function.

• Relate macrophages to the previous study of endocytosis in Chapter 2.

• Explain the extracellular matrix as ground substance + fibers + tissue fluids, except for blood.

• Describe the basement membrane as a combination of epithelium and connective tissue.

Common Conceptual Difficulties Interpreting the Art • Areolar, adipose, and reticular are all examples of loose connective tissue. Adipose tissue has structural and functional similarities to areolar connective tissue but has greater nutrient-storage capacity. Reticular connective tissue resembles areolar connective tissue but only contains reticular fibers.

• Dense (fibrous) connective tissue is similar to areolar but contains more collagen. Give examples.

• Point out similar and dissimilar characteristics of other connective tissues: cartilage, bone, and blood.

• The extracellular matrix is nonliving and makes up most of the body.

• The matrix largely determines the characteristics of connective tissue.

• All other tissues in the body border, or are embedded in, areolar tissue. Give examples.

• Connective tissue does not occur on free surfaces.

• Not all connective tissue is highly vascular.

Art Exercise Display or distribute copies of Figure 3.2, The adult human body plan, on p. 80 of the text.

Ask students to identify the dominant tissue types in the organs seen in the diagram. For example, skin is an epithelium and a dense irregular connective tissue, the ribs consist primarily of bone tissue, and the body muscles consist primarily of skeletal muscle tissue.

Critical Reasoning Display or distribute copies of Figure 22.3, showing the trachea and the esophagus. Ask students to note the different connective tissue structures of these adjacent tubelike structures.

What would happen if the trachea were not composed of such massive rings of hyaline cartilage? What might happen if the esophagus were composed of hyaline cartilage like the trachea?

Answer: The trachea is designed to allow the passage of gases, and the esophagus is designed to facilitate the movement of solids and liquids. The hyaline cartilage that encircles the trachea provides stiffness that prevents this tube from collapsing during breathing. If the esophagus were composed of similar amounts of hyaline cartilage, it could not change shape to accommodate the passage of solids.

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Supplemental Course Materials Library Research Topics 1. Basement membranes form the interface between epithelia and connective tissues. What is the chemical and fiber composition of this layer, and why is the basement membrane of great interest to cell biologists?

2. Why can some tissues regenerate and others cannot? What advantages and disadvantages are there for either case?

3. Some nutritionists suggest that obesity in later life results from overfeeding during childhood. Review some articles that support and dispute this theory.

4. Research current trends of tissue engineering and regenerative medicine.

Suggested Histology Websites Internet Atlas of Histology, College of Medicine University of Chicago at UrbanaChampaign: http://histo.life.uiuc.edu/histo/atlas/slides.php Southern Illinois University School of Medicine: http://www.siumed.edu/~dking2/index.htm The JayDoc HistoWeb: Kansas University School of Medicine: http://www.kumc.edu/instruction/ medicine/anatomy/histoweb/

Suggested Readings Eroschenko, V. DiFiore’s Atlas of Histology. 9th ed. Philadelphia: Lea and Febiger, 2004.

Gartner, L., and J. Hiatt. Color Atlas of Histology. 4th ed. Baltimore: Lippincott Williams & Wilkins, 2005.

Junqueira, L. C., et al. Basic Histology. 12th ed. Stamford, Conn.: Appleton & Lange, 2009.

Krause, William J. The Art of Examining and Interpreting Histologic Preparations: Study Guide for Histology. Boca Raton, Fla: Universal Publishers, 2004.

Krause, William J. Krause’s Essential Human Histology for Medical Students. Boca Raton, Fla: Universal Publishers, 2005.

Mironov, Vladimir, Thomas Boland, Thomas Trusk, Gabor Forgacs, and Roger R. Markwald.

Organ printing: “Computer-Aided Jet-Based 3D Tissue Engineering.” Trends in Biotechnology 22 (6) (June 2004): 265. (Also available online at doi:10.1016/S01677799(03)00033-7) Robbins, S. L., and V. Kumar. Basic Pathology. 8th ed. Philadelphia: W.B. Saunders, 2007.

Ross, M. H., and W. Pawlina. Histology: A Text and Atlas: with Correlated Cell and Molecular Biology. 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2010.

Rubin, E., and J. Farber. Essential Pathology. 5th ed. Philadelphia: Lippincott Williams & Wilkins, 2008.

Young, B., and John Heath. Wheater’s Functional Histology, 5th ed. New York: Churchill Livingstone, 2006.

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Answers to Textbook Questions Answers for multiple-choice and matching questions 1–12 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 13. A tissue is a collection of cells of similar structure and function; tissues also contain extracellular material. The four basic types of tissue are epithelial, connective, muscle, and nervous. (p. 96) 14. The classification of multicellular exocrine glands is explained in Figure 4.5 on p. 106.

Such a gland is simple if its duct does not branch, and compound if its duct branches.

It is tubular if its secretory cells are arranged in tubular units and alveolar (acinar) if its secretory cells form hollow balls at the end of the duct system. The main types are simple tubular, simple alveolar, compound tubular, compound alveolar, and compound tubuloalveolar. Specific examples of these gland types are listed in Figure 4.5.

15. 1. Support and binding other tissues: This function is performed by fibers in the extracellular matrix, especially by the tension-resisting collagen fibers. 2. Holding tissue fluid derived from blood capillaries: This function is performed by ground substance in the extracellular matrix, whose molecules act like sponges to hold water. 3. Defending the body against infection: This function is largely performed by a variety of defense cells in the connective tissue, including macrophages, plasma cells, mast cells, and various white blood cells. 4. Nutrient storage, performed by fat cells. (p. 113) 16. Fascia is defined as a fibrous membrane of dense regular connective tissue that wraps around muscles, around groups of muscles, and around large vessels and nerves. (p. 118) 17. (a) Tissue fluid, which occupies the extracellular matrix of connective tissue, is derived from blood and contains the small molecules of blood plasma. (b) The cells of the body obtain their oxygen and nutrients from the surrounding tissue fluid and deposit their waste into this fluid as well. The tissue fluid is the link between the body cells and the bloodstream. (p. 113) 18. (a) wraps and cushions organs; surrounds capillaries; (b) provides reserve food fuel; under skin in the hypodermis; (c) form a soft internal skeleton; lymphoid organs; (d) provides structural strength; fibrous capsules of organs; (e) attaches muscles to bones or to muscles; tendons; (f) allows recoil after stretching; walls of large arteries. (pp. 114–120) 19. 1. Heat: caused by more blood entering the capillaries of the inflammation site (blood is warm). 2. Redness: also caused by more blood entering the capillaries of the inflammation site (blood is red). 3. Swelling: caused by increased permeability of the capillaries, resulting in increased amounts of tissue fluid in the inflamed connective tissue (edema).

4. Pain: caused by the pressure of edema and by inflammatory chemicals that stimulate nerve endings that mediate pain. (pp. 127–129) 20. (a) Exocrine glands are glands that secrete their products onto body surfaces (skin) or into body cavities (such as the digestive tube). (b) Mucus secreting goblet cell. (pp. 104–105)

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21. Tissues that regenerate well: epithelial tissues, most types of connective tissue proper (except dense regular connective tissue), bone, blood-cell forming tissue. Tissues that regenerate poorly: cartilage, nervous tissue, cardiac and skeletal muscle. (p. 129) 22. Most epithelial tissues develop from embryonic epithelium of the ectoderm and endoderm layers. Nervous tissue in the brain and spinal cord derives from ectodermal epithelium (p. 129) 23. Nonliving material between the cells in our tissues, called extracellular material as described on p. 110. It includes the extracellular matrix of connective tissues. Because the extracellular matrix is more voluminous than the cells in the connective tissues, and because connective tissues are the most abundant tissues in the body, it makes sense to claim that extracellular matrix makes up a greater part of our body than do the cells.

24. The body’s outer surface is covered by the skin, which is referred to as the cutaneous membrane. The cutaneous membrane comprises the epidermis, which is the epithelial layer, and the dermis, which is the connective tissue layer. The epidermis is classified as stratified squamous epithelium, and the dermis is composed of dense irregular connective tissue. (p. 102, Fig. 4.3e and Fig 4.10e) 25. (a) dense regular connective tissue. (b) bone tissue. (c) muscle tissue. (d) nervous tissue. (e) elastic cartilage. (f) blood tissue. (g) simple cuboidal epithelium. (Figs. 4.3, 4.10, and 4.13) 26. Most epithelia and nervous tissue derive from ectoderm. However, endothelium and mesothelium as well as connective and muscle tissues arise from mesoderm. The epithelial lining of glands derives from endoderm. (p. 129)

Critical Reasoning and Clinical Applications Questions 1. Because connective tissue proper is extremely widespread throughout the body, lupus has widespread, not localized, effects. (p. 109) 2. ‘Kartagener’s syndrome’ is an inherited disease in which the dynein arms within the cilia fail to form, leading to the failure of bacteria clearance in the respiratory tract. As a result, one experiences recurrent infections. (p. 109) 3. Only the patient with liver damage will gain full functional recovery. This is because nervous tissue and cardiac muscle tissue cannot regenerate, but liver tissue (of glandular, epithelial origin) can. (p. 129) 4. Epithelium does. Recall that a carcinoma is a cancer arising from an epithelium, and an adenocarcinoma is a cancer arising from glandular epithelium. (p. 130) 5. Damage to the skin and blood vessels causes bleeding at the site of injury. Blood clotting is an initial step in the inflammation reaction as blood vessels surrounding the wound become more permeable, allowing the passage of white blood cells, clotting proteins, and fluid. This process prevents further bleeding and is essential for clotting. (p. 128) 6. The sperm is the only flagellated cell in the human body. In a man suffering from Kartagener’s syndrome, both his cilia and the flagellum (tail) of his sperm will not form dynein arms. Without these arms, his cilia will not be able to bend or move and his sperm will remain immotile and unable to swim toward the egg in the female reproductive tract. (pp. 109-109)

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 4: Tissues To the Student By focusing on the relationship between cellular organization and tissue function, you can easily learn the major characteristics of each tissue type. Because most organs contain all four basic tissue types, understanding tissue interactions permits you to better understand the organization and specific functions of organs and systems in the human body. As you progress through this course, it will be beneficial for you to make use of Practice Anatomy Lab 3.0 (PAL). For Chapter 4 content, refer to PAL’s Histology module. The Histology module will guide you through the steps of learning characteristic structures of each tissue type.

Step 1: Distinguish the four main types of tissue in the human body. __ Define tissue. __ List four main types of tissue and examples of each.

Step 2: Distinguish the different types of epithelia of the body. __ Devise an epithelial classification scheme based on the shape of a cell and the number of cell layers. __ List and describe the characteristics unique to epithelial tissue. __ Relate cell shape and number of layers to functions of epithelial tissue. __ List and describe three specific epithelial surface features, including detailed examples of each. __ Define gland, and explain why glands are included with epithelium. __ Explain the difference between endocrine and exocrine glands, and include examples. __ Devise a simple classification scheme for glands based on cellularity, including duct structure and secretory unit structure. Refer to Figure 4.5. __ Describe the goblet cell and its important glandular role.

Step 3: Distinguish the types of connective tissues. __ Name and describe basic components of connective tissue. __ List functions of connective tissue. __ Devise a summary outline for the four major types of connective tissues, including subtypes. __ For each type of connective tissue in your summary outline, list specific associated cells, list specific fibers, and describe mechanical properties.

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__ Also, for each type of connective tissue, discuss properties of the extracellular matrix and the nature of the ground substance. __ Explain important functions of tissue fluid.

Step 4: Analyze characteristics of covering and lining membranes. __ Define and illustrate the cutaneous membrane. __ Define and give examples of mucous membranes.

• Explain how mucus is moved along the membrane surface.

• Review the goblet cell and mucus production using Figure 4.4.

• Review Chapter 2 and summarize the roles of the rough ER, Golgi apparatus, and secretory vesicles in goblet cells. __ Define and give examples of serous membrane. __ Explain the difference between visceral and parietal serosa. __ Explain how cutaneous, serous, and mucous membranes are compositions of epithelium and connective tissues.

Step 5: Distinguish the three types of muscle tissue. __ Devise a chart to compare skeletal, smooth, and cardiac muscle tissues in terms of the following characteristics: • Cell shape

• Intercalated discs present/absent

• Number of nuclei

• Locations in body

• Cell arrangement

• Functions

• Striations present/absent

• Type of nervous control

Step 6: Describe the nature of nervous tissue. __ Define neuron. __ Define supporting cells. __ Explain the function of nervous tissue.

Step 7: Understand tissue response to injury. __ Explain inflammation. __ Describe tissue repair.

Step 8: Distinguish the embryonic origins of the four basic tissue types. __ Name tissues derived from mesenchyme, mostly of the mesoderm germ layer. __ Name tissues derived from endoderm. __ Name tissues derived from ectoderm. __ Discuss the significance of stem cells.

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CHAPTER

5

The Integumentary System

Lecture and Demonstration Objectives 1. Name the tissue types that compose the epidermis and the dermis, and describe the primary functions of skin.

2. Name the layers of the epidermis and the dermis, and describe the structure and function of each layer.

3. Describe the structure and function of the subcutaneous layer.

4. Describe the factors that contribute to skin color.

5. Describe the structure of nails.

6. List the parts of a hair and a hair follicle, and explain the function of each part.

7. Compare the structure and location of oil and sweat glands.

8. Compare eccrine and apocrine sweat glands.

9. Describe the layers involved in and the symptoms of first-, second-, and third-degree burns, and explain why serious burns are life-threatening.

10. Identify the cell type involved, the characteristic appearance, and the degree of malignancy in the three types of skin cancer.

11. Identify the primary germ layers that form the skin and its appendages.

12. Describe the changes that occur in the skin from birth to old age.

Suggested Lecture Outline I. The Skin and Subcutaneous Tissue (pp. 136–143, Figs. 5.1–5.5) A. The skin and its appendages make up the integumentary system; it is the largest of the body organs.

B. Technically, the subcutaneous tissue is not part of the integument, but it does share some of the skin’s functions. This fatty layer lies just deep to the skin.

C. The two distinct regions of the skin are the epidermis and the dermis.

1. Epidermis (pp. 137–140, Figs. 5.3–5.4) a. The epidermis is keratinized stratified squamous epithelial tissue. It consists of five layers in thick skin and four layers in thin skin. i. Stratum basale ii. Stratum spinosum iii. Stratum granulosum

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iv. Stratum lucidum (occurs only in thick, hairless skin of palms and soles) v. Stratum corneum b. Distinguish each layer of the epidermis by the types of cells present and their specific functions.

2. Dermis (pp. 140–142, Figs. 5.4–5.5) a. The leatherlike dermis is the second major layer of skin and is composed of strong, flexible connective tissue. b. The dermis is made up of the papillary dermis and the reticular dermis. c. Flexure lines are deep grooves in the palms, soles, wrists, and ankles. The lines are the result of bending the skin at the joints.

3. Subcutaneous tissue (p. 142) a. The subcutaneous tissue is the fatty layer beneath the skin that primarily contains adipose tissue and areolar connective tissue.

4. Skin Color (pp. 142–143) a. Skin color is the result of three pigments: melanin, carotene, and hemoglobin.

II. Appendages of the Skin (pp. 143–148, Figs. 5.6–5.8) A. Nails (pp. 143–144, Fig. 5.6) 1. Nails are a scalelike modification of the epidermis made of hard keratin.

B. Hair and Hair Follicles (pp. 144–146, Fig. 5.7) 1. Hair and hair follicles are considered appendages of the skin. Hair follicles are the tubular invaginations of epidermis from which hairs grow.

2. Hairs are of two types: terminal and vellus. a. Terminal hairs typify those on the head and have a growth cycle of approximately four years. b. Vellus hairs are the body hairs of children and women and have a growth cycle of several months.

C. Sebaceous Glands (p. 147, Fig. 5.8) 1. Sebaceous (oil) glands secrete sebum and occur over the entire body except palms and soles. Sebaceous glands release sebum by holocrine secretion.

D. Sweat Glands (pp. 147–148, Fig. 5.8) 1. Sweat (sudoriferous) glands are coiled simple tubular glands located over the entire skin surface except the nipples and parts of the external genitalia. (pp. 147–148) 2. Sweat is a filtrate of blood comprised primarily of water with salts and metabolic wastes.

3. Sweat glands are of two types: eccrine and apocrine. a. Eccrine sweat glands are more numerous and produce true sweat. b. Apocrine sweat glands become active at puberty, secrete a viscous substance, and are localized to the axillary and genital areas. i. Sweat from these glands may be used for sexual signaling in mate selection. ii. Secretions from apocrine glands have been identified as human pheromones.

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III. Disorders of the Integumentary System (pp. 148–150, Figs. 5.9, 5.10) A. The most common skin disorders result from microbial infections. (p. 148) 1. Burns (pp. 148–150, Fig. 5.9) a. In severe burns, the catastrophic loss of body fluids is the foremost threat to life; the second threat is overwhelming infection.

B. Skin Cancer (p. 150, Fig. 5.10) 1. Skin cancer is the most common type of cancer; primarily, it is caused by overexposure to ultraviolet (UV) rays in sunlight. a. Olfactory stem cell carcinoma is the least malignant and the most common. b. Squamous cell carcinoma arises from the keratinocytes of the stratum spinosum. c. Melanoma is the most aggressive type and has the greatest tendency to metastasize.

IV. The Skin Throughout Life (pp. 150–151) A. Structures of skin develop from several specific sources.

1. Epidermis develops from embryonic ectoderm.

2. Dermis and subcutaneous tissue arise from mesoderm.

3. Melanocytes develop from embryonic neural crest cells.

B. Most aspects of skin aging are not intrinsic but are caused by sunlight. Sun-exposed skin is wrinkled, loose, marked with age spots, and inelastic; protected aged skin is mostly unwrinkled and unmarked.

Lecture Hints 1. Distinguish epidermis from dermis, noting the types of tissue present and the major layers of each. Use Figure 5.1.

2. Tell students that the physical image they project is nothing but dead cells.

3. Describe functions of each layer of epidermis, including the role of keratinocytes, melanocytes, and cornified cells.

4. Compare human “hide” to animal hide. Also, compare human skin to a waterproof coat that automatically repairs itself and lasts a lifetime with reasonable care.

5. Because of the popularity of tattoos, students will be interested in A Closer Look in this chapter.

6. Explain fingerprints. Discuss why criminals who sand their fingertips do not permanently prevent their fingerprints from being identified.

7. Relate cleavage lines to wound healing and scarring.

8. Distinguish flexure lines from wrinkles associated with aging.

9. Describe the structure and function of the subcutaneous tissue, noting that it is not part of the skin. This layer is also called the superficial fascia and should not be confused with (deep) fascia, which is dense regular connective tissue.

10. Describe appendages of skin, and point out epidermal and dermal relationships.

11. Discuss the abundance of eccrine sweat glands and the variable amount of sweat produced on a daily basis.

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12. Parallel human apocrine sweat glands to “scent glands” of other mammals. Illustrate this relationship by discussing pheromones and mate selection.

13. Classify the two types of hair, terminal and vellus, and describe the characteristics of both groups.

14. Discuss the growth cycle of both types of hair. Relate the cycles to the fur (hair) length of other mammals. Point out that most mammals do not need haircuts, because the growth cycles of their hair are shorter than those of human hair.

15. Discuss baldness. If you are vague on the genetics of male-pattern baldness, consult a basic genetics text for an explanation.

16. Explain why chemotherapy results in hair loss.

17. Explain the following familiar circumstances: (a) suntan and why it fades, (b) pimples and blackheads, (c) wrinkled soles and palms after prolonged swimming, (d) greasy hair, (e) dandruff, (f) freckles, (g) bruises, (h) graying hair, and (i) goose bumps.

18. Classify and distinguish burns by their severity and type, then explain their devastating effects on skin.

19. Explain conditions defining a critical burn, and point out important clinical considerations for burn patients.

20. Using Figure 5.9, explain the purpose of the rule of nines and give examples.

21. Discuss the use of autografts (skin grafts from the patient) and the use of artificial skin.

Stimulate conversation by mentioning sources of skin grafts (i.e., those grown in a cell culture).

22. Emphasize that skin cancer is the most common form of cancer and that exposure to the UV rays of sunlight is the primary causative factor.

23. Discuss and distinguish among the three important types of skin cancer, and explain the ABCD (or ABCDE) rule.

24. Explain why and how skin wrinkles with age, and include discussion of photoaging.

Classroom Discussion Topics and Activities 1. Use three-dimensional models of skin to illustrate the strata of the epidermis.

2. Use a microprojector and microscope slides of skin to illustrate the layers. Use slides of skin from the scalp and palm to show how thin skin differs from thick skin. PAL 3.0 also has excellent histology slides in the Histology module that can be used for demonstration in PowerPoint presentations.

3. Describe how soaking in water for prolonged periods changes the appearance of the skin of fingertips. Have a student soak his or her hand in a dish of water to illustrate this principle.

4. Show the students a photo of a person with a heavily wrinkled face. Ask them to list all the factors that have contributed to the skin deterioration.

5. Discuss the role skin plays in the regulation of body temperature.

6. Ask students why animals with thick fur, such as Alaskan huskies, resist extremely cold air temperatures. How can polar bears and seals survive in near-freezing water temperatures?

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7. Humans are often called “naked apes.” Ask students why humans lack a full coat of body hair. What are the functions of human body hair?

8. Ask students to compare a snake shedding its “skin” with the process that takes place in humans.

9. Discuss why axillary hair does not grow as long as hair on the scalp.

10. Ask students why it is more difficult to get a suntan during the winter than in summer.

Ask why sunlight (and UV rays) is more intense in the tropics than nearer the poles of the Earth.

11. Discuss why a suntan eventually fades.

12. Ask students to talk about apocrine sweat and “scent glands” in relation to some popular colognes purported to contain pheromones for attracting a mate.

Clinical Questions 1. Jeremy, who is 14 years old, notices that his face is developing many pimples and blackheads. What is causing this problem?

Answer: Because of hormonal changes, teenagers frequently have overactive sebaceous glands, whose ducts clog with sebum. This promotes bacterial infection of the clogged gland. Scratching, squeezing, or irritating pimples can exacerbate the infection.

2. Albinos commonly contract skin cancer. What seems to be the reason, and what is a way for albinos to avoid skin cancer?

Answer: The skin of albinos lacks melanin pigment and cannot screen out UV rays from sunlight. As a result, DNA in the living epithelial cells and melanocytes at the base of the epidermis are damaged by radiation, and skin cancer can develop. Covering all body areas with clothing and avoiding bright sunlight can help albinos avoid skin cancer.

3. Mike read in his anatomy book that hair grows in cycles that last about four years. He asked why all his hair did not fall out every four years, for then he could save money on a barber. How would you answer his question?

Answer: Individual hairs do fall out every several years, but the growth cycles of the different hairs on the head are not synchronized at all. Therefore, a few dozen hairs fall out each day, but all hairs never fall out together.

4. Ahmed, an anatomy student, was watching an old movie about children in a haunted house. The children saw a ghost, and the hair on each of their heads stood straight up.

Is this pure fantasy, or does it have some basis in fact? Explain your answer.

Answer: Although the ghost movie was greatly exaggerated, fear does cause the arrector pili muscles to pull on the hair follicles so that the hair stands up.

5. Steve went to his thirty-fifth high school reunion, the first reunion he ever attended. He was hesitant to go because he had bad acne as a teenager, so he had not been popular in high school. When he arrived at the reunion, his skin looked 10 years younger than that of any of his former classmates. Was there a connection here?

Answer: Steve has unusually oily skin. This caused pimples when he was a teenager, but the oil keeps his skin from drying, so his skin looks supple and young during middle age.

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6. Define the hair matrix. What happens if this matrix is destroyed?

Answer: The hair matrix is the epithelial layer at the base of a hair follicle, and its epidermal cells divide to induce hair to grow. If the entire matrix of a hair is destroyed (as in a severe burn), that hair is lost and will not regrow.

Art Resources Figure 5.1 Figure 5.2 Figure 5.3 Figure 5.4 Figure 5.5 Figure 5.6 Figure 5.7 Figure 5.8 Figure 5.9 Figure 5.10 A Closer Look

Skin structure.

Gross structure of skin and underlying tissues.

Epidermal cells and the layers of the epidermis.

Thick skin.

Dermal modifications.

Structure of a nail.

Structure of a hair and hair follicle.

Skin glands.

Burns.

Photographs of skin cancers.

Tattoos

Teaching with Art Figure 5.3

Epidermal cells and layers of the epidermis.

Textbook p. 138 Checklist of Key Points in the Figure • Distinguish epidermis from dermis.

• The epidermis is an excellent example of stratified squamous epithelium.

• Explain why a skin surface composed of stratified squamous epithelium is better than one thicker single layer of columnar epithelial cells.

• Point out four characteristic cell types, and describe their specific functions.

• Associate stratum basale with cell division and stratum granulosum with initial keratin formation.

Common Conceptual Difficulties Interpreting the Art • Provide a concrete example of the thinness of thin skin; use the thickness of a credit card to approximate 1 mm.

• Emphasize that cells of the stratum corneum are dead because they are too far from life-sustaining capillaries in the underlying dermis.

• Describe how the production of new cells in the stratum basale literally pushes maturing and dying keratinocytes to the surface.

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Art Exercise Figure 5.3 permits students to choose a keratinocyte in the stratum basale and to diagram its significant cellular events, starting with cell division and ending with its ultimate shedding from the skin surface. Ask students to draw each phase of the cell’s life cycle with leader lines connecting to Figure 5.3. Instruct students to incorporate into their drawing a timeline based on an average 40-day life of a keratinocyte. Some key events to note are mitosis, pigment deposition, and keratin formation.

Critical Reasoning Incorporate two critical-reasoning examples into the art exercise.

1. Ask students to indicate the depth at which first-, second-, and third-degree burns are classified.

Answer: First-degree—only the epidermis; second-degree—epidermis and upper dermis; third-degree—epidermis and dermis.

2. Instruct students to indicate the depths at which three types of skin cancer originate: Olfactory stem cell carcinoma, squamous cell carcinoma, and melanoma.

Answer: Olfactory stem cell carcinoma—stratum basale; squamous cell carcinoma— stratum spinosum; melanoma—anyplace there is melanin.

Supplemental Course Materials Library Research Topics 1. What is the difference between A and B types of UV rays with respect to the types of skin damage they produce?

2. Explore the literature on the latest techniques and materials used in skin grafting (e.g., test tube-grown skin, synthetic skin, and heterograft skin).

3. The long-term effects of sunburn include severe wrinkling and increased likelihood of skin cancer. What are the latest statistics on skin damage and photoaging, and what has been done to correct it?

4. Although our skin is a barrier to microbes, prepare a list of organisms, such as bacteria, yeast, fungi, protozoans, and arthropods, that may reside on or in our skin.

5. Suggested research topics: a. Latest therapies for baldness b. New treatments for melanoma that involve immunotherapy c. Use of retinoic acid for the treatment of photoaged skin d. FDA regulations for the classification of cosmetics and drugs

Suggested Integument Website Skin cancer website, updated with current online video feed. Need Flash Player to view. http://www.goldbamboo.com/video-t1732.html

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Suggested Readings Junqueira, L. C., et al. Basic Histology. 12th ed. Stamford, Conn: Appleton and Lange, 2009.

Marieb, E. Anatomy and Physiology Coloring Workbook: A Complete Study Guide. San Francisco: Pearson Benjamin Cummings, 2006.

Young, B. and John Heath. Wheater’s Functional Histology. 5th ed. New York: ChurchillLivingstone, 2006.

Answers to Textbook Questions Answers for multiple-choice and matching questions 1–15 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 16. Generally not. Most “bald” men have fine vellus hairs that look like peach fuzz in the “bald” areas. (p. 146) 17. Thick skin occurs on the palms and soles, body areas that lack hairs. Thin skin covers all other areas of the body, and hair is present on virtually all these areas. (p. 137) 18. A sunburn normally only affects the epidermis and typically causes redness, swelling, and pain. It heals within a few days without special attention. A sunburn usually does not result in blisters, as seen in second-degree burns, or consume the entire thickness of the skin, as seen in third-degree burns. Therefore, sunburns are considered as first-degree burns. (pp. 148–149) 19. Sun exposure (UV light) activates matrix metalloproteinase enzymes in the dermis, which degrade collagen and other components of the dermis, leading to wrinkling, inelasticity, leathery nature, and age spots in the skin. (p. 151) 20. Melanocytes are spider-shaped cells located in the stratum basale, the deepest epidermal layer. They secrete the dark skin pigment melanin. Melanin shields the cell nuclei of keratinocytes from UV rays, which can damage DNA and cause cancer. (p. 137) 21. (a) When the arrector pili muscles contract to raise the hair, they also dimple the skin to produce “goose bumps.” (p. 146) (b) Noninfectious dandruff is the normal shedding of the stratum corneum of the scalp. (p. 140) (c) Stretch marks represent small tears in the dermis, as the skin is stretched by obesity or pregnancy. (p. 140) (d) Fingerprints are films of sweat derived from sweat glands that open along the epidermal ridges of the hand. (p. 140) (e) The sparseness of hair on the body surface of humans may be an adaptation that allows more efficient sweating in hot climates, for abundant body hair would inhibit the evaporation of sweat. (p. 148) (f) Graying hair results from decreased melanin production by the hair follicle and from the replacement of melanin by colorless air bubbles in the hair shaft. (p. 144) 22. The musky smell of body odor comes from bacterial decomposition of the organic molecules in the sweat produced by apocrine sweat glands. The secretions from the apocrine glands were identified as true human pheromones (chemical signals that convey information to a member of the same species). Hence, apocrine glands are involved with sexual signaling and appear to function in attractiveness and mate selection. (p.148)

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23. Any three of these: skin protects, cushions, and insulates deeper structures; helps control body temperature; excretes metabolic wastes; screens UV rays; receives sensory information; and more. (pp. 136–137) 24. Fat will be removed from the hypodermis. (p. 142).

25. Hair grows at an average rate of 2 mm per week. Hair follicles undergo growth cycles, and the newly growing hair pushes out the old hair with each new active phase. The follicles of scalp hair remain active for much longer (generally 4 years) than those of eyebrows (few months). Thus, scalp hair has more time to grow longer. (p. 146) 26. Cuticle comes from the same Latin root as cutaneous, meaning “skin” and is the most superficial layer of hair. Cortex means “bark,” a layer that surrounds the medulla. Medulla means “marrow or middle” and forms the deepest layer of the hair.

Critical Reasoning and Clinical Applications Questions 1. The continued loss of skin can result in critical or irreversible fluid loss and infection. (p. 149) 2. Lily has a type of skin cancer known as ‘malignant melanoma’, which arises from the cells producing melanin. In this case, the cancer has spread to her backbone through the blood stream. (p. 152) 3. Brett has developed callus formations in the soles of his feet. Persistent friction from a poorly-fitting shoe caused a thickening of the epidermis. (p. 140) 4. No. The blackheads are not just dirt. When a sebaceous gland is blocked (by sebum), a whitehead appears on the skin surface. If that material oxidizes and dries, it darkens to form a blackhead. Bacterial infection of that may lead to the formation of pimples. (p. 147) 5. The nail plate is the visible, attached part (not its white, free edge). The root is the proximal part that is imbedded in skin. The bed is the layer of epidermis upon which the nail body lies. The matrix is the proximal part of the nail bed, and it is responsible for nail growth. The eponychium is the cuticle around the perimeter of the nail plate. The nail is not expected to grow back because its matrix is gone. (pp. 143–144) 6. (a) about 18%. (b) about 18%. (c) about 4.5%. (p. 149, Fig. 5.9) 7. For a patch-based drug delivery system, drugs need to reach the closest blood vessels so that they can be transported to their receptor cells elsewhere in the body. Both estrogen and nicotine are small, lipid-soluble molecules that can easily move through or inbetween cells. Thus, these molecules can pass through the epidermal layer of the skin and reach the dermis where the skin’s blood vessels are located. (pp. 140–141) 8. Harmful effects of UV radiation include a decrease in levels of folic acid in light-skinned people and increased risk for all types of skin cancer. Premature aging of the skin (photo-aging) due to UV exposure leads to wrinkled, inelastic, leathery skin. UVexposed skin also loses collagen and has increased levels of abnormal elastin-containing material. (pp. 136 and 151) UV radiation is beneficial because it is necessary for the production of vitamin D by the deeper epidermal layers. Adequate vitamin D is essential for calcium uptake from dietary sources. (p. 143)

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9. (a) Basal cell carcinoma occurs in the stratum basale (as both have the same root), the deepest layer of the epidermis. (b) Squamous cell carcinoma occurs in stratum spinosum as squamous refers to the cell type (keratinocytes) found in the stratum spinosum. (c) Melanoma (from “melan” for black) occurs in melanocytes in the stratum basale. The melanocytes produce melanin, the black/brown pigment that contributes to skin coloration.

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 5: The Integumentary System To the Student This chapter relates the specifics of skin anatomy to its myriad of functions. Your concept of an organ is broadened to include the skin and its appendages, and what an organ it is! Our skin reveals our overall health, age, and emotional state. What an amazing material skin is to resist heat and cold, harsh chemicals, and bacteria. Knowledge of skin structure also will better enable you to understand damage to skin from burns and diseases, such as cancer.

Continue developing your understanding of the integumentary system by using Practice Anatomy Lab 3.0 (PAL). You will find the Histology module and the Integumentary System section in the Anatomical Models module most beneficial.

Step 1: Understand the anatomy of the skin and the subcutaneous tissue. __ Distinguish epidermis, dermis, and subcutaneous tissue. __ Identify specific types of tissues associated with the skin and the subcutaneous tissue, noting individual functions. __ Identify specific types of cells associated with skin structure, noting individual functions. __ Organize the skin and the subcutaneous tissue into recognized layers. __ Explain skin color and the relative importance of melanin, hemoglobin, and carotene.

Step 2: Describe the appendages of skin. __ Describe five general skin appendages and their individual functions.

Step 3: Learn about disorders of the integumentary system. __ Name two major bodily threats from severe burns. __ Classify burns by severity. __ Explain the rule of nines. __ Identify the major risk factor for skin cancer. __ Identify three types of skin cancer, indicating degree of occurrence and curability.

Step 4: Summarize the skin throughout life. __ Identify embryonic origins for the epidermis, dermis, subcutaneous tissue, and melanocytes. __ Describe the skin of a six-month-old fetus. __ Describe the skin of old age. __ Explain factors causing wrinkles.

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CHAPTER

6

Bones and Skeletal Tissues

Lecture and Demonstration Objectives 1. Locate the major cartilaginous structures of the adult human body, and explain the functional properties of cartilage tissue.

2. Compare the structure, functions, and locations of the three kinds of cartilage tissue.

3. Explain how cartilage grows.

4. Describe the functions of the bony skeleton and of bone tissue.

5. Describe the structure of bone tissue and the functions of its organic and inorganic components.

6. Describe the gross anatomy of a typical long bone and a typical flat bone.

7. Explain how bones withstand tension and compression.

8. Describe the types of markings found on bones.

9. Describe the histology of compact and spongy bone.

10. Compare and contrast the two types of bone formations: intramembranous and endochondral ossification.

11. Describe how endochondral bones grow at their epiphyseal plates.

12. Discuss how bone tissue is remodeled within the skeleton.

13. Explain the steps in the healing of bone fractures.

14. Relate the disease processes that cause osteoporosis, osteomalacia, rickets, and osteosarcoma to what you have learned about the structure, composition, and growth of bone tissue.

15. Identify the symptoms and treatments for each of these diseases.

Suggested Lecture Outline I. Cartilages (pp. 156–159, Figs. 6.1, 6.2) A. Location and Basic Structure (pp. 156–157, Fig. 6.1) 1. Cartilages are resilient, avascular tissues that lack innervation.

2. Cartilages are located in specific locations throughout the human body. a. Perichondrium surrounds cartilages, resists outward expansion, and aids in growth and repair.

B. Types of Cartilage (pp. 157–159, Fig. 6.2) 1. The three types of cartilage are elastic, hyaline (most abundant), and fibrocartilage.

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C. Growth of Cartilage (p. 159) 1. Cartilages grow in two ways: appositional growth and interstitial growth. a. Appositional growth occurs when chondroblasts from the surrounding perichondrium produce new cartilage tissue by actively secreting matrix. b. Interstitial growth occurs when chondrocytes within the cartilage divide and secrete new matrix.

2. Cartilage stops growing in the late teens and regenerates poorly after that time.

3. Calcified cartilage is a sign of aging; however, it remains a distinct tissue and is not bone.

II. Bones (pp. 159–175, Figs. 6.3–6.15, Tables 6.1, 6.2) A. Bones of the skeleton are considered organs because they contain different types of tissues.

1. Functions of Bones (p. 159) a. Functions of bones include the following: i. Support (give the body shape) ii. Movement (serve as levers for muscles to pull on) iii. Protection (protect soft organs) iv. Mineral storage (store calcium and phosphate) v. Blood cell formation and energy storage (contain red bone marrow, the hematopoietic tissue that makes blood cells, and yellow bone marrow for fat storage) vi. Energy metabolism (osteoblasts secrete osteocalcin) B. Bone Tissue (pp. 159–160) 1. Bone tissue consists of organic and inorganic components. a. Bone is composed of 35% organic components and 65% inorganic mineral salts.

2. Cells in bone tissue maintain the integrity of bone tissue. a. Osteogenic cells are the stem cells that differentiate into bone-forming osteoblasts. b. Osteoblasts actively produce and secrete the ground substance and collagen fibers.

Matrix secreted by osteoblasts is termed osteoid. c. Osteocytes are mature bone cells that are completely surrounded by osteoid. d. Osteoclasts are cells responsible for resorption of bone. Osteoclasts derive from a lineage of white blood cells.

C. Gross Anatomy of Bones (pp. 160–164, Figs. 6.3–6.6 Table 6.1) 1. Gross anatomy of bones classifies them according to shape: long, short, flat, or irregular. a. Long bones are longer than wide, with a definite diaphysis and two epiphyses; all limb bones are long bones except patellae, carpals, and tarsals. b. Short bones are somewhat cube-shaped and include the carpals and tarsals. Sesamoid bones, including the patellae, are a special type of short bone that forms within tendons. c. Flat bones are thin, flattened, often curved bones that include most skull bones, the sternum, scapulae, and ribs.

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d. Irregular bones do not fit any of the other categories and have complicated shapes.

Vertebrae and coxae are irregular bones.

2. Compact bone is the dense outer layer of bone; internal to this is spongy bone.

3. Structures of typical long bones: a. Diaphysis forms the “shaft” of a long bone; epiphyses form the proximal and distal ends of a long bone. b. Blood vessels feed bone tissue through the nutrient foramen. c. The medullary cavity is located along the center of a long bone and contains yellow bone marrow. d. Periosteum is a connective tissue covering the external surface of the diaphysis of a long bone; endosteum covers the internal surface of a long bone.

4. Structures of short, irregular, and flat bones are similar to those of long bones, though they have no diaphysis. They contain marrow but have no marrow cavity.

5. Bone design reflects the stresses placed on it. a. Strong, compact bone tissue occurs in the external portion of bone. b. Lack of bone tissue at a bone’s center does not impair its strength. c. Spongy bone is exquisitely organized along stress lines. d. Superficial surfaces of bones have distinct bone markings.

6. Bone markings provide significant information about the function of bone and muscle. a. Many bone markings are sites for muscle attachment. b. Other bone markings form joints. c. Openings within bones (e.g., foramina) are the passageways for blood vessels and nerves.

D. Microscopic Structure of Bone (pp. 164–167, Figs. 6.7–6.9) 1. Compact bone and spongy bone differ microscopically. a. The osteon is the important structural unit of compact bone. Osteons are structures unique to compact bone and include lamellae, the central canal, lacunae containing osteocytes, and canaliculi. b. Spongy bone is formed from osteocytes and lamellae organized in trabeculae.

However, spongy bone lacks the structural complexity of compact bone.

E. Bone Development and Growth (pp. 167–171, Figs. 6.10–6.12) 1. The process of bone tissue formation is named osteogenesis or ossification. a. Intramembranous ossification forms membrane bone from fibrous connective tissue membranes and results in the cranial bones and clavicles. b. Endochondral ossification bone tissue replaces hyaline cartilage; all bones, except the skull bones and clavicles, form this way.

2. Anatomical examination of epiphyseal growth areas reveals growing cartilage organized in several zones; this organization permits the rapid growth of bone.

3. Endochondral bones lengthen during youth and widen through appositional growth.

F. Bone Remodeling (pp. 171–173, Figs. 6.13, 6.14) 1. Bone remodeling is accomplished by deposition and resorption of new bone tissue in response to hormonal and mechanical stimuli and occurs throughout life.

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G. Repair of Bone Fractures (pp. 173–175, Fig. 6.15, Table 6.2) 1. Bone fractures are repaired by open or closed reduction.

III. Disorders of Bones (pp.143–145, Fig. 6.16, 6.17) A. Osteoporosis (pp. 175–176, Fig. 6.16) B. Osteomalacia and Rickets (p. 176, Fig. 6.17) C. Osteosarcoma (p. 177)

IV. The Skeleton Throughout Life (p. 177, Fig. 6.18) A. Beginning with bone formation in the fetus, ossification occurs in a predictable manner and in consistent stages until the death of the skeleton.

Lecture Hints 1. Identify the major locations of cartilage in the human body. Refer to Figure 6.1. Ask students why cartilage is included in a study of the bony skeleton.

2. For the three major types of cartilage, compare the structure (fibers and matrix), functions, and locations. Instruct students to devise a comparison chart for the major types of cartilage.

3. Define perichondrium. Point out that perichondrium does not cover the articular cartilages.

4. Explain the two growth patterns of cartilage: interstitial and appositional.

5. Point out the significance of water to both the resiliency and growth of cartilage. Refer to A Closer Look: The Marvelous Properties of Cartilage on p. 158.

6. Analyze bone as an organ.

7. Ask students to describe five major functions of the human skeleton, and have them include their own illustrations.

8. Distinguish the specific organic and inorganic chemical components that comprise bone tissue, and describe their functions.

9. Have students create a comparison chart for bone classification based on shape, and list names of bones for each category. Suggest Chapters 7 and 8 as references. Students often distinguish long bones from short bones based on size; emphasize that the difference is shape, not size.

10. Distinguish the specific characteristics and structures of compact bone from spongy (cancellous) bone.

11. Describe the gross anatomy of a typical long bone, such as the humerus. Refer to Figure 6.4. Use an actual dried bone from lab to indicate the gross features. An opaque projector (ELMO) is an excellent way to demonstrate bones to large lecture classes.

12. Describe the gross anatomy of a typical flat bone, such as a skull bone. Refer to Figure 6.5. Use a skull bone from lab to indicate gross features; for large classes, use of a projector is an excellent option.

13. If you are using a split, dried femur, use a projector to point out probable tension lines and evident compression lines. Explain how bones withstand tension and compression.

Pass out diagrams, and instruct students to label the lines accordingly.

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14. Using human bones (or bone models), describe the specific markings and openings.

Stress to students that understanding bone markings (discussed more in Chapters 7 and 8) is critical to understanding muscle attachments later in the course. Refer to Table 6.1.

15. Explain functional differences among bone markings, surfaces that form joints, and depressions and openings.

16. Define osteon and describe the microscopic structure of compact and spongy bone. Refer to Figures 6.7 and 6.8.

17. Illustrate the process of osteogenesis (ossification).

18. Distinguish two types of bone formation: intramembranous ossification and endochondral ossification.

19. Summarize the stages of endochondral ossification of a long bone.

20. Describe the anatomy of epiphyseal growth areas.

21. Explain postnatal growth of a long bone, including how the bone widens. The most important stimulus of epiphyseal plate activity is growth hormone from the anterior pituitary. Point out that long bone growth ends sooner in females (18 years) than in males (21 years). Stress differences between epiphyseal plate and epiphyseal line. Emphasize that bones can be remodeled or grow appositionally, even after longitudinal growth has ceased.

22. Describe the processes of bone remodeling. Describe the role of osteoblasts in bone deposition and bone resorption.

23. Emphasize that bones must be mechanically stressed to remain healthy. Physical activity pulls on bones, resulting in increased structure. Inactivity results in bone atrophy.

24. Define fracture and explain repair of bone fractures; distinguish between a simple (closed) fracture and a compound (open) fracture.

25. Using x-ray images, show several common types of fractures. Ask students which types of fractures are more common among people of different ages.

26. Discuss disorders of bones, and comment on the following diseases: osteoporosis, osteomalacia, rickets, Paget’s disease, and osteosarcoma.

27. Present a general bone/cartilage timetable that reflects the skeletal events throughout life.

Classroom Discussion Topics and Activities 1. Display examples of human bones using models or actual bones to illustrate various shapes.

2. Obtain a beef bone from a market and saw it longitudinally to demonstrate the internal structure of long bones. Fresh bone is excellent for demonstrating compact versus spongy bone and red marrow versus yellow marrow as well as the epiphyseal line.

3. Demonstrate the periosteum by peeling this membrane from the fresh beef bone or the femur of an uncooked chicken leg.

4. Obtain a fresh piece of round steak and point out the marrow in the cut femur.

5. Use a three-dimensional model of compact bone to identify the osteons, lacunae containing osteocytes, lamellae, and canaliculi.

6. As an analogy, hold a bundle of uncooked pieces of spaghetti to show the arrangement of osteons within compact bone.

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7. Illustrate the organic and inorganic composition of bone tissue by placing one chicken bone in nitric acid and another in the oven. The acid will leach out the calcium salts (making the bone bendable), and the oven will break down the organic matter (making the bone very brittle). A decalcified fibula can be tied in a knot and will resume its original shape when untied.

8. Obtain x-ray images of long bones of young children, teenagers, and adults to illustrate the conversion of the epiphyseal plate to an epiphyseal line.

9. Obtain x-ray images of carpals, metacarpals, and phalanges of young children and adults.

Compare x-rays of clavicles of young children to those of adults. Use these to illustrate the different ages of ossification of various bones.

10. Obtain a cleared and stained pig embryo to show the development of bone in the skeleton (available from most biological supply companies).

11. Set up microscopes or use photomicrograph slides from PAL 3.0 to demonstrate and contrast endochondral versus intramembranous ossification.

12. Bend a stick of clay to illustrate bending forces typically placed on long bones in the living skeleton. On one side the clay will tear apart in tension, whereas on the other side it will bunch together in compression; these forces cancel each other out in the center.

13. Bend a green twig to illustrate a greenstick fracture, which is common in children. Then break a dry twig to more closely approximate a fracture in an adult.

14. Obtain x-rays of limbs whose bones show various types of fractures. If possible, obtain x-ray images that illustrate healing stages following the fracture.

15. Discuss why infections are more common with compound fractures than simple fractures.

16. Discuss the effects on the skeleton of extended weightlessness in space. How can these effects be minimized or at least reduced?

17. Ask the question: Why are incomplete or greenstick fractures more common in children, whereas complete breaks are more common in adults?

18. Explore the statement: Multiple pregnancies will result in the mother losing all the enamel from her teeth and calcium from her bones. Is this all true, all false, or only partly true?

19. Calcium plays an important role in bone formation. Ask the class what other roles calcium plays in the body.

20. Discuss why fossil remains of vertebrate animals consist almost exclusively of bones and teeth.

21. Ask the class, If bone tissue is so hard, how can orthodontists move teeth from one location in the jaw to another?

22. Have students work in groups of three or four to build a model of an osteon. Students should label each structure of the osteon. Students may turn in the actual model or turn in a PowerPoint presentation of their labeled model.

Clinical Questions 1. Why do many elderly people develop “bowed backs” and appear shorter than they were in younger years?

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Answer: Because of osteoporosis, bone tissue tends to reabsorb faster than it is reformed, and the density of the tissue decreases. The bony trabeculae become thin within the bodies of the vertebrae; thus weakened, they experience numerous microfractures when subjected to the normal weight of the body. This compresses the vertebral bodies, causing the vertebral column to bend forward into a bow shape. The bowed spine accounts for the loss of body height.

2. A 75-year-old woman and her 9-year-old granddaughter were victims of a train crash. In both cases, trauma to the chest was sustained. X-ray films of the grandmother revealed several broken ribs, but her granddaughter’s ribs did not break. Explain these different symptoms.

Answer: The youngster has relatively more organic material in her bones, which allows them to bend, whereas the grandmother’s bones are fully calcified, with less organic material. Furthermore, the grandmother’s bones may have been weakened by osteoporosis.

3. Cyndi fractured the middle of the diaphysis of her right tibia in a skiing accident. The surrounding soft tissue (in the middle of her leg) was also damaged by the force of the accident. After prolonged immobilization of the limb in a cast, it was found that the fracture was not healing. Can you explain why?

Answer: The nutrient artery, which enters near the middle of the diaphysis of a long bone, was destroyed in the accident. Without its blood supply, the shaft of the tibia could not heal.

Art Resources Figure 6.1 Figure 6.2 Figure 6.3 Figure 6.4 Figure 6.5 Figure 6.6 Figure 6.7 Figure 6.8 Figure 6.9 Figure 6.10 Figure 6.11 Figure 6.12 Figure 6.13 Figure 6.14 Figure 6.15 Figure 6.16 Figure 6.17 Figure 6.18 Table 6.1 64

Cartilages in the body.

Types of cartilage tissue.

Classification of bones.

The structure of a long bone (humerus).

Structure of a flat bone.

Bone anatomy and bending stress.

Microscopic structure of compact bone.

A single osteon.

Spongy bone.

Intramembranous ossification.

Endochondral ossification of a long bone.

Organization of the cartilage within the epiphyseal plate of a growing long bone (80x).

Remodeling of spongy bone.

An osteoclast.

Stages in the healing of a bone fracture.

Osteoporosis.

Rickets.

Primary ossification centers in the skeleton of a 12-week-old fetus.

Bone Markings

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Table 6.2 Common Types of Fractures A Closer Look The Marvelous Properties of Cartilage

Teaching with Art Figure 6.4

The structure of a long bone (humerus).

Textbook p. 162 Checklist of Key Points in the Figure • Articular cartilage provides almost frictionless joint surfaces.

• The periosteum is a connective tissue covering of bone. Its superficial layer of dense irregular connective tissue resists tension during bending.

• The deep periosteal layer contains cells that provide lifetime bone remodeling.

• The endosteum covers internal bone surfaces and also contains osteoblasts and osteoclasts.

• Relate bone to other connective tissues using the following concepts: articulations and mobility, prenatal and postnatal growth, support and protection, and nutrition.

Common Conceptual Difficulties Interpreting the Art • The epiphyseal line is a remnant of the plate of hyaline cartilage that grows to lengthen bone.

• Differentiate the composition of bone marrow in the long bone of an infant from that of an adult.

• The periosteum provides sites for tendon and ligament attachment.

• Explain that there are separate blood supplies to either side of the epiphyseal line in an adult long bone. (Show Fig. 6.11, number 5.)

Art Exercise 1. Instruct students to compare Figure 6.4, The structure of a long bone, with Figure 6.11, Stages in endochondral ossification of a long bone. Instruct students to construct a flowchart summarizing the events that occur from the formation of an epiphyseal plate cartilage to the appearance of the epiphyseal line.

2. Provide copies of Figure 6.4 and Figure 6.11, number 5, with only leader lines. Ask students to associate specific types of connective tissue with the anatomical names of bone structures. For example, in addition to labeling the periosteum, a student would indicate that it is also dense irregular connective tissue.

Critical Reasoning 1. Bone tissue does not form the epiphyseal plate. Ask students what tissue does grow, and account for lengthening of long bones.

Answer: Hyaline cartilage.

2. As endochondral ossification occurs, a long bone widens as it grows in length. Ask students how this is accomplished.

Answer: On the external surface of the diaphysis, osteoblasts in the periosteum add bone tissue. Internally, osteoclasts in the endosteum remove bone tissue from the inner surface of the diaphysis. ..

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Supplemental Course Materials Library Research Topics 1. How are electrical fields being used to stimulate bone growth and bone repair?

2. Much research is currently being performed to determine the mechanisms by which compression and tension forces on bones stimulate the bone to respond by growing thicker. What are the mechanisms that have been hypothesized?

3. Explore the procedures used in bone tissue transplants in which pieces of bone are removed from one part of the body and implanted into another.

4. What effect does the use of illegal steroids by athletes have on their bone tissue and bone marrow?

5. Research the latest techniques, such as the Ilizarov procedure, used to lengthen bones that have been damaged in accidents or illnesses.

Suggested Bone Tissue Website Kansas University Medical Center: The JayDoc HistoWeb. http://www.kumc.edu/instruction/medicine/anatomy/histoweb/ From the home page, click on the “Bone” button.

Suggested Readings Junqueira, L. C., et al. Basic Histology. 12th ed. Stamford, Conn: Appleton & Lange, 2009.

Kotz, Rainer I., et al. “A Self-Extending Paediatric Leg Implant.” Nature 406 (6792) (July 2000): 143.

Short, Ben. “miR-34 Keep Osteoblasts Bone Idle.” Journal of Cell Biology. (197:461) (May 7, 2012) Wei, J., Yu Shi, Lihua Zheng, et al. “miR-34 Inhibit Osteoblast Proliferation and Differentiation in the Mouse by Targeting SATB2.” (197:509-521) May 7, 2012. Note: There is a $30.00 charge for accessing this article from the website.

Answers to Textbook Questions Answers for multiple-choice questions 1–18 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 19. Fibrocartilage is the least abundant cartilage in the body. It resists both strong compression and strong tension (pulling) forces. Two specific locations of fibrocartilage are in the anulus fibrosus portion of the discs between the vertebrae and in the articular discs of some joints, for example the menisci of the knee. (pp. 158–160) 20. Unlike other connective tissues in the body, bones have both organic and inorganic components. The inorganic components are the mineral salts that invade the bony matrix, making the bone tissue hard. Since these inorganic components will not decompose easily, bones can be preserved for millions of years. (p.160)

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21. Because of estrogen’s influence, the epiphyseal growth plates of females close earlier than those of males. Moreover, because growth in bone length cannot occur after the closure of the epiphyseal plates, males can grow taller than females until both sexes reach the end of puberty. (p. 169–171) 22. (a) First decade is the fastest; fourth decade is when skeletal mass starts to decline. (pp. 168 and 175) (b) Elderly people usually experience a loss of bone mass, osteoporosis, and lack of blood supply to bone. This weakens the bones, so they are more easily fractured. (p. 175) 23. Interstitial growth is a growth from within in which the chondrocytes inside a piece of cartilage divide and secrete matrix. Appositional growth, by contrast, is a growth from outside in which cells in the perichondrium around the piece of cartilage produce the new tissue. (p. 159) 24. Membrane bones are the clavicle and the bones of the skull (except some at the cranial base, such as the base of the occiput). All other bones of the skeleton are endochondral. (p. 168) 25. (a) Osteoblasts are cells that actively produce and secrete the organic components (ground substance and collagen fibers) of the bone matrix. They are abundant in the growth plate. Decreased osteoblast function in the elderly may lead to osteoporosis. (b) Osteoclasts break down bones by secreting hydrochloric acid, which dissolves the mineral component of the matrix, and lysosomal enzymes. Decreased osteoclast function in a child leads to decreased bone resorption. In this case, bones become heavy and fracture easily (e.g. marble bone disease, osteoporosis). (p. 160) 26. Bone and cartilage are both examples of connective tissue; both originate from embryonic mesenchyme, and both provide shape and support for respective body parts. Differences between bone and cartilage include the degree of vascularity, and the hard, calcified matrix of bone compared to the flexible nature of cartilage. Growth patterns vary between bone and cartilage as well. (pp. 157 and 159)

Critical Reasoning and Clinical Applications Questions 1. To remain strong, the bones of the living skeleton must be continually stressed by the weight of the body and by the force of muscles pulling on them. The lower limbs of a paraplegic in a wheelchair experience neither of these forces, so bone tissue is lost. Such bones thin and weaken. (pp. 163–164 and 165) 2. Vitamin D is essential for the mineralization of the bone matrix. Deficiency of vitamin D in a child’s diet would lead to rickets, a disease that affects the mineralization of the bones. Along with weakened and bowed leg bones, this disease causes skeletal malformations in a child’s skull and rib cage. Therefore, a child’s diet must include vitamin D supplementation. (p. 176) 3. By overdoing his exercise, Carlos had twisted and torn the cartilage in the distal epiphyseal plate of the humerus in his arm. (Recall that cartilage is weak in resisting such twisting stresses: p. 157.) Damage to the epiphyseal plates is common in child athletes (pp. 173 and 177), but it could not have happened to adult Selena, whose epiphyseal plates have already closed.

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4. The epiphyseal plates do grow fast, but the cartilage is replaced by spongy bone tissue at the diaphyseal side as quickly as it grows. Therefore, the plate remains the same width. (p. 169) 5. Egil is thought to have had Paget’s disease, an excessive remodeling of bone dominated by bone deposition. (p. 173) For more information on Egil, see pp. 114–119 in the January 1995 issue of Scientific American magazine.

6. Malcolm has suffered a greenstick fracture of the shaft of the right radius bone. In this kind of a fracture, the bone fractures incompletely and the opposite side bends. Such fractures are common in children due to the presence of a larger organic matrix and greater flexibility of the bones in comparison to adults. (p. 174) 7. Pregnancy and lactation (making milk) lead to a transfer of large amounts of calcium from a mother’s skeleton to the growing skeleton of the fetus and newborn. Therefore, it is extremely important for women to eat calcium-rich foods during pregnancy, while lactating, and between pregnancies as well. (p. 176) 8. Weight-bearing exercise (1) increases bone mass by stimulating osteoblasts in the periosteum to lay down new bone tissue; (2) increases the blood flow to bones; and (3) decreases bone resorption by hydrochloric acid-secreting osteoclasts. Weight-bearing exercise, along with a diet high in calcium and protein, is critical for maintaining bone mass. (p. 173) 9. Achondroplasia – “a” – without, “chondr” – cartilage. In this condition, cartilage in the epiphyseal plates does not form properly, resulting in stunted growth of the long bones.

Osteoporosis – “osteo” – bone, porus – pore, opening. Osteoporosis is literally “porous bone” or “holey bone.” This reflects the loss of bone in the spongy bone.

Osteogenesis imperfecta – “osteo” – bone, “gen” – produce. In ostogenesis imperfecta, bone does not form properly due to a defect in the gene for type 1 collagen.

Epiphyseal fracture – “epi” – over, above, “phy” – grow. An epiphyseal fracture is in the growth plate region of a long bone.

Osteomalacia – “osteo” – bone, “malacia” – soft. Osteomalacia, like rickets, results from inadequate calcification of the bony matrix, thus bones are not stiff but rather “soft.”

Interpreting Medical Images Questions Answers to Interpreting Medical Images questions are provided in the Instructor Resources area of Mastering A&P. Figure 6.12: The epiphyseal plate is composed of hyaline cartilage. The ground substance of cartilage holds large amounts of water; thus, this region appears dark in a radiograph.

Figure 6.17: The small oval structures above and below the long bones are the epiphyses, the distal epiphysis of the femur, and the proximal epiphysis of the tibia. Ossification of the epiphyses begins at birth. This toddler is younger than 2, so the epiphyses are not fully formed, as they are in Figure 6.12.

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Table 6.2: The superficial regions of all bones are composed of compact bone and thus are more radiopaque (whiter); the deeper areas are either spongy bone (vertebrae and skull) or contain marrow cavities (in the long bones). These regions are more radiotranslucent (gray) because they contain less calcified material and more fluid (bone marrow).

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 6: Bones and Skeletal Tissues To the Student During your study of Chapter 6, you will discover the amazing structure and functions of bone tissue and cartilage. Together they form your skeleton. You will gain insight as to how an individual bone functions as an organ in its own right and explore the important relationship of cartilage to bone during development. Understanding the basics in this chapter prepares you for succeeding chapters, where you will learn the bones forming the axial and appendicular skeletons, how joints form, attachments of muscles to bones, and movements.

Please make use of Practice Anatomy Lab 3.0 (PAL). For Chapter 6 content, refer to the Histology module (connective tissue slides 13–23) and the Skeletal System sections in the Human Cadaver and Anatomical Models modules. These sections of PAL will guide you through learning bone landmarks and the histology of bone tissue.

Step 1: Understanding cartilage. __ Define cartilage. __ Identify major locations of cartilage in the adult human body. __ Explain the functional properties of cartilage as a tissue. __ Prepare a comparison chart of each type of cartilage, including notes on structure, functions, and locations. __ Describe interstitial and appositional growth of cartilage. __ Define perichondrium and describe its location and functions.

Step 2: Understanding bone tissue. __ Describe why a bone is an organ. __ Summarize each of the six major functions of the bony skeleton. __ Describe the gross anatomy of a typical long bone and the gross anatomy of a typical flat bone. __ Describe the functions of osteogenic cells, osteoblasts, osteocytes, and osteoclasts. __ Explain how bones withstand tension and compression. __ Analyze each of the bone markings based on their locations and functions. __ Draw and label an osteon. Describe histological features. __ Describe differences between compact bone tissue and spongy bone tissue. __ Describe the chemical composition of bone, and distinguish its organic from its inorganic components. __ Distinguish intramembranous and endochondral ossification as types of bone formation. __ Explain how bone is remodeled in the skeleton.

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__ List and describe the common types of fractures described in the text. __ Explain basic steps in the repair of a fracture.

Step 3: Explore bone disorders and changes of bone tissue throughout life. __ List symptoms of osteoporosis. __ Name two ways aged bone differs from young bone.

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CHAPTER

7

Bones, Part 1: The Axial Skeleton

Lecture and Demonstration Objectives 1. Compare the functions of the cranial and facial bones.

2. Name and describe the bones of the skull. Identify their important features.

3. Define the bony boundaries of the nasal cavity, paranasal sinuses, and orbit.

4. Name a function performed by both the spinal curvatures and the intervertebral discs.

5. Describe the general structure of the vertebral column, and list its components.

6. Discuss the structure of a typical vertebra, and describe the special features of cervical, thoracic, and lumbar vertebrae.

7. Identify the distinctive features of the ribs and sternum.

8. Differentiate true ribs from false ribs, and explain how they relate to floating ribs.

9. Describe how a typical rib attaches to the vertebral column.

10. Describe the causes and consequences of cleft palate.

11. List three types of abnormal curvatures of the spinal column, and explain spinal stenosis.

12. Describe how the axial skeleton changes as we grow.

Suggested Lecture Outline I. Bones, Part 1: The Axial Skeleton (pp. 182–183, Fig. 7.1) A. The 206 bones of the body are grouped into the axial and appendicular skeletons.

1. The axial skeleton is composed of the skull, vertebral column, and thoracic cage.

2. The appendicular skeleton is made up of the upper and lower limbs, including the pectoral and pelvic girdles.

II. The Skull (pp. 184–202, Figs. 7.2–7.17, Table 7.1) A. The skull is the most complex bony structure in the body; it is formed from the cranial and facial bones. Cranial bones protect the brain. Facial bones form the framework of the face, anchor the muscles, provide openings for the passage of air and food, and form cavities for the sense organs of sight, smell, and taste.

1. Overview of Skull Geography (pp. 184–185, Figs. 7.2–7.3) a. The anterior, middle, and posterior cranial fossae are prominent internal bony ridges that divide the cranial base into three distinct “steps.” b. Approximately 85 named foramina, canals, and fissures are located within the skull bones.

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B. Cranial Bones (pp. 185–194, Figs. 7.4–7.12, Table 7.1) 1. Sutures are located between the bones of the skull. We look at sites at which the parietal bones articulate with other cranial bones. These are the four largest sutures. a. Coronal suture b. Squamous suture c. Sagittal suture d. Lambdoid suture 2. The cranium, or calvaria, is the bony cavity protecting the brain. Several cranial bones are paired, whereas others occur singly. Eight major bones form the calvaria (frontal, parietal, occipital, temporal, sphenoid, and ethmoid bones).

C. Facial Bones (pp. 194–199, Fig. 7.13, Table 7.1) 1. Fourteen facial bones form the cheeks, nose, and chin (mandible, maxillae, zygomatic, nasal, lacrimal, palatine, vomer, and inferior nasal conchae).

D. Special Parts of the Skull (pp. 199–202, Figs. 7.14–7.17, Table 7.1) 1. Special parts of the skull are formed by parts of many skull bones. a. Nasal cavity b. Paranasal sinuses c. Orbits d. Hyoid bone

III. The Vertebral Column (pp. 202–210, Figs. 7.18–7.23) A. The spinal column, or spine, consists of 24 individual vertebral bones, plus the two composite bones: the sacrum and the coccyx.

1. Regions and Normal Curvatures (pp. 202–203, Fig. 7.18) a. The 70-cm vertebral column has five major regions. i. Seven cervical vertebrae are in the neck. ii. Twelve thoracic vertebrae form the rib cage. iii. Five lumbar vertebrae support the lower back. iv. The sacrum articulates with coxal bones. v. The tiny coccyx is the most inferior portion.

2. The normal curvatures of the spine are the cervical and lumbar curvatures and the thoracic and sacral curvatures.

B. Ligaments of the Spine (p. 203, Fig. 7.19) 1. The major supporting ligaments of the spine are the anterior and posterior longitudinal ligaments. Additionally, the ligamentum flavum connects the lamina of adjacent vertebrae.

C. Intervertebral Discs (pp. 203–204, Figs. 7.18, 7.19) 1. Intervertebral discs separate the 24 individual vertebrae and function as shock absorbers; they also contribute to the flexibility of the spine.

D. General Structure of Vertebrae (pp. 204–205, Fig. 7.20) 1. All vertebrae have several common structural features. a. Body (centrum) b. Vertebral arch

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c. Pedicles d. Laminae e. Vertebral foramen f. Spinous process g. Transverse processes h. Superior and inferior articular processes i. Intervertebral foramina (between adjacent vertebrae) E. Regional Vertebral Characteristics (pp. 205–210, Figs. 7.21–7.23, Table 7.2) 1. Vertebral structure shows regional variations. a. C1–C7 are the smallest and lightest vertebrae. C1–C6 have bifid spinous processes, and all cervical vertebrae possess transverse foramina. The atlas (C1) lacks a vertebral body, the axis (C2) possesses a process called the dens, and C7 is termed the vertebra prominens. b. The vertebral bodies of T1–T12 articulate with the heads of ribs. Transverse processes of T1–T10 articulate with the tubercles of ribs, whereas T11 and T12 lack such articulations. T1–T10 have direct or indirect attachments to the sternum. Superior and inferior articular facets lie in the frontal (coronal) plane. c. L1–L5 possess massive vertebral bodies and blunt posterior-facing spinous processes. d. The sacrum forms from the fusion of S1–S5. Transverse ridges mark the regions where the sacral vertebrae fuse. The ala of the sacrum is formed from fused rib elements of S1–S5. The sacrum forms the posterior wall of the pelvis. e. The coccyx (tailbone) is formed from three to five variously fused vertebrae, which offer slight support to the pelvic organs.

IV. The Thoracic Cage (pp. 210–212, Figs. 7.24, 7.25) A. The protective bony framework of the chest (thorax) includes the sternum and costal cartilages, the 12 pairs of ribs, and the thoracic vertebrae.

1. Sternum (p. 211, Fig. 7.24) a. The sternum articulates with the clavicles, rib pairs 1 and 2, and costal cartilages of rib pairs 3–7.

2. Ribs (pp. 211–212, Figs. 7.24–7.25) b. The 12 pairs of ribs are classed as true or false ribs. Rib pairs 1–7 articulate directly to the sternum by way of costal cartilages. Rib pairs 8–12 are false ribs because they attach to the sternum indirectly or not at all. Ribs 11–12 are floating ribs because they have no anterior attachments.

V. Disorders of the Axial Skeleton (pp. 212–213, Figs. 7.26, 7.27) A. Cleft Palate (p. 212, Fig. 7.26) 1. Cleft palate is the most common congenital abnormality of the skull. It results when the right and left halves of the palate fail to fuse medially during embryonic development.

B. Stenosis of the Lumbar Spine (p. 212) 1. Spinal stenosis is a narrowing of the vertebral canal in the lumbar region.

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C. Abnormal Spine Curvatures (pp. 212–213, Fig. 7.27) 1. Abnormal spinal curvatures include scoliosis (lateral curvature), kyphosis (exaggerated thoracic curvature), and lordosis (exaggerated lumbar curvature).

VI. The Axial Skeleton Throughout Life (pp. 213–214, Fig. 7.28) A. Beginning with ossification of skull bones late in month 2, skull bones change throughout life. Changes are most dramatic during childhood.

B. Primary curvatures of the vertebral column are well developed at birth; secondary curvatures are usually evident by year 1.

C. Aging results in loss of bone mass.

Lecture Hints 1. Name the bones of the axial skeleton, and list their functions.

2. Name, describe, and identify the skull bones, their locations relative to each other, and their major markings. Explain the significance of the 85 or so openings for the passage of blood vessels, nerves, the spinal cord, and spinal nerves.

3. Identify the bones of the cranium and the significant markings of each. Define suture, and explain its role as an immovable joint. Point out that the temporomandibular joint is the only movable joint of the skull (excluding the tiny ear ossicles).

4. Describe the facial bones and their significant features; explain articulations.

5. Explain the role of the sphenoid as a keystone bone of the skull and the role of the maxillae as the keystones of the face.

6. Define the bony framework of the nasal cavity and orbital cavities; summarize the structural content of the orbit: eyeball, muscles, fat, and lacrimal gland.

7. Using Figures 7.11 and 7.14, demonstrate how the floor of the nasal cavity is the same as the roof of the oral cavity.

8. Explain the structure and function of paranasal sinuses; comment on the epithelial lining and openings.

9. Bones vary with individuals, giving people individual characteristic features.

10. Describe the location and functions of the hyoid; explain to students that it is the only bone in the body that does not articulate directly with another bone.

11. Identify the general structure and function of the vertebral column. Explain regions, curvatures, supporting ligaments, and intervertebral discs.

12. Describe the general gross anatomy of a typical vertebra; distinguish regional differences between cervical, thoracic, and lumbar vertebrae.

13. Point out unique characteristics of the atlas, axis, vertebra prominens, sacrum, and coccyx. Refer to Greek mythology and make the connection between the function of the atlas and the story that “Atlas supported the world.”

14. List components of the thorax; describe the gross anatomy and articulations of the sternum and ribs.

15. Distinguish true ribs, false ribs, and floating ribs. Explain the atypical features of rib pairs 1 and 10–12.

16. Comment on spinal clinical disorders: scoliosis, kyphosis, lordosis, and stenosis. ..

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17. Describe the gross anatomy of a fetal skull. Distinguish fontanelles and metopic suture.

Remind students of intramembranous ossification. Refer to Figure 7.28.

Classroom Discussion Topics and Activities 1. Demonstrate a complete, articulated skeleton, showing how the skeleton forms the framework of the body and the difference between axial and appendicular skeletons.

2. Demonstrate a skull (with the calvaria cut) and a vertebral column to illustrate how these bones provide protection for the delicate neural tissue of the brain and spinal cord.

3. Using a disarticulated Beauchene skull demo, ask students to list all the bones of the skull and to name all the bones that articulate with each one.

4. Using bone specimens, compare and contrast the structural features of different vertebrae: atlas, axis, cervical, thoracic, lumbar, sacral, and coccygeal vertebrae.

5. Display x-ray images of skull and spinal columns with normal anatomy. Ask students to identify individual bones while comparing the x-ray images to models or bone specimens.

6. Display x-ray images of spinal columns that exhibit abnormal curvatures, such as scoliosis, lordosis, and kyphosis.

7. Explain in mechanical terms why the vertebral bodies become progressively larger from the cervical to the lumbar regions of the spine.

8. Years ago, students carried heavy books on one arm or the other. Today, most students are using knapsacks (backpacks). Ask students how these different ways of carrying books affect the spinal column.

9. Various religious writings have suggested that a rib was taken from man to create woman.

Ask students whether any ribs are missing from the male rib cage. You might offer the following explanation if students have trouble understanding that men and women both have 12 pairs of ribs. Give an example of a man having surgery to remove his appendix.

Ask students whether that man’s children would be born without an appendix. Logic may prevail, but be sensitive to students’ religious upbringing. This explanation, or one like it, may offer students an opportunity to see that science does not threaten their beliefs.

10. Humans have a short neck, but giraffes have a long one. Ask students whether giraffes have more neck vertebrae to accommodate this extra length. Do the rats and cats used in many anatomy courses have more vertebrae and ribs than humans?

11. Discuss what information skeletons provide in forensic medicine.

12. Place a disarticulated bone in a brown paper bag, and have the students identify it through the bag using only their sense of touch.

Clinical Questions 1. During a severe cold accompanied by nasal congestion, Helen complained of a frontal headache and said that the right side of her face ached. What specific bony structures did the cold viruses probably infect?

Answer: The paranasal sinuses were affected, most specifically the right frontal sinus in the frontal bone.

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2. While cleaning out his garage, Otis bent over to lift a heavy box and heard a “pop” in his mid back. Within minutes he started experiencing waves of severe back pain that forced him to seek medical treatment. What may have happened to Otis’s back?

Answer: Most likely, Otis suffered a herniated intervertebral disc of his thoracic spine.

The nucleus pulposus of the damaged disc is pressing against the spinal cord or spinal nerve roots, causing the unrelenting pain and discomfort. (See Figures 7.19c–d)

Art Resources Figure 7.1 Figure 7.2 Figure 7.3 Figure 7.4 Figure 7.5 Figure 7.6 Figure 7.7 Figure 7.8 Figure 7.9 Figure 7.10 Figure 7.11 Figure 7.12 Figure 7.13 Figure 7.14 Figure 7.15 Figure 7.16 Figure 7.17 Figure 7.18 Figure 7.19 Figure 7.20 Figure 7.21 Figure 7.22 Figure 7.23 Figure 7.24 Figure 7.25 Figure 7.26 Figure 7.27 Figure 7.28 Table 7.1 Table 7.2

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The human skeleton.

The skull: cranial and facial divisions and fossae.

Major cavities of the skull, frontal section.

Lateral aspect of the skull.

Posterior view of the skull.

Anterior view of the skull.

Inferior aspect of the skull.

The temporal bone.

Floor of the cranial cavity.

The sphenoid bone.

Midsagittal section through the skull.

The ethmoid bone.

Detailed anatomy of the mandible and maxilla.

Bones of the nasal cavity.

Paranasal sinuses.

Bones that form the orbit.

The hyoid bone.

The vertebral column.

Ligaments and intervertebral discs of the spine.

Structure of a typical vertebra.

Posterolateral views of articulated vertebrae.

The first and second cervical vertebrae.

The sacrum and coccyx.

The thoracic cage.

Ribs.

Cleft palate.

Abnormal spinal curvatures.

Skull of a newborn.

Bones of the Skull Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae

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Teaching with Art Figure 7.16

Bones that form the orbit.

Textbook p. 201 Checklist of Key Points in the Figure • State that the orbit is roughly conical in shape and that it projects about 21/2 inches into the skull’s interior.

• Cite the bones and their parts that form the roof, lateral wall, medial wall, and floor of the orbit.

• Explain a suture as a characteristic articulation.

• Emphasize that understanding the orbital articulations increases overall understanding of the very complicated articulations of the skull.

• Point out special features of the orbit for passage of nerves, blood vessels, and ducts, with special attention to the evident foramina and fissures found in the sphenoid bone and between the sphenoid and the maxillary bones.

• Point out the lacrimal fossa and other foramina that border the orbit.

• Mention structures that occupy the orbit: eyeball, muscles, fat, lacrimal gland.

Common Conceptual Difficulties Interpreting the Art • A colored diagram is necessary to show the difficult-to-distinguish suture lines within the orbit of an actual bony skull.

• When viewing bones of the skull in isolation (e.g., the sphenoid bone), students often fail to appreciate the contribution the bone makes to the construction of the orbits.

• Students may not make the connection between an orbital bone’s surface features and its functions, such as a foramen that allows for the passage of a nerve.

Art Exercises 1. Provide students with unlabeled copies of Figure 7.16. Instruct them to color and label the surface of each bone that forms a portion of the orbit.

2. Using Practice Anatomy Lab 3.0 (PAL), provide students with copies of a disarticulated sphenoid and a disarticulated maxilla. Ask them to color the portion of each bone that contributes to the formation of the orbit. (This exercise may be expanded to include all the bones of the orbit.)

Critical Reasoning Ask students to explain why bones have foramina, fissures, passageways, and depressions.

Provide a copy of Figure 7.16 and ask students to identify and label several surface markings of the orbit and to indicate the anatomical structures associated with them (e.g., nerves, blood vessels, ducts). Although Table 7.1, Bones of the Skull, lists the specific names of the blood vessels or nerves involved, it is usually sufficient to ask students to focus on general categories of anatomy at this point.

Answer: The following surface features permit passage of cranial nerves and/or blood vessels: supraorbital foramen, infraorbital foramen, infraorbital groove, optic foramen, superior orbital fissure, and inferior orbital fissure. The lacrimal fossa houses the lacrimal sac that helps to drain tears into the nasal cavity.

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Supplemental Course Materials Library Research Topics 1. A technique called percutaneous automated discectomy involves back surgery without stitches. How safe is it, and when can it be used? What are some other common techniques used to relieve herniated discs?

2. Spinal deviations such as scoliosis are difficult to repair. What are the current methods of treatment, both invasive and noninvasive?

3. Paleontologists and archaeologists have unearthed many prehistoric skulls and bones of humanlike creatures and animals. How can they reconstruct the soft features and tissues of these animals from only their skeletal remains?

4. Trace the origin of congenital disorders of the skeleton, such as spina bifida and cleft palate, starting in the human embryo. What is the explanation for these defects?

Suggested Readings Agur, A. M. Grant’s Atlas of Anatomy. 13th ed. Baltimore: Lippincott Williams & Wilkins, 2012.

Alexander, R. M. Human Bones: A Scientific and Pictorial Investigation. New York: Pi Press, 2004.

Basmajian, J. V. Grant’s Method of Anatomy. 11th ed. Baltimore: Lippincott Williams & Wilkins, 1989.

Gray, H., et al. Gray’s Anatomy. 38th ed. London: Churchill Livingstone, 1995.

McMinn, R., R. Hutchings, et al. Color Atlas of Human Anatomy. 5th ed. Chicago: Year Book Medical Publishers, 2003.

Moore, K. L. Clinically Oriented Anatomy. 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2009.

Netter, F. H. Atlas of Human Anatomy. 4th ed. Philadelphia: Saunders, 2006.

White, T. D. Human Osteology. 2nd ed. San Diego: Academic Press, 2000.

White, T. D. The Human Bone Manual. Burlington, Mass: Academic Press, 2005.

Williams, P. L., et al. Gray’s Anatomy. 38th ed. New York: Churchill Livingstone, 1995.

Answers to Textbook Questions Answers for multiple-choice and matching questions 1–7 are located in Appendix of the textbook.

Short Answer and Essay Questions 8. At birth the cranium is huge relative to the face and body. The face (including jaw and nose) enlarges during youth to reach its adult proportions. (p. 213) 9. The normal vertebral curvatures are cervical, thoracic, lumbar, and sacral. The thoracic and sacral curvatures are primary. The cervical and lumbar are secondary. (pp. 202–203)

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10. Superiorly, the atlas articulates with the occipital bone; i.e., the superior articular facets of the atlas articulate with the occipital condyles of the occipital bone. Inferiorly, the atlas articulates with the axis; i.e., the inferior articular facets of the atlas articulate with the superior articular facets of the axis, whereas the dens of the axis articulate with the facet for the dens on the atlas. (p. 206, Fig. 7.7 and Fig 7.22) 11. (a) The discs act as shock absorbers, bind successive vertebrae together, and allow the spine to flex and extend. They also resist tension forces placed on the vertebral column. (b) The anulus fibrosus is a series of about 12 concentric rings that contain fibrocartilage and surround the nucleus pulposus. The nucleus pulposus is a sphere of gelatinous substance in the center of each intervertebral disc. (c) The nucleus pulposus herniates in a prolapsed disc. (pp. 203–204) 12. (a) The superior seven pairs of ribs of the thoracic cage (Ribs 1-7) which attach to the sternum directly are called true ribs or vertebrosternal ribs. (b) The interior five pairs of ribs (Ribs 8-12) are called false ribs because they attach to the sternum either indirectly or not at all. (c) Ribs 11 and 12 are called floating ribs because they do not attach to the sternum at all. (p. 211) 13. Cleft palate: a persistent opening in the medial part of the hard palate that interferes with sucking and can lead to aspiration of food into the lungs. A cleft palate is a common birth defect. (p. 212) 14. In the young adult skeleton, bone mass is maximal, and the water content in the intervertebral discs is optimal. In old age, the water content of the discs declines, and the discs become thinner and less resilient. The spine is shorter and may assume a flexed arc. All the bones lose mass. The thorax becomes more rigid with increasing age, mainly because of ossification of the costal cartilages. The cranial bones decline in mass less extensively than do the other bones, but the facial contours of aging individuals change (jaws look smaller, especially if the teeth are lost). (pp. 213–214) 15. Movements allowed by the lumbar region: flexion and extension of the spine, but not rotation. Movements allowed by the thoracic region: rotation and some lateral flexion, but not flexion or extension. (pp. 205–212, Table 7.2) 16. Anterior cranial fossa: frontal, ethmoid, sphenoid. Middle cranial fossa: sphenoid, temporal. Posterior cranial fossa: temporal, occipital. (pp. 187–194, Figs. 7.2b–c) 17. The thoracic cage forms a protective cage around the heart, lungs, and other organs. It also supports the shoulder girdles and upper limbs and provides attachment points for many muscles of the back, neck, chest, and shoulders. In addition, the intercostal spaces are occupied by the intercostal muscles, which lift and depress the thorax during breathing. (pp. 210–211) 18. While the cervical region has the largest range of movement, the lumbar region has the smallest. In order to position the head (and the special senses it houses), the cervical region allows for flexion, extension, lateral flexion, and rotation. However, the lumbar region only allows for flexion, extension, and some lateral flexion. In fact, this region needs to be more stable to carry the weight of the head, thorax, and upper limbs. (pp. 207–208, Table 7.2)

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19. The anterior fontanelle is between the frontal and parietal bones; the posterior fontanelle is between the parietal and occipital bones; and the sphenoidal fontanelle is between the greater wing of the sphenoid and temporal, and parietal and frontal bones. The mastoid fontanelle is between the occipital, temporal, and parietal bones. (p. 213, Fig. 7.28) 20. (a) Occipital bone - spinal cord (b) Temporal bone - facial nerve (CN VII) (c) Sphenoid bone - the mandibular division of trigeminal nerve (CN V) (d) Frontal bone - supraorbital arteries and nerves. (pp. 196–197) 21. In personalizing a scheme for distinguishing cervical, thoracic, and lumbar vertebrae, list specific distinguishing characteristics for each type of vertebra. Then, when you are handed an isolated vertebra, compare that vertebra to your list. For example, a vertebra with transverse foramina and a bifid spinous process is a cervical vertebra. A vertebra with demifacets or facets for rib articulation and a long and inferiorly pointing spinous process is a thoracic vertebra. A vertebra that has blunt posterior-facing spinous processes, a robust vertebral body, and lacks demifacets is a lumbar vertebra. Lower thoracic vertebrae resemble lumbar vertebrae, but these vertebrae are easily distinguished by observing the superior articular facets: Superior facets of thoracic vertebrae face posteriorly, and superior facets of lumbar vertebrae face posteromedially (or medially). (pp. 205–210, Table 7.2) 22. A head of a typical true rib articulates with vertebral bodies by two demifacets: One facet joins the body of the thoracic vertebra of the same number; the other joins the body of the immediately superior vertebra. The tubercle of the rib articulates with the transverse process of the vertebra of the same number. Costal cartilages provide secure and flexible attachments of the ribs to the sternum. (pp. 211–212, Figs. 7.24, 7.25)

Critical Reasoning and Clinical Applications Questions 1. Nina should not be worried. It is not unusual for a child to have a soft spot right in the middle of the skull. During birth, the skull bones are separated by spaces called ‘fontanelles’. They provide room for the brain to grow. The soft spot that Nina felt was the anterior fontanelle, which is likely to be felt up to 1½ to 2 years after birth. (p. 213) 2. Injury to the neck during automobile accidents, where the neck is suddenly forced forward, may be fatal. The dens of the second cervical vertebra may be forced into the brain stem, resulting in death. (p. 206) 3. Mr. Chester has lordosis, an exaggerated lumbar curvature of the spine. It is caused by the large weight of his anterior abdomen and by the fact that he must continuously thrust his shoulders posteriorly to counterbalance this anterior weight. (p. 213, Fig. 7.27) 4. Most herniated discs occur in the lumbar region, which continually experiences the largest compressive stresses. Lumbar vertebrae must support the weight of the entire upper body, plus whatever heavy objects one lifts. (p. 204, Fig. 7.19b) 5. The EMT could palpate Mary’s right side in the thoracic region, beginning along the superior aspect of her first rib and continuing inferiorly to the bottom of her twelfth rib.

Mary will probably wince in pain when the EMT reaches the exact location of the broken rib. (p. 211, Fig. 7.24)

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Interpreting Medical Images Questions Answers to Interpreting Medical Images questions are provided in the Instructor Resources area of Mastering A&P. Clinical Application: Herniated Disc: The herniated disc is located between lumbar vertebra 5 (L5) and the sacrum. The sacrum is identifiable by the sacral promontory, the convex curvature of the sacrum, and the fusion of the sacral vertebral segments.

Figure 7.24: As the rib extends from posterior to anterior, it curves inferiorly; thus, the anterior portion of the rib is located inferior to its posterior attachment to the vertebral column.

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 7: Bones, Part 1: The Axial Skeleton To the Student In Chapter 7, you are introduced to the 80 bones of the axial skeleton. The axial skeleton includes the skull, vertebral column, and thoracic cage. You will begin to master some important new terminology while you are learning the bones of the axial skeleton and their articulations with one another. Pay particular attention to bony markings of the axial skeleton because those landmarks are often sites for muscle attachment or articulation with other bones. By learning the functions of the many processes on bones, you are setting a great foundation for learning origins and insertions of muscles (Chapter 11). Additionally, pay close attention to the many named openings of the skull that are passageways for nerves, blood vessels, or other structures.

It will also benefit you greatly to include Practice Anatomy Lab 3.0 (PAL) (BC; DVD, Website) in your study of the axial skeleton. The Skeletal System section of the Human Cadaver module offers comprehensive study tools for learning bones of the axial skeleton.

Step 1: Distinguish the axial skeleton from the appendicular skeleton. __ List the major components of the axial skeleton. __ Describe the bones of the axial skeleton. __ Distinguish the axial skeleton from the appendicular skeleton by listing some of the bones of the appendicular skeleton.

Step 2: Comprehend general characteristics, bones, major sutures, and special cavities of the skull. __ Describe the posterior, middle, and anterior cranial fossa, the bones that comprise them, and the region of the brain contained within each fossa. __ Describe bones of the cranium and the bones with which each articulates. __ Distinguish the four major sutures of the skull. __ Describe each of the facial bones and the bones with which they articulate. __ Discuss why the sphenoid bone is considered the “keystone” of the skull and the maxillae are considered the “keystones” of the face. __ Describe the major cavities within skull and facial bones, particularly the orbital fossae, the nasal cavities, and the paranasal sinuses.

Step 3: Describe the general structures, functions, and regions of the vertebral column. __ Describe the general structure of the vertebral column, its major regions, and normal spinal curvatures. __ Explain the functions of each of the spinal curvatures and the function of the intervertebral discs. __ Describe each of the typical features common to all vertebrae.

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__ Distinguish among cervical, thoracic, and lumbar vertebrae by describing the specific regional characteristics of each category of vertebra. __ Describe the intervertebral foramina, and distinguish them from the vertebral canal.

Step 4: Describe the components of the thoracic cage and its general functions. __ Describe the bones that comprise the thoracic cage. __ Describe the components and major landmarks of the sternum, including clinically relevant regions for locating underlying structures. __ Describe the gross anatomy of a rib, and distinguish “true” from “false” ribs. __ Describe the unique characteristics of rib 1 and of ribs 10–12.

Step 5: Describe the major disorders of the axial skeleton. __ Describe the causes and consequences of cleft palate. __ Discuss the characteristics of and origins of kyphosis, lordosis, and scoliosis. __ Describe stenosis of the lumbar spine.

Step 6: Describe the changes in the axial skeleton throughout life. __ List several important reasons for the presence of fontanelles in an infant’s skull. __ List the name and location of each fontanelle of the infant skull. __ List the skull bones that form by intramembranous ossification as well as those formed by endochondral ossification. __ Describe changes in the skull from birth through old age. __ Discuss age-related changes that occur in the remainder of the axial skeleton.

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CHAPTER

8

Bones, Part 2: The Appendicular Skeleton

Lecture and Demonstration Objectives 1. Identify the bones that form the pectoral girdle, and explain their functions.

2. Identify the important bone features on the scapula and clavicle.

3. Identify the bones of the upper limb and their important features, and describe how they articulate with each other.

4. Name the bones contributing to the hip bone, and relate the structure of the pelvic girdle to its function.

5. Compare and contrast the male and female pelves.

6. Identify the bones of the lower limb and their important features, and describe how they articulate with each other.

7. Name the three supporting arches of the foot, and explain their importance.

8. Describe two congenital disorders: hip dysplasia and clubfoot.

9. Describe how the lengths of the limbs change, relative to the length of the head and trunk, as humans grow.

Suggested Lecture Outline I. The Appendicular Skeleton (p. 217, Table 8.1, Table 8.2, and Table 8.3) A. The appendicular skeleton consists of the pectoral and pelvic girdles and the bones of the upper and lower limbs.

II. The Pectoral Girdle (pp. 218–219, Figs. 8.1, 8.2) A. The pectoral girdle (shoulder girdle) is composed of a clavicle and scapula; the paired girdles do not form a complete ring as the term girdle implies.

1. Pectoral girdles are specialized for mobility and attach the upper limbs to the bony thorax.

B. Clavicles (pp. 218–219, Fig. 8.1) 1. The S-shaped clavicle (collarbone) functions as a brace for the shoulder; it also provides sites for muscle attachments. a. Clavicles articulate with the sternum of the axial skeleton as well as the scapulae.

Additionally, a ligament runs from the clavicle to the first rib.

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C. Scapulae (p. 219, Figs. 8.1–8.2) 1. The scapula articulates with the acromial end of the clavicle and with the head of the humerus.

III. The Upper Limb (pp. 219–226, Figs. 8.3–8.7, Table 8.1) A. The upper limb (extremity) is made up of 30 bones and forms the arm, forearm, and hand; it is specialized for mobility.

B. Arm (pp. 219–222, Fig. 8.3, Table 8.1) 1. The humerus is the single bone of the arm, or brachium. a. The head of the humerus articulates with the glenoid cavity of the scapula. b. At its distal end, the humerus articulates with the head of the radius and the trochlear notch of the ulna.

C. Forearm (p. 223, Figs. 8.4, 8.5, Table 8.1) 1. Two parallel long bones, the radius and ulna, form the skeleton of the forearm or antebrachium.

D. Hand (p. 224, Fig. 8.6, Table 8.1) 1. The skeleton of the hand includes the eight carpals of the wrist or carpus; the palm or metacarpus consists of five small long bones numbered I–V; the digits, or interphalangeals, consist of 14 miniature long bones called phalanges.

IV. The Pelvic Girdle (pp. 226–229, Figs. 8.7, 8.8, Tables 8.2, 8.3) A. The pelvic girdle (hip girdle) attaches the lower limbs to the spine of the axial skeleton and supports the visceral organs of the pelvis.

B. The pelvic girdle consists of the paired coxal bones (hip bones) and sacrum.

C. The hip bones unite anteriorly with each other and with the sacrum posteriorly to form the pelvis.

D. Each hip bone is formed by three bones that fuse at the acetabulum.

1. Ilium (pp. 226–228, Fig. 8.7, Tables 8.2, 8.3) a. Forms the superior region of the hip bone.

2. Ischium (p. 228, Figs. 8.7–8.8, Tables 8.2, 8.3) a. Forms the posteroinferior region of the hip bone.

3. Pubis (p. 228–229, Fig. 8.7, Tables 8.2, 8.3) a. Forms the anterior region of the hip bone.

4. Pelvic Structure and Child Bearing (p. 229, Fig. 8.8, Table 8.3) a. The true and false pelves are the two divisions of the bony pelvis. The false pelvis is part of the abdomen, and the true pelvis forms a deep bowl containing the pelvic organs. b. The female pelvis is adapted for childbearing: it is lighter, wider, and shallower than the male pelvis.

V. The Lower Limb (pp. 229–236, Figs. 8.9–8.12, Table 8.3) A. The three segments of the lower limb (lower extremity) are the thigh, leg, and foot; collectively, 30 bones compose the lower limb; it is specialized for weight bearing and locomotion.

1. Thigh (pp. 229–231, Fig. 8.9, Table 8.3) 86

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a. The femur is the single bone of the thigh. The femur is the longest and strongest bone in the body.

B. Leg (pp. 231–234, Fig. 8.10, Table 8.3) 1. The leg is the region between the knee and ankle. Its two bones are the tibia and fibula. a. The tibia is the weight-bearing bone of the leg. b. The fibula does not bear weight, but it is the origin of several muscles.

C. Foot (pp. 234–236, Figs. 8.11–8.12, Table 8.3) 1. The foot includes seven bones of the tarsus, five bones of the metatarsus, and 14 phalanges of the toes. a. The seven bones of the tarsus make up the posterior half of the foot. b. The metatarsus is formed from five metatarsals numbered I–V. c. Each of the phalanges has a proximal, middle, and distal phalanx, except the great toe, which has only a proximal and distal phalanx.

2. The foot is supported by three arches that distribute the weight of the body to the heel and ball of the foot.

VI. Disorders of the Appendicular Skeleton (p. 236, Fig. 8.13) A. Most disorders are bone fractures; other significant disorders are birth defects, such as hip dysplasia and clubfoot.

VII. The Appendicular Skeleton Throughout Life (p. 237, Fig. 8.14) A. During growth, the arms and legs grow faster than the head and trunk.

1. At birth, the head and trunk are roughly 1.5 times the length of the lower limbs.

2. Lower limbs grow more rapidly than the trunk, and at age 10 the head and trunk are about the same length as the lower limbs.

B. After middle age, all bones lose bone mass; osteoporosis and limb fractures become more common.

Lecture Hints 1. Distinguish among basic parts of the appendicular skeleton. Emphasize that the pectoral girdle and the pelvic girdle are “appended” because they attach the limb bones to the rest of the skeleton. Students erroneously think the pelvic girdle is a part of the axial skeleton in the “midline.”

2. Using Figure 8.1, describe the bones of the pectoral girdle and their functions. Explain that the clavicle functions as a brace and, if it is fractured, the entire shoulder collapses medially.

3. Demonstrate important bone markings on the clavicle and scapula.

4. Encourage students to thoroughly master identification of all processes of the scapula to facilitate the future study of shoulder and arm muscle attachments.

5. Explain the articulation between the clavicle and the scapula.

6. Describe how the scapula articulates with the humerus.

7. Explain to students that the word “arm” is used in a strict anatomical sense, referring to only the upper portion of the limb between the shoulder and elbow joints. ..

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8. Emphasize the importance of anatomical position to the bones of the forearm. Refer to Figures 1.3 and 8.4.

9. Devise a simple mnemonic for remembering the names of the bones of the wrist.

10. Using Figure 8.7, identify the bones of the pelvic girdle; explain their locations and markings.

11. Explain the bones of the pelvic girdle and three separate bones of the composite hip bone. Refer to Figure 8.7b.

12. Describe how when the body is seated, the weight of the body is borne by the ischial tuberosities, the strongest parts of the pelvic girdle.

13. Distinguish the true from the false pelvis.

14. Identify points of comparison between male and female pelves. Refer to Table 8.2.

15. Relate female pelvic structure to childbearing.

16. Name and describe bone markings, and explain the articulations of the bones of the lower limb. Refer to Figures 8.9–8.12.

17. Explain to students that the word “leg,” used in a strict anatomical sense, refers to only the portion of the lower limb between the knee and ankle.

18. Distinguish the tibia from the fibula in terms of size, location, bony features, functions, articular surfaces, and articulations.

19. Explain the importance of arches of the foot and clues provided by a wet footprint.

20. Describe disorders of the appendicular skeleton—hip dysplasia and clubfoot (Figure 8.13). Also review and emphasize the importance of understanding the different types of fractures and their causes (covered in Chapter 6).

21. Using Figure 8.14, discuss the changes in body proportions throughout life.

Classroom Discussion Topics and Activities 1. Obtain male and female pelvic girdles; point out the childbearing features of the female pelvis.

2. List several skeletal landmarks that are used to guide a nurse or physician in giving shots, locating areas for surgery, and assisting in the diagnosis of internal conditions.

3. Discuss the effects of exaggerated exercise or the complete lack of exercise on bones such as the tibia, femur, and humerus (a) during childhood and (b) during adulthood.

Then explain why the bones of the lower limb are the thickest and heaviest bones in the body.

4. Numerous children are born with a congenital hip defect. Ask students why this area is affected so often and what can be done to correct the defect.

5. Place a disarticulated appendicular bone in an opaque paper bag and have the students identify it using only their sense of touch.

6. Provide a complete disarticulated skeleton, and instruct students to arrange bones in their correct positions.

7. Use an articulated skeleton to demonstrate its protective and support aspects; have students identify the individual bones.

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8. Provide students with unlabeled diagrams of Figure 8.6, and instruct students to mark the position of a ring and/or a watch on the figure.

Clinical Questions 1. A group of high school students suffered a serious car accident as they drove to the prom.

Brad suffered multiple injuries to his lower left limb. Protruding through the skin was a splintered portion of the longest bone in the body. This bone was the (a) ____ . Adrian didn’t consider her injuries serious, so she walked several blocks to find help. Then she noticed that her right knee was not functioning normally; examination revealed a fractured kneecap. Another name for the kneecap is the (b) ____ . She also realized that she had fractured several toe bones, or (c) ____ . Greg fractured his heel bone, more correctly called the (d) ____.

Answers: (a) femur; (b) patella; (c) phalanges; (d) calcaneus.

2. The femur is the strongest bone in the body, but it is also one of the most often fractured bones in the skeleton. How come the strongest bone can break so often?

Answer: The neck of the femur is not as strong as its shaft, and it is often weakened in people with osteoporosis. When weakened, the neck of the femur breaks under the weight of the body; this is a broken hip.

Art Resources Figure 8.1 Figure 8.2 Figure 8.3 Figure 8.4 Figure 8.5 Figure 8.6 Figure 8.7 Figure 8.8 Figure 8.9 Figure 8.10 Figure 8.11 Figure 8.12 Figure 8.13 Figure 8.14 Table 8.1 Table 8.2 Table 8.3

The pectoral girdle and clavicle.

The scapula.

The humerus of the right arm and detailed views of articulation at the elbow.

Radius and ulna of the right forearm.

Location of radial and ulnar styloid processes.

Bones of the hand.

Bones of the pelvic girdle.

Midsagittal section through the pelvis.

The right patella (a) and femur (b).

The tibia and fibula of the right leg.

Bones of the right foot.

Arches of the foot.

Congenital disorders of the lower limb.

Change in body proportions throughout life.

Bones of the Upper Limb Comparison of the Male and Female Pelves Bones of the Lower Limbs

Teaching with Art Figure 8.7

Bones of the pelvic girdle.

Textbook p. 227

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Checklist of Key Points in the Figure • Explain that a complete pelvic girdle contains two hip bones as well as the sacrum and coccyx of the vertebral column.

• Review the concept of fused sacral vertebrae; explain (review) transverse fusion lines, articular processes, sacroiliac joints, the median crest as fused spinous processes, and the lateral crest as fused tips of transverse processes.

• Review the foramina; introduce the role of the foramina in anticipation of a discussion of spinal nerves in the chapter covering the nervous system.

• Explain the location and significance of the body’s center of gravity, which lies 1 cm posterior to the sacral promontory.

• Point out the sacroiliac joint.

• Relate the strength of the pelvic girdle to its functions.

• Discuss why so many names of bones are used for the hip bone and how to distinguish the Y-shaped junction within the acetabulum.

• Point out several prominent bony features, such as the iliac crest, obturator foramen, and acetabulum; explain functions of each.

• Explain the difference between the false pelvis and the true pelvis.

Common Conceptual Difficulties Interpreting the Art • A hip bone is a fusion of three bones with distinguishable sutures in a child but with indistinguishable sutures in the adult.

• The acetabulum and obturator foramen result from the fusion of these three bones.

• A dense, fibrous membrane fills most of the opening of the obturator foramen, leaving room for the passage of blood vessels and nerves.

Art Exercise 1. Provide students with unlabeled copies of Figure 8.7a. Instruct students to color the bony pelvic brim to distinguish the upper (greater) false pelvis from the lower (lesser) true pelvis.

2. Instruct students to indicate the bony landmarks of the pelvic brim: pubic crest, arcuate line of the ilium, inferior edges of the sacral ala, and the sacral promontory.

3. Using an unlabeled copy of Figures 8.7b–c, instruct students to color the individual bones; also instruct students to indicate right or left, directional view, and to label bony landmarks.

Critical Reasoning Ask students to name specific organs located in the false pelvis and the true pelvis. For assistance, students may refer to Chapter 1.

Answer: The rectum and anal canal of the large intestine, urinary bladder, and urethra as well as male and female reproductive organs (male: prostate gland and seminal glands; female: ovaries, uterine tubes, and uterus) occupy the true pelvis. The false pelvis is actually part of the abdomen and contains abdominal organs, such as portions of the large intestine and small intestine.

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Supplemental Course Materials Library Research Topics 1. Research congenital skeletal malformation to find examples of abnormalities of the appendicular skeleton.

2. Research bipedal locomotion, and explore the adaptations that led to this type of movement.

3. Research current trends in bone repair.

4. Archaeologists and paleontologists have unearthed many prehistoric bones and skulls.

How are the soft features and tissues of humanlike creatures and animals reconstructed using their skeletal remains?

Suggested Readings Agur, A. M. Grant’s Atlas of Anatomy. 13th ed. Baltimore: Lippincott Williams & Wilkins, 2012.

Alexander, R. M. Human Bones: A Scientific and Pictorial Investigation. New York: Pi Press, 2004.

Bass, William. Death’s Acre: Inside the Legendary Forensic Lab—the Body Farm—Where the Dead Do Tell Tales. New York: Berkley Trade, 2004.

Gray, H., et al. Gray’s Anatomy. 38th ed. London: Churchill Livingstone, 1995.

Katzenberg, A. M. and S. R. Saunders. Biological Anthropology of the Human Skeleton.

2nd ed. New Jersey: John Wiley & Sons, Hoboken, 2008.

McMinn, R., et al. Color Atlas of Human Anatomy. 5th ed. Chicago: Year Book Medical Publishers, 2003.

Moore, K. L. Clinically Oriented Anatomy. 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2009.

Netter, F. H. Atlas of Human Anatomy. 4th ed. Philadelphia: Saunders, 2006.

Rohen, J. W. Color Atlas of Anatomy: A Photographic Study of the Human Body. 6th ed.

Baltimore: Lippincott Williams & Wilkins, 2006.

Schwartz, J. H. Skeleton Keys: An Introduction to Human Skeletal Morphology, Development and Analysis. 2nd ed. Oxford: Oxford University Press, 2006.

White, T. D. The Human Bone Manual. Burlington, Mass.: Academic Press, 2005.

White, T. D. Human Osteology. 2nd ed. San Diego: Academic Press, 2000.

Zeliadt, Nicholette, “Skeleton Key: Bone Cells May Play a Part in Regulating the Body’s Metabolism.” Scientific American July 26, 2010.

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Answers to Textbook Questions Answers for multiple-choice questions 1–10 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 11. The typical male and female pelvic girdles exhibit several differences (Table 8.2 p. 230).

The female pelvis, adapted for childbearing, tends to be wider, shallower, and lighter than that of a male. These features provide more room in the true pelvis that must be wide enough for an infant’s head to pass during birth. (p. 229) 12. The female pelvic inlet and outlet are wider, the pelvis is shallower, lighter, and wider than that of the male, and the ischial tuberosities are farther apart. Furthermore, the pubic arch forms a larger angle. (p. 230, Table 8.2) 13. The three arches of the foot function to distribute the weight of the body. Together, they form a half dome that distributes approximately half of a person’s standing and walking weight to the heel bones and half to the heads of the metatarsals. Prolong standing and running on hard surfaces may cause the arches of the foot to flatten, leading them to function improperly. (p. 235) 14. Hip dysplasia: The acetabulum is incompletely formed, and the head of the femur slips out of the hip joint. Hip dysplasia is a common birth defect. (p. 236) 15. The true pelvis is the pelvic region inferior to the pelvic brim. The false pelvis, actually part of the abdomen, lies superior to the pelvic brim (and extends to the level of the iliac crest). (p. 229) 16. The correct names are tibia (not “fibia”) and fibula (not “tibula”). (pp. 233–234) 17. See Figure 8.2 on p. 220.

18. (a) Lesser trochanter: femur (p. 231) (b) intercondylar eminence: tibia, superior part. (p. 232) (c) capitulum: the lateral condyle on the distal end of the humerus. (p. 221) (d) olecranon: ulna, proximal posterior end. (p. 223) (e) acromion: scapular, posterolateral side (p. 225) (f) capitate: carpal bones, distal row. (p. 225) (g) navicular: tarsal bones, middle. (p. 233) 19. (a) The leg’s tibia and fibula and the foot’s talus are a part of the ankle. (p. 234-235) (b) Usually, ankle fractures involve the lateral malleolus of the fibula and/or the medial malleolus of the tibia because of the forceful inversion or eversion of the foot. (p. 234) 20. Tom was helping the students learn the obturator foramen in the hip bone. (p. 229) 21. The bones of the appendicular skeleton that have a tuberosity are the humerus, radius, and tibia. These tuberosities are the deltoid tuberosity, radial tuberosity, and tibial tuberosity, respectively. (pp. 221, 223, and 234) 22. The structural features of the foot related to its weight-bearing and locomotory functions include short phalanges, the arrangement of tarsals and metatarsals, and the arches of the foot. Body weight is carried primarily by the posterior two tarsals, the talus and calcaneus. Additionally, the first metatarsal plays an important role in supporting the weight of the body. The three arches of the foot also play a critical role in supporting body weight.

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longitudinal arch, whose keystone is the cuboid, redistributes some weight to the calcaneus and fifth metatarsal. The transverse arch follows the line of joints between the tarsals and metatarsals. The three arches act together so that approximately half a person’s standing and walking weight is distributed to the calcaneus and talus and half is carried by the heads of the metatarsals. (pp. 235–236)

Critical Reasoning and Clinical Applications Questions 1. The shoulder joint is formed between the scapula’s glenoid cavity and the humerus’ head. During a shoulder dislocation, the humerus’ head is pushed/pulled out of its socket (glenoid cavity). Unlike shoulder dislocations, hip dislocations happen less frequently because the hip bone’s acetabulum forms a deeper cup for the femur’s head to firmly fit into. Thus, the hip bone is less likely to be pulled out of its socket. (pp. 218–219, 226) 2. The newborn has a deformity known as ‘clubfoot’. This is characterised by the feet being medially rotated and the toes directed downwards, making walking difficult. This needs to be corrected at an early stage using plaster cast, passive exercises, or by surgery in severe cases. (p. 236) 3. These are the symptoms of the repetitive strain disorder called carpal tunnel syndrome. (p. 226) 4. The tibia is the bone of the leg that receives the weight of the body from the femur and transmits it to the foot. In its upper part, its condyles and tuberosity are palpable. The anterior border, medial surface and the medial malleolus are also subcutaneous which could be palpated. (pp. 233–234) 5. Fracture of the neck of the femur on the right side would be the most likely diagnosis.

Aging usually leads to osteoporosis. Bone loss due to osteoporosis causes the neck of the femur to weaken and fracture from stresses that a normal, healthy bone can withstand.

This fracture may cause walking to be painful or result in a person falling. (p. 229)

Interpreting Medical Images Questions Answers to Interpreting Medical Images questions are provided in the Instructor Resources area of Mastering A&P. Figure 8.2: The Y of the scapula in the lateral view is composed of the coracoid process, acromion and spine of the scapula, and the lateral border of the scapula. This view is used to assess the position of the humeral head in the glenoid.

Clinical Application: Palpation of Colles’ Fracture: The left hand is shown in these radiographs: a lateral view in the x-ray image on the left, and an anterior-posterior (AP) view in the xray image on the right. The two carpals, from lateral to medial, that articulate with the radius are the scaphoid and lunate.

Figure 8.10: The bones viewable in this radiograph are the femur, tibia, fibula, and patella (in a shadow over the femur).

Clinical Application: Ankle Fractures: The portion of the tibia that is fractured is the medial malleolus. The lateral malleolus, part of the fibula, is also fractured in this radiograph.

Figure 8.12: The two tarsals that articulate with the talus are the calcaneus inferiorly and the navicular anteriorly.

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 8: Bones, Part 2: The Appendicular Skeleton To the Student Chapter 8 is an introduction to the bones of the appendicular portion of the human skeleton.

Of the 206 total bones in the body, you mastered all the bones of the skull, vertebral column, and thoracic cage in the preceding chapter. This chapter covers the remaining bones. Continued mastery of new terminology is necessary. Your goal is to understand how the individual bones of the appendicular skeleton form the pectoral and pelvic girdles and upper and lower limbs.

In addition to studying the textbook, you will benefit greatly from utilizing Practice Anatomy Lab 3.0 (PAL) (BC; CD-ROM, website) in your study of the appendicular skeleton.

The Skeletal System section of the Human Cadaver module offers comprehensive study tools for learning bones of the appendicular skeleton and their bony landmarks.

Step 1: Distinguish the axial from the appendicular skeleton. __ Name the bones of the axial skeleton. __ Name the bones of the appendicular skeleton.

Step 2: Understand the bones that form the pectoral girdle and upper limb. __ Name the bones that form the pectoral girdle. __ Explain how bones of the pectoral girdle articulate with each other. __ Explain the functions of the pectoral girdle. __ Indicate major bone markings of the bones of the pectoral girdle and upper limb. __ Describe the bones of the arm, forearm, wrist, and hand, including articulations.

Step 3: Understand the bones that form the pelvic girdle and lower limb. __ Name the bones that form the pelvic girdle. __ Explain the articulations between the bones forming the pelvic girdle. __ List the functions of the pelvic girdle. __ Indicate the major bone markings of the bones of the pelvic girdle and lower limb. __ Compare and contrast male and female pelves. __ Describe the bones of the thigh, leg, and foot, including articulations. __ Describe the three arches of the foot. Include the bones that form each arch, keystones of the arches, and functions of the arches.

Step 4: Describe disorders of the appendicular skeleton. __ Describe causes and consequences of congenital hip dysplasia, and list relevant treatments. __ Describe causes of clubfoot and its treatments.

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Step 5: Understand changes in the appendicular skeleton throughout life. __ Explain how the upper-lower (UL) body ratio changes with age. __ List age-related changes that occur in the appendicular skeleton.

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Joints

Lecture and Demonstration Objectives 1. Classify the joints by structure and by function.

2. Describe the general structure of fibrous joints. Provide examples of the three types of fibrous joints.

3. Describe cartilaginous joints, and give examples of the two main types.

4. Describe the structural characteristics shared by all synovial joints.

5. Discuss the role of weeping lubrication in the function of synovial joints.

6. Describe the structure and function of articular discs, bursae, and tendon sheaths.

7. Name and describe the common types of body movements.

8. Classify synovial joints into six categories according to the shapes of their joint surfaces and the types of movement they allow. Give examples of joints in each class.

9. List three factors that influence the stability of synovial joints.

10. Describe the key features of the temporomandibular, sternoclavicular, shoulder, elbow, wrist, hip, knee, and ankle joints.

11. Name the most common injuries to joints, and discuss the problems associated with each.

12. Name and describe the types of arthritis.

13. Describe how joints develop and how their function may be affected by aging.

Suggested Lecture Outline I. Classification of Joints (p. 241, Table 9.1) A. Joints (articulations) are sites where two or more bones meet; joints give the human skeleton mobility and hold it together.

B. Joints are classified by both structure and function.

1. Functional classification focuses on the amount of movement allowed at the joint.

There are three functional classifications for joints: synarthroses (immovable joints), amphiarthroses (slightly movable joints), and diarthroses (freely movable joints).

2. Structural classification is based upon the material binding the joint together and the presence or absence of a joint cavity. There are three structural classifications for joints: fibrous joints, cartilaginous joints, and synovial joints.

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II. Fibrous Joints (pp. 241–242, Fig. 9.1, Table 9.1) A. Fibrous joints are connected by dense regular connective tissue and lack a joint cavity.

1. Sutures (p. 241, Fig. 9.1, Table 9.1) a. Sutures (immovable and located between skull bones) B. Syndesmoses (p. 242, Fig. 9.1, Table 9.1) 1. Syndesmoses (connected exclusively by ligaments and amount of movement varies from no movement to slightly or freely movable, depending on length of ligaments) C. Gomphoses (p. 242, Fig. 9.1, Table 9.1) 1. Gomphoses (a peg-in-socket joint for tooth attachment)

III. Cartilaginous Joints (p. 242, Fig. 9.2, Table 9.1) A. Bones are united by cartilage in cartilaginous joints, and a joint cavity is lacking.

1. Synchondroses (p. 242, Fig. 9.2, Table 9.1) a. Synchondroses (united by hyaline cartilage and immovable) B. Symphyses (p. 242, Fig. 9.2, Table 9.1) 2. Symphyses (united by fibrocartilage and slightly movable)

IV. Synovial Joints (pp. 242–243, Figs. 9.3–9.17, Tables 9.2, 9.3) A. Synovial joints are characterized by a fluid-filled joint cavity; all synovial joints are freely movable (diarthrotic), and most of the body’s joints are in this class.

1. General Structure of Synovial Joints (pp. 243–245, Figs. 9.3–9.5, Table 9.1) a. All synovial joints have general structural characteristics in common. i. Articular cartilage ii. Joint (articular) cavity iii. Articular capsule iv. Synovial fluid v. Reinforcing ligaments vi. Nerves and vessels B. Certain synovial joints contain menisci (articular discs).

C. Bursae and tendon sheaths are bags of lubricant (synovial fluid) that reduce friction between adjacent structures associated with synovial joints.

D. Synovial joints are able to function because a mechanism called weeping lubrication reduces friction in the joint.

2. Movements Allowed by Synovial Joints (pp. 245–249, Figs. 9.6–9.7) a. Synovial joints allow three basic types of movements. i. Gliding of one bone across another bone ii. Angular movements (flexion, extension, abduction, adduction, and circumduction) iii. Rotation of a bone around its long axis b. Special movements of the body do not fit the basic categories. i. Supination and pronation of the forearm ii. Dorsiflexion and plantar flexion of the foot iii. Inversion and eversion of the foot ..

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iv. Protraction and retraction of the mandible and scapula v. Elevation and depression of the mandible and scapula vi. Opposition of the thumb C. Types of Synovial Joints (p. 249, Fig. 9.8) 1. Shapes of the articulating bone surfaces determine the movements allowed at the joint. i. Plane (translational) ii. Hinge or pivot (uniaxial) iii. Condylar or saddle (biaxial) iv. Ball and socket (multiaxial) D. Factors Influencing the Stability of Synovial Joints (pp. 249–252) 1. Several factors influence the stability of synovial joints: shapes of the articulating surfaces, ligaments, and tone of muscles whose tendons cross the joint.

V. Selected synovial joints. Each of the selected joints contains all structures common to synovial joints. (pp. 253–266, Figs. 9.9–9.17) A. Temporomandibular Joint (pp. 254–256, Fig. 9.9, Table 9.3) 1. Temporomandibular joint—a diarthrotic joint; the condyle of the mandible articulates with the mandibular fossa of the temporal bone.

B. Sternoclavicular Joint (p. 256, Fig. 9.10, Table 9.3) 1. Sternoclavicular joint—a saddle joint formed between the manubrium of the sternum and the medial end of the clavicle. This joint’s unique shape allows for multiple complex movements.

C. Shoulder (Glenohumeral) Joint (pp. 256–258, Fig. 9.11, Table 9.3) 1. Shoulder (glenohumeral) joint—the most movable joint of the body; formed between the head of the humerus and the glenoid cavity of the scapula.

D. Elbow Joint (pp. 258–259, Fig. 9.12, Table 9.3) 1. Elbow joint—a hinge joint, which is stabilized by the articulation of the trochlear notch of the ulna and the trochlea of the humerus. (Fig 9.12) E. Wrist Joint (p. 259, Fig. 9.13, Table 9.3) 1. Wrist joint—has two major joint surfaces: the wrist joint and the intercarpal joint.

F. Hip Joint (p. 260, Fig. 9.14, Table 9.3) 1. Hip joint—a true ball-and-socket joint. Movement is possible in all axes but is limited by the deep articular surface ligaments. (Fig. 9.14) G. Knee Joint (pp. 261–264, Figs. 9.15–9.16, Table 9.3) 1. Knee joint—the most complex joint; acts primarily as a hinge.

H. Ankle Joint (pp. 264–266, Fig. 9.9, Table 9.3) 1. Ankle joint—a single hinge between the inferior ends of the tibia and fibula and the talus of the foot.

VI. Disorders of Joints (pp. 266–269, Figs. 9.18–9.20) A. Joint Injuries (pp. 266–267, Fig. 9.18) 1. There are three basic types of joint injuries: sprains, dislocations, and torn cartilage.

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B. Inflammatory and Degenerative Conditions (pp. 267–269, Figs. 9.19–9.20) 1. Examples of joint inflammatory and degenerative conditions are bursitis, tendonitis, many types of arthritis (including osteoarthritis, rheumatoid arthritis, and gout), and Lyme disease.

VII. The Joints Throughout Life (p. 269) A. Joints are derived from embryonic mesenchyme between the cartilaginous “bone models” in the late embryo.

B. Osteoarthritis is the most common joint problem associated with advancing age.

Lecture Hints 1. Distinguish clearly the two systems of joint classification: structural and functional.

Continue to emphasize the anatomical theme of how structure relates to function.

2. Distinguish fibrous, cartilaginous, and synovial joints. Include general structure, specific examples and body locations, and type of movements allowed by each joint classification.

3. Characterize fibrous and cartilaginous joints by their lack of a joint cavity.

4. Explain the significance of synovial fluid as a filtrate of blood and its role in joint lubrication.

5. Explain to students that joints are the weakest part of the skeleton. Discuss how joints are subjected to the same physical forces as the bony skeleton and are more vulnerable to injuries because they are composed of soft tissues. Emphasize that the structure and function of joints relate directly to joint disorders such as sprains or arthritis.

6. Remind students that although most articulations unite bone to bone, some articulations join bone to cartilage.

7. Point out the difference between the joint of the first rib and sternum in contrast to those of ribs 2–10.

8. Reinforce that the structure of the joint determines a specific movement at a joint.

Explain why the shoulder joint is the most freely movable joint in the body.

9. During discussion of movements of synovial joints, review body planes as planes of movement for better comprehension of specific movements.

10. Emphasize that a muscle must cross a joint to cause movement. Explain how two or more different movements are possible at some joints.

11. Explain carefully to students that movement occurs when a muscle contracts. Students should study movement carefully and thoroughly so that the study of muscles in the next chapter will not be so difficult to master.

12. Compare and contrast the structures and functions of the glenoid cavity and acetabulum.

13. For each of the following selected synovial joints, name the articulating bones, the structural type of joint, the functional type of joint, and all movements permitted: temporomandibular joint, shoulder joint, elbow joint, hip joint, and ankle joint.

14. If only one selected synovial joint is discussed in detail, the best choice is the knee.

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Classroom Discussion Topics and Activities 1. Select a student to illustrate several types of movements, such as abduction and adduction, and flexion and extension. Encourage group participation by playing “The Chicken Song” and having students make movements of each joint as you demonstrate. (Example: Flex the thigh, abduct the arm, extend the leg at the knee.)

2. Ask a student to crouch into a fetal position with hands forming fists. Instruct the rest of the class to identify the flexed joints.

3. Instruct students to perform an action as the instructor announces it. The class will look and sound like an aerobics class if done energetically. Be sure to include the command “flex arm” because as many as 95% of the students may flex the forearm instead of the arm.

4. Using a synovial joint model of the knee or shoulder, illustrate all the characteristic features of a synovial joint.

5. Use a fresh beef joint to provide an excellent demonstration of joint features: capsule, cavity, ligaments, articular cartilage, periosteum, and articular disc or meniscus. If enough muscle is attached, demonstrate movement by pulling the muscle or the tendon.

6. Use an articulated human skeleton to demonstrate joints such as sutures, cartilaginous joints, gomphoses, and synovial joints. Show how articulating bone surfaces have complementary shapes. Ask students to explain how the shapes of some specific bone surfaces at joints determine the movements possible at those joints. The elbow, jaw, ankle, hip, and intercarpal joints are especially good for this purpose.

7. To illustrate weeping lubrication, use a smooth plastic ball to press soapy water from a damp sponge.

8. Obtain x-ray films of patients with osteoarthritis, rheumatoid arthritis, and joint replacements. Ask students to identify bones and which structures show abnormalities.

9. Discuss how shots of an antiinflammatory hormone, a corticosteroid called cortisone, can readily reduce the swelling that follows joint injuries. Why is it dangerous for athletes to continue getting these shots? (Corticosteroids are discussed in depth in Chapter 17, The Endocrine System, so you may refer students to that chapter.)

10. Ask students why physical therapists suggest that athletes warm up with various stretching exercises before proceeding with rigorous physical activity. Of what value are these exercises for the joint areas?

11. Ask students to make an informal survey of family and friends to find out how many of them have an artificial joint or know of someone who does. The numbers will be surprising. Some individuals may volunteer information about their pets as well.

12. Provide a fill-in-the-blank worksheet for an exercise in joint classification. Instruct students to apply three terms to each of the joints on a numbered list.

Suggested terms: amphiarthrosis, diarthrosis, synarthrosis, ball and socket, condylar, gliding, hinge, pivot, saddle, suture, symphysis, synchondrosis, syndesmosis, gomphosis, fibrous joint, cartilaginous joint, and synovial joint.

Suggested joints: (1) interlocking joint between cranial bones, (2) knee joint, (3) elbow joint, (4) intervertebral joint between articular processes, (5) articulation between tibia and fibula at distal ends, (6) shoulder joint, (7) symphysis pubis, (8) joint between the diaphysis and epiphysis of a long bone of a child, (9) joint between the first metacarpal and 100

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carpal (trapezium), (10) wrist (carpals to carpals), (11) ankle (tarsals to tarsals), (12) ankle (talus to tibia and fibula), (13) hip joint, (14) axis and atlas, (15) interphalangeal joint (between phalanges), (16) phalanges to metacarpals, (17) interphalangeal joint (between phalanges), (18) phalanges to metatarsals, (19) teeth and mandible or maxilla, (20) temporomandibular joint, (21) occipital bone and atlas, (22) sternum and ribs, (23) vertebrae and ribs, and (24) intervertebral joint between adjacent vertebral bodies.

Clinical Questions 1. Paul Jones fell off the staging while painting his house. His left arm and side struck the ground with a good deal of force. When he picked himself up, he felt sharp pain in his left shoulder and was unable to move his left arm. During the examination, his physician recorded that the normal roundness of the left shoulder was absent and that there was a bulge inferior to the lateral end of the left clavicle. What is your diagnosis?

Answer: Inferior and anterior dislocation of the left shoulder.

2. Jenny’s father loved to hold his 4-year-old daughter by her hands and swing her around in great circles. One day Jenny’s glee was suddenly replaced with tears, and she screamed that her left elbow hurt. When examined, the little girl was holding her elbow semiflexed and her forearm pronated. What is your diagnosis?

Answer: The annular ligament around the head of the radius had been torn, and the head of the radius had been pulled distally to slip out of this ring. (The swinging accident may also have pulled and injured the child’s biceps brachii muscle.)

3. Crazy Legs Girsh, an American League pitcher, had been warming up for an important baseball game when he threw an extremely hard sidearm pitch and felt something “pop” in his shoulder. The trainer said he had injured his rotator cuff. What and where is the injury?

Answer: The rotator cuff is a collection of muscles and tendons that encircles the shoulder joint and fuses with the articular capsule. The injury probably resulted from stretching and tearing some of these muscles.

4. Amy studied at her desk for seven straight days for her nursing board exams. Soon she noticed extreme pain and swelling on the point (olecranon) of both her elbows. What had happened?

Answer: Amy had developed “student’s elbow,” or olecranon bursitis. Obviously, she had rested her elbows on the desk as she studied, and the continual pressure eventually irritated the bursa deep to the skin over the olecranon.

Art Resources Figure 9.1 Figure 9.2 Figure 9.3 Figure 9.4 Figure 9.5 Figure 9.6 Figure 9.7 ..

Fibrous joints.

Cartilaginous joints.

General structure of synovial joints.

Dissection of the knee.

Bursae and tendon sheaths.

Movements allowed by synovial joints.

Some special body movements.

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Figure 9.8 Figure 9.9 Figure 9.10 Figure 9.11 Figure 9.12 Figure 9.13 Figure 9.14 Figure 9.15 Figure 9.16 Figure 9.17 Figure 9.18 Figure 9.19 Figure 9.20 Table 9.1 Table 9.2 Table 9.3

Types of synovial joints.

The temporomandibular (jaw) joint.

The sternoclavicular joint.

The shoulder joint.

The elbow joint.

The wrist joints.

The hip joint.

The knee joint.

Stabilizing function of the cruciate ligaments.

The ankle joint.

Arthroscopic photograph of a torn medial meniscus.

Osteoarthritis of the knee.

A hand deformed by rheumatoid arthritis.

Summary of Joint Classes Movements at Synovial Joints Structural and Functional Characteristics of Body Joints

Teaching with Art Figure 9.15

The knee joint: (a) Sagittal section; (b) Superior view.

Textbook pp. 261–262 Checklist of Key Points in the Figure • Explain that the knee is the largest and most complex joint in the body; review articulations.

• Explain the bicondylar shape of the knee joint.

• Review basic synovial joint structure.

• Explain that joints are the weakest part of the bony skeleton and that the knee joint has exceptional features for added stability.

• Point out the many different types of ligaments that stabilize and strengthen the capsule of the knee joint.

• Explain that the knee capsule is reinforced by muscle tendons such as the strong tendons of the quadriceps femoris group of muscles and the tendon of the semimembranosus.

• Identify the medial and lateral menisci. Knee menisci deepen the articulating surface of the tibia to prevent side-to-side rocking of the femur on the tibia and absorb shock transmitted to the knee.

• Note the intracapsular (cruciate) ligaments, including their attachment points. The cruciate ligaments prevent anterior/posterior displacement of the articulating bone and help secure the joint.

Common Conceptual Difficulties Interpreting the Art • Although enclosed in one joint cavity, the knee joint is actually three joints in one; the femoropatellar joint, the lateral and medial joints between the femoral condyles, and the menisci of the tibia, known collectively as the tibiofemoral joint.

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• Note that the articular capsule merges with the tissue of the periosteum.

• Explain that the articular capsule is missing from the anterior surface of the knee joint and is replaced at that location with ligaments: the patellar ligament, and the medial and lateral patellar retinacula.

• Point out that the patellar ligament is a continuation of the tendon of the quadriceps femoris group of muscles.

Art Exercises 1. Provide students with unlabeled copies of Figure 9.3a, A typical synovial joint. Instruct students to add modifications to the drawing that are characteristic of the knee joint, including menisci and intracapsular ligaments.

2. Provide students with copies of unlabeled anterior/posterior views of a skeleton. (Fig. 7.1 or Table 9.2) Instruct students to label the joints in the illustration that contain hyaline cartilage, fibrocartilage, or fibrous tissue.

Critical Reasoning Using Figure 9.15, instruct students to study the arrangement of the intracapsular ligaments and to explain which ligament primarily is responsible for the prevention of the following undesirable movements: (a) the forward sliding of the femur, (b) the backward displacement of the tibia when the leg is flexed, (c) anterior sliding of the tibia on the femur when the leg is flexed, and (d) hyperextension of the leg at the knee.

Answers: (a) posterior cruciate ligament, (b) posterior cruciate ligament, (c) anterior cruciate ligament, (d) anterior cruciate ligament.

Supplemental Course Materials Library Research Topics 1. Explore temporomandibular joint disorders in more depth. What is known of the causes?

What methods of treatment are available, and how successful are they? Suggest that students interview a dentist or oral surgeon to learn current techniques and treatments.

2. Recognize that much debate surrounds the use of the drug dimethyl sulfoxide (DMSO) for treating joint pains. Why is the Food and Drug Administration so reluctant to provide full approval of DMSO for use in humans when it is widely used in horses?

3. Research the use of arthroscopic surgery to treat disorders of joints other than the knee.

4. Review the literature on the procedures and materials used for joint prostheses. How close are scientists to developing an artificial hip or knee joint that can withstand the demands of a young, active athlete?

5. Rheumatoid arthritis appears to be an autoimmune disease. What are the current methods of treatment, and what are some proposals for providing a cure in the future?

6. Joints often are injured during sports activities. What are the major joint injuries associated with football, baseball, basketball, and tennis?

7. Research methods of growing new cartilage from adult stem cells.

8. Use online and library resources to research treatments for “the unhappy triad” knee injury. ..

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9. Use online and library resources to research treatments and therapies for “Frozen shoulder” (adhesive capusulitis).

Suggested Readings Cram, Peterm Xin Lu, Peter J. Kaboli, Mray S. Vaughan-Sarrazin, Xueya Cai, Brian R. Wolf, et al. “Clinical Characteristics and Outcomes of Medicare Patients Undergoing Total Hip Arthroplasty,” 1991–2008. Journal of the American Medical Association 305 (15): 1560– 1567 (April 2011) (or doi:10/1001/jama.2011.478).

DeLee, Jesse C., and David Drez. Orthopaedic Sports Medicine: Expert Consult. 3rd ed.

Philadelphia: Saunders, 2009.

Emery, C. A., Jian Kang, Ian Shrier, Claude Goulet, Brent E. Hagel, Brian W. Benson, et al.

“Risk of Injury Associated with Body Checking Among Youth Ice Hockey Players.”

Journal of the American Medical Association 303 (22): 2265–2272 (June 2009) (or doi:10/1001/jama.2010.755).

Fu, Freddie, and Steven Cohen. Current Concepts in ACL Reconstruction. Thorofare, N.J.: SLACK Incorporated, 2008.

Germain, B. C. Anatomy of Movement. Seattle, Wash: Eastland Press, 2007.

Grande, D. A., J. Mason, E. Light, and D. Dines.“Stem cells as platforms for delivery of genes to enhance cartilage repair.” The Journal of Bone and Joint Surgery 85 (2003): 111–116.

Gunn, C. Bones and Joints: A Guide for Students. 5th ed. London: Churchill Livingstone, 2007.

Ramamoorthi, N. “The Lyme Disease Agent Exploits a Tick Protein to Infect the Mammalian Host.” Nature 436 (July 2005): 573–577.

Rozbruch, R., and S. Ilizarov. Limb Lengthening and Reconstruction Surgery. New York: Informa, 2006.

Shin, J. J., Lisa J. Glickstein, and Allen C. Steere. “High levels of inflammatory chemokines and cytokines in joint fluid and synovial tissue throughout the course of antibioticrefractory Lyme arthritis.” Arthritis & Rheumatism 56:4 (May 2007), 1325–1335.

Walker, Brad. The Anatomy of Sports Injuries. Berkeley, Calif.: North Atlantic Books, 2007.

Wang, L. “Fat Harbors Cells That Could Aid Joints.” Science News 159 (9) (March 2001): 134.

Weinstein, J. N., Tor D. Tosteson, Jon D. Lurie, Anna N. A. Tosteson, et al. “Surgical vs Nonoperative Treatment for Lumbar Disk Herniation: The Spine Patient Outcomes Research Trial (SPORT): A Randomized Trial.” Journal of the American Medical Association 296 (20): 2441–2450 (November 22, 2006) (or doi:10/1001/jama.296.20.2441).

Wilkins, Philip, M Chiro, Inger B. Scheel, Oliver Grundnes, et al. “Effect of Glucosamine on Pain-Related Disability in Patients with Chronic Low Back Pain and Degenerative Lumbar Osteoarthritis: A Randomized Controlled Trial.” Journal of the American Medical Association. 304 (1) (July 7, 2010): 45–52 (or doi: 10.1001/jama.2010.893).

Williams, P. L., et al. Gray’s Anatomy. 38th ed. New York: Churchill Livingstone, 1995.

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Answers to Textbook Questions Answers for multiple-choice and matching questions 1–8 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 9. Joints are defined as sites of contact between two elements of the skeleton, usually between two bones and occasionally between bone and cartilage. (p. 241) 10. Synovial fluid is derived from the synovial membrane of synovial joints. It is primarily a tissue fluid derived from capillaries in the synovial membrane. It also contains a glycoprotein (sugar protein) lubricant that is secreted by fibroblasts in the connective tissue of the synovial membrane. (p. 243) 11. When pressure on a synovial joint pushes the adjacent articular cartilages together, it squeezes synovial fluid from the cartilages onto the cartilage surfaces. This fluid acts as a slippery lubricant, allowing the cartilages to glide across one another without friction.

This is weeping lubrication. (p. 243) 12. Being poorly vascularized, partially torn ligaments take time to heal, but they eventually do so. However, when a ligament ruptures completely, the inflamed joint breaks down the tissues in its surroundings and turns the ligament to pulp. Therefore, completely torn ligaments need to be repaired surgically. (p. 266) 13. Hinge joint: elbow and ankle (the knee and temporomandibular joints could be called modified hinge joints); plane joint: intertarsal, intercarpal, superior tibiofibular, and sacroiliac joints; condylar joint: atlanto-occipital joint, wrist, and metacarpophalangeal; ball-and-socket joint: shoulder and hip. (pp. 252–254, Table 9.3) 14. The most dangerous injury that the intracapsular ligaments tend to suffer from is a lateral blow that tears the anterior cruciate ligament (ACL), the tibial collateral ligament, and the medial meniscus. A torn ACL heals poorly, so it must be replaced surgically with a graft from the patellar ligament, the calcaneal tendon, or the semitendinosus tendon. (p. 263) 15. When a person is “double-jointed,” he or she has looser and more stretchable joint ligaments and capsules compared to most other people. (p. 252) 16. (a) The humerus dislocates anteroinferiorly; (p. 258) (b) the ulna dislocates posteriorly; (p. 259) (c) the femur dislocates posteriorly. (p. 260) 17. Examination of the complete thorax of a human skeleton reveals the following classifications of joints. The sternoclavicular joint, joints between ribs 2 through 7 and the sternum, costovertebral joints, and joints between articular processes of vertebrae are all synovial joints that contain hyaline cartilage. The sternocostal joint between the first rib and the manubrium is a cartilaginous joint containing hyaline cartilage. Intervertebral joints between adjacent vertebrae are cartilaginous joints containing fibrocartilage.

18. (a) abduction, glenohumeral joint; (b) extension, elbow joint; (c) lateral rotation, hip joint; (d) protraction, temporomandibular joints; (e) inversion, intertarsal joints. (pp. 245–246, Table 9.2, Table 9.3) 19. Muscle tone is a constant, low level of contractile force generated by a muscle, even when it is not causing movement. Muscle tone helps stabilize joints by keeping tension

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on the muscle tendons that cross over joints just external to the joint capsule, like a ligament holding the adjoining bone surfaces together. (p. 252) 20. A bursa is a thin, fibrous sac of synovial fluid that is lined by a synovial membrane.

Bursae function to prevent friction and are located where ligaments, muscles, or skin overlie and rub against bone. A tendon sheath is essentially an elongated bursa that wraps around a tendon like a bun around a hot dog. Tendon sheaths surround tendons where several tendons crowd together in a narrow space, and they serve to reduce friction between these tendons. (p. 245) 21. (a) acromioclavicular joint. (b) intervertebral joints. (c) sternocostal joints. (d) costovertebral joints. (e) intertarsal joints. (pp. 252–254, Table 9.3) 22. (a) shoulder joint. (b) knee joint. (c) proximal radioulnar joint. (d) elbow joint. (e) ankle joint.

23. Arcuate popliteal ligament – “arcu” – bow or arch, “poplit” – back of the knee, arched ligament at the back of the knee. This ligament arches over the muscle popliteus.

Anular ligament – “anular” – ring, a ring or circle-shaped ligament.

Deltoid ligament – “delta” – triangle, triangular ligament.

Oblique popliteal ligament – “obliqu” – slanted sidewise, “poplit” – back of the knee, slanted ligament that crosses against the back of the knee.

Critical Reasoning and Clinical Applications Questions 1. (a) Dorsiflexion and plantar flexion only (some call these movements flexion and extension). (p. 249, Table 9.2) (b) No: Dislocation and spraining do not indicate broken bones. (c) Reduction is returning the dislocated bone ends to their original, proper positions. (d) Sprains heal slowly and need surgical repair to stabilize the joint. (e) In arthroscopic surgery, only small incisions are needed instead of a large surgical wound. There is less chance of infection, and healing of the incision is considerably faster.

2. Lisa is suffering from an inflammation of the prepatellar bursa, also known as ‘housemaid’s knee’. Due to the physical blow of falling or repeated friction during work, the bursa swells with fluid leading to bursitis. This is why her knee was warm to touch and full of fluid. (p. 267) 3. (a) Gouty arthritis. (b) Gouty arthritis is caused by uric acid build-up in the body fluid, which leads to the formation of urate crystals in the synovial membranes. Since estrogen increases the rate of excretion of uric acid from the blood, women have fewer problems of such a build-up of these acids. (c) Non-steroidal anti-inflammatory drugs such as ibuprofen. (pp. 268–269) 4. A common injury to the forearm in young children like Tom (who are less than 5 years of age) is subluxation of the proximal radioulnar joint. When the forearm is pulled with the arm outstretched, as in swinging by his hands, the head of the radius can be pulled away from the anular ligament, resulting in the entrapment of the anular ligament in the humeroradial joint. The immediate pain that occurs upon injury subsides and is followed by a reluctance to use the injured arm. (p. 267) 5. Jim has all the classical symptoms of osteoarthritis, as described on p. 267.

6. This movement is called ‘opposition’ of the thumb and occurs at the saddle joint between the first metacarpal and trapezium bone. This is the action by which the thumb could be 106

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moved across the palm to touch the tips of other fingers on the same hand. This unique action enables the human hand to grasp and manipulate objects. (p. 249) 7. Both upper and lower limbs are attached to the skeleton by ball-and-socket joints; the shoulder joint is modified for mobility, and the hip joint is modified for weight bearing and stability. In the shoulder joint, stability is sacrificed to provide the most freely moving joint of the body. The shallow glenoid cavity and remarkably thin joint capsule contribute only slightly to joint stability but make significant contributions to joint mobility.

In the hip joint, the deeply cupped acetabulum provides a site of secure attachment for the head of the femur. Additionally, the strongly reinforced capsule of the hip joint provides stability and supports weight bearing. (pp. 256 and 258–259) 8. (a) subcutaneous prepatellar bursa – “sub” – below, ”cutane” – skin, “pre” – before, ahead → bursa found below the skin and anterior to the patella. (b) subluxation – “sub” – below, “luxat” – dislocate → partial or incomplete dislocation of a joint. (c) osteoarthritis – “osteo” – bone, “arthr” – joint, “itis” – inflammation → inflammation of the bones in a joint. (d) chondromalacia patellae – “chondr” – cartilage, “malacia” – soft → soft cartilage of the patallea. (e) arthroscopy – “arthro” – joint, “scope” – see, watch, look → visual examination of a joint.

Interpreting Medical Images Questions Answers to Interpreting Medical Images questions are provided in the Instructor Resources area of Mastering A&P. Figure 9.11: The viewable features of the scapula are the glenoid cavity and the spine of the scapula between supraspinatus and infraspinatus; the features of the humerus that can be identified are the head, the greater tubercle, the anatomical neck, and the surgical neck of the humerus.

Figure 9.15g: The intercondylar eminence appears as the prominence between the medial and lateral condyles of the tibia; the intercondylar eminence divides the tibial plateau into an anterior and posterior region. The anterior cruciate ligament arises from the anterior portion of the intercondylar region.

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 9: Joints To the Student Now that you know the names of the bones of the skeleton, it is time to explore the union of bones and how movement of the skeleton is accomplished. Chapter 9 introduces you to the variety of joints (articulations) that form where bone attaches to bone. Although most joints unite bone to bone, some articulations join bone to cartilage. Relate the structure of the joint to the specific type of joint and the degree of mobility permitted. A specific movement is determined by the structure of the joint. When a muscle contracts, movement occurs. Study movements carefully and thoroughly so that your next step, the study of muscles in Chapter 10, will not be difficult to master.

It will also benefit you greatly to include Practice Anatomy Lab 3.0 (PAL) (BC; DVD, Website) in your study of the joints of the human body. Study the three-dimensional animations of muscle actions in PAL: It is one of the best sections for you to use while learning movements possible at each type of synovial joint. The Skeletal System and Muscular System sections of the Human Cadaver module offer comprehensive study tools for applying what you have learned about those systems to the joints of the human body.

Step 1: Be able to classify joints. __ Define joint (articulation). __ Classify joints according to structure. __ Classify joints according to function.

Step 2: Describe and understand fibrous joints. __ Describe the general structure of fibrous joints. __ Give examples of three types of fibrous joints, and describe the mobility of each type. __ Point out examples of fibrous joints on a diagram of a skeleton.

Step 3: Describe and understand cartilaginous joints. __ Describe the general structure of cartilaginous joints. __ Name two examples of cartilaginous joints, and describe the mobility of each type. __ Point out examples of cartilaginous joints on a skeletal diagram.

Step 4: Describe and understand synovial joints. __ List basic structural characteristics of a synovial joint. __ Explain the mobility of a synovial joint. __ Explain how synovial joints function, including weeping lubrication. __ Distinguish between bursae and tendon sheaths and explain their significance within a synovial joint. __ Name and explain three factors that influence joint stability. __ Distinguish between gliding, angular, and rotation types of movements.

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__ Give examples of gliding joints. __ Define and give examples of five types of angular movements: flexion and extension, abduction and adduction, and circumduction. Include the plane of movement for each action. __ Define and give examples of rotation. __ Define and give examples of the following special movements: supination and pronation, dorsiflexion and plantar flexion, inversion and eversion, protraction and retraction, elevation and depression, and opposition. __ List and give examples of six structural types of synovial joints. __ Distinguish among nonaxial, uniaxial, biaxial, and multiaxial joints. __ For each of the following selected synovial joints, name the articulating bones, the structural type of joint, the functional type of joint, and all movements permitted.

• Temporomandibular joint • Shoulder joint • Elbow joint • Hip joint • Ankle joint Step 5: Fill in the following joint classification worksheet.

Apply three of the following terms to each of the joints on the numbered list.

Amphiarthrosis Diarthrosis Synarthrosis Ball and socket Condylar Gliding Hinge Pivot Saddle Suture Symphysis Synchondrosis Syndesmosis Gomphosis Fibrous joint Cartilaginous joint Synovial joint 1. Interlocking joint between cranial bones: 2. Knee joint:

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3. Elbow joint: 4. Intervertebral joint between articular processes: 5. Articulation between the tibia and fibula at distal ends: 6. Shoulder joint: 7. Symphysis pubis: 8. Joint between the diaphysis and epiphysis of a long bone of a child: 9. Joint between the first metacarpal and carpus (trapezium): 10. Wrist (carpals to carpals): 11. Ankle (tarsals to tarsals): 12. Ankle (talus to tibia): 13. Hip joint: 14. Axis-atlas rotation: 15. Interphalangeal joint (between phalanges): 16. Phalanges to metacarpals: 17. Toe joint (between phalanges): 18. Phalanges to metatarsals: 19. Teeth and mandible or maxilla: Step 6: Describe disorders of joints and the changes in joints that occur with aging. __ Describe the three main types of joint injuries. __ Describe the inflammatory and degenerative conditions that often affect joints. __ Describe the changes in joints that occur throughout the life span.

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Skeletal Muscle Tissue

Lecture and Demonstration Objectives 1. List four functional properties that distinguish muscle tissue from other tissues.

2. Compare and contrast skeletal, cardiac, and smooth muscle tissue.

3. Name the layers of connective tissue that occur in and around a skeletal muscle, and briefly describe a muscle’s blood and nerve supply.

4. Define muscle fascicles.

5. Describe the various ways in which muscles attach at their origins and insertions.

6. Describe the microscopic structure of a skeletal muscle fiber and the arrangement of its contractile thick and thin filaments into sarcomeres and myofibrils.

7. Describe the structure and functions of sarcoplasmic reticulum and T tubules in muscle fibers.

8. Explain the sliding filament mechanism of muscle contraction, including the role of titin.

9. Describe the innervation of skeletal muscle fibers at neuromuscular junctions. Define a motor unit.

10. Compare and contrast the three kinds of skeletal muscle fibers.

11. Explain some symptoms of muscular dystrophy, myofascial pain syndrome, and fibromyalgia.

12. Describe the embryonic development and capacity for regeneration of skeletal muscle tissue.

13. Explain the changes that occur with age in skeletal muscle.

Suggested Lecture Outline I. Overview of Muscle Tissue (pp. 274–276, Tables 10.1, 10.2) A. Properties of Muscle Tissue (p. 274) 1. In all its forms, muscle tissue makes up nearly half the body’s mass.

2. Special functional characteristics separate muscle tissue from other tissues; special properties include contractility, excitability, extensibility, and elasticity.

B. Functions of Muscle Tissue (p. 274) 1. Functions of muscle tissue include movement, posture maintenance, joint stabilization, and generation of body heat.

C. Types of Muscle Tissue (pp. 274–276, Tables 10.1, 10.2) ..

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1. The three types of muscle tissue are skeletal, cardiac, and smooth; a cell in skeletal and smooth muscle tissue is called a fiber.

2. There are important similarities among the three types of muscle tissue. a. Muscle cells of skeletal and smooth muscle tissue are called fibers. b. All three types of muscle tissue depend on myofilaments for contraction. c. The plasma membrane of all types of muscles cells is called a sarcolemma, and the cytoplasm is called sarcoplasm.

II. Skeletal Muscle (pp. 276–287, Figs. 10.1–10.10, Tables 10.1, 10.2) A. Skeletal muscles are organs made up of several types of tissue.

1. Gross Anatomy of a Skeletal Muscle (pp. 276–278, Figs. 10.1–10.3, Table 10.1) a. Several sheaths hold muscles and muscle fibers together. These connective tissues, from external to internal, are epimysium (surrounding an entire muscle), perimysium (surrounding muscle fascicles), and endomysium (surrounding individual muscle fibers). b. In general, each muscle is supplied by one nerve, one artery, and one or more veins. c. Muscle attachments on bone cross at least one movable joint. Attachments of muscle to bone are termed origin and insertion. Attachments may be direct (fleshy) or indirect (by way of a tendon).

2. Microscopic Structure of Skeletal Muscle Tissues (pp. 278–281, Figs. 10.4–10.5, Table 10.1) a. Skeletal muscle fibers are long, cylindrical, multinucleate cells formed by the fusion of embryonic myoblasts. b. Myofibrils are specialized contractile organelles found in skeletal muscle tissue.

Myofilaments are contractile proteins located within myofibrils. c. Sarcomeres are repeating subunits along myofibrils. The sarcomere is the basic unit of contraction in skeletal muscle. d. Sarcoplasmic reticulum and T tubules are sets of tubules that regulate muscle contraction. Sarcoplasmic reticulum (SR) is a specialized smooth endoplasmic reticulum (ER) that stores calcium ions, and T tubules are invaginations of the sarcolemma.

3. Functional Anatomy of Skeletal Muscle Tissue (pp. 281–287, Figs. 10.6–10.10, Tables 10.1, 10.2) a. The two types of muscle contraction are concentric contraction and eccentric contraction. b. The sliding filament mechanism is the method by which skeletal muscles contract. c. Muscle tissue can be stretched by contraction of opposing muscle groups. d. The optimal resting length for skeletal muscle fibers is the length that generates the greatest pulling force when the muscle contracts. e. Titin and other myofibril proteins help sarcomeres resist overstretching. f. Nerve cells that innervate skeletal muscles are motor neurons. g. The neuromuscular junction is the point where a nerve ending and a muscle fiber meet.

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h. A motor unit consists of a motor neuron and all the muscle fibers it innervates. i. The three types of skeletal muscle fibers are slow oxidative fibers, fast glycolytic fibers, and fast oxidative fibers.

III. Disorders of Muscle Tissue (pp. 287–289, Fig. 10.11) A. Examples of disorders of skeletal muscle tissue are muscular dystrophy, myofascial pain syndrome, and fibromyalgia.

1. Muscular Dystrophy (pp. 287–288, Figs. 10.11) 2. Myofascial Pain Syndrome (p. 288) 3. Fibromyalgia (p. 288)

IV. Skeletal Muscle Throughout Life (pp. 289–290, Fig. 10.12) A. Almost all muscle tissues develop from embryonic mesoderm.

B. Skeletal muscle fibers do not undergo mitosis after they form. However, they lengthen and thicken throughout childhood and adolescence.

C. The body strength of adult men is usually greater than that of adult women. This biological difference is due primarily to the effects of androgen hormones in males.

D. Aging results in increased amounts of connective tissue in skeletal muscles and a decrease in the number of muscle fibers (sarcopenia).

Lecture Hints 1. Discuss four basic functions of muscle tissue, and explain the four functional features of muscle tissue that distinguish it from other tissues. Be sure to clearly differentiate functions from functional features of muscle tissue.

2. Compare and contrast skeletal, cardiac, and smooth muscle tissue, including histological similarities as well as differences. Refer to Table 10.2 on pp. 286–287 in the text.

3. Explain why skeletal and smooth muscle cells are referred to as fibers.

4. Describe sarcolemma and sarcoplasm, including a reference to the plasma membrane and cytoplasm of other cell types.

5. Remind students that skeletal muscles are also organs.

6. Figure 10.1 on p. 276 in the text shows the continuity of tough fibrous connective tissue connecting bone and muscle, and also provides an excellent illustration of how structure is related to function in the musculoskeletal system.

7. Using Figure 10.1, explain the multilevel relationships of connective tissue to muscle: (a) the covering of bone (periosteum) merges with tendons and ligaments; (b) it forms a structural framework by wrapping muscles and muscle groups; and (c) it also penetrates muscles, providing passage for blood vessels and nerves. This is an important concept, so spend some time on this topic and reiterate it in a variety of formats—visual, auditory, and kinesthetic.

8. Explain the supply of blood vessels and nerves to muscle tissue.

9. Emphasize that students will see the anatomical terminology prefixes endo-, epi-, and peri- for the duration of their studies. Stress their meanings, and emphasize the recurring usage.

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10. Distinguish the origin from the insertion of a muscle; explain several points of comparison. Relating origin and insertion to muscle action makes a tough topic easier to comprehend. You could go back to the skeletal system and describe some sites for muscle attachment to emphasize the importance of remembering this material for Chapter 11.

11. Distinguish direct from indirect attachment, including definitions of tendon and aponeurosis.

12. Using Figure 10.4, explain the microscopic anatomy of a skeletal muscle fiber by describing the following structural features: fibers, sarcolemma, sarcoplasm, striations, myofibrils, myofilaments, sarcomere, and contractile proteins. Point out that the multinucleate characteristic is due to the fusion of embryonic myoblasts. There are good online visual aids and excellent slides of muscle tissue in the Histology module of PAL 3.0.

13. Explain the structure of a sarcomere and the roles of the sarcoplasmic reticulum and T tubules.

14. Compare concentric and eccentric contraction in skeletal muscles. Have students demonstrate several examples of each type of contraction.

15. Explain the sliding filament mechanism of muscle contraction. You can have a group of students come to the front of the lecture hall to act out the roles of thin and thick filaments and myosin heads.

16. Explain the source of energy that enables muscle contraction to occur.

17. Explain the difference between contraction of a muscle and extension of a muscle.

Students often are confused with the terminology used in the description of the functional characteristics of muscles. Explain that extend is a root of the word extensibility, and it is easy to associate stretching with extending. Elasticity (the passive ability to recoil) is the opposite of extensibility. Contraction is simply the shortening of the muscle and generation of a strong pulling force.

18. Explain that what is true for a muscle fiber physiologically is true for the entire muscle, and relate this to muscle fiber length and force of contraction. List examples of the specific types of fascicle arrangement and how those arrangements influence the strength of contraction and the distance over which a muscle can contract.

19. Emphasize the importance of understanding the innervation of skeletal muscles by motor neurons. Comprehension of this basic concept will help students understand neuronal function in Chapters 14 and 15.

20. Explain that one motor unit is made up of a motor neuron and all the skeletal muscle fibers it innervates.

21. Distinguish three types of skeletal muscle fibers. When explaining the differences between slow and fast (oxidative) fibers, give examples of different types of athletes and the types of muscle fibers that predominate as a result of specific exercises.

22. Describe the disorders of skeletal muscle tissue. Include an explanation of the inheritance of different types of muscular dystrophy and the specific causes, symptoms, and treatment of myofascial pain syndrome. Also describe the mysterious chronic pain syndrome called fibromyalgia.

23. Illustrate the changes that occur in skeletal muscle tissue throughout life. Pay special attention to the formation of skeletal muscle fibers by fusion of embryonic myoblasts.

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Classroom Discussion Topics and Activities 1. Obtain three-dimensional models of the three types of muscle fibers (skeletal, cardiac, smooth) to exhibit their histological characteristics. Ask students how a cell can have more than one nucleus.

2. Obtain a three-dimensional model of a sarcomere to exhibit myofilaments and the sliding filament theory of muscle contraction.

3. To demonstrate the sliding filament mechanism, orient two stools horizontally, feet to feet, hold yardsticks between the stools, and ask students to move the stools together and apart. Each stool represents a Z disc with attached thin filaments, and each yardstick is a thick filament. The same demonstration is possible on a smaller scale using pipe cleaners.

4. Use slides from the Histology module of PAL 3.0 of skeletal, smooth, and cardiac muscle to compare and contrast these three muscle tissues.

5. So that students do not confuse such similar terms as fiber, fibril, fascicle, and filament, instruct them to describe all the levels of organization of a skeletal muscle, from the whole muscle to the molecular level. The list will read as follows: muscle, fascicle, fiber, myofibril, sarcomere, and myofilament.

6. Ask students what rigor mortis means. What causes it? What happens approximately 20 hours later to end this physical state?

7. Ask students why they feel muscle fatigue after strenuous exercise.

8. Discuss the consequences of taking anabolic steroids. Refer to A Closer Look: Anabolic Steroid Abuse on textbook p. 289. Why are Olympic committees so adamant against the use of “performance-enhancing” drugs?

9. Discuss why it is important to keep moving and exercising rather than sitting on the ground, motionless, waiting for rescue if lost in a snowstorm.

10. Discuss muscle atrophy and hypertrophy. Ask students why muscles immobilized for long periods of time, as in a cast, tend to get smaller. What is necessary to revitalize them?

11. Ask students why weight lifters have such enormous muscles, whereas distance runners have lean muscles.

12. Ask students why “warming up” is necessary prior to strenuous exercise and why the exerciser is out of breath afterward.

13. Students always enjoy a discussion of potential dinner topics. Explain the difference between red meat and white meat. Also, comment on what makes steak tender.

14. A simple way to demonstrate that muscles shorten when contracted is to ask students to stand on one foot and notice that the leg shortens enough that the other leg has to bend.

15. Remind students that additional media resources are available using PAL 3.0 and at MasteringA&P, www.masteringaandp.com, including an interactive multiple-choice quiz.

16. Instruct students to design a chart for the comparison of skeletal, cardiac, and smooth muscle tissue; features for comparison should include location in the body, cell shape, cell nuclei, type of innervation, connective tissue components, presence of striations, presence of gap junctions, and presence of neuromuscular junctions.

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17. Use an articulated skeleton to demonstrate origins and insertions (a piece of cloth or a cut rubber band easily mimics a muscle); ask students to identify potential movements of the muscle based on how the bones move with the rubber band or cloth between them.

Clinical Questions 1. What is the immediate cause of death in most people who have Duchenne muscular dystrophy?

Answer: When the main respiratory muscles weaken, death results from an inability to breathe.

2. Why are elderly people who have intermittent claudication extremely susceptible to developing frostbite in their toes?

Answer: Because claudication is a restriction of the blood flow to the lower limb, an insufficient amount of warming blood reaches the toes on a cold day.

3. Backaches are among the most common of all maladies. Many people think that most backaches result from herniated intervertebral discs. Is this true?

Answer: No. Most backaches are caused by strains and spasms in the deep muscles of the back that interconnect the vertebrae. (See the discussion of lower back pain in the Related Clinical Terms section of Chapter 10, p. 290.)

Art Resources Figure 10.1 Figure 10.2 Figure 10.3 Figure 10.4 Figure 10.5 Figure 10.6 Figure 10.7 Figure 10.8 Figure 10.9 Figure 10.10 Figure 10.11 Figure 10.12 Table 10.1 Table 10.2

Connective tissue sheaths in skeletal muscle: epimysium, perimysium, and endomysium.

Photomicrograph of the capillary network surrounding skeletal muscle fibers.

Muscle attachments (origin and insertion).

Microscopic anatomy of the skeletal muscle fiber (cell).

Sarcoplasmic reticulum and T tubules in the skeletal muscle fiber.

Sliding filament mechanism for concentric contraction in a skeletal muscle.

Changes in striations as skeletal muscle contracts.

The neuromuscular junction.

Motor units.

Cross-section of the three types of fibers in skeletal muscle.

Duchenne muscular dystrophy.

Formation of a multinucleate skeletal muscle fiber by fusion of myoblasts.

Structure and Organizational Levels of Skeletal Muscle Comparison of Skeletal, Cardiac, and Smooth Muscle

Teaching with Art Figure 10.1

Connective tissue sheaths in skeletal muscle.

Textbook p. 276.

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Checklist of Key Points in the Figure • Demonstrate the sheaths of connective tissue (from external to internal) in a skeletal muscle: epimysium, perimysium, and endomysium.

• Stress that a muscle fiber is a cell.

• Explain that bundles of fibers form fascicles.

• Explain that the entire group of fascicles (i.e., the muscle) is an organ.

• The intramuscular connective tissues allow passage for blood vessels and nerves.

• Explain that a skeletal muscle generally has one nerve, one artery, and one or more veins that repeatedly branch within the layers of the intramuscular connective tissue.

• Point out that a tendon attaches muscle to bone (as well as to skin or another muscle).

Common Conceptual Difficulties Interpreting the Art • Stress the continuity of the system of intramuscular connective tissue. The collagen fibers in the epimysium, perimysium, and endomysium converge at the origin and insertion of a muscle to form a fibrous tendon.

• Point out that a tendon is part of the muscle itself and acts to attach the muscle to the bone.

Remind students that bone is covered with periosteum, a connective tissue that joins with the tendon to help anchor the muscle.

• Explain that when a muscle contracts, the connective tissue sheaths are pulled, which in turn applies mechanical force to the bone.

• State that connective tissue sheaths are responsible for muscle elasticity, a property that enables a muscle to resume its resting length.

• Explain the relationship of the epimysium to the deep fascia.

Art Exercise The following exercises stress the ubiquity of connective tissue in a muscle: 1. Distribute unlabeled copies of Figure 10.1. Instruct students to color or shade all parts of the illustration that represent connective tissue.

Comment: The ubiquity of connective tissue in a muscle should become evident when everything except muscle fibers and blood vessels is colored, including the tendon and bone surface. A very alert student will also color the blood inside the vessels as an example of a very atypical type of connective tissue.

2. Provide a copy of Figure 11.6, and instruct students to color the connective tissues that form the compartments of the arm and forearm.

Critical Reasoning 1. Ask students to describe the relationship of the deep fascia to the muscles, tendons, and bones in Figure 10.4 and Figure 11.5.

Answer: Deep fascia, a dense connective tissue, wraps around the muscle and tendon, separating them from adjacent muscles. Also, deep fascia compartmentalizes and binds muscles forming functional groups, such as the anterior and posterior compartments of the arm and forearm.

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2. Ask students why the tenderest cut of a steak comes from the center of the belly of the muscle instead of near the ends of the muscle.

Answer: There is much more connective tissue near the ends than in the belly.

Supplemental Course Materials Library Research Topics 1. What do you think is the functional “reason” why skeletal and cardiac muscle tissues have little or no ability to regenerate? What current research is being done in this area?

2. Investigate the long-term effects of anabolic steroid use on muscle tissue.

3. Explore the current theories for the causes of muscular dystrophy, fibromyalgia, or myofascial pain syndrome.

4. What current research is being done concerning developing cures or remedies for diseases affecting skeletal muscle?

Suggested Readings Agur, A. M. Grant’s Atlas of Anatomy. 13th ed. Baltimore: Lippincott Williams & Wilkins, 2012.

Blau, H. and Jason H. Pomerantz. “Re'evolutionary' Regenerative Medicine”. Journal of the American Medical Association. 305 (1): 87–88 January 5, 2011.

Clemente, C. D. Anatomy: A Regional Atlas of the Human Body. 5th ed. Baltimore: Lippincott Williams & Wilkins, 2008.

Gray, H., et al. Gray’s Anatomy. 38th ed. London: Churchill Livingstone, 1995.

Shahinaz, M., Marie Lund, Ruth Pfeiffer, Sanne Gortz, Christine Mueller. “Cancer Risk Among Patients with Myotonic Muscular Dystrophy.” Journal of the American Medical Association. 306 (22): 2480–2486 December 14, 2011.

Yokochi, C. and J. W. Rohen. Photographic Anatomy of the Human Body. 6th ed. (paperback) Baltimore: Lippincott Williams & Wilkins, 2006.

Answers to Textbook Questions Answers for multiple-choice and matching questions 1–9 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 10. Muscles are required to produce movement to open and close the body’s passageways, to maintain posture and stabilize joints, and to generate heat. To facilitate vision, the eyelids need to open and the pupil’s size needs to adjust with the help of muscles so that light can enter the eye. (p. 274) 11. The epimysium forms an outer layer of dense, irregular connective tissue surrounding the whole skeletal muscle. Within each skeletal muscle, the muscle fibers are separated into fascicles by the fibrous connective tissue called perimysium. Within a fascicle, each muscle fiber is surrounded by a fine sheath of lose connective tissue (consisting mostly 118

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of reticular fibers) called the endomysium. These sheaths are continuous with each other.

Thus, the endomysium merges with the perimysium, which in turn is continuous with the epimysium. (b) All three sheaths converge to form the tendon, a connective tissue structure that joins skeletal muscles to bones. (p. 277) 12. The myosin heads near the ends of the thick filaments grip the thin filaments and pivot inward, thereby pulling adjacent Z discs together (Fig. 10.7). The student’s drawing should resemble those in Figure 10.7 on p. 282.

13. A motor unit consists of one motor neuron and all the muscle fibers it innervates. (p. 283) 14. Slow oxidative fibers (SO): thin, red, many mitochondria, abundant capillary supply.

Fast glycolytic fibers (FG): thick, white, contain glycogen granules, few mitochondria, supplied by relatively few capillaries. Fast oxidative fibers (FO): intermediate thickness, many mitochondria, and an abundant capillary supply. (p. 285) 15. Her list read: “From smallest to largest: 1. Myofilaments: rods made of protein; contain actin or myosin; contribute to sarcomeres. 2. Myofibril: a long row of sarcomeres that are lined up back to back within the cytoplasm of a muscle cell. 3. Fiber: a skeletal muscle cell. 4. Fascicle: a bundle of muscle fibers.” (p. 275, Table 10.1) 16. (a) Myofibrils are unbranched long, rod-shaped contractile organelles that make up more than 80% of the sarcoplasm. They are specialized organelles unique to muscle tissue and contain myofilaments. (b) Myofibrils in a fiber are separated by mitochondria and glycosomes, both of which supply energy for muscle contraction (p. 278) 17. The sarcolemma is the plasmalemma of a muscle cell, and the sarcoplasm is the cytoplasm of a muscle cell. (p. 274) 18. Yes, John is correct. Titin is a springlike molecule in sarcomeres that resists overstretching. It does not resist stretching in the ordinary range of extension, but it becomes stiffer the more it uncoils. In turn, it strongly resists excessive stretching that tries to pull the sarcomere apart. (p. 280) 19. Acetylcholinesterase is the enzyme responsible for breaking down acetylcholine, a neurotransmitter released by terminal boutons at the neuromuscular junction. Without this enzyme, acetylcholine would accumulate in the synaptic cleft and remain bound to its receptors on the sarcolemma. This accumulation would result in the continued induction of nerve impulses in the sarcolemma and undesirable muscle twitches or contraction. (p. 283)

Critical Reasoning and Clinical Applications Questions 1. Regular exercise leads to increased muscle strength by causing muscle cells to hypertrophy or increase in size. The number of myofilaments per cell also increases. Satellite cells may fuse together to form new skeletal muscle fibers. (p. 285) 2. A strain is the pulling and tearing of a muscle while a sprain is the tearing of a joint ligament. (p. 290) 3. Because fast and slow oxidative fibers are resistant to fatigue, ducks can maintain prolonged flight. Incidentally, this explains why chicken breast is white meat and duck breast is dark meat. (pp. 284–285)

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4. George does not need to worry about the twitching. Twitching or muscle fasciculation is the sudden abnormal contraction of a motor unit in a muscle, commonly triggered by stress or anxiety. As George was preparing for his exams, the twitching could be related to anxiety or stress. Twitching also appears as a symptom in a few central nervous disorders and dietary deficiencies. (p. 284) 5. According to the intensity of a task, motor units are added in a muscle to allow a movement to take place. The total number of muscle fibers innervated by a single motor neuron is called a ‘motor unit’. Lesser motor units are needed when the muscle lifts a feather, whereas a large number of motor units are added when the muscle lifts a heavy bag. The same muscle accomplishes both these tasks, with the only difference being the number of motor units recruited to complete the tasks. (p. 283) 6. RICE stands for Rest, Ice, Compression, Elevation. (p. 266) 7. The presence of a pigment named ‘myoglobin’ in the sarcoplasm makes the muscle fibers red. Such muscles are abundant in mitochondria and are helpful in prolonged contraction.

They are extremely resistant to fatigue. Red muscle fibers are commonly observed in the muscles of the lower back, which maintains posture. (p. 285) 8. To increase his endurance, he needs to undergo intense resistance training and convert the fast glycolytic fibers in his muscles into fast oxidative fibers. When he stops training, the muscle fibers will then convert back to their original type. (p. 249) 9. Skeletal muscle cells are surrounded by satellite cells; these cells fuse together to produce new skeletal muscle fibers after injury to a young or adult muscle cell. (pp. 289–290)

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 10: Skeletal Muscle Tissue To the Student Chapter 10 provides the opportunity to learn about muscle tissue. One of the four major types of body tissues, muscle tissue constitutes nearly half the body’s mass. Contraction of muscle tissues allows you to move in countless ways, blood to move through vessels, air to enter and exit lungs, and food to move along the digestive tract. Chapter 10 builds the foundation for your future study of myology, the skeletal muscles of your body, the heart and circulation, and the many internal organs that have muscle tissue in their walls.

It will also benefit you greatly to include Practice Anatomy Lab 3.0 (PAL) (BC; DVD, Website) in your study of muscles and muscle tissues. The Muscular System sections of the Human Cadaver module offer comprehensive study tools for studying skeletal muscles, and the Histology module offers the opportunity for further study of the histology of muscle tissues.

Step 1: Characterize muscle tissue. __ Explain why a muscle cell is a muscle cell. __ List and describe four functional properties distinguishing muscle tissue from other tissues. __ Using the following characteristics, design a chart for the comparison of skeletal, cardiac, and smooth muscle tissue: • Location in body • Cell shape • Cell appearance • Type of contraction • Connective tissue components • Presence of striations • Presence of gap junctions • Presence of neuromuscular junctions Step 2: Understand the basic features of a skeletal muscle. __ List the levels of organization in a muscle going from a whole muscle to a myofilament. __ List and explain the connective tissue components of skeletal muscle. __ Explain the vascular nature of skeletal muscle. __ Describe innervation of skeletal muscle. __ Distinguish the origin from the insertion of muscle in several ways. __ Distinguish a tendon from an aponeurosis.

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Step 3: Understand the microscopic and functional anatomy of the skeletal muscle. __ Describe the shape of a skeletal muscle cell, and explain why it is multinucleated. __ Define a myofibril. __ Draw a myofibril, showing all structures and indicating the myofilaments responsible for striations. __ Define a sarcomere. __ Draw a sarcomere and label the following functional units: actin, myosin, titin, Z disc, and M line. __ Explain the sliding filament mechanism of muscle contraction. __ Explain how myofilaments determine the striation pattern in skeletal and cardiac muscle fibers. __ Describe the functional feature of elasticity of the skeletal muscle and how overextension is prevented. __ Describe the role of the sarcoplasmic reticulum and T tubules in the skeletal muscle fiber. __ Describe the innervation of skeletal muscle fibers. __ Describe the components of a motor unit and its function. __ Define terminal bouton and synaptic cleft. __ Distinguish three types of skeletal muscle fibers: slow oxidative fibers, fast glycolytic fibers, and fast oxidative fibers.

Step 4: Describe disorders of skeletal muscle tissue. __ Describe the types of muscular dystrophy and their patterns of inheritance. __ Discuss myofascial pain syndrome and its treatments. __ List symptoms and treatments for fibromyalgia.

Step 5: Explain muscle tissue throughout life. __ Describe the embryonic origin of muscle tissue. __ Indicate the degree of regeneration for each type of muscle tissue. __ Explain why men have more muscle mass than women. __ Compare muscles of old age and youth.

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Muscles of the Body

Lecture and Demonstration Objectives 1. Describe the different fascicle arrangements that occur in skeletal muscles. Give an example of a muscle with each arrangement.

2. Describe the functional implications of fascicle arrangement.

3. Describe the three types of lever systems by which muscles function, and indicate the relative positions of effort, fulcrum, and load in each.

4. Describe how a muscle’s position as it crosses a joint determines the muscle’s action.

5. Describe the functions of prime movers (agonists), antagonists, synergists, and fixators.

6. Organize the body’s muscles into four functional groups based on their developmental origin.

7. Identify the muscular compartments of the upper and lower limb. Identify the general action of the muscles in each compartment, and name the muscles located in each compartment.

8. List the criteria used in naming muscles.

9. Identify the muscles described Tables 11.1–11.17. State the origin, insertion, and primary action of each muscle.

10. Use surface landmarks to locate and identify underlying muscles.

Suggested Lecture Outline I. Mechanics of Muscle Function (pp. 295–300, Figs. 11.1–11.4) A. Arrangements of Fascicles in Muscles (p. 295, Fig. 11.1) 1. Muscles have different shapes and actions because of different arrangements of fascicles; patterns of fascicles are circular, parallel, convergent, and pennate.

2. The arrangement of fascicles influences the range of movement and the power of a muscle.

B. Lever Systems: Bone-Muscle Relationships (pp. 296–298, Figs. 11.2, 11.3) 1. Define lever, fulcrum, load (resistance), and effort (applied force); distinguish among first-class lever, second-class lever, and third-class lever relationships; in the human body, bones are the levers, joints are the fulcrums, and the effort is exerted by skeletal muscles pulling on their insertions. (pp. 296–298, Fig. 11.2) 2. Most muscles in the human body are third-class lever systems that provide speed of movement. (p. 298, Fig. 11.3) ..

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C. Muscle Actions and Interactions (pp. 298–300, Fig. 11.4) 1. Muscles are classified into functional types with respect to their actions; these classes include prime movers (agonists), antagonists, synergists, and fixators.

2. Opposing groups of skeletal muscles are arranged across movable joints so that one group can reverse or modify the action of the other group.

II. Organization of Skeletal Muscles (pp. 300–304, Figs. 11.5–11.7) A. Organizational Scheme Based on Embryonic Development (pp. 300–302,

Fig. 11.5) 1. Skeletal muscles have specific embryonic origins, though all arise from the mesoderm.

2. The first seven myotome-like structures of the head are somitomeres.

3. The development-based scheme organizes muscles into four groups. a. Musculature of the visceral organs b. Pharyngeal arch muscles c. Axial muscles d. Limb muscles B. Muscle Compartments of the Limbs (pp. 302–304, Figs. 11.6, 11.7) 1. Dense fibrous connective tissue divides the limb muscles into compartments.

2. Muscles in opposing compartments act as agonist/antagonist pairs.

3. A single named nerve usually innervates each compartment.

4. The upper limb has two compartments: anterior and posterior.

5. The thigh is divided into three compartments: anterior, posterior, and medial.

6. The leg is divided into three compartments: anterior, posterior, and lateral.

III. Major Skeletal Muscles of the Body (pp. 305–364, Figs. 11.8–11.28, Tables 11.1–11.17) A. There are 600+ muscles in the human body; understanding all the body movements previously covered is required to master human musculature.

B. Important data included in each of the muscle tables are origin, insertion, action, and nerve supply. Also included is a basic physical description of each muscle.

1. Naming the Skeletal Muscles (p. 305) a. Names of muscles provide information about the muscle; several criteria are location, shape, relative size of the muscle, direction of the fascicles and muscle fibers, location of attachments, number of origins, and actions.

C. The Muscle Tables (pp. 305–364, Figs. 11.8–11.28, Tables 11.1–11.17) 1. Examine the muscle tables (Tables 11.1–11.17) and accompanying figures (Figs.

11.8–11.28) to explore the muscles of the body.

IV. Regional Surface Anatomy (pp. 364–376) A. Surface anatomy forms the foundation for the clinical assessment of body structures, usually by an integrated regional approach.

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B. Surface anatomy is the study of external landmarks of the body and of the internal structures that may be observed or palpated through the body surface.

1. The Head (pp. 365–366, Fig. 11.29) a. The cranium has numerous bony and muscular structures that may be palpated through the skin. Among the cranial structures are the superciliary arches, the mastoid process of the temporal bone, external occipital protuberances, and temporalis muscle. b. Facial structures are further divided into the orbital, nasal, auricular, and oral regions. Facial structures that may be palpated through the skin include the zygomatic arch, the bridge of the nose, the temporomandibular joint, and the body of the mandible.

2. The Neck (pp. 366–367, Fig. 11.30) a. Skeletal landmarks of the neck include the hyoid bone, the spine of the C7 vertebra, and the laryngeal prominence. b. Muscles of the neck include the sternocleidomastoid muscles and a portion of the trapezius. c. The neck is divided into anterior and posterior triangles. i. The boundaries of the anterior triangle are the inferior margin of the mandible, the midline of the neck, and the sternocleidomastoid. ii. The boundaries of the posterior triangle are the clavicle, sternocleidomastoid, and trapezius.

3. The Thorax (p. 367, Fig. 11.31) a. Skeletal landmarks of the thorax include several specific regions of the sternum, ribs, midaxillary lines, midclavicular line, and infrasternal angle. b. Muscles of the thorax used as landmarks are the serratus anterior and the pectoralis major.

4. The Abdomen (pp. 367–368, Fig. 11.31) a. The anterior abdominal wall begins at the costal margin. b. The inferior bony landmarks of the abdomen include the iliac crests, the anterior superior iliac spines, and the pubic crest. c. Muscles and other superficial features of the abdomen include the linea alba, the rectus abdominis muscles, the inguinal ligament, the umbilicus, and the external oblique muscles.

5. The Back (pp. 368–369, Fig. 11.32) a. Bony structures of the back that may be palpated include the vertebral spinous processes, the spines of the scapulae, and the iliac crests. b. Prominent muscles of the back include the trapezius, latissimus dorsi, and erector spinae.

6. The Upper Limb and Shoulder (pp. 369–372, Figs. 11.33–11.36) a. The axilla is the armpit. The anterior axillary fold is formed by the pectoralis major muscle while the posterior axillary fold is formed by the latissimus dorsi. b. Shoulder palpation reveals the locations of the acromion, the clavicle, the greater tubercle of the humerus, and the deltoid muscle.

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c. The arm is the upper portion of the upper limb, formed by the humerus and underlying muscles. Muscles in the arm regions are the biceps brachii and triceps brachii. d. The elbow region is characterized anteriorly by the cubital fossa (antecubital fossa).

The lateral and medial epicondyles of the humerus form the lateral and medial boundaries of the elbow while the olecranon process of the ulna forms the posterior point of the elbow.

5. The forearm and hand are comprised of the ulna, radius, carpals, metacarpals, and phalanges. a. The Lower Limb and Gluteal Region (pp. 372–376, Figs. 11.37–11.39) i. The gluteal region is dominated by the “cheeks” of the buttocks, formed primarily by the gluteus maximus muscles. ii. Bony landmarks of the thigh include the greater trochanter of the femur, the medial and lateral condyles of the femur, and the patella. Muscular landmarks are the femoral triangle and popliteal fossa. iii. The leg and foot are home to several bony landmarks. Among them are the tibial tuberosity, medial malleolar, lateral malleolar, and head of the fibula.

Lecture Hints 1. Review the definition of fascicle, and describe specific arrangement patterns of fascicles.

Refer to Figure 11.1.

2. Ask students to list specific muscles that illustrate the various patterns of fascicular arrangements and to associate relationships of range of motion and degree of power with listed muscles.

3. Emphasize that muscles work in groups to accomplish a specific function, such as flexion, rotation, or abduction. Explain the significance of opposing groups of muscles crossing movable joints; review basic actions of major muscle groups.

4. Distinguish among functional groups: prime movers (agonists), antagonists, synergists, and fixators. Use selected muscles and ask students to list one action of each. Further suggest that students name an agonist, antagonist, and synergist for the selected muscles.

Suggested muscles to use are pectoralis major, biceps femoris, flexor carpi ulnaris, adductor magnus, and rectus abdominis.

5. List and explain the criteria for naming muscles. Provide students with a list of the criteria used for naming muscles, and instruct them to identify at least one muscle that meets each criterion.

6. List the names of the principal skeletal muscles you want your students to learn. Clearly identify features and the degree of detail for which students are responsible. Possible features to emphasize are physical locations, meaning of muscle names, origins, insertions, actions, and innervation.

7. Stress and repeatedly emphasize that the proper way to begin studying muscles is not through memorization but rather by understanding the relationships between origins and insertions and the actions of the individual muscles and muscle groups. When a student learns a muscle, the student must learn the origin, insertion, and action at the same time to fully comprehend the musculoskeletal relationship.

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8. Discuss the importance of learning surface anatomy, emphasizing that both internal and external structures may be located by palpation.

9. Emphasize that surface anatomy plays a critical role in understanding anatomy by a regional approach.

10. Note that females usually have a higher percentage of body fat, which may contribute to differences in the way that subcutaneous structures are perceived through a patient’s skin.

11. Ask students to practice finding their own radial pulse and to then practice on a willing classmate.

12. Describe the relationships of the cranium to the scalp, explaining why scalp wounds bleed profusely.

13. Identify the triangle of auscultation and explain its clinical significance.

14. Identify the precise sites for intramuscular injections in the arm, thigh, and gluteal regions.

15. Ask for student participation in showing the cubital fossa and popliteal fossa.

Classroom Discussion Topics and Activities 1. If a human cadaver is unavailable, obtain preserved animal specimens such as cats or mink and exhibit the major muscle groups.

2. Obtain three-dimensional models and laminated wall charts to show the major human muscle groups.

3. Use implements such as scissors, a wheelbarrow, and forceps to illustrate the three types of lever systems.

4. Select a muscular volunteer or invite a bodybuilder to class, and use him or her to show the main groups of muscles bulging through the skin.

5. Have students perform various movements and confirm the muscles that are responsible for these movements by feeling particular muscles bulge and tighten beneath their skin.

6. Ask students to bring in photographs of athletes, weightlifters, or other muscular individuals and to label evident muscles. Make a scrapbook for storage and easy student use. Plan to use the same photos later to label evident blood vessels.

7. Obtain a copy of The Illustrations from the Works of Andreas Vesalius of Brussels, with annotations and discussions. Instruct students to compare and contrast these muscle and skeletal drawings of the sixteenth century with their textbooks.

8. Display a skeleton for quick review of sites of origins and insertions.

9. Mimic a muscle and its actions by attaching the ends of a scarf or cut rubber band to appropriate bony locations and moving the skeletal end of insertion.

10. Discuss what happens if a prime mover muscle such as the pectoralis major is surgically removed. How will the actions provided by that muscle be replaced?

11. Injections are often made directly into a muscle. Ask students to discuss the advantages and disadvantages of intramuscular injections compared to other methods of administering injections (intravenous, subdermal, subcutaneous, and intraperitoneal).

12. Discuss why it is necessary for pregnant women to strengthen their “pelvic floor.”

13. Discuss the properties possessed by bones that allow them to act as effective levers. ..

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14. Call out an action and ask students to respond with the name of a muscle responsible for that action.

15. Provide the name of a muscle, and ask students to identify its antagonists or synergists.

16. Invite a muscular male and a muscular female to visit a lecture as models. Demonstrate specific structures of surface anatomy using these people’s bodies. Students may palpate their own bodies as you demonstrate on the models. Provide a human skeleton for reference during these exercises.

17. Create a handout listing body structures that students may palpate on themselves and a willing classmate. Focus on structures of the head, neck, and limbs because some students may be too embarrassed to palpate structures of the abdomen and thorax.

18. Ask for student volunteers to permit counting of their ribs. The trick is to find the costal cartilages of the second ribs at the sternal angle and then to count down along the sides of the sternum.

19. Ask for another student volunteer to permit a demonstration of auscultation sites of the thorax and abdomen. Provide stethoscopes for students to listen to each other’s body sounds.

20. Discuss clinical conditions that are usually recognized and diagnosed through palpation and conditions that are not detectable through palpation techniques.

Clinical Questions 1. A receiver for the Dallas Cowboys “pulled” his hamstrings. What specific muscles could be affected, and what would the effect be?

Answer: The hamstring muscles are the biceps femoris, semitendinosus, and semimembranosus on the dorsum of the thigh. They flex the leg at the knee and help extend the thigh at the hip. Injury to these muscles interferes with these movements.

2. Malcolm was bending over to pick up a heavy box when he was startled by a mouse. He experienced severe pain in his back with muscle spasms, and it hurt most when he straightened up (extended his spine). What muscles could have been affected?

Answer: Malcolm probably pulled his erector spinae muscles because these muscles readily go into painful spasms when the back is injured during lifting.

3. Micki went to her childbirth class, in which the instructor spoke of the importance of strengthening the muscles of the pelvic floor. What are these muscles?

Answer: The levator ani and coccygeus form the pelvic diaphragm in the pelvic floor.

Some muscles of the urogenital diaphragm might also be included (sphincter urethrae and transverse perineal muscles). Strengthening these muscles makes them less likely to be torn by the passage of the baby’s head during delivery.

4. An elderly woman with osteoarthritis of her left hip joint entered the hospital to have total hip-joint replacement surgery (prosthesis implantation). After the surgery, her left thigh had to be maintained in adduction to prevent dislocation of the prosthesis during healing. Physical therapy was prescribed to prevent atrophy of the gluteal muscles during this healing period. Name the gluteal muscles, and describe the action of each that was being prevented while the hip was adducted.

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Answer: Gluteus maximus, gluteus medius, and gluteus minimus. The gluteus maximus is a major extensor and lateral rotator of the thigh at the hip, and the other two gluteal muscles normally function to abduct and medially rotate the thigh.

5. On his first day of nursing school, Calvin learned an easy way to locate the pulse point of the radial artery in the anterior distal forearm. How did Cal locate this pulse point?

Answer: It is directly lateral to the tendon of the flexor carpi radialis, which is visible deep to the skin of the anterior distal forearm when the hand is flexed against resistance.

6. Kay was stuffing garbage into a garbage can and cut her wrist on a piece of broken glass that she had forgotten was in the trash. The wound bled more than she expected. At the emergency room, the doctor told Kay that the cut was across the “snuff box.” How does this explain the relatively large amount of bleeding?

Answer: The main trunk of the radial artery runs through the anatomical snuff box in the lateral wrist (on its way to form the deep palmar arch in the hand).

7. After Tina was born, her parents saw a cherry-size bulge in the skin of her navel that enlarged when she cried. What is it, and should it be corrected surgically?

Answer: This was a congenital umbilical hernia, and the bulge is formed by a loop of the small intestine that has pushed through a circular weakening in the anterior abdominal wall. Small umbilical hernias like this usually correct themselves before the child’s second birthday.

8. During a physical examination, Hilda, a heavy woman, was noticed to have a large bulge below the skin of the anterior surface of her superior thigh, several centimeters inferior to the inguinal ligament. What is the probable diagnosis?

Answer: The bulge is in the skin of the femoral triangle, so Hilda probably has a femoral (not inguinal) hernia. In such hernias, intestines push inferiorly deep to the inguinal ligament and raise a bulge in the superior thigh. Incidentally, femoral hernias are more common in women than in men because of the greater width of the female pelvis.

Art Resources Figure 11.1 Figure 11.2 Figure 11.3 Figure 11.4 Figure 11.5 Figure 11.6 Figure 11.7 Figure 11.8 Figure 11.9 Figure 11.10 Figure 11.11 Figure 11.12

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Patterns of fascicle arrangement in muscles.

Lever systems operating at a mechanical advantage and a mechanical disadvantage.

Lever systems.

Focus Figure: Muscle Action.

Development and basic organization of the muscles.

Muscle compartments in the arm and forearm.

Muscle compartments in the thigh and leg.

Superficial muscles of the body.

Muscles of the scalp, face, and neck.

Muscles of mastication and tongue movements, left lateral view.

Muscles of the anterior neck and throat used in swallowing.

Muscles of the neck and vertebral column causing movements of the head and trunk.

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Figure 11.13 Figure 11.14 Figure 11.15 Figure 11.16 Figure 11.17 Figure 11.18 Figure 11.19 Figure 11.20 Figure 11.21 Figure 11.22 Figure 11.23 Figure 11.24 Figure 11.25 Figure 11.26 Figure 11.27 Figure 11.28 Figure 11.29 Figure 11.30 Figure 11.31 Figure 11.32 Figure 11.33 Figure 11.34 Figure 11.35 Figure 11.36 Figure 11.37 Figure 11.38 Figure 11.39 Table 11.1 Table 11.2 Table 11.3 Table 11.4 Table 11.5 Table 11.6 Table 11.7

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Muscles of respiration.

Muscles of the abdominal wall.

Muscles of the pelvic floor and perineum.

Superficial muscles of the thorax and shoulder acting on the scapula and arm.

Muscles crossing the shoulder and elbow joint, acting on the arm and forearm, respectively, right side.

Muscles of the anterior fascial compartment of the forearm acting on the wrist and interphalangeals.

Muscles of the posterior fascial compartment of the forearm acting on the wrist and interphalangeals.

Cross-section through the proximal forearm.

Intrinsic muscles of the hand.

Anterior and medial muscles of the right thigh.

Posterior muscles of the right hip and thigh.

Cross section through the mid-thigh.

Muscles of the anterior compartment of the right leg.

Muscles of the lateral compartment of the right leg.

Muscles of the posterior compartment of the right leg.

Muscles of the right foot.

Surface anatomy of the lateral aspect of the head.

Surface anatomy and regions of the neck.

The anterior thorax and abdomen.

Surface anatomy of the back.

Shoulder and arm.

Intramuscular injection in the deltoid muscle.

Surface features of the arm and forearm.

Surface features of the distal forearm and hand.

The gluteal region.

Surface anatomy of the lower limb.

Surface anatomy of the lower limb, posterior view.

Muscles of the Head, Part I: Facial Expression (Fig. 11.9) Muscles of the Head, Part II: Mastication and Tongue Movement (Fig. 11.10) Muscles of the Anterior Neck and Throat: Swallowing (Figure 11.11) Muscles of the Neck and Vertebral Column: Head Movements and Trunk Extension (Fig. 11.12) Deep Muscles of the Thorax: Breathing (Fig. 11.13) Muscles of the Abdominal Wall: Trunk Movements and Compression of Abdominal Viscera (Fig. 11.14) Muscles of the Pelvic Floor and Perineum: Support of Abdominopelvic Organs (Fig. 11.15)

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Table 11.8 Table 11.9 Table 11.10 Table 11.11 Table 11.12 Table 11.13 Table 11.14 Table 11.15 Table 11.16 Table 11.17

Superficial Muscles of the Anterior and Posterior Thorax: Movements of the Scapula (Fig. 11.16) Muscles Crossing the Shoulder Joint: Movements of the Arm (Humerus) (Fig. 11.17) Muscles Crossing the Elbow Joint: Flexion and Extension of the Forearm (Fig. 11.17) Muscles of the Forearm: Movements of the Wrist, Hand, and Interphalangeals (Figs. 11.18–11.20) Summary of Actions of Muscles Acting on the Arm, Forearm, and Hand Intrinsic Muscles of the Hand: Fine Movements of the Interphalangeals (Fig. 11.21) Muscles Crossing the Hip and Knee Joints: Movements of the Thigh and Leg (Figs. 11.22–11.24) Muscles of the Leg: Movements of the Ankle and Toes (Figs. 11.25–11.27) Summary of Actions of Muscles Acting on the Thigh, Leg, and Foot Intrinsic Muscles of the Foot: Toe Movement and Foot Support (Fig. 11.28)

Teaching with Art Figure 11.17

Muscles crossing the shoulder and elbow joint, which cause movements of the arm and forearm, respectively. (a) Superficial muscles of the anterior thorax, shoulder, and arm; (b) triceps brachii muscle; (c) biceps brachii muscle; (d) brachialis muscle.

Figure 11.30

Surface anatomy and regions of the neck.

Textbook pp. 335–336 and 366.

Checklist of Key Points in the Figure • Remind students that the term arm refers to the portion of the upper limb between the shoulder and elbow.

• Review the concepts of superficial and deep with respect to the muscles in this figure.

• Remind students that the shoulder joint is the most flexible joint in the body but pays the price of instability. Comment on the trade-offs between flexibility and instability in the configuration of the shoulder joint; compare glenoid cavity and acetabulum.

• Identify the nine muscles that cross the shoulder joint to act on the humerus; explain the scapular origins of seven of these muscles and the axial origins of the other two; explain the insertions; stress the relationship between origins, insertions, and actions.

• Identify the three largest of these muscles as the prime movers; they are the pectoralis major, latissimus dorsi, and deltoid. The other six are synergists and fixators.

• Identify the four muscles in this group that collectively form the rotator cuff: supraspinatus, infraspinatus, teres minor, and subscapularis (“SITS”); explain the function of the rotator cuff and relate the cuff to sports injuries.

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• The remaining two muscles of this group are teres major and coracobrachialis.

• Emphasize that muscles that originate anterior to the shoulder joint flex the arm; muscles that originate posterior to the shoulder joint extend the arm; identify the flexors and extensors of the arm.

• Focus on the biceps brachii as the prime mover and the triceps brachii as the antagonist in forearm flexion.

• Focus on the triceps brachii as the prime mover and the biceps brachii as the antagonist in forearm extension.

• Identify the skeletal landmarks of the neck, such as the hyoid, jugular notch, and clavicles.

• Review the major muscles of the neck; explain that the entire sternocleidomastoid muscle can be palpated only when the head is turned to the side. Review head rotation.

• Identify the important structures that pass through the neck, such as the spinal cord, trachea, esophagus, major vessels (common carotid artery and internal jugular vein), and major nerves (vagus and phrenic).

• Explain the boundaries of the anterior and posterior triangles of the neck, and comment on the clinical significance.

• Make the terminology connection between cervical and cervix. Cervix is Latin for “neck.”

• Point out anatomical features of the larynx; mention “Adam’s apple”; point out that the cricoid cartilage serves as a landmark for locating the rings of cartilage of the trachea if an emergency airway (tracheotomy) is needed.

Common Conceptual Difficulties Interpreting the Art • Explain the complex nature of the interactions of shoulder muscles.

• Remind students that muscles usually work in groups, not individually, to accomplish a particular movement.

• It is often difficult for a student to understand that some prime movers can cause several different actions at the same joint. Remind students that portions of a prime mover may contract independently of the rest of the muscle and that synergists prevent an inappropriate movement at any given time. This is especially true at the shoulder joint.

• Remind students that muscles return to their relaxed length following contraction.

• Remind students that many visual landmarks are not easy to find if covered by subcutaneous fat.

• Explain a regional approach to the study of the neck as opposed to a systemic approach.

• Review the importance of the study of surface anatomy.

Art Exercises 1. Provide copies of Figure 8.2, the scapula, and Figure 8.3, the humerus of the right arm.

Referring to Figures 11.16 and 11.17, begin by asking students to identify the origins and insertions of the muscles that form the rotator cuff. Ask students to mark the origin and insertion points on the skeletal diagrams. Use red to denote the muscle origins and blue to denote the insertion points.

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2. Neck Structures Drawing Exercise: Instruct students to sketch the following structures as they relate to the sternocleidomastoid muscle: a. Sternal head b. Clavicular head c. Cervical lymph nodes d. External jugular vein e. Internal jugular vein f. Common carotid artery g. External carotid artery h. Internal carotid artery i. Subclavian artery j. Brachial plexus k. Cervical plexus l. Mastoid process of the occipital bone 3. Regional Anatomy Exercise: Ask students to label an unlabeled copy of Figure 11.32 with each body system represented along the back and specific structures from each system. Tell students to be particularly cognizant of clinically relevant structures as well as the boundaries of the triangle of auscultation.

Critical Reasoning 1. Looking at the colored diagrams produced in the art exercise, ask students to identify the muscles of the rotator cuff group responsible for the following actions: a. Medial rotation of the arm b. Lateral rotation of the arm Ask them to explain their answers.

Answer: (1) The subscapularis is primarily responsible for medial rotation of the arm because of its insertion on the anteriorly positioned lesser tubercle of the humerus.

(2) The infraspinatus and the teres minor rotate the arm laterally. Both insert posteriorly on the greater tubercle of the humerus. (Infraspinatus inserts on the greater tubercle posterior to the insertion of supraspinatus, and teres minor inserts on the greater tubercle inferior to infraspinatus.)

2. Ask students why trauma to the posterior triangle of the neck may interfere with breathing.

Answer: The phrenic nerve leaves the cervical plexus within the posterior triangle to innervate the diaphragm.

3. Ask students to name the chambers that blood may potentially flow into in the case of a severe blow to the side of the neck and head that results in a ruptured internal carotid artery.

Answer: Spaces of the temporal bone.

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Supplemental Course Materials Library Research Topics 1. Given that skeletal muscle cells do not regenerate well, what methods of treatment are available if a major group of muscles is lost or paralyzed? What is the status of skeletal muscle transplants?

2. What are the most appropriate modes of therapy for pulled hamstring or groin muscles?

3. What effect does aging have on skeletal muscle? What research is underway concerning this topic?

4. Olympic athletes use scientific training methods to improve their physical performance.

Find out what some of these methods are, and if you are an athlete, try to employ them to better your performance.

5. Research the major causes of injuries to the following major muscle groups: hamstrings, rotator cuff, quadriceps, and adductors of the thigh. Simultaneously, research current therapies and treatments for each of these injuries.

6. What effects does a sedentary lifestyle have on skeletal muscle? What research has been done in this area?

7. What effects does obesity have on skeletal muscle? What therapies and treatments are available to stem the obesity epidemic?

Suggested Readings Agur, A. M. Grant’s Atlas of Anatomy. 13th ed. Baltimore: Lippincott Williams & Wilkins, 2012.

Blau, H. and Jason H. Pomerantz. “Re'evolutionary' Regenerative Medicine.” Journal of the American Medical Association. 305 (1): 87–88 (January 5, 2011).

Clemente, C. D. Anatomy: A Regional Atlas of the Human Body. 5th ed. Baltimore: Lippincott Williams & Wilkins, 2008.

Gray, H., et al. Gray’s Anatomy. 38th ed. London: Churchill Livingstone, 1995.

McMinn, R. and R. Hutchings, et al. Color Atlas of Human Anatomy. 5th ed. St. Louis: CV Mosby, 2003.

Moore, K. L. Clinically Oriented Anatomy. 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2009.

Williams, P. L., et al. Gray’s Anatomy. 38th ed. New York: Churchill Livingstone, 1995.

Answers to Textbook Questions Answers for multiple-choice and matching questions 1–13 are located in the Answers Appendix of the textbook.

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Short Answer and Essay Questions 14. (a) Mechanical advantage refers to the use of a small effort to move a large load, while mechanical disadvantage is defined as the need of a large effort to move a small load. (b) A third class lever in the body, such as the flexing of the forearm (load) by the biceps brachii muscle (effort), operates on the basis of a mechanical disadvantage. (pp. 296–298) 15. (a) Rectus abdominis, external oblique, internal oblique, transversus abdominis. (b) The fascicles of adjacent muscle sheets are arranged at cross-directions to each other. (c) Rectus abdominis. (a, b, and c: pp. 325–327, Table 11.8) (d) Diaphragm. (pp. 323–324, Table 11.7) 16. Movements of the humerus possible at the shoulder joint are flexion (pectoralis major, deltoid, biceps brachii, and coracobrachialis), extension (deltoid, latissimus dorsi, and teres major), abduction (deltoid and supraspinatus), adduction (pectoralis major, latissimus dorsi, teres major, and coracobrachialis), medial rotation (deltoid, latissimus dorsi, teres major, and subscapularis), lateral rotation (infraspinatus and teres minor). Muscles involved in shoulder stabilization include the subscapularis, supraspinatus, infraspinatus, and teres minor.

17. (a) Extensor carpi radialis longus and brevis. (b) Flexor digitorum profundus. (c) Opponens pollicis and opponens digiti minimi. (pp. 338–346, Tables 11.13, 11.14) 18. (a) Piriformis, obturator externus, obturator internus, gemellus muscles, quadratus femoris, and sartorius. (b) Gluteus maximus is the most powerful extensor of the thigh at the hip; gluteus medius and gluteus minimus adduct the thigh at the hip. (pp. 347–354, Table 11.15) 19. The dorsal muscles of the leg must propel the entire weight of the body as they flex the plantar muscle of the foot during walking. The ventral leg muscles need only lift (dorsiflex) the foot to prevent it from dragging on the ground during the foreswing of walking. (pp. 355–360, Table 11.16) 20. Fascial compartments group together muscles of similar developmental origin and function. Muscles in the same compartment have similar actions and often function synergistically to produce a particular movement. While muscles in opposite compartments function as agonist/antagonist pairs. In most cases, each compartment is innervated by a single named nerve. (p. 302) 21. (a) abductor pollicis brevis, flexor pollicis brevis, opponens pollicis, adductor pollicis (any two: p. 344). (b) extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum, extensor carpi ulnaris, supinator, abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, extensor indicis (any two: pp. 341–342). (c) flexor pollicis longus, flexor digitorum profundus, pronator quadratus (any two: p. 341). (d) biceps brachii, brachialis, brachioradialis (any two: p. 337). (e) masseter, temporalis, medial pterygoid, lateral pterygoid, buccinator (any two: pp. 312–314). (f) flexor hallucis brevis, adductor hallucis, flexor digiti minimi brevis (any two: pp. 361–362). (g) gastrocnemius, soleus, plantaris, flexor digitorum longus, flexor hallucis longus, tibialis posterior (any two: p. 358). (h) adductor magnus, adductor longus, adductor brevis, pectineus, gracilis (any two: pp. 347–349). (i) biceps femoris, semitendinosus, semimembranosus (any two: p. 351).

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22. (a) extrinsic eye muscles, tongue muscles, and pharyngeal arch (branchiomeric) muscles. (b) muscles of facial expression, chewing muscles, suprahyoid muscles, pharyngeal constrictors, sternocleidomastoid, and trapezius. (c) superior, middle, and inferior pharyngeal constrictors. (pp. 298–300) 23. The external urethral sphincter and the deep transverse perineal muscle form the urogenital diaphragm. While the external urethral sphincter constricts the urethra (voluntary control of urination) and helps support the pelvic organs, the deep transverse perineal muscle supports the pelvic organs and steadies the perineal body. (pp. 326–327) 24. The tibialis anterior lies on the tibia in the anterior region of the leg; temporalis is located in the temple on the temporal bone of the skull; and the erector spinae is a group of muscles that extends the vertebral column (makes the spine erect). (p. 302) 25. (a) A muscle that has the major responsibility for producing a specific movement is the agonist, or prime mover of that motion. (b) Muscles that oppose or reverse a particular movement act as antagonists. (c) Synergists help the prime movers either by adding a little extra force to the movement being carried out or by reducing undesirable extra movements that the prime mover may produce.

As muscles lack the ability to push, they cannot undo the actions they produce. Therefore, for an action produced by a single muscle, there will be another muscle to counter that action. (p. 298) 26. Feeling internal body structures through the skin with the interphalangeals is called palpation. (p. 364) 27. (a) One way to locate the ventral gluteal site is to draw an imaginary line laterally from the posterior superior iliac spine to the greater trochanter and then proceed 5 cm superiorly from the midpoint of this line. (pp. 373–374) (b) Intramuscular injections are often given into the deltoid muscle, about 5 cm inferior to the greater tubercle of the humerus. (p. 370) 28. C7 is the first prominent spinous process that is felt as one runs an interphalangeals down the neck in the posterior median sulcus; T3 is the spinous process that lies at the same level as the medial end of the spine of the scapula; T7 lies at the level of the scapula’s inferior angle; L4 lies at the level of the supracristal line (line connecting the highest points of the two iliac crests on the back). (pp. 366 and 368–369) 29. The borders of the triangle of auscultation are formed by the latissimus dorsi, trapezius, and scapula. (p. 369) 30. (a) On the lateral side of the hip, just anterior to a hollow and about one hand’s breadth inferior to the iliac crest (p. 375). (b) Medial thigh. (Figs. 11.22–11.24) (c) Lateral anterior thigh. (Fig. 11.22) (d) This is the ischial tuberosity, just superior to the medial part of the gluteal fold. (p. 375)

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Critical Reasoning and Clinical Applications Questions 1. Traumatic injury to the leg can lead to swelling of the muscles. Due to the inelastic nature of the fascia surrounding the muscle compartment, pressure builds in the compartments of the leg, compressing the vessels and nerves, causing incredible pain. To minimize further ischemic damage to the tissues, the doctor asked for a fasciotomy to be conducted, which would reduce the intra-compartmental pressure. (p. 302) 2. Levator ani and the muscles of the urogenital diaphragm (especially sphincter urethrae). (pp. 328–329) 3. To get a grip onto spherical objects, e.g., a hammer, a glass, or a pencil, the thumb and little finger needs to perform opposition, which is made possible by contracting muscles in the thenar and hypothenar muscle groups. All muscles responsible for opposition are innervated by the median and/or ulnar nerve. In fact, when these nerves get damaged, problems related to grip strength will be encountered. (pp. 343–344) 4. Chao-Jung injured her adductor muscles, probably adductor longus, and the medical name for her condition is “adductor strain.” (p. 376) (Also see Chapter 11, “Related Clinical Terms.”)

5. Mr. Jones is suffering from ‘tennis elbow’. Trauma or overuse of the forearm’s extensor muscles at the lateral epicondyle of the humerus leads to pain at that site. As Mr. Jones is involved in construction work, there is a high likelihood of him suffering from this condition. (p. 336) 6. Based on fascicle orientation, sartorius is designed for range of movement; other muscles, such as rectus femoris, latissimus dorsi, subscapularis, flexor pollicis longus, and gluteus maximus, are designed for power. (p. 295) 7. The baseball player injured the subscapularis, a rotator cuff muscle that inserts anteriorly on the lesser tuberosity of the humerus. (p. 336) 8. Plantar flexion of the foot by the soleus is a second-class lever; abduction of the arm by the deltoid is a third-class lever; doing push-ups using the triceps brachii is a third-class lever. (pp. 296–298) 9. Mrs. Schultz has both Colles’ fracture of the wrist and a proximal dislocation of the ulna at the elbow. The force of landing on her outstretched hand has driven the distal end of the radius proximally into the radial shaft, which explains why the radial styloid process lies more proximally than normal. The same force also dislocated the ulna superiorly by 2 cm, for the olecranon normally lies directly in line with the two epicondyles of the humerus. (pp. 371–372) 10. Henry is correct in his observation. Wearing tight shoes may lead to permanent displacement of the great toe towards the other toes. The sesamoid bones at the head of the first metatarsal will be displaced laterally, resulting in ineffective action of the abductor halluces muscle. The muscle fails to abduct the great toe back to its normal position. This condition is known as hallux valgus. (p. 376)

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 11: Muscles of the Body To the Student In previous chapters, you learned about the skeleton, joints, movements, and muscle tissues.

Now it is time to study the skeletal muscles of the body, which will bring together many aspects of Chapters 7–10. Movements are determined by muscle attachments to bone, lever systems, arrangement of fascicles, and skeletal muscle group interactions. Many muscles are listed in the tables, and your instructor will tell you which individual muscles you must learn.

Keep in mind that muscles act in groups to perform specific functions, such as flexion or extension, and rarely, if ever, act individually. For simplicity, you will examine specified skeletal muscles on a cadaver or animal specimen, learning their origins, insertions, actions, and innervations of each. The proper way to study muscles initially is not through memorization but a thorough understanding of origin, insertion, and action. If needed, please review the movements made at specified joints covered in Chapter 9.

Primarily, your study of anatomy has incorporated the systemic approach, until this chapter. Now you have the unique opportunity to combine everything you have studied by using an anatomical regional approach. There is a chance you looked at the some of the information in this chapter when your instructor covered bones and muscle tissue in Chapters 7–10. However, if this is your first look into Chapter 11, realize that it builds upon information in previous chapters: This is a great opportunity to embrace the “put-it-all-together” concept that pervades this chapter.

The regional approach of Chapter 11 enables you to better understand the relationships between muscles, bones, blood vessels, lymph nodes, nerves, internal organs, and sites where injections are given, blood drawn, and tubes inserted. Whether your career goal is a healthcare profession, it is to your advantage to be able to understand the normal body so that you can detect something that is abnormal. Careful observation and knowledge of palpation techniques will aid this understanding. And do not forget, your own body is the best “cheat sheet” possible in anatomy. It is the one thing you cannot leave behind when you go into the classroom for your exam!

It will also benefit you greatly to include Practice Anatomy Lab 3.0 (PAL) (BC; DVD, Website) in your study of skeletal muscles. The Muscular System sections of the Human Cadaver module offer comprehensive study tools for studying skeletal muscles. The threedimensional animations provide a review of muscle actions.

Step 1: Summarize the different arrangements of fascicles in muscles. __ Describe the parallel pattern of arrangement, and name an example. __ Describe the convergent pattern of arrangement, and name an example. __ Describe pennate (unipennate, bipennate, and multipennate) patterns of arrangement, and name examples. __ Describe the circular pattern of arrangement, and name an example.

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Step 2: Describe lever systems and their relationships to bone and muscle. __ Define lever. __ Distinguish the terms effort, fulcrum, and load. __ Explain the conceptual relationship of leverage to bone, joints, and muscle. __ Describe first-class, second-class, and third-class levers. __ Explain why most lever systems in the body are third-class.

Step 3: Summarize skeletal muscle group interactions in the body. __ Define and give an example of a prime mover (agonist). __ Define and give an example of an antagonist. __ Define and give an example of a synergist. __ Define and give an example of a fixator.

Step 4: Understand the naming of skeletal muscles. __ List criteria for the naming of skeletal muscles. __ Give an example of a muscle that fits each criterion listed.

Step 5: Organize the body’s muscles into functional groups based on developmental origins. __ Distinguish myotomes from somitomeres. __ Explain the developmental-based scheme for the development of musculature of the visceral organs. __ Describe the developmental-based scheme for the development of pharyngeal arch muscles. __ Describe the developmental-based scheme for the development of axial muscles. __ Explain the developmental-based scheme for the development of limb muscles.

Step 6: Focus on specific skeletal muscles and respective groups described in Tables 11.1–11.17 as assigned by your instructor. __ List criteria for determining the origin and insertion of a muscle. __ Make sure you understand all the body movements detailed in Figures 9.5 and 9.6. __ Describe the action of each assigned muscle, and explain the action based on the origin and insertion of the muscle. __ Design flashcards for assigned muscles, including muscle shape, location, attachments, actions, and innervation.

Step 7: Describe surface anatomy as a field of study. __ Define surface anatomy. __ Explain the importance of surface anatomy to the “living” body. __ Define palpation. __ Distinguish systemic from regional approaches to the study of anatomy. __ List several ways surface anatomy provides information for a clinician.

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Step 8: Describe the major surface features of the head. __ Distinguish the cranium from the face. __ Palpate major surface features of the cranium as described by your textbook. __ Distinguish the cranium from the scalp. __ Palpate major surface features of the face as described by your textbook.

Step 9: Describe and palpate the major surface features of the neck. __ Palpate the major skeletal landmarks of the neck as described by your textbook. __ Palpate the major muscles of the neck. __ Define and describe the anterior and posterior triangles. __ Using the triangles of the neck as a reference, describe locations for palpations of a pulse, the larynx, cervical lymph nodes, and the trachea. __ Sketch the anterior and posterior triangles, labeling important surface features. __ List at least three vitally important structures that lie deep in the neck, explaining why they are so important.

Step 10: Describe and palpate the major surface features of the trunk. __ Define the back, and count and palpate vertebral processes, naming the easy ones to find as landmarks. __ Distinguish the posterior median fissure from the supracrestal line. __ Define and describe the posteriorly located triangle of auscultation, explaining the clinical significance of this area. __ Explore the anterior thoracic surface, palpating all bony and muscular features described in your textbook. __ Distinguish the midaxillary line from the midclavicular line. __ Map the location of the pleural cavities, the lungs, and the heart using the ribs as a reference. __ List and palpate all features of the anterior abdominal wall listed in your textbook. __ Define umbilicus and explain the examination for an inguinal hernia. __ Define linea alba, explaining why this is a site of clinical significance. __ Distinguish between linea semilunaris and tendinous intersections. __ Explain the clinical significance of a physician placing a stethoscope on the abdominal wall, describing the sites of placement and the clues various sounds provide. __ Describe the bony boundaries of the perineum.

Step 11: Describe and palpate the major surface features of the upper limb and shoulder. __ Define axilla, naming important superficial structures associated with this part of the body. __ Explain why women should palpate the axilla during a breast self-examination. __ Identify and palpate the bony landmarks of the shoulder.

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__ Identify an upper limb location for an intramuscular injection. __ Identify and palpate the bony and muscular surface features of the arm. __ Identify and palpate the bony landmarks of the elbow region. __ Explain where and why you feel a tingling sensation if you bump your elbow or, in more common vernacular, “hit your crazy/funny bone.” (Be careful with your explanation, because the reference is not to your “humerus.”) __ Define and describe the cubital fossa, and explain the clinical significance of the median cubital vein. __ Describe and palpate the bony and muscular structures of the forearm and hand listed in your textbook. __ Assume the anatomical position. Pronate your hand, and identify which forearm bone remains more stationary. __ Make a clenched fist, and identify both tendons evident on the anterior wrist. __ Describe and palpate pulse points in the distal forearm. __ Identify an important site for drawing blood and administering an IV on the upper extremity.

Step 12: Describe and palpate the major surface features of the lower limb and gluteal region. __ Identify and palpate the bony landmarks of the gluteal region. __ Distinguish the natal cleft from the gluteal fold. __ Explain the clinical procedures and concerns for administering intramuscular injections in the gluteal region (i.e., the “safe area”). __ List and palpate the bony and muscular landmarks of the thigh. __ Explain the femoral triangle, and describe the clinical significance of this area. __ Define and palpate the popliteal fossa. __ List and palpate the bony landmarks of the leg and foot described in your textbook. __ Identify the location of the pulse of the posterior tibial artery and the dorsalis pedis artery.

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CHAPTER

12

Fundamentals of the Nervous System and Nervous Tissue

Lecture and Demonstration Objectives 1. List the main functions of the nervous system.

2. Explain the structural and functional divisions of the nervous system.

3. Define neuron, describe its structural components, and relate each structure to its functional role.

4. Describe the structure of a synapse.

5. Classify neurons both structurally and functionally.

6. List the six types of neuroglia in nervous tissue, and distinguish them by location and function.

7. Describe the structure of myelin sheaths.

8. Distinguish gray matter from white matter in the CNS. 9. Define nerve and describe the structural components of nerves.

10. Describe the structural link between the peripheral nervous system and the central nervous system.

11. Define reflex, and list the basic components of a reflex arc. Distinguish monosynaptic reflexes from polysynaptic reflexes.

12. Describe the roles of interneurons in the CNS. 13. Differentiate serial processing and parallel processing.

14. Define convergent and divergent circuits and give an example of each.

15. Describe how multiple sclerosis relates to myelin and axon function.

16. Describe the process of neuronal regeneration in the peripheral nervous system.

17. Describe the development of the nervous system in the embryo.

Suggested Lecture Outline I. The Functional Organization of the Nervous System (pp. 382–385, Figs.

12.1–12.3, Table 12.1) A. Functions of the Nervous System (p. 382, Fig. 12.1) 1. The nervous system is the master control and communications system of the body; it has the chief functions of sensory input, integration, and motor output.

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B. Basic Divisions of the Nervous System (pp. 382–385, Figs. 12.2–12.3, Table 12.1) 1. The basic divisions of the nervous system are the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves and ganglia).

2. The information of sensory (afferent) input travels from a point of somatic reception or a point of visceral reception to the CNS; integration of this information dictates a response, then motor (efferent) signals are carried from the CNS to sites of somatic motor, branchial motor, or visceral motor responses.

3. The four main subdivisions of the PNS are somatic sensory, visceral sensory, visceral motor, and somatic motor. This organization breaks down the PNS into functionally related groupings.

II. Nervous Tissue (pp. 385–393, Figs. 12.4–12.8) A. The Neuron (pp. 385–389, Figs. 12.4, 12.5, Table 12.2) 1. The human body contains billions of nondividing neurons, or nerve cells.

2. Several functions characterize neurons: ability to conduct electrical impulses, extreme longevity, no cell division, and high metabolic rate.

3. Neurons are composed of three main parts: the cell body (soma), dendrites, and an axon. a. The cytoplasm of the cell body contains all the usual organelles and chromatophilic bodies. Most neuronal cell bodies are located within the CNS; those in the PNS are termed ganglia. b. Dendrites are branching processes extending from the cell body. Dendrites function as receptive sites for receiving signals from other neurons. c. Neurons have only one axon. An axon is an “impulse generator,” which takes impulses away from the neuronal cell body.

4. A synapse is the functional junction and the site of communication between neurons; explain structural components and how a synapse works; identify the major categories.

5. Neurons are classified by structure and by function. a. Structural classification groups neurons as multipolar, bipolar, or unipolar neurons. b. Functional classification is based on the direction the nerve impulse travels; sensory (afferent) neurons conduct impulses toward the CNS; motor (efferent) neurons carry impulses away from the CNS; interneurons lie in the CNS between motor and sensory neurons.

B. Neuroglia (pp. 390–393, Figs. 12.6, 12.7) 1. Nonnervous supporting cells in the nervous system support, protect, nourish, and insulate neurons. The support cells are capable of division throughout life. a. The four types of support cells in the CNS are collectively called neuroglia.

Astrocytes, microglial cells, ependymal cells, and oligodendrocytes are neuroglial cells of the CNS. b. The two types of support cells in the PNS are Schwann cells and satellite cells.

2. Myelin sheaths cover axons and provide insulation and increased speed of impulse conduction; myelinated axons are present in the CNS and PNS.

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III. Gross Anatomy of the Nervous System: An Overview (pp. 393–394, Fig. 12.9) A. Gray and White Matter of the CNS (p. 393, Fig. 12.8) 1. Gray matter is gray colored and surrounds the central cavities of the CNS. Gray matter is composed primarily of neuronal cell bodies, neuroglia, and nonmyelinated axons. In the cerebral cortex and cerebellum, an additional layer of gray matter surrounds the white matter of the CNS. 2. White matter lies external to the gray matter of the CNS. White matter is composed of myelinated axons passing between specific regions of the CNS. Tracts are bundles of axons traveling to similar destinations.

B. Nerves (pp. 393–394, Fig. 12.9) 1. Nerves are bundles of axons in the PNS. a. Axons of the PNS are surrounded by Schwann cells, which are covered by endoneurium. b. Perineurium is connective tissue surrounding nerve fascicles. c. Epineurium is a tough connective tissue surrounding the entire nerve.

IV. Neuronal Integration (pp. 395–398, Figs. 12.10–12.13) A. The CNS and PNS are functionally interrelated. Nerves of the PNS serve as information pathways to and from the periphery of the body. The CNS is composed of interneurons that process sensory information, direct information to specific CNS regions, initiate appropriate motor responses, and transport information from one region of the CNS to another.

1. Reflex Arcs (pp. 395–396, Fig. 12.11) a. Reflexes are rapid, automatic motor responses to external as well as internal stimuli. b. The reflex arc is a simple chain of neurons that determines the basic structural plan of the nervous system; there are five basic components to a reflex arc: the receptor, a sensory neuron, an integration center, the motor neuron, and the effector.

2. Neuronal Circuits (pp. 396–397, Fig. 12.12) a. Multiple and complex neuronal circuits are formed by interneurons; these circuits are termed diverging, converging, and reverberating circuits. b. The types of neuronal processing are serial processing and parallel processing.

3. Integration Between the PNS and CNS (pp. 398, Fig. 12.13) a. The basic simplified plan of the nervous system emphasizes the reflex arcs associated with the spinal cord; sensory neurons enter the spinal cord dorsally, and motor neurons exit the spinal cord ventrally.

V. Disorders of the Nervous System (pp. 399–400, Figs. 12.14, 12.15) A. Multiple Sclerosis (pp. 399–400, Fig. 12.14) 1. The most common cause of neural disability in young adults is multiple sclerosis (MS); an autoimmune disease that destroys myelin in the CNS, MS is characterized by periods of relapses and remissions.

B. Neuronal Regeneration (p. 400, Fig. 12.15) 1. Regeneration of injured axons is possible in the PNS, but not possible in the CNS. 144

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VI. Nervous Tissue Throughout Life (pp. 401–402, Fig. 12.16; 12.17) A. Embryonic Development of Nervous Tissue (pp. 401–402, Fig. 12.16) 1. Invagination of the ectoderm forms the neural tube and neural crest; the neural tube becomes the CNS; sensory and motor neurons are derived from neuroblasts.

2. Neurons form rapidly until the sixth month of development. Neuroepithelium begins to produce astrocytes and oligodendrocytes, which extend outward and provide pathways along which young neurons migrate to their final destination.

3. Sensory neurons arise from neural crest cells, which explains why their cell bodies lie outside the CNS in ganglia.

4. Neuroscientists are investigating how growing neurons meet and form synapses.

5. Fully differentiated neurons do not divide. There is no obvious replacement of dead neurons.

Lecture Hints 1. Identify several general ways the nervous system functions as the master control and communication system of the human body. Ask introductory questions: “If you touch something hot, how do you react?” and, “Did you have to consciously think about moving your hand?” Theoretically, students will remember that the basic logic of a neural pathway consists of a sensory structure, some way of conveying the information to the brain, and some way to cause a motor response.

2. Explain and repeatedly emphasize the concepts of sensory input, integration, and motor output, which are key to understanding the nervous system.

3. The initial presentation should be an overview of the nervous system; stress the difference between the CNS and the PNS; explain that future study consists of information about all the initial components; tell students to refer to earlier text and figures as the material becomes increasingly complicated so that they keep the overall concepts in view throughout their study of the nervous system.

4. Devise a simple schematic diagram to summarize the functional organization of the nervous system.

5. Visually demonstrate the structure of a neuron using a model.

6. Relate each structural neuronal feature with its functional role; explain and emphasize that most cell bodies (except for ganglia) are located in the CNS, where they are protected by the bony skull and vertebral column; ganglia are located in the PNS. 7. Draw and label a simplified illustration of a synapse; use root-word dissection to emphasize the difference between pre- and postsynaptic neurons.

8. Draw a comparison illustration of a monosynaptic reflex arc and a polysynaptic arc; label all specific parts and features; refer to the “Teaching with Art” exercise for Figure 12.11 (p. 396) for lecture hints.

9. Myelin sheath and neurilemma always confuse students; point out that both are part of the same cell; use visual aids to explain saltatory conduction; devise comparison diagrams of myelinated and nonmyelinated axons.

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10. Students often do not understand regeneration and myelination; for example, they may not understand why regeneration is sometimes possible in the PNS and not in the CNS, even though CNS and PNS neurons are both myelinated.

11. As the anatomy of the nerve is discussed, point out the similarity between the basic structure of muscle tissue and nervous tissue; mention the similarity of nomenclature; explain that knowing the anatomy of muscle, they already know the basics of nerve anatomy.

12. White matter and gray matter become increasingly common, and increasingly more complex in future discussions of the CNS and PNS. In the initial discussion, emphasize that the outer white matter surrounds the inner gray matter in the CNS, but also introduce the exception of the cerebral cortex. Clearly distinguish gray from white matter; define the terms, identify components, and describe locations. Introduce the relationship of the hollow cavity in the extreme center of the brain and spinal cord to gray and white matter.

Classroom Discussion Topics and Activities 1. Use prepared microscope slides of neurons, supporting cells, and peripheral nerves to illustrate the histology of nervous tissue. Additionally, use photomicrographs from the Histology module of PAL 3.0.

2. Demonstrate nervous tissue stained by a variety of procedures (Golgi method versus basic chromatophilic substance stains versus stains that demonstrate neurofibrils).

Discuss the strengths and weaknesses of each stain for studying the structure of neurons.

3. To illustrate proprioception, instruct students to close their eyes and move a hand toward the side of their head; ask students to visualize the location of their hand.

4. Select a student to help in the demonstration of reflexes, such as the patellar and stretch reflexes.

5. Ask students to compare and contrast the regenerative capacities of the two tissues that regenerate most poorly (nervous tissue and cardiac muscle) with those of the tissues that regenerate most effectively (epithelium and bone).

6. Ask students why supporting cells divide and regenerate better than neurons.

7. Point out that the chemical acetylcholine has long been recognized as a neurotransmitter.

Ask students why has it been so difficult to identify other neurotransmitters.

8. Ask students to identify structures in the adult body, other than the sensory neurons, derived from the neural crest.

9. Instruct students to list some human activities that are reflexive, some subconscious behaviors that involve higher levels of neural integration, and some behaviors that involve conscious thought.

Clinical Questions 1. Zoe was bitten on the leg by a mad dog that was foaming at the mouth. She was unaware of the dangers of rabies and never sought treatment. What symptoms did she develop from this disease?

Answer: When the rabies virus in the dog’s saliva entered the bite wound, the virus was transported through Zoe’s peripheral nerve axons to her spinal cord and brain. It led to inflammation of the brain, madness, and death.

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2. Mr. Kelly staggered home after a “rough night” at the local pub. While attempting to navigate the stairs, he passed out cold and lay (all night) with his right armpit straddling the staircase banister. When he awoke the next morning, he had a severe headache, but what bothered him more was that he had no sensation in his right upper limb, which seemed to be paralyzed. Explain.

Answer: Continuous pressure interrupts blood circulation (along with oxygen and nutrients) to the neuronal processes. As a result, the transmission of impulses through the nerves was inhibited temporarily.

Art Resources Figure 12.1 Figure 12.2 Figure 12.3 Figure 12.4 Figure 12.5 Figure 12.6 Figure 12.7 Figure 12.8 Figure 12.9 Figure 12.10 Figure 12.11 Figure 12.12 Figure 12.13 Figure 12.14 Figure 12.15 Figure 12.16 Figure 12.17 Table 12.1 Table 12.2

Functions of the nervous system.

Divisions of the nervous system: the central nervous system (CNS) and the peripheral nervous system (PNS).

Schematic of levels of organization in the nervous system.

Structure of a typical neuron (a motor neuron).

Structure of an axodendritic synapse.

Neuroglia.

Schwann cells on myelinated and nonmyelinated axons in the PNS. Cross-section through the spinal cord.

Structure of a nerve.

Components of a reflex arc.

Types of reflex arcs.

Types of neuronal circuits.

Focus Figure: Neuronal Pathways.

Multiple sclerosis.

Regeneration of an axon in a peripheral nerve.

Development of the nervous system in weeks 5 and 6 of the embryonic period.

A neuronal growth cone.

Types of Sensory and Motor Fibers of the Peripheral Nervous System Comparison of Structural Classes of Neurons

Teaching with Art Figure 12.8

Cross-section through the spinal cord.

Figure 12.11

Types of reflex arcs.

Textbook p. 393 and p. 396.

Checklist of Key Points in the Figures • Review the principal structural features of a neuron.

• Differentiate the roles of sensory neurons, motor neurons, and interneurons.

• Review the structure of a synapse, and point out the synapse locations.

• Identify the locations in the body of some typical sensory receptors.

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Common Conceptual Difficulties Interpreting the Art • Differentiate the components of the CNS from those of the PNS. • Explain why action potentials travel only from dendrite to axon in a unipolar neuron.

• Characterize the sensory integration role of interneurons in the CNS. (Refer students to Figures 12.8 and 12.11 to depict the structural variety of interneurons and to highlight the presence of interneurons in the brain.)

• Describe the structure and function of a ganglion.

Art Exercise 1. Provide unlabeled copies of Figure 12.8. Instruct students to color code each type of neuron represented. Students should label all parts of each neuron and indicate the direction of impulse transmission with arrows, especially at a synapse.

2. Provide unlabeled copies of Figure 12.11, and instruct students to color code the neurons of the reflex arcs. Label all neuronal parts (cell bodies, axon, and dendrites); indicate the direction traveled by the nerve impulse.

3. Ask students to apply the concepts of Figures 12.11a–b to their own bodies; for each type of arc, identify (a) the site of receptor stimulation, (b) the type of reflex, (c) the name of the specific effector, and (d) the type of action produced in response to the stimulus.

Answers: Figure 12.11a: (a) the patellar ligament, (b) monosynaptic stretch (somatic) reflex, (c) the quadriceps femoris group of muscles, and (d) extension of the knee. Figure 12.11b: (a) pain sensory receptor, (b) polysynaptic withdrawal reflex, (c) biceps brachii, and (d) forearm flexion.

Critical Reasoning Ask students to study Figure 12.13. Trace the circuit of interneurons, starting from the body of the interneuron in the simple reflex arc at the left, extending upward through the brain, and returning back to the synapse of the interneuron and motor neuron. Explain that this circuit signifies that the brain somehow modifies the action of the reflex arc. Ask the following question: “Can you think of an example of how you benefit from being able to voluntarily modify the action of some reflex arcs?”

Answer: You are modifying the action of a reflex arc whenever you voluntarily control the reaction to a painful stimulus. For example, when you receive a hypodermic injection at your doctor’s office, you voluntarily overcome (or strongly suppress) your reflex to flinch and pull away from the needle stick.

Supplemental Course Materials Library Research Topics 1. What is the value of the study of recombinant DNA technology to the study of proteinbased neurotransmitters?

2. Why do most tumors of nervous tissue develop in neuroglia rather than neurons?

3. Scientists have recently begun to appreciate the fact that many small neurons within the gray matter of the central nervous system have dendrites but no axon, or they have very

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short “axons” that conduct graded potentials rather than action potentials. How can a neuron communicate without carrying an impulse?

4. What are the most recent advances in the quest to stimulate effective regeneration of the CNS to aid accident victims who have had their spinal cords severed?

5. Explore the ultrastructure of dendrites, axons, and synapses. Can the detailed ultrastructure of a synapse reveal whether it is excitatory versus inhibitory in function?

6. Research the mechanism and functions of axonal transport, and relate them to the known functions of the cytoskeleton.

7. What chemical factors signal the development of the central nervous system?

Suggested Readings Blumenfeld, Hal. Neuroanatomy through Clinical Cases. 2nd Edition, Sinauer Associates, Inc., 2011.

Brodal, P. The Central Nervous System: Structure and Function. 4th ed. New York: Oxford University Press, 2010.

Gallo, Vittoria, and Ramesh Chittajallu. “Unwrapping Glial Cells from the Synapse: What Lies Inside?” Science 292 (5518) (May 2001): 872–873.

Haydon, Philip G. Glia: “Listening and Talking to the Synapse.” Nature Reviews: Neuroscience 2 (3) (March 2001): 185–192.

Helmuth, Laura. “Glia Tell Neurons to Build Synapses.” Science 291 (5504) (January 2001): 569–570.

Kandel, E. R., J. Schwartz, and T. Jessell. Principles of Neural Science. 5th ed. New York: McGraw-Hill, Health Professions Division, 2012.

Nestler, Eric J. “Total recall—The memory of Addiction.” Science 292 (5525) (June 2001): 2266–2267.

Parent, André. Carpenter’s Human Neuroanatomy. 9th ed. Baltimore: Williams and Wilkins, 1996.

Parpura, Vladimir, and Phillip G. Haydon. Astrocytes in (Patho)Physiology of the Nervous System. New York: Springer Science+ Business Media, 2009.

Williams, P. L., et al. Gray’s Anatomy. 38th ed. New York: Churchill Livingstone, 1995.

Answers to Textbook Questions Answers for multiple-choice and matching questions 1–14 are located in the Answers Appendix of the textbook.

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Short Answer and Essay Questions 15. The receptors of the general somatic senses are spread widely throughout the outer tube of the body. Some examples of these senses are touch, pain, pressure, vibration, and temperature. (p. 384) 16. Proprioception, as it relates to muscles, senses muscle stretch. The skeletal muscles innervated are in the outer, somatic, part of the body and are widespread (general innervation)—thus, general somatic sensory. (p. 384) 17. An interneuron can be the middle neuron in a reflex arc (between a sensory neuron and a motor neuron), but more broadly, an interneuron is any neuron that is confined entirely within the central nervous system. (p. 389) 18. Gray matter, which occupies the central region of the spinal cord and brain, is where neuron cell bodies are clustered. More specifically, it consists of neuron cell bodies, dendrites, and short nonmyelinated axons. White matter, which lies external to the central gray matter, consists of axons running between different parts of the CNS. Its white color reflects the color of the myelin around many of its axons. (p. 393) 19. Structurally, neurons are classified into unipolar, bipolar, and multipolar neurons. Functionally, neurons are classified into sensory, motor, and interneurons. (pp. 387–389) 20. Neurons and neuroglia differ in structure, location, and function. Neurons conduct electrical impulses, have extreme longevity, do not divide, and have exceptionally high metabolic rates. Neurons have a cell body, dendrites, and an axon. Most neuronal cell bodies are located within the CNS, but some cell bodies are located in ganglia in the PNS. Neuroglial cells are the support cells specific to the CNS. They are capable of cell division, are smaller than neurons, and provide supportive roles to neurons. (p. 385 and 390–391) 21. A neuron is a nerve cell, a nerve fiber is a long axon, and a nerve is a collection of nerve fibers in the PNS. (p. 394) 22. Multiple sclerosis is an autoimmune disease in which the immune system attacks the myelin sheaths around a nerve’s axons in the CNS. It is specifically the patient’s lymphocytes that break down the myelin sheaths. Thus, by administering mitoxantrone for suppressing these cells, the destruction of myelin will be slowed down. (pp. 399–400) 23. The drawing should show a sensory neuron, interneuron, and motor neuron, as they relate to the dorsal root, spinal cord, ventral root, and spinal nerve. The reflex would not function if the cells in the sensory ganglion (sensory neurons) were destroyed because that would break the chain of neurons in the arc. (pp. 395–396) 24. An axon is a neuronal process that carries impulses (action potentials) away from the cell body, whereas a dendrite is a process that carries signals (graded potentials) toward the cell body. (p. 386) 25. Microglial cells originate from blood cells called monocytes. Like macrophages in other organs, microglial cells engulf invading microorganisms and injured or dead neurons. (pp. 390–391) 26. In the PNS, thicker axons are coated with a myelin sheath of concentric layers of the Schwann cell plasma membrane; Schwann cells also surround thinner nonmyelinated fibers but do not form concentric layers of membrane; a single Schwann cell may enclose several nonmyelinated axons, whereas a myelinated axon has several Schwann cells arranged sequentially along a single axon. (pp. 390–391) 150

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Critical Reasoning and Clinical Applications Questions 1. The peripheral process could be called an axon because (1) it conducts an action potential, and (2) its fine structure is identical to that of a true axon. The peripheral process could be called a dendrite because it conducts signals toward the cell body of the neuron. (pp. 388–389) 2. An ependymoma is a tumor that arises from the ependymal cells. These cells line the brain’s central cavity and spinal cord. (p. 391) 3. Blood began reflowing through the blood vessels in the arm as soon as the vessels were rejoined to the vessels of the body trunk. In the nerves of the severed arm, by contrast, all the axons degenerated, and reinnervation occurred only after sprouting axons grew back into the limb structures. (p. 400) 4. Leena is suffering from an extremely painful disorder called ‘trigeminal neuralgia’.

Compression of the trigeminal nerve by the adjacent blood vessels causes degeneration and loss of the myelin sheath that surrounds the sensory nerve fibres. Due to the demyelination, touch impulses carried by the nerve are experienced as pain because of the stimulation of pain fibers in the same nerve. Thus, even the softest touch to the face can produce excruciating pain. (p. 391) 5. All reflexes are involuntary motor responses to stimuli. Visceral motor responses activate smooth muscle, cardiac muscle, or glands (vomiting is an example); somatic reflexes result in the contraction of skeletal muscle (a knee jerk is an example). (p. 395) 6. Neuroblastoma is a malignant tumor of the cells that have retained a neuroblast-like structure. These blastomas sometimes originate in the brain, but most are of neural crest origin in the peripheral nervous system. (p. 403)

Interpreting Medical Images Questions Answers to Interpreting Medical Images questions are provided in the Instructor Resources area of Mastering A&P. Figure 12.14: The outermost layer of the brain is composed of gray matter. This region is called the cerebral cortex. In this MRI, the gray matter is light and the white matter is darker. The image shown in Figure 12.14 is a type of MRI known as FLAIR (fluid attenuated inversion recovery). This type of MRI is commonly used in brain imaging. In a FLAIR image, gray matter appears lighter than white matter; the cerebrospinal fluid filling the hollow regions appears black. The appearance of gray and white matter varies depending on the specific type of MRI used to produce the image. By looking at the coloring/shade of the cerebral cortex and knowing that this is gray matter, you can determine which structures deep in the brain are gray matter and which regions are composed of white matter. In this image, you can also see light clusters of lighter gray matter surrounding the central hollow regions (black in this image).

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 12: Fundamentals of the Nervous System and Nervous Tissue To the Student It is important to understand an overview of the human nervous system before focusing on the functional anatomy of the nervous tissue, especially neurons. Without a complete understanding of sensory input, integration, and motor output, basic principles of neural function are elusive. The nervous system shares important functions with the endocrine system; you will explore the endocrine system in detail in a later chapter. The nervous system is the master controller of the other systems and enables you to respond to internal and external environmental information.

You will also find that incorporating Practice Anatomy Lab 3.0 (PAL) (BC; DVD, Website) into your studies of the nervous system will improve your understanding. For a review of nervous system structures, refer to the Nervous System sections in the Human Cadaver and Anatomical Models modules. Additionally, refer to the Histology module for a review of nervous tissue.

Step 1: Explain the basic organization of the nervous system. __ List functions of the nervous system. __ Distinguish afferent input from efferent output. __ Define integration. __ Define CNS. __ Define PNS. __ Explain the following types of sensory and motor information carried by the nervous system: • Somatic sensory • Visceral sensory • Somatic motor • Visceral motor • Branchial motor Step 2: Describe nervous tissue. __ Define neuron and list its structural features. __ Relate each structural feature of a neuron to its functional role. __ Define and describe a synapse. __ Classify neurons structurally. __ Classify neurons functionally. __ Name six types of supporting cells, and describe them by shape and function. __ Describe the structure of myelin sheaths.

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Step 3: Explain nerves and the basic neuronal organization of the nervous system. __ Define nerve. __ Describe basic components of nerves. __ Define reflex, distinguishing monosynaptic from polysynaptic reflexes. __ Draw a reflex arc, including its basic features: sensory neuron, interneuron, and motor neuron. __ Explain how the reflex arc relates to the basic organization of the nervous system. __ Distinguish gray matter from white matter in the CNS. Step 4: Understand the development and disorders of nervous tissue. __ Describe the symptoms of multiple sclerosis. __ Describe the embryological development of nervous tissue.

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The Central Nervous System

Lecture and Demonstration Objectives 1. Describe the development of the five embryonic divisions of the brain.

2. Name the major parts of the adult brain.

3. Name and describe the locations of the ventricles of the brain.

4. Describe the distribution of gray and white matter in each part of the brain.

5. Identify the three subdivisions of the brain stem, and list the major structures in each.

6. Using the framework of gray matter versus white matter, relate the structures of the brain stem to the general functions of this part of the brain.

7. Describe the structure and function of the cerebellum.

8. Name the three divisions of the diencephalon and their functions.

9. List the major lobes, fissures, and functional areas of the cerebral cortex.

10. Name three classes of fiber tracts in the white matter of the cerebrum.

11. Describe the form and function of the basal nuclei (ganglia).

12. Describe the locations and functions of the limbic system and the reticular formation.

13. Describe the meningeal coverings surrounding the brain, and explain how the meninges and cerebrospinal fluid protect the structures of the central nervous system.

14. Explain how cerebrospinal fluid is formed, and describe its pattern of circulation.

15. Describe the gross structure of the spinal cord.

16. Identify the regions of white matter and gray matter in a cross section through the spinal cord.

17. Describe the organization of the neurons in the gray matter of the spinal cord.

18. Identify the major ascending and descending tracts in the spinal cord, and indicate the types of stimuli carried on each.

19. Trace the major neuronal pathways to and from the brain.

20. Explain the effects of severe injuries to the spinal cord.

21. Describe the signs and symptoms of concussions (traumatic brain injuries), strokes, and Alzheimer’s disease.

22. Describe causes and consequences of the congenital disorders anencephaly, cerebral palsy, and spina bifida.

23. Explain the effects of aging on brain structure.

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Suggested Lecture Outline I. The Brain (pp. 406–439, Figs. 13.1–13.23, Tables 13.1–13.2) A. The CNS is composed of the brain and spinal cord. (p. 406) B. Directional terms unique to the CNS are rostral and caudal. (p. 406) C. Functions of the brain range from life-sustaining activities to the most complex neural functions.

1. The brain maintains the internal environment through control of the ANS and endocrine system.

2. The brain is involved in peripheral innervation through cranial nerves.

3. The brain performs tasks associated with intelligence, memory, emotion, behavior, and socialization.

4. Embryonic Development of the Brain (pp. 407–408, Figs. 13.1, 13.2) a. Understanding the embryonic development of the brain is essential to understanding adult brain structures. During week 4 of development, the brain arises from the rostral end of the neural tube, which is immediately followed by development of the three primary brain vesicles. During week 5, the secondary brain vesicles develop along with the midbrain flexure and cervical flexure.

5. Basic Parts and Organization of the Brain (pp. 408–410, Figs. 13.3, 13.4) a. The brain is classified into four parts: the cerebrum (or cerebral hemispheres), the diencephalon, the brain stem (midbrain, pons, and medulla), and the cerebellum. b. Names and locations of ventricles of the brain are as follows: paired lateral ventricles in the cerebral hemispheres, third ventricle in the diencephalon, cerebral aqueduct in the midbrain, and fourth ventricle in the hindbrain.

6. The Brain Stem (pp. 410–415, Figs. 13.5–13.7, Table 13.2) a. The brain stem is the most caudal of the four major brain regions. Its primary functions are to produce programmed automatic behaviors, provide a passageway for fiber tracts running between the cerebrum and spinal cord, and provide innervation of the face and head through cranial nerves III–XII. There are three regions of the brain stem. i. The medulla oblongata is attached to the five most inferior pairs of cranial nerves, a major portion of the reticular formation passes through it, and it contains the cardiac, respiratory, and vasomotor centers. Pyramidal tracts cross over to the opposite side of the body, resulting in the cerebral hemispheres controlling the voluntary actions of the opposite side of the body. ii. The pons forms a “bridge” between the brain stem and cerebellum. Cranial nerves V–VII attach to the pons, and the middle cerebellar peduncles carry information between the cerebral cortex and cerebellum. iii. The midbrain is the most rostral of the three parts of the brain stem. White fiber tracts and relay nuclei in the midbrain include the cerebral peduncles, superior cerebellar peduncles, substantia nigra, and red nucleus. Cell bodies of cranial nerves III and IV are located in the midbrain. Periaqueductal gray matter initiates the fight-or-flight response, and the corpora quadrigemina are brain nuclei involved in visual and auditory reflexes.

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7. The Cerebellum (pp. 415–417, Figs. 13.8, 13.9, Table 13.2) a. The cerebellum is the brain’s second largest region. Its functions are to smooth and coordinate body movements and to maintain posture, equilibrium, and motor memory. i. Major components of the cerebellum are the anterior, posterior, and flocculonodular lobes, vermis, folia, cortex, cerebellar peduncles, and arbor vitae (white matter of the cerebellum). ii. The cerebellum receives information from the cerebrum on planned movements, compares planned movements with current body position, and sends instructions to the cerebral cortex. The cerebellum is involved in learning new motor skills and motor memory, and it also plays some role in language, problem solving, and task planning. All fibers to and from the cerebellum are ipsilateral.

8. The Diencephalon (pp. 417–420, Figs. 13.6, 13.9, and 13.10, Table 13.2) a. The diencephalon forms the central core of the forebrain and is surrounded by the cerebral hemispheres. The components of the diencephalon are the thalamus, hypothalamus, and epithalamus. i. The thalamus is a relay station for sensory information ascending to the primary sensory areas of the cerebral cortex; the thalamus is the “gateway” to the cerebral cortex. ii. The hypothalamus is the main visceral control center of the body and regulates many activities of visceral organs, including control of the ANS. iii. The epithalamus is the pineal gland, which secretes melatonin.

9. The Cerebrum (pp. 420–431, Figs. 13.11–13.18, Tables 13.1, 13.2) a. The cerebrum is the most rostral portion of the brain, comprising 83% of the brain’s mass. Gross anatomical features of the cerebrum include the lobes, gyri, sulci, and fissures. i. The cerebral cortex is the location of the “conscious mind.” It is made of gray matter and composed primarily of neuronal cell bodies and dendrites. Each cerebral cortex is divided into five major lobes: the frontal, parietal, occipital, and temporal lobes, and the insula. The cerebral cortex is arranged into functionally distinct areas: the motor areas, sensory areas, and multimodal association areas. Lateralization of cortical functioning is exhibited by 90–95% of the human population; the left cerebral hemisphere has control over logic, whereas the right hemisphere is more involved with emotion and artistic and musical skills. ii. Myelinated fibers of the cerebral white matter are organized into tracts, which are classified as commissural, projection, or association tracts. Corpus callosum, internal capsule, and corona radiata are examples of cerebral white matter. iii. Deep gray matter of the cerebrum consists of the basal nuclei (motor control), basal forebrain nuclei (formation of memory), and claustrum.

10. Functional Brain Systems (pp. 431–433, Figs. 13.19, 13.20, Table 13.2) a. Functional brain systems are networks of neurons that work together and span large distances in the brain. The two functional brain systems are the limbic system and the reticular formation. i. The limbic system is known as the “emotional brain”: a group of structures on the medial aspect of the cerebral hemispheres and the diencephalon.

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ii. The reticular formation has branching axons that project to the thalamus, cerebellum, and spinal cord, which make it ideal for governing the arousal of the brain as a whole.

11. Protection of the Brain (pp. 433–439, Figs. 13.21–13.23) a. Physical protection of the brain is provided by skull bones, the meninges, and cerebrospinal fluid. The blood-brain barrier protects the brain internally from most harmful toxins. i. The skull provides a bony housing for the delicate brain. ii. The dura mater, arachnoid mater, and pia mater surround the brain, with several significant modifications to the dura mater to accommodate venous blood drainage and CSF reabsorption. iii. Cerebrospinal fluid fills the subarachnoid space, the ventricles of the brain, and the hollow cavities of the spinal cord. iv. The blood-brain barrier results from the tight junctions joining epithelial cells of brain capillaries.

II. The Spinal Cord (pp. 439–445, Figs. 13.24–13.27, Tables 13.3, 13.4) A. The spinal cord extends from the foramen magnum to L1 or L2 inferiorly. There are three major functions of the spinal cord: It is involved with sensory and motor innervation of the body through spinal nerves; it provides conduction pathways for messages between the body and the brain through ascending and descending tracts; and it is a major center for reflexes.

B. The gross anatomy of the spinal cord includes several physical characteristics, including the filum terminals, conus medullaris, cervical and lumbar enlargements, and the cauda equina.

C. Spinal cord segments refer to the region of the spinal cord from which the fibers of a given spinal nerve emerge.

1. White Matter of the Spinal Cord (pp. 442–443, Fig. 13.26) a. White matter is composed of myelinated axons, and it forms the outer regions of the spinal cord. Tracts of white matter are classified according to the direction in which they run: ascending, descending, or commissural.

2. Gray Matter of the Spinal Cord and Spinal Roots (pp. 443–444, Figs. 13.26, 13.27) a. Gray matter of the spinal cord is composed of neuronal cell bodies, neuroglia, short nonmyelinated axons, and dendrites. Gray matter forms the H-shaped central region of the spinal cord. Gray matter is arranged into functionally related groups based on the innervation of somatic or visceral regions of the body.

3. Protection of the Spinal Cord (pp. 444–445, Fig. 13.26) a. Three separate layers of meninges protect the spinal cord: the dura mater, the arachnoid mater, and the pia mater. Cerebrospinal fluid fills the subarachnoid space and the ventricles of the brain and spinal cord.

III.

Sensory and Motor Pathways in the Central Nervous System (pp. 445–451, Figs. 13.2–13.30, Tables 13.3, 13.4) A. Ascending Pathways (pp. 446–448, Fig. 13.29, Table 13.3) 1. Ascending pathways conduct general sensory impulses superiorly through chains of two or three neurons to specific brain regions.

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B. Descending Pathways (pp. 448–451, Fig. 13.30, Table 13.4) 1. Descending pathways transport motor instructions from the brain to the spinal cord.

IV. Disorders of the Central Nervous System (pp. 451–453, Fig. 13.31) A. Spinal Cord Damage (p. 451) 1. Spinal cord injuries result in loss of voluntary movement and sensation in regions inferior to the transection. Paraplegia results when damage is between T1 and L2 segments, and quadriplegia results when damage is in the cervical region.

B. Brain Dysfunction (pp. 451–453, Fig. 13.31) 1. Examples of brain disorders are traumatic brain injuries, such as concussion and contusion, and degenerative brain diseases, including cerebrovascular accidents (strokes) and Alzheimer disease.

V. The Central Nervous System Throughout Life (pp. 453–454) A. Embryonic Development and Congenital Conditions (pp. 453–454, Fig. 13.32) 1. Embryonic development and congenital birth defects that involve the brain are anencephaly, spina bifida, and cerebral palsy.

B. Postnatal Changes in the Brain (p. 454) 1. Postnatal changes in the brain represent many neuronal connections during childhood that are based on early experiences; brain growth stops in early adulthood, and cognitive functions decrease with age.

Lecture Hints 1. Contrast the spinal dura sheath with the cranial dura mater, pointing out significant differences; emphasize that the meningeal protection of the brain and spinal cord is continuous but that the spinal cord has an epidural space whereas the brain does not.

2. Explain the clinical procedure of lumbar puncture, commenting on the relative safety and diversity of uses.

3. Distinguish dorsal sensory roots from ventral motor roots of spinal nerves, and emphasize that roots are in the PNS, not CNS. 4. Introduce the central nervous system, stressing its fantastic complexity and myriad functions.

5. Describe the consistency and weight of the brain.

6. Define the unique CNS directional terms rostral and caudal; review the embryological germ layer, the ectoderm.

7. Draw a diagram relating the primary and secondary brain vesicles to adult brain structures. Figure 13.2 provides an excellent basic comparison of embryonic and adult features.

8. Explain to students why the cerebral cortex is the “conscious mind.”

9. Describe basic features of the gray matter of the cerebral cortex, including components, thickness, approximate surface area, and approximate total mass of the brain.

10. During discussion of the cerebral cortex, caution students not to confuse sensory and motor areas with sensory and motor neurons. All the neurons in the cerebral cortex are interneurons.

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11. Stress that the left and right primary motor cortexes control muscles on the right and left sides of the body, respectively.

12. Summarize the functions of the right and left cerebral hemispheres: The left side is specialized for languages and math skills, and the right side is more concerned with visual-spatial and creative abilities.

13. During discussion of the tracts of cerebral white matter, stress the difference between a tract and a nerve. Both are bundles of fibers, but a tract is a bundle in the CNS and a nerve is a bundle in the PNS. 14. Instruct students to devise a simple illustration of the pathways traveled by cerebral white matter tracts in the brain.

15. Students often confuse the terminology brain nuclei with nuclei of cells; stress the difference.

16. Summarize the cranial structural features layer by layer, beginning with the scalp and ending with brain tissue: scalp, cranial bone, periosteal layers of the dura mater, subdural space, arachnoid, subarachnoid space, pia mater, and brain tissue.

Classroom Discussion Topics and Activities 1. Display a three-dimensional model of a human brain, and compare it to a preserved human brain and/or a dissected sheep brain.

2. Display a three-dimensional model of a spinal cord, both in longitudinal section and in cross-section, to illustrate its important characteristics.

3. Display stained, thin cross sections of a brain (or thicker sections sliced with a knife) to illustrate the differences between gray and white matter and to show the internal parts of the brain.

4. Demonstrate a three-dimensional model or cast of the ventricles of the brain. Ask students how they think a cast of the ventricles was obtained.

5. Using a preserved human brain specimen or a model, instruct students to sketch a lateral view of the brain and to label the cerebral hemisphere, lobes of the cerebrum, precentral gyrus, postcentral gyrus, central sulcus, lateral sulcus, transverse fissure, cerebellum, pons, and medulla oblongata.

6. Display a sheep brain or, if possible, a preserved human brain with the meninges still intact.

7. When discussing the inferior colliculus, make an unexpected large noise (such as banging a yardstick against the table). When the students jump reflexively and look up, tell them that their reflex was mediated by the inferior colliculus.

8. Discuss why prefrontal lobotomies (cutting the fiber tracts to the prefrontal lobes) have been used in psychotherapy along with electrical shock. Ask students how and why these techniques have been used. Ask why lobotomies are now in disfavor.

9. Given that a right-handed person’s left cerebral hemisphere appears to dominate many cerebral functions, ask what activities could be done to increase the use of the right hemisphere.

10. Mention that anencephalic children always die soon after birth. There is currently a desire among some medical groups to transplant the organs of these children to help others. Discuss the pros and cons of this type of organ transplantation. ..

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11. Discuss the actions/effects of opiates, antidepressants, and anesthetics as well as the biology of drug addiction.

12. Discuss the role of the hypothalamus and the medulla in controlling homeostasis, a topic that arises later in the course.

13. Assign A Closer Look: Traumatic Brain Injury, on p. 452 of the textbook as required reading for classroom discussion.

Clinical Questions 1. Describe the cause of hydrocephalus, and explain why this condition is much more serious in adults than in newborns.

Answer: Hydrocephalus refers to a blockage of the normal circulation and drainage of cerebrospinal fluid throughout the ventricles and meninges. If allowed to accumulate, the fluid will exert excessive pressure on the brain. In newborns, the fontanelles and sutures allow the skull to enlarge, but in adults the cranial bones are fused and no expansion is possible. Thus, the danger of crushing the brain is greatest in adults.

2. Six-year-old Jeremy is confined to a wheelchair. He frequently drools, and his limbs hang limply in angular positions. His diagnosis is cerebral palsy. Name several possible causes of cerebral palsy.

Answer: Cerebral palsy may be due to lack of oxygen at birth; a viral infection; or excessive smoking, radiation exposure, drug intake, or alcohol consumption by the mother during pregnancy. Cerebral palsy is a disability of the motor regions of the brain, in which the voluntary muscles are poorly controlled or paralyzed.

3. Lucy is suffering from right-sided paralysis and sensory loss. She cannot speak at all.

Cerebral angiography and a CT scan have shown no cerebral vascular defects, but the CT scan did reveal a mass wedged between the left thalamus and basal nuclei. Using your knowledge of anatomy, explain Lucy’s symptoms in terms of the specific lesion site.

Answer: The mass, located in the left half of the brain, will affect the right side of the body because of the crossing over of sensory and motor pathways. The mass indicates damage to the fibers of the internal capsule, which carry both motor and sensory signals to and from the cerebral cortex. Thus, Lucy has both motor and sensory disorders.

4. A victim of a motorcycle accident fractured vertebra T12, and there was concern that the spinal cord was crushed at the level of this vertebra. At what spinal cord segment was the damage expected? Choose from the following and explain your choice: (a) between C4 and C8, and the ability to move the arms was tested; (b) at C1, and the respiratory movements of the diaphragm were tested; (c) spinal cord level L3; (d) there could be no deficits, because the cord always ends above T12; and (e) the functions of all the cranial nerves were tested.

Answer: The correct choice is (c), the injury was at spinal cord level L3. Recall that the spinal cord levels are several segments superior to vertebral levels (L3 corresponds to T12).

5. Harold, a 70-year-old man, walks up and down the street in front of his house daily.

Initially, he has trouble getting going, but once started, he walks quickly and in a mechanical fashion. Although he says hello to those he passes, he never smiles and has been considered generally unpleasant for this reason. His hands tremble when he is not voluntarily moving them. What is Harold’s problem?

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Answer: Harold has Parkinson’s disease, a depression of the “starter motor” function of the basal nuclei (see p. 431 in the textbook).

Art Resources Figure 13.1 Figure 13.2 Figure 13.3 Figure 13.4 Figure 13.5

Figure 13.23 Figure 13.24 Figure 13.25 Figure 13.26 Figure 13.27 Figure 13.28 Figure 13.29 Figure 13.30 Figure 13.31 Figure 13.32

Embryonic development of the brain.

Brain development from week 5 to birth.

Pattern of gray and white matter in the CNS. Ventricles of the brain.

Ventral view of the brain showing the three parts of the brain stem: medulla oblongata, pons, and midbrain.

Three views of the brain stem (shades of green) and diencephalon (purple).

Cross-sections through the brain stem.

Cerebellum.

Midsagittal section of the brain.

Nuclei of the thalamus and hypothalamus.

Lobes, sulci, and fissures of the cerebral hemispheres.

Functional neuroimaging (fMRI) of the cerebral cortex.

Functional areas of the cerebral cortex.

Body maps in the primary motor cortex and somatosensory cortex of the cerebrum.

Visual pathways through the multimodal association areas.

Auditory pathways through the multimodal association areas.

White fiber tracts of the cerebral hemispheres.

Basal nuclei (ganglia).

The limbic system.

The reticular formation.

Meninges around the brain.

Partitions of the dura mater in the cranial cavity and the dural venous sinuses.

Formation, location, and circulation of CSF. Gross structure of the spinal cord, dorsal view.

Spinal cord segments.

Anatomy of the spinal cord.

Organization of the gray matter of the spinal cord.

Major fiber tracts in the white matter of the cervical spinal cord.

Pathways of selected ascending spinal cord tracts.

Three descending pathways by which the brain influences movement.

Brain activity differences with Alzheimer disease.

Newborn with a lumbar myelomeningocele.

Table 13.1

Structures and Functions of the Cerebrum

Table 13.2

Functions of Major Parts of the Brain

Figure 13.6 Figure 13.7 Figure 13.8 Figure 13.9 Figure 13.10 Figure 13.11 Figure 13.12 Figure 13.13 Figure 13.14 Figure 13.15 Figure 13.16 Figure 13.17 Figure 13.18 Figure 13.19 Figure 13.20 Figure 13.21 Figure 13.22

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Table 13.3

Major Ascending (Sensory) Pathways and Spinal Tracts

Table 13.4

Major Descending (Motor) Pathways and Spinal Tracts

Teaching with Art Figure 13.23

Formation, location, and circulation of CSF.

Textbook p. 438.

Checklist of Key Points in the Figure • Review the principal functions of cerebrospinal fluid (CSF).

• Describe CSF’s watery consistency, and mention its rate of formation—about 500 ml per day.

• Point out that there is only 100 to 160 ml (about 1/2 cup) of CSF in a healthy adult.

• Contrast the rate of CSF formation with the average CSF volume to reinforce the concept of CSF circulation.

• Point to the locations of the choroid plexuses—part (a)—and describe the functional relationship between the ependymal cells and the highly vascular pia mater—part (b).

• Emphasize the continuity between the ventricles, subarachnoid space, and central canal, which allows circulation of CSF. • Display Figure 13.4 (“transparent” three-dimensional views of the brain) to demonstrate the continuity and extent of the ventricles.

• Describe the typical pattern of circulation of CSF from its point of origin to its return to the venous blood.

Common Conceptual Difficulties Interpreting the Art • Point out that a venous sinus is a specialized blood vessel (vein).

• Describe the function of ependymal cells; comment on the ciliated ependymal epithelium lining the ventricles.

• Describe how CSF differs from blood.

• Describe the structural differences in the capillaries of the choroid plexuses that enable them to form the blood-brain barrier.

• Remind students that CSF obtained from a lumbar puncture can provide clinical information about an injury, infection, or disease of the CNS. (Refer to Clinical Application, “Diagram of a lumbar puncture (spinal tap),” on p 413.)

Art Exercise 1. Referring to Figure 13.23, instruct students to design a flow diagram tracing the pathway of CSF from its formation sites to its ultimate return to the circulatory system.

2. Provide unlabeled copies of Figure 13.23, and instruct students to label the CSF pathway using the flow diagram devised in the previous exercise.

3. Using an unlabeled copy of Figure 13.23, ask students to trace CSF movement in this enlarged view of the meninges around the brain.

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Critical Reasoning The production and circulation of CSF is a continuous process. If a blockage causes CSF to accumulate in ventricles or the subarachnoid space, excessive pressure is exerted on the brain, a condition called hydrocephalus. Refer students to Clinical Applications, “Hydrocephalus in the newborn,” and ask, “Why do you think the skull of an infant with hydrocephalus distorts so noticeably?”

Answer: An infant lacks fused cranial sutures, and the skull expands.

Supplemental Course Materials Library Research Topics 1. The sensory and motor areas of the cerebral cortex around the precentral gyrus and postcentral gyrus have been carefully mapped. How was this done?

2. How can fetal tissue be used to repair adult tissue exhibiting CNS dysfunctions?

3. What techniques are currently used to locate and treat tumors of the brain?

4. How has the human brain changed in size and shape over the millions of years of evolution? Explore the evolution of the human brain, especially of the cerebral cortex.

5. What drugs are used to enhance memory? Where and how do they work?

6. What kinds of experiments have been used to study the limbic system? What research has been done to determine whether some habitual criminals have defects in this system?

7. Some research indicates humans experience circadian rhythms. How are these rhythms coordinated, and do we really have them? Do they occur in other animals?

8. What are PET and functional MRI revealing about the functional organization of the cerebral cortex?

9. Research whether there is a link between maternal vitamin deficiency (for example, of folic acid) and neural tube defects in newborns.

Suggested Readings Barr, M. L. and J. Kiernan. The Human Nervous System: An Anatomical Viewpoint. 9th ed.

Philadelphia: Lippincott Williams & Wilkins, 2008.

Blumenfeld, H. Neuroanatomy Through Clinical Cases. 2nd ed. Sunderland, Mass.: Sinauer Associates, 2011.

Brodal, P. The Central Nervous System: Structure and Function. 4th ed. New York: Oxford University Press, 2010.

Goldberg, S. Clinical Neuroanatomy Made Ridiculously Simple. 4th ed. Miami: MedMaster Publishing Company, 2010.

Haines, D. Neuroanatomy: An Atlas of Structures, Sections, and Systems. 8th ed. Philadelphia: Lippincott Williams & Wilkins, 2011.

Kandel, E. R., J. R. Schwartz, and T. Jessell. Principles of Neural Science. 5th ed. New York: McGraw-Hill Medical, 2012.

Martin, J. H. Neuroanatomy: Text and Atlas. 4th ed. New York: McGraw-Hill Medical, 2012.

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McAlonan, G. M., E. Daly, V. Kumari, D. H. Critchley, et al. “Brain Anatomy and Sensorimotor Gating in Asperger’s Syndrome.” Brain: A Journal of Neurology 125 (7) (July 2002): 159–160.

McDonald, J. W. and M. J. Howard. “Repairing the Damaged Spinal Cord: A summary of our early success with embryonic stem cell transplantation and remyelination.” Progress in Brain Research 137 (2002): 299–309.

Pitkin, R. M. “Folate and Neural Tube Defects.” The American Journal of Clinical Nutrition 85 (January 2007): 285–288.

Purves, D. Neuroscience. 5th ed. Sunderland, Mass.: Sinauer Associates. 2011.

Rabins, P. V. and G. Pearlson. “Treating Dementia: Progress and promise.” The American Journal of Geriatric Psychology 17 (9) (September 2009): 723–725. (Also available at doi: 10.1097/ JGP.0b013e3181b1222f) Shors, T. J. “Saving New Brain Cells.” Scientific American (March 2009): 46–54.

Williams, P. L., et al. Gray’s Anatomy. 38th ed. New York: Churchill Livingstone, 1995.

Answers to Textbook Questions Answers for multiple-choice and matching questions 1–5 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 6. See Figure 13.1 on p. 407 for a diagram of the embryonic brain vesicles and their adult derivatives.

7. (a) The drawing will roughly resemble those in Figures 13.11 and 13.13. (b) Right. (c) Primary motor cortex: voluntary (skilled) movements; premotor cortex: controls complex movements in three-dimensional space; somatosensory association area: perception (understanding) of the general somatic senses being felt; primary visual area: conscious awareness of what is being viewed; anterior association area (prefrontal cortex): complex learning abilities (cognition) and higher thought functions, perseverance, mood; Broca’s area: speech production. (pp. 420–421, 392) 8. (a) The brain nuclei that make up the basal nuclei are the caudate nucleus, globus pallidus, and putamen. (b) The basic functions of the basal nuclei are to start, stop, and regulate the intensity of voluntary movements, control repetitive tasks, and estimate the passage of time. (c) The caudate nucleus arches over the thalamus. (pp. 430–431) 9. The anterior and posterior lobes of the cerebellar hemisphere help to coordinate the movements of the limbs and the trunk. (p.415) 10. (a) The medial aspect of each cerebral hemisphere and in part of the diencephalon. (b) Septal nuclei, cingulate gyrus, hippocampal formation, part of the amygdaloid body, fornix, anterior nucleus of the thalamus, and the hypothalamus. (c) The limbic system acts as our “emotional” brain and forms factual and emotional memories. (pp. 431–433) 11. (a) The reticular formation extends through the central core of the brain stem (medulla, pons, and midbrain). (b) RAS means reticular activating system, which is our arousal mechanism. It maintains the cerebral cortex in a conscious, alert state. (pp. 432–433)

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12. (a) The CNS is protected by (1) the bony cranium and vertebrae; (2) meninges; (3) cerebrospinal fluid; and (4) blood-brain barrier. (b) Cerebrospinal fluid is formed by choroid plexuses and drained by arachnoid granulations. See Figure 13.23 on p. 438 for the circulatory pathway.

13. (a) The medulla/spinal cord junction is in the foramen magnum superiorly, and the tip of the conus medullaris is at the level of vertebrae L1–L2 inferiorly. (b) In a spinal tap, the needle enters the vertebral canal inferior to L2, whereas the spinal cord (conus medullaris) terminates superior to this. (pp. 439–441, Fig. 13.24, Clinical Applications, “Diagram of a lumbar puncture (spinal tap)”) 14. (a) The corticospinal tract or the direct pathway. (b) The tectospinal tract. (p. 450, Table 13.4) 15. (a) The cell bodies of the first-order neurons of the spinothalamic pathway are located in the dorsal root ganglia, for these first neurons are the sensory neurons. The cell bodies of the third-order neurons are located in the thalamus. (b) The pyramidal-tract pathway extends from the motor cerebral cortex to the spinal gray matter and then continues via short interneurons to spinal motor neurons. (Fig. 13.29) 16. Brain weight and volume decline with aging. (p. 454) 17. (a) The thalamus makes up 80% of the diencephalon. (b) Every part of the brain that communicates with the cerebral cortex must relay its signals through a nucleus of the thalamus. Therefore, it is known as the “gateway” to the cerebral cortex. (p. 417) 18. The layers the surgeon cuts through are the skin of the scalp, periosteum, bone of the skull, dura mater (periosteal and meningeal layers), subdural space, arachnoid mater, subarachnoid space, pia mater, and brain. (pp. 435–436) 19. As the left cerebral hemisphere has greater control over language abilities, math, and logic, Thomas is correct in claiming that his success is due to the left cerebral hemisphere. The right cerebral hemisphere, on the other hand, has greater control over visual-spatial skills, reading facial expressions, intuition, emotion, and artistic and musical skills. (p. 428) 20. See Figure 13.26 on pages 442 and 443 for a diagram on the anatomy of the spinal cord.

21. The association fibers are present in the white matter of the cerebrum and connect different parts of the same cerebral hemisphere. While short association fibers connect neighboring areas of the cortex, long association fibers connect widely separated cortical lobes. (p. 428) 22. For the locations of these streams in the parietal and temporal lobes, see Figure 13.15.

The dorsal stream locates what we see in space (“where”), and the ventral stream recognizes what we see (“what”). (pp. 427–428)

Critical Reasoning and Clinical Applications Questions 1. Both Kim and L’Shawn are correct. Although the basic structural design of the CNS is “gray matter internally/white matter externally,” there is a tendency in the brain for collections of gray to migrate externally into the white during development. The most extreme examples of this are the outer gray cortex of the cerebrum and cerebellum. (pp. 420–423) 2. Greg is having trouble maintaining balance because of damage to the flocculonodular nodes in his cerebellum. As these nodes regulate the body’s equilibrium, damage to them may result in a loss of balance in affected individuals. One may develop a wobbly, ..

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drunken gait and always be at a risk of falling. As the right side of Greg’s brain has been damaged, the same side of his body has been affected. (p. 415) 3. Miriam’s baby lacked a cerebrum and cerebellum; thus, he/she had an incomplete brain.

When the rostral neural tube fails to close during neurulation, the cerebrum and cerebellum fail to develop. Consequently, an anenchephalic baby is born with only a brain stem and traces of the basal nuclei. The baby is totally vegetative and has no mental capacity. (p. 453) 4. The prefrontal cortex—involved with intelligence and social skills—was damaged. (p. 428) 5. In a quadriplegic (paralysis and paresthesia in all four limbs), the injury to the spinal cord is in the cervical region. In a paraplegic (paralysis and paresthesia in the lower limbs only), the injury to the spinal cord is inferior to the T1 segment. (p. 451) 6. As several pyramidal cells control the delicate and skilled movements of the face and hand muscles, these organs are mapped in a disproportionately large manner in the primary motor cortex. (p.426) 7. Transection or crushing of the spinal cord permanently eliminates voluntary movements and sensation inferior to the damage site at C2. The phrenic nerve receives fibers from C3 to C5 and innervates the diaphragm; breathing is impaired, and use of a respirator is required. (pp. 439–441 and 451) 8. In teenagers, the “rational” frontal lobe is still organizing itself. Additionally, the “emotional” limbic structures are in developmental overdrive from the effects of sex hormones. (pp. 431 and 454) 9. A lumbar puncture procedure is usually performed either between the vertebrae L3 and L4 or between the vertebrae L4 and L5. As the adult spinal cord extends up to the level of vertebra L1 or L2, Myra can safely insert the needle into the subarachnoid space inferior to that location, without damaging the spinal cord. (p. 445)

Interpreting Medical Images Questions Answers to Interpreting Medical Images questions are provided in the Instructor Resources area of Mastering A&P. Figure 13.22: a. Blood from the lateral regions of the frontal, parietal, and occipital lobes drains into the superior sagittal sinus. b. The tentorium cerebelli encloses the transverse sinus. It is located in the transverse fissure and separates the cerebrum from the cerebellum.

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 13: The Central Nervous System To the Student This chapter most likely will be one of the most challenging and intriguing ones you will deal with in your study of human anatomy. Much is known about the structure and function of the brain and spinal cord. But so much is unknown that many scientists consider the brain a final frontier in the study of neuroanatomy. It is amazing that the most highly organized structure known to man does not understand itself. Only the future will answer questions about memory, senility, and mental illness. Approach your study with a clear understanding of the overall organization of the nervous system, and the details and concepts presented to you in Chapter 13 will be easier to understand.

You will also find that incorporating Practice Anatomy Lab 3.0 (PAL) (BC; DVD, Website) into your studies of the central nervous system will improve your understanding.

For a comprehensive review of structures of the brain and spinal cord, refer to the Nervous System sections in the Human Cadaver and Anatomical Models modules. You may also access PAL 3.0 via the www.myaandp.com website.

Step 1: Describe the embryological development, basic parts, organization, and protection of the brain. __ Summarize basic functions of the brain, and describe its consistency and weight. __ Define rostral and caudal. __ Draw a diagram with labels representing the primary brain vesicles of the neural tube dividing into secondary brain vesicles followed by differentiation into adult structures.

Refer to Figure 13.6 for help.

Step 2: Describe the basic parts and organization of the brain. __ Devise a quick reference vocabulary list of all the bold terms and key terms, adding to it as your study progresses. __ Classify the brain parts according to the system used by your textbook. __ Explain the organization of the white matter and gray matter of the brain stem, and compare it to that of the matter in the cerebrum and cerebellum. __ Explain the ventricles of the brain as adult neural canal regions, including specific locations. __ Describe the gross anatomy of the cerebral hemispheres, including sulci, gyri, fissures, and lobes. __ Identify specific functions of the cerebral cortex. __ Identify specific functional areas for (1) recognizing objects, (2) spatial relationships, and (3) language. __ Define somatotopy, and give examples. Include the concept of the homunculus in your response. __ Describe the visual and auditory pathways to multimodal association areas.

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__ Distinguish left cerebral hemisphere specialization from right hemisphere specialization. __ Distinguish commissural tracts, association tracts, and projection tracts in the white matter. __ Distinguish the caudate, lentiform, and amygdaloid body basal nuclei of gray matter. __ Name the three parts of the diencephalon, and describe the basic function, location, and any associated structural details for each part. __ Name the three parts of the brain stem, and describe the basic function, location, and any associated structural details for each part. __ Describe the structure and function of the cerebellum. __ Explain the functional brain systems: limbic system and reticular formation.

Step 3: Describe the protective structures associated with the brain. __ Name four structures that protect the brain. __ Describe the three meninges, including the dural extensions. __ Describe cerebrospinal fluid (CSF), including formation and circulation pattern. __ Describe the blood-brain barrier.

Step 4: Describe the spinal cord. __ Describe the gross anatomy of the spinal cord, including location, enlargements, and conus medullaris. __ Summarize functions of the spinal cord. __ Describe the meningeal coverings of the spinal cord and indicate the differences from cranial meninges. __ Distinguish the epidural space, subdural space, and subarachnoid space. __ Distinguish dorsal sensory roots from ventral motor roots. __ Describe the organization of the white matter of the spinal cord. __ Distinguish ascending tracts (sensory pathways) from descending tracts (motor pathways) of the spinal cord.

Step 5: Describe sensory and motor pathways in the CNS. __ Describe each of the ascending spinal tracts and their functions. __ Describe each of the descending spinal tracts and their functions.

Step 6: Describe disorders of the CNS. __ Distinguish among spinal cord injuries based upon level of injury to the spinal cord. __ Distinguish contusion from concussion. __ Describe what happens to cause a stroke and the potential results of stroke. __ Describe the progress of Alzheimer disease.

Step 7: Describe the CNS throughout life. __ List several birth defects that involve the brain and spinal cord. __ Discuss the formation of neuronal connections during early childhood. __ List effects of normal aging on the CNS. 168

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The Peripheral Nervous System

Lecture and Demonstration Objectives 1. Outline the organization of the peripheral nervous system.

2. Describe the structural components of the peripheral nervous system.

3. Classify sensory receptors according to body location, stimulus detected, and structure.

4. Name the 12 pairs of cranial nerves, and describe the structures innervated by each.

5. Describe the location of a spinal nerve, and distinguish spinal roots from rami.

6. Describe the somatic innervation of the back, trunk, and limbs.

7. Define nerve plexus. Name the four main plexuses formed by ventral rami, and the body region innervated by each. Describe the major nerves originating from each plexus.

8. Define dermatomes, and explain Hilton’s law of the innervation of joints.

9. Explain the causes and symptoms of shingles, migraine headaches, and peripheral neuropathy.

10. Relate the development of the PNS to the basic segmental pattern of the outer tube of the human body.

Suggested Lecture Outline I. Organization of the Peripheral Nervous System (p. 460, Fig. 14.1) A. The PNS is composed of nervous system structures outside the brain and spinal cord; the basic structural components of the PNS are the sensory receptors, motor endings that innervate effectors, nerves, and ganglia; basic functional components are reviewed in Figure 14.1.

B. Nerves are spinal nerves or cranial nerves; most nerves contain both sensory and motor axons and are called mixed; some cranial nerves are purely sensory or primarily motor in function.

II. Peripheral Sensory Receptors (pp. 460–464, Figs. 14.2, 14.3, Table 14.1) A. Sensory receptors detect stimuli (environmental changes) inside the body as well as outside the body; classification is based on body location, stimulus detected, and structure.

1. Functional Classification (p. 461) B. The three classes of sensory receptors based on location in the body are exteroceptors, interoceptors, and proprioceptors.

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2. A second way to classify sensory receptors is by the kinds of stimuli that activate the receptors; examples are mechanoreceptors, thermoreceptors, chemoreceptors, photoreceptors, and nociceptors. (p. 461) B. Structural Classification (pp. 461–464, Figs. 14.2, 14.3, Table 14.1) 1. The third way to classify general sensory receptors is by their structure (special senses are covered in Chapter 16); the nerve endings of these receptors are structurally free nerve endings (nonencapsulated) or encapsulated nerve endings. a. Free nerve endings are present everywhere in the body and respond primarily to pain, temperature, and itch. b. Encapsulated nerve endings respond to a wide variety of individualized stimuli. The main types of encapsulated nerve endings are tactile corpuscles, lamellar corpuscles, bulbous corpuscles, and proprioceptors.

III. Cranial Nerves (pp. 464–476, Fig. 14.4, Table 14.2) A. Twelve pairs of cranial nerves attach to the brain and innervate the head and neck; the vagus nerves are the only pair that “wanders” into the thorax and abdomen.

B. The name, number, and brief function summary follow: 1. Olfactory—smell 2. Optic—vision 3. Oculomotor—eye movement (four of the six extrinsic eye muscles) 4. Trochlear—eye movement (superior oblique eye muscle) 5. Trigeminal—general sensation of the face 6. Abducens—eye movement (lateral rectus eye muscle) 7. Facial—chief motor nerves of the face 8. Vestibulocochlear—hearing and equilibrium 9. Glossopharyngeal—innervates part of the tongue and pharynx for swallowing and taste 10. Vagus—innervates heart, lungs, and abdominal organs 11. Accessory—moves structures associated with the head and neck (larynx, pharynx, soft palate, trapezius, and sternocleidomastoid muscles) 12. Hypoglossal—serves the tongue muscles C. Cranial nerves are grouped according to function: Some are purely sensory (I, II, and VIII); some are primarily (or exclusively) motor (III, IV, VI, XI, and XII); and some are mixed (V, VII, IX, and X).

D. Four cranial nerves (III, VII, IX, and X) also contain general visceral motor fibers of the parasympathetic division of the autonomic nervous system (ANS).

IV. Spinal Nerves (pp. 476–493, Figs. 14.5–14.16, Tables 14.3–14.6) A. Thirty-one pairs of spinal nerves attach to the spinal cord, and their names reflect the point of issue from the spinal cord. There are eight pairs of cervical spinal nerves (C1– C8), 12 pairs of thoracic spinal nerves (T1–T12), five pairs of lumbar spinal nerves (L1– L5), five pairs of sacral spinal nerves (S1–S5), and one pair of coccygeal spinal nerves (Co1).

B. Roots are for attachment of a spinal nerve to the spinal cord; rami are branches of a spinal nerve.

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1. Innervation of the Back (p. 478, Fig. 14.6) a. Muscles and skin of the back (posterior portion of the trunk—from the neck to the sacrum) are innervated by dorsal rami.

2. Innervation of the Anterior Thoracic and Abdominal Wall (p. 478, Figs. 14.5, 14.6) a. The anterior and lateral walls of the thorax and abdomen are innervated by ventral rami; thoracic ventral rami do not form plexuses.

3. Nerve Plexuses (pp. 478–491, Figs. 14.5–14.14, Tables 14.3–14.6) a. A nerve plexus is a network of nerves. b. The cervical plexus (C1–C4) innervates the muscles and skin of the shoulder; the most important nerve issued from the cervical plexus is the phrenic nerve. c. The brachial plexus (C5–C8 and part of T1) serves the muscles and skin of the upper limb, including the shoulder; the main nerves from the brachial plexus are the musculocutaneous, median, ulnar, radial, and axillary. d. The lumbar plexus (L1–L4) innervates the muscles and skin of the anterior and medial thigh; the main nerves issued from the lumbar plexus are the femoral and obturator nerves. e. The sacral plexus (L4–S4) supplies the muscles and skin of the posterior thigh and almost all of the leg; its main branches are the sciatic nerve, tibial nerve, and common fibular nerve; other branches of the sacral plexus innervate the pelvic girdle and perineum.

4. Innervation of Joints of the Body (p. 491) a. Joints of the body are innervated by branches of the nerves of the muscles that cross the joint (Hilton’s law).

5. Innervation of the Skin: Dermatomes (pp. 491–492, Fig. 14.15) a. The area of skin innervated by the cutaneous branches from a single spinal nerve is called a dermatome.

V. Disorders of the Peripheral Nervous System (pp. 493–494) A. Shingles (p. 493) 1. Shingles (herpes zoster) is a varicella-zoster viral infection of sensory neurons innervating the skin.

B. Migraines (p. 493) 1. Migraines are extremely painful, episodic headaches that affect 29.5 million Americans.

C. Peripheral Neuropathy (pp. 493–495) 1. Peripheral neuropathy refers to any pathologic condition of the peripheral nerves that disrupts nerve function.

VI. The Peripheral Nervous System Throughout Life (pp. 494–495) A. During embryonic development, each spinal nerve grows out between newly formed vertebrae to provide the motor innervation of an adjacent myotome (future trunk muscle) and the sensory innervation of the adjacent skin region (dermatome).

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Lecture Hints 1. Review the overall organization of the nervous system, and make sure students understand how information flows through the system, including the difference between nerve and tract, and nucleus and ganglion.

2. Stress the functional organization of the peripheral nervous system, and carefully compare structural features.

3. List the 12 cranial nerves in a rostral-to-caudal sequence, including their Roman numeral designations, and identify the structures innervated by each; stress that all cranial nerves have ventral attachments except the trochlear cranial nerve. Review the foramina in the skull through which each cranial nerve passes.

4. Offer students a fun way to remember the cranial nerves using a favorite mnemonic such as, “Oh, Oh, Oh, To Touch And Feel Very Good Velvet AH!” or, “Oh, Oh, Oh, To Touch And Feel Very Green Vegetables AH!” Students may come up with their own mnemonics, but suggest that any “unsavory” ones be kept private.

5. Point out the unique nature of the highly branched olfactory nerves (I).

6. Explain the difference between a tract and nerve using optic nerves (II) as examples.

7. Distinguish the location of spinal nerves; emphasize that there are eight pairs of cervical spinal nerves and seven cervical vertebrae; clearly distinguish root from ramus; emphasize that spinal nerves are “short” and that their branches (rami) are “longer.”

8. Using skull figures or PowerPoint images from Chapter 7, identify/review each of the cranial nerve passageways.

9. Identify the type of sensory receptor associated with 10 of the 12 pairs of cranial nerves; note the two cranial nerves that lack sensory receptor associations. Refer to this chapter’s “Critical Reasoning” feature (p. 218 of this guide) for answers.

10. Define nerve plexus, and name four major nerve plexuses formed by ventral rami, indicating the body region innervated by each.

11. Students enjoy the humorous reference to the brachial plexus as “armpit spaghetti.”

Classroom Discussion Topics and Activities 1. Using a skull and colored pipe cleaners, demonstrate the openings through which the cranial nerves pass.

2. Using a preserved sheep brain or preserved human brain with the cranial nerves intact, demonstrate where these nerves attach to the brain.

3. Demonstrate the distribution of the spinal nerves using a three-dimensional model of the peripheral nervous system.

4. Invite a police officer to class to discuss field sobriety tests and motor and sensory dysfunction caused by alcohol.

5. Discuss why injecting Novocain or other anesthetics used by dentists into just one point in the lower jaw can anesthetize one entire side of the jaw and tongue.

6. Ask students how seat belts for both the front and back seat prevent serious neurological damage in auto accidents. How can the use of lap belts without shoulder belts cause severe damage?

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7. Ask students what neural damage can result from some overly enthusiastic parents swinging their infants around by the hands.

8. Discuss why pregnant women often experience numbness in their interphalangeals.

9. Ask students how knowledge of dermatomes benefits a physician. (Some benefits were mentioned in the textbook, but there are more.)

Clinical Questions 1. While working in the emergency room, you receive two patients who were in an auto collision. One is dead on arrival, having sustained a transection of the spinal cord at the level of C2. The other patient suffered a similar injury, but at the level of C6, and is still alive. Explain briefly, in terms of the origin and function of the phrenic nerves, why one injury was fatal and the other was not.

Answer: Cell bodies of the motor neurons whose axons contribute to the phrenic nerves lie in the C3–C5 segments of the spinal cord. Transection of the cord above this level—at C2 in the first victim of the auto accident—cuts the axons from the respiratory centers in the brain stem that signal these motor neurons, thereby inactivating them and halting the respiratory movements of the diaphragm. This leads to death. Transection of the cord inferior to the C3–C5 does not interrupt this respiratory nervous pathway, so the phrenic nerves are still functional and ventilation remains normal.

2. Rodney sustained a leg injury in a bowling accident and had to use crutches. Unfortunately, he did not take the time to learn how to use them properly. After two weeks of use, he noticed his interphalangeals were becoming numb. Shortly after this, the entire upper limbs were getting weaker and tingling. What could be his problem?

Answer: Simply speaking, he is probably compressing the brachial plexus, thus affecting the sensory and motor innervation of the upper limbs.

3. Dominic, a minor-league baseball player, was struck on the left side of his face with a fast pitch while batting. His zygomatic arch was crushed, and the left ramus of his mandible was broken. Following the incident and reconstructive surgery, he noticed that his left lower eyelid was still drooping and that the corner of his mouth sagged. What nerve had been damaged?

Answer: He suffered damage to the left facial nerve, which caused paralysis to the muscles of facial expression.

Art Resources Figure 14.1 Figure 14.2 Figure 14.3 Figure 14.4 Figure 14.5 Figure 14.6 Figure 14.7 Figure 14.8 Figure 14.9 ..

Functional organization of the peripheral nervous system (PNS).

Structure of free and encapsulated general sensory receptors.

Structure of proprioceptors: muscle spindles and tendon organ.

The cranial nerves.

Spinal nerves, posterior view.

Formation of spinal nerves and rami distribution.

The functional components of a spinal nerve, anterior view.

The cervical plexus, anterior view.

The brachial plexus, anterior view.

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Figure 14.10 Figure 14.11 Figure 14.12 Figure 14.13 Figure 14.14 Figure 14.15 Table 14.1 Table 14.2 Table 14.3 Table 14.4 Table 14.5 Table 14.6

Focus Figure: Innervation of the upper limb.

Course of the axillary and radial nerves.

The lumbar plexus.

Focus Figure: Innervation of the Lower Limb.

The sacral plexus.

Map of dermatomes.

General Sensory Receptors Classified by Structure and Function Cranial Nerves Branches of the Cervical Plexus Branches of the Brachial Plexus to Trunk and Shoulder Muscles Branches of the Lumbar Plexus Additional Branches of the Sacral Plexus

Teaching with Art Figure 14.4

The cranial nerves.

Table 14.2

Cranial Nerves

Textbook pp. 466–475.

Checklist of Key Points in the Figure • Differentiate the cranial nerves from the spinal nerves.

• Emphasize that cranial nerves are part of the PNS, not the CNS. • Point out that the cranial nerves are numbered using Roman numerals I–XII in a rostral-tocaudal order of attachment.

• Note that almost all cranial nerves attach to the ventral side of the brain, pointing out the trochlear nerves as exceptions.

• Note that all cranial nerves serve the structures of the head and neck except for the vagus nerve (X), and describe the structures innervated by each.

• Explain the unique anatomical features of the first two pairs of cranial nerves—the olfactory nerve (I) and the optic nerve (II).

• Display Table 14.2, and for each cranial nerve, describe the sensory function, motor function, or mixed function.

• Note the cranial nerves that have parasympathetic fibers, and briefly explain the significance.

Common Conceptual Difficulties Interpreting the Art • Distinguish the forebrain from the brain stem when noting attachments.

• Distinguish a tract from a nerve, including the optic chiasma in the discussion.

• Explain that each cranial nerve passes through specific skull openings, describing the origin and pathway of fibers.

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Art Exercises 1. Provide students with unlabeled copies of Figure 14.4 with instructions to color and label the 12 pairs of cranial nerves. Encourage students to devise a mnemonic to aid in learning the cranial nerves.

2. Provide students with unlabeled copies of Figure 7.7, Inferior aspect of the skull. Instruct students to label the foramina responsible for the passage of cranial nerves, along with the name and number of the nerve that passes through each opening.

Critical Reasoning 1. Sensory receptors are classified according to their location in the body or the location of the stimuli to which they respond. Ask students to identify the type of sensory receptor (exteroceptors, interoceptors, proprioceptors, or none) associated with each of the 12 cranial nerves.

Answer: I. Olfactory—exteroceptors II. Optic—exteroceptors III. Oculomotor—proprioceptors IV. Trochlear—proprioceptors V. Trigeminal—exteroceptors and proprioceptors VI. Abducens—proprioceptors VII. Facial—interoceptors, proprioceptors, and exteroceptors (bit of skin on ear) VIII. Vestibulocochlear—exteroceptors IX. Glossopharyngeal—interoceptors, proprioceptors, and exteroceptors (bit of skin on ear) X. Vagus—interoceptors, proprioceptors (laryngeal muscles), and exteroceptors (bit of skin on ear) XI. Accessory—none XII. Hypoglossal—none 2. Why might certain smells trigger strong emotions?

Answer: The olfactory cortex is part of a brain area called the rhinencephalon, and the rhinencephalon connects to the limbic system, which is known as the “emotional brain.”

Some fibers of the olfactory nerve terminate at the limbic system. Thus, when a smell is associated with a particularly strong emotional memory, the same smell experienced again may evoke a similar emotional response or, at least, the recollection of the original response.

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Supplemental Course Materials Library Research Topics 1. How does the placement of acupuncture needles relate to the distribution of spinal nerves?

2. Will all victims of polio be rendered paralyzed? What different forms of polio are there?

3. How has microsurgery been used to reconnect severed peripheral nerves?

4. What are the standard tests by which clinicians evaluate the functions of the 12 cranial nerves?

5. Some people who have lost a limb experience a phenomenon called phantom limb pain.

What is the basis of this phenomenon, and what methods are available to treat it?

Suggested Readings Binder, D. K., D. C. Sonne, and N. J. Fischbein. Cranial Nerves: Anatomy, Pathology, Imaging. Thieme Medical Publishers, 2010.

Gillespie, P. G. and R. G. Walker. “Molecular Basis of Mechanosensory Transduction.”

Nature 413 (6852) (September 2001): 194–202.

Goldberg, S. Clinical Neuroanatomy Made Ridiculously Simple. 4th ed. Miami: MedMaster Publishing Company, 2010.

Haines, D. Neuroanatomy: An Atlas of Structures, Sections, and Systems. 8th ed.

Philadelphia: Lippincott Williams & Wilkins, 2011.

Martin, J. H. Neuroanatomy: Text and Atlas. 4th ed. New York: McGraw-Hill Medical, 2012.

Monkhouse, S. Cranial Nerves: Functional Anatomy. Cambridge: Cambridge University Press, 2005.

Moore, K. L. Clinically Oriented Anatomy. 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2009.

Purves, D. Neuroscience. 5th ed. Sunderland, Mass.: Sinauer Associates, 2010.

Zuker, C. S. “A Cool Ion Channel.” Nature 416 (6876) (March 2002): 27–28.

Answers to Textbook Questions Answers for multiple-choice and matching questions 1–10 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 11. The capsules consist of connective tissue (connective tissue proper). (p. 463) 12. (a) Spinal nerves form from dorsal and ventral roots that unite at the dorsal root ganglion in the intervertebral foramen to form the spinal nerve. Spinal nerves contain both sensory and motor fibers. (b) These roots are outside the spinal cord, so they are in the PNS. (c) Major branches of each spinal nerve are the ventral and dorsal rami, which supply the somatic region of the body. The ventral rami and their branches supply the lateral and anterior body regions (including limbs), and the dorsal rami supply the dorsal body region (the back). (pp. 476–478) 176

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13. (a) Lumbar plexus, L1–L4 (Table 14.4), (b) Cervical plexus, C1–C4 (Table 14.3), (c) Sacral plexus, L4–S4 (Table 14.6), (d) brachial plexus, C5–T1 (Table 14.5), (e) Sacral plexus, L4–S4 (Table 14.6) (pp. 478–491) 14. None of Jeremy’s muscles will be completely paralyzed. The ventral rami of all spinal nerves except T2–T12 branch and join one another to form nerve plexuses. Within the plexuses, fibers from the different ventral rami converge and diverge and redistribute so that each end branch of the plexus contains fibers from several different spinal nerves, and fibers from each ventral ramus travel to the body periphery via several different routes or branches. Therefore, each muscle receives its nerve supply from more than one spinal nerve. (p. 478) 15. The dentist will inject the anesthetic into the alveolar branch of the mandibular (V3) division of the trigeminal nerve, which innervates the muscles of mastication (temporalis, masseter, pterygoids, and anterior belly of digastric) to contract while chewing. (pp. 469–470) 16. The correct answer is (c) just superior to S1. Except in the neck, every spinal nerve exits through the intervertebral foramen directly inferior to its correspondingly numbered vertebra. Nerve L5, therefore, exits just inferior to vertebra L5, or just superior to S1. (pp. 487–490) 17. Because the spinal cord usually ends between vertebrae L1 and L2, the highest roots in the cauda equina must belong to L2. Thus, the cauda equina contains the roots of L2, L3, L4, L5, S1, S2, S3, S4, S5, and Co1. That is 10 nerves per side, multiplied by two sides (right and left), multiplied by two roots per nerve (dorsal and ventral). That comes to 40 roots.

(Figs. 14.12, 14.13, Tables 14.5, 14.6)

Critical Reasoning and Clinical Applications Questions 1. He had stretched the brachial plexus, damaging and tearing its nerves. (p. 481) 2. Susan is suffering from a trochlear nerve (Cranial nerve IV) lesion, which causes diplopia or double vision. The diplopia is more profound when looking downwards, as when walking down the stairs, since CN IV that supplies the superior oblique muscle, is responsible for inferolateral rotation of the eyeball. Oculomotor (Cranial nerve III), Trochlear (Cranial nerve IV) and Abduscens nerve (Cranial nerve VI) supply the muscles of the eyeball. (pp. 468–470) 3. The correct answer is (a) a few dorsal (sensory) roots in the cauda equina. All the other choices would have produced motor disorders as well as sensory disorders and are, therefore, impossible in this case. (pp. 487–491, Table 14.6) 4. The sciatic nerve is formed by the tibial nerve and the common fibular nerve. Derick injured his tibial nerve, which is responsible for cutaneous innervation on the back of the leg and for plantar flexion of the foot. (p. 487, 489–461) 5. Hiccups are caused by abrupt, rhythmic contractions of the diaphragm, induced by the phrenic nerve when the diaphragm or the stomach is irritated, as with spicy food or abdominal gas. Since the phrenic nerve receives fibers from spinal nerves C3 and C4, pain during irritation of the phrenic nerve is sometimes perceived on the shoulder, which also receives sensory innervation by the same spinal segments. (p. 479) 6. (1) Because the elbow is crossed by the biceps brachii, the triceps brachii, and many flexor muscles on the forearm (including the flexor carpi ulnaris), the nerves that innervate the elbow joint are the musculocutaneous, radial, median, and ulnar nerves. ..

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(Fig. 14.10) (2) Because the hip joint is crossed by the iliopsoas, gluteus maximus, gluteus medius, biceps femoris, the adductors, and other muscles, the nerves that innervate the hip joint are the femoral, superior and inferior gluteal, sciatic, and obturator nerves. (p. 489, Figs. 14.13, 14.14) 7. Gunshot or stab injuries can injure the axillary nerve. Weakness of the deltoid muscle, decreased sensation in the shoulder area, and the inability to abduct and lift one’s arm above the head is indicative of axillary nerve injuries. The axillary nerve is a branch of the posterior cord of the brachial plexus. (p. 485) 8. Cranial nerves that innervate the tongue are the trigeminal (V) (pp. 469–470), the facial (VII) (pp. 471–472), the glossopharyngeal (IX) (p. 473), and the hypoglossal (XII) (p. 475).

9. (a) paralysis – “para” – beside, near, “lysis” – loosening or breaking down, breaking down of muscle strength (b) dermatome – “derm” – skin, “tome” = cut or section, a section of skin innervated by a spinal nerve (c) postherpetic neuralgia – “post” – after, behind, “herpetic” – creeping (herpes virus “creeps” along nerve pathways), “neuro” – nerve, “algia” – pain, nerve pain after a herpes outbreak (d) peripheral neuropathy – “peripher” – outer surface, “neuro” – nerve, “pathy” – disease, a disease of the peripheral nervous system

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 14: The Peripheral Nervous System To the Student Chapter 14 introduces you to the peripheral nervous system and its sensory and motor connections that enable you to interact with the outside environment. Without these structures that lie outside the CNS, you would have no links to the real world. Material covered includes peripheral sensory receptors, peripheral motor endings, cranial nerves, and spinal nerves.

Chapter 14 focuses on somatic functions, and Chapter 15 addresses the visceral nervous system. It is important to review any material that is unclear and to ask questions if you do not grasp a concept.

You will also find that incorporating Practice Anatomy Lab 3.0 (PAL) (BC; DVD, Website) into your studies of the peripheral nervous system will improve your understanding.

For a comprehensive review of peripheral nervous system structures, refer to the Nervous System sections in the Human Cadaver and Anatomical Models modules. You may also access PAL 3.0 through the DVD or the www.myaandp.com website.

Step 1: Understand the PNS and peripheral sensory receptors. __ Define peripheral nervous system, and draw a flowchart representing the functional organization of the PNS. __ Distinguish efferent (motor) from afferent (sensory) divisions. __ Distinguish somatic from visceral. __ Distinguish branchial from brachial. __ Classify peripheral sensory receptors by location in the body or the location of the stimuli to which they respond. __ Classify peripheral sensory receptors by the kind of stimuli to which they respond. __ Classify peripheral sensory receptors by structure.

Step 2: Understand cranial nerves. __ List the 12 cranial nerves, including their Roman numeral designations. __ Distinguish rostral from caudal. __ Identify structures innervated by each cranial nerve. __ Describe the origin and course followed by each nerve, including skull foramina. __ Explain the classification of cranial nerves as sensory, motor, or mixed. __ Identify the types of sensory receptors (exteroceptors, interoceptors, proprioceptors, or none) associated with each cranial nerve.

Step 3: Understand spinal nerves. __ Distinguish cranial nerves from spinal nerves. __ Describe the location of spinal nerves. __ Distinguish roots from rami.

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__ Identify the cauda equina. __ Describe the somatic innervation of the neck, trunk, and limbs. __ Define nerve plexus. __ Name four main plexuses formed by ventral rami, including body regions innervated. __ Name major nerves originating from each plexus, including structures innervated. __ Define dermatomes.

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CHAPTER

15

The Autonomic Nervous System and Visceral Sensory Neurons

Lecture and Demonstration Objectives 1. Define the autonomic nervous system (ANS), and explain its relationship to the peripheral nervous system as a whole.

2. Compare autonomic neurons to somatic motor neurons.

3. Describe the basic differences between the parasympathetic and sympathetic divisions of the ANS. 4. Describe the pathway of sympathetic innervation through cranial nerves and sacral spinal nerves to the visceral organs.

5. Describe the effect of parasympathetic innervation on each visceral organ innervated by the division of the ANS. 6. Describe the pathways of sympathetic innervation from the spinal cord to the effector organs in the body periphery, the head, and the visceral organs.

7. Describe the effect of sympathetic innervation on each effector organ.

8. Explain the sympathetic function of the adrenal medulla.

9. Describe the role and location of visceral sensory neurons relative to autonomic neurons.

10. Explain the concept of referred pain.

11. Explain how visceral reflexes regulate some functions of visceral organs.

12. Explain how various regions of the CNS help to regulate the autonomic nervous system.

13. Briefly describe some diseases of the autonomic nervous system.

14. Describe the embryonic development of the ANS. 15. List some effects of aging on autonomic functions.

Suggested Lecture Outline I. Overview of the Autonomic Nervous System (pp. 500–504, Figs. 15.1–15.3, Table 15.1) A. The autonomic nervous system (ANS) is a system of motor neurons that innervates the smooth muscle, the cardiac muscle, and the glands of the body.

B. The ANS is the general visceral motor division of the peripheral nervous system.

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1. Comparison of the Autonomic and Somatic Nervous Systems (pp. 500–502, Fig. 15.2) a. Basic points of comparison between the autonomic and somatic motor systems include (1) types of effectors, (2) number of motor neurons forming the pathway, (3) speed of impulses along the fibers, (4) types of ganglia, and (5) neurotransmitters released.

C. Divisions of the Autonomic Nervous System (pp. 502–504, Fig. 15.3, Table 15.1) 1. The ANS has two divisions: the sympathetic division and the parasympathetic division. Anatomical similarities and differences are multiple and varied; effects on various organs are multiple and varied as well. a. The sympathetic division is responsible for the fight-or-flight response, increasing the heart rate, dilating the bronchioles, and innervating the smooth muscle in the walls of blood vessels. b. The parasympathetic division is active when the body is at rest. Respiratory rate and heart rate are at low-to-normal levels. c. Anatomical differences in the sympathetic and parasympathetic divisions: i. They originate from different regions of the CNS. ii. Sympathetic pathways have long postganglionic fibers, and parasympathetic postganglionic fibers are relatively short. iii. Sympathetic fibers branch profusely, whereas parasympathetic fibers do not. iv. The main biochemical difference is the neurotransmitter released by postganglionic axons. Sympathetic fibers release norepinephrine, and parasympathetic fibers release acetylcholine.

II. The Parasympathetic Division (pp. 504–505, Figs. 15.4, 15.5, Table 15.2) A. The type of outflow in the parasympathetic division is termed craniosacral outflow.

1. Cranial Outflow (pp. 504–505, Figs. 15.4, 15.5, Table 15.2) a. Cranial parasympathetic fibers arise in the brain stem nuclei of cranial nerves III, VII, IX, and X; the very important vagus innervates the organs in the thorax and most of the abdomen.

B. Sacral Outflow (p. 505, Figs. 15.4, 15.5) 1. Sacral parasympathetic pathways innervate the pelvic viscera.

III. The Sympathetic Division (pp. 505–512, Figs. 15.6–15.9, Table 15.2) A. Basic Organization (pp. 505–508, Figs. 15.6, 15.7, Table 15.2) 1. The basic anatomical organization of the sympathetic division involves thoracolumbar outflow; cell bodies are located in the spinal gray matter of T1–L2; innervation to superficial structures (arrector pili, sweat glands, and smooth muscle of peripheral blood vessels) not supplied by the parasympathetic system; two types of ganglia, sympathetic trunk ganglia and prevertebral ganglia.

B. Sympathetic Pathways (pp. 509–512, Figs. 15.6–15.8) 1. Sympathetic pathways innervate several body regions: the body periphery, the head, thorax, abdomen, and pelvis.

C. The Role of the Adrenal Medulla in the Sympathetic Division (p. 512, Fig. 15.9, Table 15.2)

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1. The medulla of each of the two adrenal glands contains modified sympathetic postganglionic neurons that secrete the hormones epinephrine and norepinephrine that are responsible for the “surge of adrenaline” felt during excitement.

IV. Visceral Sensory Neurons (p. 513, Fig. 15.10) A. The visceral division of the PNS contains sensory as well as motor (autonomic) neurons; general visceral sensory neurons monitor stretch, temperature, chemical changes, and irritation within the visceral organs; referred pain is visceral, not somatic in origin.

V. Visceral Reflexes (pp. 513–514, Figs. 15.11, 15.13) A. Examples of visceral reflexes are the defecation reflex and the micturition reflex.

B. Some visceral reflexes involve only peripheral neurons.

C. The baroreceptor reflex is a visceral reflex that regulates blood pressure.

VI. Central Control of the Autonomic Nervous System (p. 515, Fig. 15.13) A. Control by the Brain Stem and Spinal Cord (p. 515, Fig. 15.13) 1. The brain stem provides the most direct influence over the autonomic nervous system.

B. Control by the Hypothalamus and Amygdaloid Body (p. 515, Fig. 15.13) 1. The hypothalamus is the main integration center of the autonomic nervous system C. Control by the Cerebral Cortex (p. 515, Fig. 15.13) 1. The cerebral cortex exerts some control over the autonomic nervous system.

VII. Disorders of the Autonomic Nervous System (pp. 515–516, Fig. 15.14) A. Most autonomic disorders reflect problems with control of smooth muscle; examples of disorders of the ANS are Raynaud’s disease, hypertension, autonomic hyperreflexia, achalasia, and congenital megacolon.

VIII. The Autonomic Nervous System Throughout Life (pp. 516–517, Fig. 15.15) A. Preganglionic neurons develop from the neural tube; ganglionic neurons and visceral sensory neurons develop from the neural crest.

Lecture Hints 1. Encourage students to continue using Practice Anatomy Lab 3.0 (PAL) and the resources available on the Website www.myaandp.com.

2. Stress the position of the ANS in the nervous system hierarchy; emphasize that the ANS is the general visceral motor division of the PNS and is distinct from the general somatic motor division that innervates skeletal muscles.

3. When comparing the autonomic and somatic motor systems, (1) stress that effectors in the ANS are smooth muscle and glands and that effectors in the PNS are skeletal muscles, (2) emphasize the presence of one motor neuron in PNS and two motor neurons in ANS, (3) explain why the speed of impulse is slower in ANS than PNS, (4) compare ANS motor ganglia with PNS sensory ganglia, and (5) identify neurotransmitters released.

4. Explain to students that there is overlap between the autonomic and somatic nervous systems; body responses to internal and external stimuli involve both skeletal muscle activity and visceral organ responses. .. CHAPTER 15 The Autonomic Nervous System and Sensory Neurons 183

5. Explain and summarize several important points of comparison between the sympathetic and parasympathetic divisions; suggested topics are (1) craniosacral versus thoracolumbar outflow, (2) length of preganglionic and postganglionic neurons, (3) locations of cell bodies, (4) names and locations of ganglia, and (5) neurotransmitters released at effectors.

6. To illustrate sympathetic tone, use the example of vasomotor control. Point out that dilation (to decrease blood pressure) is not a muscle contraction response but that relaxation of smooth muscle in the wall of the blood vessel is the actual cause. To vasoconstrict, increase sympathetic stimulation. Therefore, for dilation to be possible, there must be a certain amount of constant sympathetic stimulation (tone) even during the relaxed state.

7. Emphasize that there is a constant level of parasympathetic stimulation (tone) to many visceral organs and that there is just enough sympathetic stimulation to keep systems in homeostasis. To probe, ask the students, What would happen to the resting heart rate if parasympathetic stimulation were cut?

8. Stress sympathetic effects on visceral organs as “fight-or-flight” and parasympathetic effects as “resting and digesting.”

9. Identify the cranial nerves containing the cranial outflow of the parasympathetic division, indicating the part of the head, thorax, or abdomen served by each.

10. Stress the parasympathetic role of the vagus nerve (X), which is due to its vast distribution to the viscera of the thorax and abdomen; explain intramural ganglia; name several associated plexuses; and discuss the functional significance of the vagus nerve.

11. Point out the lack of parasympathetic innervation to the arrector pili, sweat glands, and the smooth muscle of peripheral blood vessels, and stress its significance.

12. Select several organs to compare the effects of the parasympathetic and sympathetic divisions; some suggestions are the heart, blood vessels, gastrointestinal tract, lungs, adrenal medulla, and external genitalia.

13. Explain how the adrenal medulla functions as a major organ of the sympathetic system, describe its structure, and explain the meaning of “surge of adrenaline.”

14. Explain why “Visceral Sensory Neurons” is part of the chapter title.

15. Stress that the focus of the chapter is general visceral motor (ANS), although general visceral sensory (PNS) continuously monitors visceral organ activity to maintain optimal performance of visceral functions.

Classroom Discussion Topics and Activities 1. Without announcing your intentions, walk quietly into the lecture room, set down your notes, and yell very loudly to scare the students. Ask the students to list all organs affected by the fright and what the organ response was. (If you are too quiet-natured to scream in class, simply blow a very shrill whistle to elicit a startled response.)

2. Interact with students to prepare a list of visceral organs. Ask students to surmise the effects of sympathetic and parasympathetic stimulation on each organ. Help the students deduce these effects logically (sympathetic = fight or flight; parasympathetic = resting and digesting). Ask students to compare their results with Table 15.2 in their textbooks.

3. Ask students to illustrate the sympathetic pathway from the spinal cord to the heart using a simple line drawing, including labels for neurons and ganglia.

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4. Ask students to illustrate the parasympathetic pathway to the heart with a simple drawing, including labels for neurons, cranial nerve involvement, and ganglia.

5. Bring a string of white beads to class as a model of the sympathetic trunk.

6. Demonstrate a human cadaver or a preserved cat dissected to illustrate the sympathetic trunk, celiac ganglion, some splanchnic nerves, and the vagus nerve.

7. Demonstrate a model of a spinal cord that is cut in cross-section in the thoracic or lumbar region. Point out the lateral gray columns (sympathetic cell bodies) of the gray matter and, if present on the model, the gray and white rami communicantes.

8. Lie-detector (polygraph) machines have been used for decades. In light of autonomic functions, discuss how such machines work. In light of autonomic functions, why do they sometimes give false answers? How could someone fool a lie-detector machine?

9. At certain times when people are very excited or scared, their bowels and/or urinary sphincters lose control. Ask students why this occurs in terms of the role of the autonomic nervous system.

10. Ask students why most people feel very tired after eating a big meal.

11. When someone is punched in the solar plexus, he or she may lose consciousness. What autonomic structure is the solar plexus?

Clinical Questions 1. How are hypertension and the ANS related?

Answer: The ANS is involved in nearly every process that goes on in the body. Because it controls the rate and force of the heartbeat and the constriction action of smooth muscles in the blood vessels, it is not surprising that hypertension and the ANS are related. Overstimulation of the sympathetic response, caused by long-term stress, can keep the arterioles constricted and the heart rate and blood pressure elevated excessively. Drugs that block the release of neurotransmitters from adrenergic nerve endings can be used in treatment.

2. Jed, a rather obese couch potato, likes to eat a very large meal in the evening. After the meal, his wife asks him to help clean the dishes, but Jed explains that he is too tired and promptly goes to sleep. What seems to be his problem?

Answer: The parasympathetic division is involved in activating the digestive viscera and conserving body energy. Following a meal, this system promotes digestive activity and lowers the heart rate and respiratory rate. The sympathetic division is only minimally active at this time. Therefore, the person will feel very sleepy. If the person is overweight, he probably should not overexert himself. However, doing the dishes would not be hazardous to his health.

3. Amy, a high-strung teenager, was suddenly startled by a loud bang that sounded like a gunshot. Her heartbeat accelerated rapidly. When she realized that the noise was only a car backfiring, she felt greatly relieved, but her heart kept beating heavily for half an hour. Why does it take a long time to calm down after being startled?

Answer: Sympathetic innervation is widespread throughout the body, and because large amounts of epinephrine from the adrenal medulla pour into the blood, it will take time for the hormone to be broken down throughout the body. (Later, in their physiology

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class, the students will also learn that both epinephrine and norepinephrine are inactivated very slowly, prolonging their effects.)

4. Ms. Johnson, who has been paralyzed from the neck down since an automobile accident four years ago, lives in a nursing home. One night on evening rounds, her nurse discovered her in a fetal position, her body drenched with sweat. She was incontinent of feces and urine, and her blood pressure was dangerously high. After a while she was stabilized.

What had happened to Ms. Johnson?

Answer: She had experienced an autonomic hyperreflexia reaction, perhaps because her bladder had overfilled with urine. The autonomic hyperreflexia reaction is a lifethreatening condition involving extensive activation of both somatic motor and autonomic output from the spinal cord. The high blood pressure that results from a massive sympathetic activation may precipitate a stroke. The exact mechanism is unknown.

5. Susan was attracted to Ryan, one of her classmates, because he looked intriguingly “different.” One of his pupils was larger than the other, and his skin was redder on one side of his face. She looked up these traits in a medical encyclopedia and learned that Ryan’s exotic features simply reflected a mild pathological condition. What was Ryan’s condition?

Answer: Ryan has Horner’s syndrome, reflecting damage to the cervical part of a sympathetic trunk in the inferior region of the neck. (p. 510)

Art Resources Figure 15.1 Figure 15.2 Figure 15.3 Figure 15.4 Figure 15.5 Figure 15.6 Figure 15.7 Figure 15.8 Figure 15.9 Figure 15.10 Figure 15.11 Figure 15.12 Figure 15.13 Figure 15.14 Figure 15.15 Table 15.1 Table 15.2

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Place of the autonomic nervous system (ANS) and visceral sensory components in the structural organization of the nervous system.

Comparing the somatic motor and autonomic innervation.

Overview of the subdivisions of the ANS. Parasympathetic division of the ANS. Autonomic nerves, plexuses, and ganglia.

The sympathetic trunk, thoracic region.

Three pathways of sympathetic innervation.

Sympathetic division of the ANS. Sympathetic innervation of the adrenal medulla.

A map of referred pain.

Visceral reflexes.

Baroreceptor reflex.

Levels of ANS control.

Raynaud’s disease in an elderly man.

Embryonic development of some sympathetic structures, including the adrenal medulla.

Anatomical and Physiological Differences Between the Parasympathetic and Sympathetic Divisions Effects of the Parasympathetic and Sympathetic Divisions on Various Organs

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Teaching with Art Figure 15.8

Sympathetic division of the ANS.

Textbook p. 511.

Checklist of Key Points in the Figure • Define sympathetic division, and explain why it is more complex than the parasympathetic division.

• Differentiate preganglionic from postganglionic neurons, indicating locations of cell bodies and defining thoracolumbar outflow.

• Describe and define sympathetic trunk (chain).

• Distinguish paravertebral ganglia from prevertebral ganglia, including specific names and locations of each.

• Explain the difference between white and gray rami communicantes.

• Indicate several specific plexuses, also explaining the significance of splanchnic nerves.

• Present an overview of the basic two-neuron sympathetic pathway, explaining variations of the pathway to various body regions: the body periphery, the head, thorax, abdomen, and pelvis.

Common Conceptual Difficulties Interpreting the Art • Review the concepts of ganglion, plexus, and splanchnic nerve.

• Explain that there are two sympathetic trunks (chains), each one lateral to the vertebral column and attached to spinal nerves.

• Note that the number of sympathetic trunk ganglia is not identical to the number of spinal nerves because some adjacent ganglia fuse during development, mostly evident in the cervical region.

• Indicate locations of ganglia as sites of synapses.

• Mention the lack of parasympathetic innervation to the body periphery: blood vessels, sweat glands, and arrector pili.

• Explain why gray rami occur on all the sympathetic trunk ganglia and white rami occur only in the region of thoracolumbar outflow.

Art Exercises 1. a.

Provide unlabeled copies of Figure 15.8, and instruct students to color code and label the paravertebral ganglia, including the three cervical ganglia as well as the four prevertebral ganglia.

b. Provide labeled copies of Figure 7.13, The vertebral column, and instruct students to identify and color code the specific locations of the sympathetic ganglia as described in their textbooks on p. 511.

2. Provide unlabeled copies of Figure 15.8, and instruct students to color code and label parts of a sympathetic pathway to any one (or more) of the following: eye, heart, stomach, adrenal gland, and/or urinary bladder.

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3. Provide unlabeled copies of Figure 15.6, and instruct students to color code and label parts of the sympathetic pathways to various body regions: the periphery of the body, the head, thoracic organs, abdominal organs, and pelvic organs.

Critical Reasoning Ask students to study Figure 15.8 to perform the following exercise. For each of the following sympathetic pathways, indicate whether the synapse between the preganglionic and postganglionic neurons occurs in trunk ganglia, prevertebral ganglia, or in both: a. Pathway to the head structures (eye and various glands) b. Pathway to the thoracic viscera (e.g., heart, lungs) c. Pathway to abdominal viscera (e.g., stomach, small intestine) d. Pathway to pelvic viscera (e.g., bladder, large intestine) Answers: (a) trunk ganglia, (b) trunk ganglia, (c) prevertebral ganglia, and (d) both.

Supplemental Course Materials Library Research Topics 1. Do other groups of vertebrates (fish, amphibians, reptiles, and lower mammals) have an autonomic nervous system? If so, is it more or less advanced than ours?

2. The autonomic nervous system regulates peristalsis of the alimentary canal. If the ganglia and nerve fibers that control this activity were damaged, what would happen? What bacterial toxins or types of trauma could cause this?

3. Ulcers seem to occur in people who have high blood pressure. What are the causes of ulcers, and what treatments are available?

4. Research the manipulation of autonomic functions through the use of drugs, such as alpha blockers and beta blockers.

5. Research the current methods for helping people who suffer from panic disorder, Raynaud’s disease, achalasia of the cardia, or other disorders of the ANS.

Suggested Readings Jänig, W. Integrative Action of the Autonomic Nervous System: Neurobiology of Homeostasis. Reissue of 1st ed. Cambridge University Press, 2008.

Llewellyn-Smith, I. J., and A. J. Verberne. Central Regulation of Autonomic Functions.

2nd ed. Oxford University Press, 2011.

Low, P., and E. E. Benarroch. Clinical Autonomic Disorders. 3rd ed. Baltimore: Lippincott Williams & Wilkins, 2008.

Mathias, C. J.and R. Bannister. Autonomic Failure: A Textbook of Clinical Disorders of the Autonomic Nervous System. 5th ed. Oxford University Press, September 2012.

Robertson, D., I. Biaggioni, G. Burnstock, and P. Low. Primer on the Autonomic Nervous System. 3rd ed. London: Elsevier Inc., 2012.

Williams, P. L., et al. Gray’s Anatomy. 38th ed. New York: Churchill Livingstone. 1995.

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Answers to Textbook Questions Answers for multiple-choice and matching questions 1–8 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 9. No. As it was originally defined, the autonomic nervous system is strictly motor in nature, the general visceral motor division of the peripheral nervous system. (However, some modern authorities do now include the visceral sensory neurons as part of the ANS.) (p. 500) 10. (a) The rami communicantes attach to the proximal part of the ventral ramus, directly lateral to the spinal nerve. Gray rami are medial to white rami. (White rami consist of myelinated preganglionic fibers; gray rami consist of nonmyelinated postganglionic fibers.) (b) Gray rami communicantes consist of postganglionic sympathetic axons, and postganglionic axons are nonmyelinated. Bundles of nonmyelinated axons have a gray color. (p. 508) 11. Parasympathetic impulses signal (a) eye pupils to constrict; (b) salivary glands to secrete saliva; (c) airways to constrict; (d) digestive organs to increase motility and increase secretion, (e) — The adrenal gland is not innervated by the parasympathetic nervous system. (p. 507, Table 15.2) 12. The sympathetic nervous system causes relaxation of the smooth muscles of the bladder wall, constricts the urethral sphincter, inhibits voiding, and causes ejaculation from the penis and contractions of the vagina. The parasympathetic nervous system causes contraction of the smooth muscles of the bladder wall, relaxes the urethral sphincter, promotes voiding, and causes erection of the penis and clitoris. (p. 507, Table 15.2) 13. No. Even though a counteraction exists between the SNS and PNS in most organs, not all organs innervated by the SNS are innervated by the PNS. For example, the blood vessels, the sweat glands, the arrector pili muscles, the liver, and the kidneys are not innervated by the PNS. (pp. 506–507, Table 15.2) 14. Elderly people often complain of constipation and dry eyes, and they may faint if they stand up too fast. (p. 516) 15. (a) postganglionic sympathetic. (b) postganglionic parasympathetic. (c) postganglionic parasympathetic. (Figs. 15.4, 15.7, and 15.8; intramural ganglia are defined on p. 505) 16. (a) Cell bodies of preganglionic neurons are in the upper thoracic spinal cord; axons run in thoracic ventral roots, spinal nerves, and ventral rami; to white rami communicantes; ascend in sympathetic trunk to synapse in superior cervical ganglion; postganglionic axons run on head arteries to reach the submandibular gland. (pp. 509–510 and Figs. 15.7 and 15.8) (b) Cell bodies of preganglionic neurons are in the thoracic and lumbar spinal cord; axons run in thoracic ventral roots, spinal nerves, and ventral rami; to white rami communicantes; descend in sympathetic trunk; synapse there or pass through and synapse in inferior hypogastric ganglia; postganglionic axons run through hypogastric plexus to bladder. (p. 510 and Figs. 15.7 and 15.8) (c) See the pathway in Figure 15.7 on p. 509. (d) Cell bodies of preganglionic neurons are in the lower thoracic spinal cord; axons run in thoracic ventral roots, spinal nerves, and ventral rami; to white rami communicantes; .. CHAPTER 15 The Autonomic Nervous System and Sensory Neurons 189

pass through sympathetic chain ganglia without synapsing and run in thoracic splanchnic nerves; pass through celiac plexus; reach adrenal medulla; synapse with adrenal medulla cells, which are modified postganglionic neurons. (p. 510 and Fig. 15.9) (e) Preganglionic cell bodies in upper thoracic cord; axons in thoracic ventral roots, spinal nerves, white rami. Some ascend in nearest trunk ganglia, with postganglionic axon running through cardiac plexus to heart. Other preganglionic axons ascend in sympathetic trunk to synapse in a cervical ganglion, with postganglionic axon descending through cardiac plexus to heart. (p. 510, Fig. 15.8) (f) Preganglionic cell bodies in inferior half of thoracolumbar spinal cord; axons run in thoracic ventral roots, spinal nerves, white rami, through trunk ganglion to splanchnic nerve to synapse in the celiac prevertebral ganglion. From there, postganglionic axons run to stomach. (Fig. 15.8) 17. (a) Preganglionic cell bodies are in midbrain; axons run in oculomotor nerve; synapse in ciliary ganglion in orbit; postganglionic axons run to eye. (p. 504 and Fig. 15.4) (b) Preganglionic cell bodies in sacral spinal cord; axons run in ventral roots, spinal nerves, ventral rami, and pelvic splanchnic nerves; through inferior hypogastric plexus; synapse with postganglionic neurons in the intramural ganglia in the bladder wall. (p. 505, Fig. 15.4) (c) Preganglionic cell bodies are in medulla oblongata; axons run in vagus nerve (into abdomen and through inferior mesenteric plexus); synapse with postganglionic neurons in intramural ganglia in intestinal wall. (p. 505 and Fig. 15.4) 18. The vagus descends through the neck, travels along the esophagus, and follows the esophagus inferiorly onto the stomach. From there, it sends branches through the celiac and superior mesenteric plexuses to specific abdominal organs (e.g., intestines, liver, pancreas). (Fig. 15.4) 19. All preganglionic fibers in both parasympathetic and sympathetic divisions, all parasympathetic postganglionic fibers, and a few postganglionic sympathetic fibers (innervation of sweat glands and blood vessels of skeletal muscles) are cholinergic. (p. 503, Table 15.1) 20. Anatomically, a single motor neuron forms the somatic motor (efferent) PNS pathway running from the CNS to the effector; in contrast, in the ANS visceral motor pathway, a chain of two neurons—the preganglionic neuron and the ganglionic (or postganglionic) neuron—runs between the CNS and the effectors. Functionally, the somatic motor PNS pathway innervates all skeletal muscles; the ANS visceral motor pathway innervates smooth muscle, cardiac muscle, and glands. (pp. 500–502 and Table 15.1)

Critical Reasoning and Clinical Applications Questions 1. The infant probably has congenital megacolon (Hirschsprung’s disease). In this condition, the parasympathetic innervation of the distal region of the large intestine has failed to develop normally. Feces are not propelled through, and so they accumulate in the bowel. (p. 516) 2. Henry is suffering from a condition called achalasia cardia, where the normal downward persistalsis of the esophagus is affected due to a defect in the autonomic nerves in the esophagus. The inferior part of the esophagus remains constricted, preventing the passage of food into the stomach, and that causes excessive distension of the upper and middle part of the esophagus. (p. 516) 3. Visceral pain exhibits an unusual feature: One often feels no pain when a visceral organ (lining of the large intestine) is torn. However, the true skin around the anus is innervated by somatic sensory fibers, which do transmit pain. (p. 513) 190

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4. Yes. The pain in the right shoulder could be caused by liver problems such as inflammation, which is a complication related to alcohol consumption. (p. 513, Fig. 15.10) 5. Raynaud’s disease, a sympathetic-vasoconstrictive disorder. (p. 516, Fig. 15.14) 6. Mrs. Jennings is suffering from diabetic autonomic neuropathy. A lesser understood complication of chronic diabetes, autonomic neuropathy is characterized by volatility in heart rate, blood pressure levels, and blood sugar levels. Other complications include increased constipation with occasional instances of diarrhea and urinary incontinence. (p. 503) 7. Destruction of the ciliary ganglia would cause an inability to constrict the pupil (which would remain wide open) and an inability to focus the eye for near vision. Destruction of the sphenopalatine ganglia would make it impossible to cry and would interfere with the ability of the mucous glands in the nose to produce mucus. Destruction of the submandibular ganglia would stop secretion of saliva from two large salivary glands, the submandibular and the sublingual (although the largest salivary gland, the parotid, would still function normally). None of the above symptoms is really life-threatening, so the death ray is a failure. (pp. 504–505) 8. Job-related stress may increase sympathetic nerve activity. Some health-related problems that result from chronic sympathetic stimulation are sleep disorders, duodenal ulcers, anxiety disorders, depression, and hypertension. Hypertension increases wear and tear on artery walls and the workload of the heart.

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 15: The Autonomic Nervous System and Visceral Sensory Neurons To the Student A study of the autonomic nervous system enables you to understand actions the body performs without conscious thought. You involuntarily experience countless smooth muscle and cardiac muscle contractions and gland secretions that provide a stable internal environment for you. Some of the important visceral functions under the regulation of the ANS are maintenance of heart rate and blood pressure, digestion, and urination. Anatomically, the ANS is described as a motor (efferent) pathway made up of two neurons, and Chapter 15 does focus on the general visceral motor functions. You must also realize that the general visceral sensory system constantly monitors these activities. Otherwise, how would you know you had a tummy ache? It is necessary to thoroughly review the peripheral nervous system hierarchy, as represented in Figure 15.1, to ensure a complete and factual understanding of the autonomic nervous system.

You will derive great benefit from continuing to use Practice Anatomy Lab 3.0 (PAL) (BC; DVD, Website), which you can access from www.myaandp.com or from the CD-ROM. The Self-Review section of the Nervous System section of the Human Cadaver and Anatomical Models modules offers a detailed look at ANS structures. The Quiz and Lab Practical sections offer in-depth practice in test taking.

Step 1: Understand the relationship of the autonomic nervous system to the body’s nervous system as a whole. __ Define the autonomic nervous system (ANS). __ Explain the relationship of the ANS to the PNS and the CNS. __ Summarize functions of the ANS, including the influence of the general visceral senses.

Step 2: Compare the autonomic nervous system to the somatic motor system. __ Distinguish effectors of the ANS from the effectors of the rest of the motor (efferent) division. __ Compare the number of neurons in a somatic (or branchial) motor pathway to the number of neurons in an autonomic motor pathway, including location of cell bodies. __ Distinguish preganglionic from postganglionic neurons.

Step 3: Describe the autonomic nervous system. __ Name the two divisions of the ANS. __ Outline the basic functional differences between the sympathetic and parasympathetic divisions of the ANS. __ Give examples of “fight or flight” responses experienced by your body. __ Name examples of “resting and digesting” responses experienced by your body. __ Describe three major anatomical differences between the sympathetic and parasympathetic divisions.

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__ Describe major biochemical differences between the sympathetic and parasympathetic neurotransmitters. __ Study textbook Table 15.1 for a summary of major anatomical and physiological differences between the sympathetic and parasympathetic divisions.

Step 4: Explain the outflow of the parasympathetic division of the ANS. __ Describe how the parasympathetic division relates to the brain, and define cranial outflow. __ Name the cranial nerves that support parasympathetic fibers. __ Describe the precise locations of the preganglionic and postganglionic neurons for each of the following cranial nerves: • Outflow via the oculomotor nerve (III)

• Outflow via the glossopharyngeal nerve (IX)

• Outflow via the facial nerve (VII)

• Outflow via the vagus nerve (X)

__ Explain how the parasympathetic division relates to the sacral spinal cord, and describe sacral outflow.

Step 5: Explain the sympathetic division of the ANS. __ Describe the anatomy of the sympathetic division. __ Describe why the sympathetic division is more complex than the parasympathetic division. __ Distinguish trunk ganglia from paravertebral ganglia, including examples of each. __ Explain how the sympathetic division relates to the spinal cord and spinal nerves. __ Describe and draw simple diagrams representing sympathetic innervation to the following body regions: • Periphery of the body

• Abdominal viscera

• The head

• Pelvic viscera

• Thoracic viscera __ Explain the role of the adrenal medulla in the sympathetic division.

Step 6: Understand the central nervous system control of the ANS. __ Using Chapter 13, The Central Nervous System, review structures of the brain and spinal cord, as needed. __ Explain the role played by the brain stem and spinal cord, including reticular formation and spinal visceral reflexes. __ Explain the role played by the hypothalamus as the main integration center. __ Discuss the amygdala in terms of fear-related behavior. __ Explain the role of the cerebral cortex and conscious control over some autonomic functions.

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Step 7: Explain the relationship of visceral sensory neurons and visceral reflexes to the ANS. __ Define visceral sensory neurons. __ Explain the role played by visceral sensory neurons, including examples of visceral information provided. Refer to Figure 15.1. __ Describe the concept of referred pain. __ Explain how spinal and peripheral reflexes regulate some functions of visceral organs.

Step 8: Understand the ANS throughout life. __ Distinguish the embryonic origin of postganglionic neurons from the embryonic origin of postganglionic neurons. __ List examples of age-related problems that are associated with the declining efficiency of the ANS. __ Briefly describe some disorders of the ANS, such as Raynaud’s disease and hypertension.

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Lecture and Demonstration Objectives 1. Describe the receptors for taste and smell.

2. Describe the paths by which sensory information from these receptors travels to the brain.

3. Describe the anatomy and function of the accessory structures of the eye.

4. Describe the movements produced by each of the six extrinsic eye muscles and the cranial nerve that innervates each.

5. Describe the structure and function of the three layers of the eye, of the lens, and of the humors of the eye.

6. Explain the structure of the retina and the photoreceptors.

7. Explain how light is focused for close vision.

8. Trace the pathway of nerve impulses from the retina to the cerebral cortex.

9. Describe the embryonic development of the eye.

10. List the basic structures of the external and middle ear and their corresponding functions.

11. Name the parts of the bony and membranous labyrinths in the internal ear.

12. Describe the receptors for hearing and equilibrium.

13. Describe the pathways taken by auditory and equilibrium information through the brain.

14. Compare and contrast the embryonic derivations of the external ear, middle ear, and internal ear.

15. List the causes and symptoms of motion sickness, Ménière’s syndrome, and deafness.

16. Describe the changes in the special senses that occur with aging.

Suggested Lecture Outline I. The Chemical Senses: Taste and Smell (pp. 521–524, Figs. 16.1–16.3) A. The receptors for taste (gustation) and smell (olfaction) are classified as chemoreceptors.

1. Taste (Gustation) (pp. 521–522, Figs. 16.1, 16.2) a. Anatomically, taste receptors are located in taste buds in the mouth, in the pharynx, and on the epiglottis; most taste buds are on the tongue and occur in fungiform and vallate papillae. b. The four basic sensations of taste are sweet, sour, salty, and bitter; a fifth distinctive taste, umami, is also recognized. ..

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c. The gustatory pathway from taste buds to the brain stem and cerebral cortex is served by cranial nerves VII, IX, and X. B. Smell (Olfaction) (pp. 522–523, Fig. 16.3) 1. The receptors for smell (olfaction) lie in the olfactory epithelium in the roof of the nasal cavity; smells are analyzed in the olfactory cortex and limbic system; olfactory nerves and tracts serve the sense of smell.

C. Embryonic Development of the Chemical Senses (p. 523) 1. In the embryo, olfactory epithelium is derived from olfactory placodes; taste buds develop from epithelium lining the embryonic mouth and pharynx.

D. Disorders of the Chemical Senses (p. 524) 1. Disorders of smell are more common than disorders of taste; examples are anosmia and uncinate fits.

II. The Eye and Vision (pp. 524–538, Figs. 16.4–16.15) A. Vision is the dominant sense in humans; 40% of the cerebral cortex is involved in processing visual information. (p. 524) 1. Accessory Structures of the Eye (pp. 524–527, Figs. 16.4–16.6) a. The accessory structures of the eye include the eyebrows, eyelids, conjunctiva, lacrimal apparatus, and extrinsic eye muscles.

B. Anatomy of the Eyeball (pp. 527–533, Figs. 16.7–16.12) 1. The anatomical features of the eyeball are the following: the fibrous tunic, the vascular tunic, the sensory tunic (retina), internal chambers and fluids, and the lens. a. Special features of the retina are photoreceptors, regional specializations of the retina, and the blood supply to the retina.

C. The Eye as an Optical Device (pp. 533–534, Fig. 16.13) 1. As an optical device, light enters the eye, and then the cornea and the lens bend it; light is then focused on the retina.

D. Visual Pathways (pp. 534–536, Fig. 16.14) 1. Visual information processing begins in the retina and travels to the brain for complex processing; the visual pathway to the cerebral cortex is the main visual pathway and is supported by cranial nerve II and optic tracts; additional pathways go to the midbrain.

E. Embryonic Development of the Eye (pp. 536–538, Fig. 16.15) 1. The eyes develop from outpocketings of the embryologic brain.

F. Disorders of the Eye and Vision (p. 538) 1. Examples of disorders of the eye and vision are types of blindness due to retinal damage and corneal damage.

III. The Ear: Hearing and Equilibrium (pp. 538–549, Figs. 16.16–16.24) A. The External Ear (pp. 538–540, Fig. 16.16) 1. The outer (external) ear consists of the auricle and the external auditory meatus; the tympanic membrane is the boundary between the outer ear and the middle ear.

B. The Middle Ear (pp. 540–541, Figs. 16.16, 16.17)

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1. The middle ear (tympanic cavity) is an air-filled space housed in the temporal bone; it contains three tiny ear ossicles and an opening into the pharyngotympanic tube.

C. The Internal Ear (pp. 541–547, Figs. 16.18–16.22, Table 16.1) 1. The internal ear consists of two main divisions: the bony labyrinth and the membranous labyrinth; identify specific anatomical structures and their functions of the internal ear.

D. Auditory and Equilibrium Pathways (p. 547, Fig. 16.23) 1. Information on equilibrium and hearing travels to the brain for processing and integration; impulses generated by the equilibrium receptors travel along the vestibular nerve; impulses generated by the hearing receptors travel along the cochlear nerve.

E. Embryonic Development of the Ear (pp. 547–548, Fig. 16.24) 1. Embryonic development of the ear begins in the fourth week.

F. Disorders of Equilibrium and Hearing (p. 549) 1. Disorders of equilibrium and hearing include motion sickness, Ménière’s syndrome, and deafness.

IV. The Special Senses Throughout Life (pp. 549–550) A. The senses of taste and smell are sharpest in newborns; vision develops during early childhood; hearing is reflexive in infants, and critical hearing develops in toddlers.

B. By age 60, most people experience obvious age-related loss of hearing and vision deterioration.

Lecture Hints 1. Point out the importance of smell (and other sensations) on the perception of taste.

2. Emphasize that each taste sensation is not localized to a specific area, but rather that there is significant overlap of the different sensation areas. Students often assume that a particular point on the tongue responds to a single type of substance; the “taste map” is a myth.

3. During the lecture on olfactory anatomy, ask the class what would happen to olfaction if mucous glands below the olfactory epithelium were absent.

4. Emphasize that olfactory receptors are the only renewable neurons in the body and are therefore the one exception to the rule that neurons do not replicate; remind students that olfactory nerves are highly branched and should not be confused with olfactory tracts.

5. Explain that the eye is a receptor for light impulses as well as an energy transducer because the eye converts light energy into the electrical energy of an action potential.

6. Initially, it is difficult for even the sharpest students to grasp the concept of ciliary muscle contraction leading to lens thickening (for close focus). Intuitively, most think of the process of stretching the lens as a consequence of muscle contraction, not relaxation.

Spend time reinforcing this concept.

7. Although the sclera is avascular, explain to students why we see blood vessels in the white of the eye.

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8. Explain to students how it is possible that the cornea is transparent and the sclera is opaque when they are both constructed of the same material and continuous with each other.

9. Have students try out focusing on objects at night. Explain that they should not look directly at the object, but slightly to one side, and the object should look brighter. Relate this exercise to the distribution of rods and cones in the eye. Viewing stars in the night sky is a perfect example of how to do this experiment, if you live in an area where there is no light pollution from city lights or streetlights.

10. Explain that the ear is a receptor for sound impulses as well as an energy transducer because the ear converts sound energy into the electrical energy of an action potential.

11. Students are often confused by the anatomy of the internal ear; clearly distinguish the bony labyrinth from the membranous labyrinth; textbooks often picture the bony labyrinth as if it were a solid object, but it is actually a cavity.

12. Explain the anatomy of the pharyngotympanic tube; identify locations of each end. Ask students what they do to “pop” their ears when they drive up a mountain or fly off in an airplane; explain that the yawn or swallow is actually an attempt to open both ends of the pharyngotympanic tube at the same time so air pressure is equalized on both sides of the tympanic membrane.

13. As a point of interest, mention that the smallest synovial joints in the body join the ossicles.

14. Emphasize the difference between static and dynamic equilibrium by comparing and contrasting the anatomy of each type of equilibrium.

Classroom Discussion Topics and Activities 1. Display a large three-dimensional model of an eye and ear to illustrate the anatomy of both. If you have access to an opaque projector, place the models on the projector.

2. Use an onion, orange, and apple to test the interaction among taste, smell, and sight. Cut pieces in similar sizes and shapes, and provide water between samplings. First, ask two student volunteers to taste and smell each item normally. Second, cover their eyes and have them taste each item and identify the item. Third, instruct them, with eyes still covered, to pinch shut their noses, then taste and identify. Ask the class to explain the results.

3. Spray cologne with a strong scent into the air and ask students to raise their hands to indicate when they first smell it. Instruct students to time their detection of the presence of the cologne until it is no longer detectable. This is a jumping-off point for a discussion on adaptation of the sensory apparatus (receptors).

4. To demonstrate that rods do not distinguish color, lower or turn off the lights in the classroom, and ask students to identify variously colored papers.

5. Dissect a preserved cow (or sheep) eye to illustrate its anatomical structure and the nature of its tissues and fluids. Point out the very fragile retina and demonstrate its single point of attachment, the optic disc.

6. Obtain a human skull or high-quality model of a human skull to illustrate the bony structures associated with our senses. Also, review the foramina through which the special sensory nerves pass (olfactory, optic, vestibulocochlear, facial, glossopharyngeal, and vagus).

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7. Demonstrate a set of human ear ossicles to illustrate how tiny they really are. Use a human skull to reinforce the bony location of the ossicles. Remind students that ossicles form the tiniest synovial joints in the body; ask students to carefully examine the articulating surfaces to identify the structural types of synovial joint represented.

8. Have one student twirl like a dancer, another run straight forward from a standing position, and another stand still with a tilted head to demonstrate angular acceleration and linear acceleration (the two aspects of dynamic equilibrium) and static equilibrium.

9. Display Ishihara’s color plates, and permit students to test for evidence of color blindness and/or display an eye chart so students can assess their visual acuity.

10. Display examples of optical illusions, and ask students to explain them.

11. To demonstrate that substances must be dissolved in saliva to be tasted, ask students to dry their tongue surface with a paper towel and then drop a few grains of sugar or salt on the tongue surface.

12. Provide a jumbled list of various eye and ear structures, and ask students to arrange the structures in the order that light or sound signals travel through these receptors to the brain.

13. Most people with sinus infections cannot smell, and their ability to taste is much diminished. Ask students why.

14. Amplified rock-and-roll music and listening to loud music through ear buds has been implicated in sensorineural deafness. Ask students for suggestions to help alleviate this problem in teenagers.

15. Fish- and plant-eating mammals (such as horses) have eyes on the sides of their heads.

Ask students why this is useful to these animals.

16. Certain types of sunglasses can cause more harm than good. Ask students what is wrong with these inexpensive sunglasses.

17. One’s ears “ring” after prolonged loud noise stops. Ask students what causes ringing in the ears.

Clinical Questions 1. Brenda, a 6-year-old girl, told the clinic physician that her “ear lump” hurt and that she kept “getting dizzy and falling down.” As she told her story, she pointed to her mastoid process. An otoscopic examination of the external auditory canal revealed a red, swollen eardrum, and her throat was inflamed. Her condition was described as mastoiditis with secondary labyrinthitis (inflammation of the labyrinth). Describe the most likely route of infection in Brenda’s case. Also explain the cause of her dizziness and falling.

Answer: Most ear infections start as throat infections that spread through the pharyngotympanic tube into the middle ear. Brenda’s infections had spread farther, through the mastoid antrum behind the middle ear to the mastoid air cells. It had also spread medially to infect the internal ear, and the pressure of inflammatory fluids in the internal ear disrupted the balance receptors, making Brenda dizzy and prone to falling.

2. A 60-year-old woman is experiencing vertigo. She ignores the symptoms at first, but now her attacks are accompanied by severe nausea, and following each attack she hears a crackling in her ears. What do you think her problem is, and what is its suspected cause?

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Answer: She probably has Ménière’s syndrome. It affects both the balance receptors in the semicircular ducts and the hearing receptors in the cochlear ducts. The cause is uncertain, but it probably results from excessive production of endolymph, whose pressure distorts the membranous labyrinth.

3. Mariam, a 75-year-old grandmother, complained that her vision was becoming obscured.

Upon examination by an ophthalmologist, she was told she had cataracts. What are they, and how are they treated?

Answer: A cataract is a clouding of the lens that causes the world to appear distorted, as though a person were looking through frosted glass. Some cataracts are congenital, but most are related to the age-related hardening and thickening of the lens or are a secondary consequence of diabetes mellitus. The direct cause is probably inadequate delivery of nutrients to the deeper lens fibers, followed by an unfolding of the crystalline proteins in these fibers. Fortunately, the offending lens can be removed surgically and an artificial lens implanted.

4. After trauma to the head during an automobile accident, Warren, a 50-year-old man, is diagnosed as having anosmia. Define anosmia. Why is this condition fairly common after head injuries?

Answer: Anosmia means loss of the sense of smell. As trauma to the head shakes the brain, it can pull and tear the delicate filaments of the olfactory nerve where they pass through the cribriform plate of the ethmoid bone.

Art Resources Figure 16.1 Figure 16.2 Figure 16.3 Figure 16.4 Figure 16.5 Figure 16.6 Figure 16.7 Figure 16.8 Figure 16.9 Figure 16.10 Figure 16.11 Figure 16.12 Figure 16.13 Figure 16.14 Figure 16.15 Figure 16.16 Figure 16.17 Figure 16.18 Figure 16.19 Figure 16.20

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Taste buds on the tongue.

The gustatory pathway.

Olfactory receptors.

Accessory structures of the eye.

The lacrimal apparatus.

Extrinsic eye muscles.

Internal structure of the eye (sagittal section).

Pupil dilation and constriction, anterior view.

Microscopic anatomy of the retina.

Photoreceptors of the retina.

The posterior wall of the right eye as seen with an ophthalmoscope.

The anterior segment of the eye and circulation of the aqueous humor.

Focusing for distant and close vision.

Visual pathway to the brain and visual fields, inferior view.

Embryonic development of the eye.

Structure of the ear.

Skeletal muscles associated with the auditory ossicles (right ear, medial view).

The internal ear.

Anatomy of the cochlea.

Role of the cochlea in hearing.

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Figure 16.21 Figure 16.22 Figure 16.23 Figure 16.24

The maculae in the internal ear.

Location, structure, and function of the crista ampullaris in the internal ear.

The auditory pathway.

Embryonic development of the ear.

Teaching with Art Figure 16.14

Visual pathway to the brain and visual fields, inferior view.

Textbook p. 536.

Checklist of Key Points in the Figure • Describe the formation of optic nerves as a bundle of axons of ganglia cells of the retina.

• Clearly distinguish the optic nerve, optic chiasma, and optic tract.

• Explain decussation of axons from the medial half of each eye.

• Clearly differentiate ipsilateral from contralateral fibers.

• Point out how overlapping fields of vision permit depth perception.

• Point out the termination point of impulses in the visual cortex in the occipital lobe.

Common Conceptual Difficulties Interpreting the Art • Describe the beginning of the visual pathway in the retina, pointing out that light traveled through the retina and in the reverse neuron sequence to get to the rod and cone cells.

• Explain stereoscopic vision and monocular vision, relating these visual fields to colored parts of the figure.

• Discuss the significance of the optic chiasma, decussation, and depth perception.

• Clarify the difference between perception and sensation.

• Explain why some visual information goes to the midbrain and diencephalon.

• Explain the role of the lateral geniculate nucleus of the thalamus.

• Explain the role of the occipital cerebral cortex.

Art Exercise Provide students with unlabeled copies of Figure 16.14. Instruct students to trace the visual pathway to the brain from the right eye and left eye using color-coded fibers, and to label each part of the pathway from the retina to the visual cortex.

Critical Reasoning Instruct students to look at Figure 16.14 and answer the following questions: 1. If the optic chiasma is cut longitudinally, or possibly compressed by a tumor in the optic chiasma or pituitary gland, what is the effect on vision?

Answer: Peripheral vision is lost in both eyes, leaving only “tunnel vision.”

2. If the left visual cortex (or any area beyond the optic chiasma, such as the optic tract or thalamus) is damaged, what is the effect on vision?

Answer: Blindness occurs throughout the right half of the visual field.

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3. If the left eye or left optic nerve is destroyed, what is the effect on vision?

Answer: True depth perception is eliminated, and peripheral vision on the left side is lost.

4. If an optic tract is cut, what is the effect on vision?

Answer: Both eyes will be partially blind: One eye loses the medial field of vision, and the other eye loses the lateral field of vision.

Supplemental Course Materials Library Research Topics 1. How successful are cochlear implants? What surgical techniques are used? What advantages and disadvantages are there in the use of cochlear implants?

2. Some permanently deaf people have been helped by means of computers and electrical probes connected to certain areas of the brain. How is this possible and what is the current research in this area?

3. Contact lenses have been used for decades to correct vision problems. What is the status of contact lens implants, and why do many ophthalmologists hesitate to prescribe them?

4. How effective is the technique of reshaping the cornea (Lasix surgery) with lasers as a means of correcting focusing disorders (farsightedness or nearsightedness)?

5. If hearts, lungs, livers, and kidneys can be transplanted, why not eyes? What would be some technical and functional difficulties?

6. What are the present treatments for otitis media, and are they really effective?

7. Research the phenomenon of synesthesia. How does it affect those who have it?

Suggested Readings Berson, D. M. “Phototransduction by retinal ganglion cells that set the circadian clock.”

Science 295 (5557) (February 2002): 1070–1073.

Busskamp, V., Jens Duebel, David Balya, Mathias Fradot, et al. “Genetic Reactivation of Cone Photoreceptors Restores Visual Response in Retinitis Pigmentosa.” Science 329 (5990) (23 July 2010): 413–417. (Also available at doi:10.1126/science.119897) Chandrashekar, J., David Yarmolinksky, Lars von Buchholtz, Yuki Oka, et al. “The Taste of Carbonation.” Science 326 (5951) (16 October 2009): 443–445. (Also available at doi:10.1126/science.1174601) Firestein, S. “How the Olfactory System Makes Sense of Scents.” Nature 413 (6852) (September 2001): 211–218.

Gagescu, R. “Hear, hear.” Nature Reviews: Molecular Cell Biology 2 (8) (August 2001): 565.

Gozem, S., Igor Schapiro, Nicolas Ferre, and Massimo Olivucci. “The Molecular Mechanism of Thermal Noise in Rod Photoreceptors.” Science 337 (6099) (7 September 2012): 1225–1228. (Also available at doi:10.112/science.1220461) Marcucci, F., D. J Zou, and S. Firestein. “Sequential Onset of Presynaptic Molecules During Olfactory Sensory Neuron Maturation.” Journal of Comparative Neurology 516 (3) (September 2009): 187–198.

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Pichaud, F., and C. Desplan. “A New View of Photoreceptors.” Nature 416 (6877) (March 2002): 139–140.

Shinozaki, A., Yoshinao Hosaka, and Tomhiro Imagawa. “Topography of Ganglion Cells and Photoreceptors in the Sheep Retina.” The Journal of Comparative Neurology Volume 518, Issue 12, (June 2010): 2305–2315. (Also available at doi:10.1002/cne.22333)

Answers to Textbook Questions Answers for multiple-choice and matching questions 1–12 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 13. The student is clearly correct because the “traditional” five senses (vision, hearing, smell, touch, and taste) do not acknowledge the existence of balance (equilibrium), an important sense. Our many senses include touch, pain, pressure, vibration, temperature, proprioception, vision, smell, hearing, equilibrium, sensing chemical changes and irritation in viscera, nausea, hunger, and smell. (p. 384, Table 12.1) 14. (a) The olfactory epithelium, containing the olfactory receptors, lies in the superior part of the nasal cavity, on the superior nasal concha and the superior part of the nasal septum. (pp. 522–523) (b) The pathway of olfactory stimuli from the olfactory epithelium to the olfactory cortex: Axons of olfactory sensory neurons enter the connective tissue of lamina propria and gather into bundles that form cranial nerve I, which passes through the cribriform plate of the ethmoid bone and enters the olfactory bulb. From there, olfactory nerve axons branch and synapse with mitral cells. The mitral cells transmit impulses along the olfactory tract to the limbic region (where smells elicit emotion) and to the piriform lobe of the cerebral cortex (for conscious interpretation of smell). (p. 523) 15. The optic disc is a circular elevation where the axons of ganglion cells converge to exit the eye as the optic nerve. It is located a few millimeters medial to the fovea on the retina. It is important because it is the blind spot of the eye. It lacks photoreceptors, and light focused on it cannot be seen. (p. 531) 16. The receptor cells for taste and smell are replaced throughout life. (pp. 521–523) The receptor cells for vision, hearing, and balance are not effectively replaced. (pp. 529, 544, and 545) 17. Otitis media usually starts as a throat infection that spreads to the middle ear via the pharyngotympanic tube. Fluid and pus can build up in the middle ear cavity and exert painful pressure within this enclosed space. More children than adults develop otitis media because the child’s pharyngotympanic tube is shorter and enters the pharynx at a less acute angle. The infection may spread to the meninges and the brain, the mastoid sinus, and clot the blood in the jugular vein. (p. 540) 18. With age, the lens loses its crystal clarity and becomes discolored. It becomes less able to round up for accommodation, leading to presbyopia. (p. 550) Atrophy of the spiral organ (of Corti) reduces hearing acuity, especially to high-pitched sounds. (p. 550)

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19. Auditory pathway: hair cells in the internal ear, to the cochlear nerve (VIII), to cochlear nuclei in the medulla, to the superior olivary nucleus or inferior colliculus (some fibers only), to the medial geniculate nucleus in the thalamus, to the primary auditory cerebral cortex in the temporal lobe. (p. 547, Fig. 16.23) 20. LR6 (SO4)3 represents the cranial nerves that control the extrinsic eye muscles. These include the lateral rectus muscle controlled by CN VI, the superior oblique muscle controlled by CN IV, and the medial rectus, superior rectus, inferior rectus, and inferior oblique muscles controlled by CN III. (p. 526) 21. (a) A semicircular canal is a tube-shaped space carved in the petrous temporal bone, whereas a semicircular duct is a membrane-walled duct that lies within the semicircular canal. The semicircular canal is part of the bony labyrinth, and the semicircular duct is part of the membranous labyrinth. Similarly, the cochlea is the curved space that holds the membranous cochlear duct. (b) (1) semicircular ducts and (2) utricle/saccule (for balance); (3) cochlear duct (for hearing). (pp. 542–547) 22. In dim light, the dilator pupillae muscles of the iris will contract. During contraction, the pupil will widen (size increases) to allow more light to enter the eye for better vision. (p. 529, Fig. 16.8)

Critical Reasoning and Clinical Applications Questions 1. The early stages of age-related macular degeneration (AMD) is characterized by the build-up of visual pigments in the macula. This is caused by a loss of cells in the pigmented layer of the retina that are responsible for clearing the damaged visual pigments.

Continued accumulation of the pigment is connected to the dry form of AMD, in which many of the macular photoreceptors die. (p. 531) 2. Maria is suffering from otosclerosis, a common cause of hearing loss that increases with age. Excessive growth of bone tissue in the walls of the middle ear cavity can cause the fusion of the footplate of the stapes to the oval window. As a result, the stapes cannot move, resulting in deafness. (p. 541) 3. Mrs Wiese has a cataract in her right eye, which can be treated by replacing the damaged lens with an artificial one. (p. 533) 4. The left optic tract carries all the visual information from the right half of the visual field.

Thus, Lionel cannot see the right half of visual space. (p. 535, Fig. 16.14a) 5. The babies had retinopathy of prematurity. (p. 538: “Disorders” section) They received oxygen after birth, which caused retinal vessels to grow, rupture, and detach the retina, leading to blindness.

6. Jessica is suffering from Meniere's disease which is characterized by disturbed equilibrium (to the extent that standing is nearly impossible), nausea, vertigo, vomiting, tinnitus and hearing roaring or buzzing sounds in the ear (eventually leading to hearing loss). It is caused by the accumulation of excessive amounts of endolymph in the membranous labyrinth of the inner ear. (p. 549) 7. Peripheral vision would be lost on both the right and left sides of the visual field. Central vision would remain intact, so the person could see only straight ahead (tunnel vision). (p. 535, Fig. 16.14a)

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 16: The Special Senses To the Student The special senses explored in this chapter are the chemical senses of taste and smell, vision in the eye, and hearing and equilibrium in the ear. These senses have specific receptor cells that differ from the receptors of the general senses and are not like the dendritic endings of sensory neurons. The receptors for taste, smell, hearing, and equilibrium are specialized sensory epithelium that interfaces with the nervous system and the environment. Photoreceptors in the eye are considered neurons, but they also closely resemble epithelial cells.

This chapter summarizes the basic functional anatomy of the special senses and explains the basic concepts of sensory processing for taste, smell, vision, hearing, and equilibrium.

You will also find that incorporating Practice Anatomy Lab 3.0 (PAL) (BC; DVD, Website) into your studies of the special senses will improve your understanding. For a good review of the special senses, refer to the Special Senses category within the Nervous System sections in the Human Cadaver and Anatomical Models modules. Additionally, refer to the Histology module for a review of the histology of special senses. You may access PAL 3.0 through the DVD or the www.myaandp.com website.

Step 1: Understand the chemical senses: taste and smell. __ Describe the receptors for taste and outline the gustatory pathway. __ Distinguish sensation from perception. __ Identify the taste sensations. __ Describe the receptors for smell, and outline the pathway of the smell sensory information to the brain. __ Distinguish the olfactory tract from the olfactory nerve.

Step 2: Understand the eye and vision. __ Describe the structure and function of the accessory structures of the eye: eyebrows, eyelids, conjunctiva, lacrimal apparatus, and extrinsic eye muscles. __ List the three tunics of the eyeball, describing the parts and functions of each. __ Describe the structure and function of the lens. __ Describe the structure and function of the internal chambers and fluids (humors) of the eyeball. __ Explain the structure of the retina and the photoreceptors. __ Distinguish the rod cells from the cone cells. __ Explain how light is focused for close vision. __ Trace the pathway of visual information from the retina to the cerebral cortex. __ Label a card with each of the structures in the visual pathway, and practice placing the cards in the correct sequence. __ Define decussation.

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__ Distinguish optic nerve, optic tract, and optic chiasma. __ Describe stereoscopic vision. __ Explain the visual fields of the eyes.

Step 3: Understand the ear: hearing and equilibrium. __ List the basic structures of the outer ear, middle ear, and internal ear, and name their corresponding functions. __ Name the parts of the bony labyrinth in the internal ear. __ Name the parts of the membranous labyrinth and corresponding functions in the internal ear. __ Describe the receptors for hearing. __ Describe the receptors for equilibrium. __ Describe how the equilibrium pathway transmits information on the position and movements of the head. __ Discuss how the auditory pathway transmits auditory information from the cochlear receptors to the cerebral cortex.

Step 4: Distinguish disorders of equilibrium and hearing. __ Describe the theories of the causes of motion sickness. __ Describe Ménière’s syndrome and its treatments. __ Distinguish conduction deafness from sensorineural deafness.

Step 5: Describe the changes in special senses throughout life. __ Describe the senses of a newborn child. __ Describe the fine-tuning of synaptic connections of the visual pathway during the first eight months of life. __ Describe how the senses of smell, taste, vision, and hearing decrease with age. __ Describe congenital abnormalities of vision and hearing. __ Explain gene therapy techniques that may lead to treatment of hearing loss.

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CHAPTER

17

The Endocrine System

Lecture and Demonstration Objectives 1. List the major endocrine organs, and describe their locations.

2. Describe how hormones are classified chemically.

3. Describe the basic interaction between hormones and their target cells. Describe three mechanisms that control hormone secretion.

4. Name the basic divisions of the pituitary gland.

5. List the hormones secreted by the anterior lobe and the cell type that secretes each. State the basic functions of each hormone.

6. Explain how the hypothalamus controls secretion of anterior lobe hormones. Define releasing hormones, and trace their path through the pituitary gland.

7. Describe the structure of the posterior lobe and the functions of the hormones it releases.

8. Describe the anatomy of the thyroid gland.

9. Define and describe the effects of thyroid hormone (TH) and calcitonin, and explain how TH is secreted.

10. Describe the anatomy of the parathyroid gland and the function of parathyroid hormone.

11. Name the two divisions of the adrenal gland, and compare and contrast them in terms of their structure and the hormones they secrete.

12. Describe the endocrine functions of the pineal gland, pancreas, thymus, and gonads.

13. Name a hormone produced by the heart, and define diffuse neuroendocrine system (DNES).

14. Briefly explain the endocrine functions of the placenta, kidney, and skin.

15. Describe the effects of excessive and inadequate hormonal secretion by the pituitary, thyroid, and adrenal glands; define diabetes mellitus.

16. Describe the development of the major endocrine glands.

17. Describe the effect of aging on some endocrine organs.

Suggested Lecture Outline I. Overview (pp 523–525, Figs. 17.1, 17.2) A. The endocrine system is composed of ductless glands that release hormones directly into the blood or lymph; hormones trigger physiological changes in target cells throughout the body. ..

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1. The endocrine system controls and integrates the functions of other systems in the body and closely interacts with the nervous system.

A. Endocrine Organs (p. 555, Fig. 17.1) 1. Endocrine organs are small and widely separated from each other in the body; endocrine cells are mostly epithelial in origin, but others are hormone-secreting neurons, muscle cells, and fibroblast-like cells. a. The primary (“pure”) endocrine glands are the pituitary, thyroid, parathyroid, adrenal, and pineal glands. b. Endocrine cells also are located in the gonads, pancreas, kidney, alimentary canal, heart, thymus, and skin.

B. Hormones (pp. 555–557. Fig. 17.2) 1. Hormones are messenger molecules that signal changes in target cells. a. Classes of hormones are either amino acid derivatives (amines, peptides, or proteins) or lipid-based steroids. b. Basic hormone action incorporates circulation throughout the entire body and contact with specific target cells. c. Control of hormone secretion is regulated by three major types of stimuli: humoral, neural, or hormonal feedback.

II. The Major Endocrine Organs (pp. 557–569, Figs. 17.3–17.10, Table 17.1) A. The major endocrine glands of the body are the pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pineal gland, pancreas, thymus, and gonads.

1. The Pituitary Gland (pp. 557–563, Figs. 17.3, 17.4, Table 17.1) a. The pituitary gland is suspended from the diencephalon of the brain and secretes at least nine major hormones; the pituitary has two basic divisions: the anterior pituitary and the posterior pituitary. i. The anterior pituitary has three divisions; the largest is the pars distalis, with five cell classes that secrete seven different protein hormones. ii. Hypothalamic control of hormone secretion from the anterior pituitary is exerted by peptide hormones called releasing hormones (factors). iii. The posterior pituitary secretes two hormones and is structurally part of the brain.

B. The Thyroid Gland (pp. 563–564, Fig. 17.5) 1. The thyroid gland is located in the anterior neck; it secretes thyroid hormone and calcitonin.

C. The Parathyroid Gland (pp. 564–565, Fig. 17.6) 1. The parathyroid glands usually lie on the posterior aspect of the thyroid gland and secrete a hormone (parathormone) that is essential for increasing blood Ca2+.

D. The Adrenal (Suprarenal) Glands (pp. 566–568, Figs. 17.7, 17.8) 1. The adrenal (suprarenal) glands are located on the superior surface of the kidneys; each adrenal gland is two glands in one: the adrenal medulla and the adrenal cortex. a. The adrenal medulla is part of the autonomic nervous system (Chapter 15) and secretes amine proteins that enhance the “fight or flight” response.

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b. The adrenal cortex secretes a variety of hormones, all of which are lipid-based steroid hormones.

E. The Pineal Gland (p. 568, Figs. 17.3b, 17.9) 1. The pineal gland lies on the roof of the diencephalon and secretes the hormone melatonin, which helps regulate circadian rhythms.

F. The Pancreas (pp. 568–569, Fig. 17.10) 1. The pancreas is located in the posterior wall of the abdominal cavity; it functions as a dual organ in that it secretes digestive enzymes as well as hormones.

G. The Thymus (p. 569, Fig. 17.1) 1. The thymus, an important organ of the immune system, secretes thymic hormones that are essential for the production of T lymphocytes.

H. The Gonads (p. 569) 1. The gonads (testes and ovaries) are the main source of the steroid sex hormones.

III. Other Endocrine Structures (pp. 569–570) A. Endocrine cells occur within various organs of the body, including the heart, gastrointestinal tract and its derivatives, placenta, kidneys, and skin.

IV. Disorders of the Endocrine System (pp. 570–572, Figs. 17.11–17.13) A. Most disorders of the endocrine glands involve either a hypersecretion (oversecretion) or a hyposecretion (undersecretion) of a given hormone.

1. Pituitary Disorders (p. 570, Fig. 17.11) a. Pituitary disorders include gigantism, acromegaly, pituitary dwarfism, and diabetes insipidus.

B. A Disorder of the Pancreas: Diabetes Mellitus (pp. 570–571) 1. A disorder of the pancreas, diabetes mellitus is caused by either insufficient insulin or by resistance of body cells to the effects of insulin.

C. Disorders of the Thyroid Gland (pp. 571–572, Fig. 17.12) 1. Disorders of the thyroid gland include Graves’ disease, adult hypothroidism, and endemic goiter.

D. Disorders of the Adrenal Cortex (p. 572, Fig. 17.13) 1. Disorders of the adrenal cortex include Cushing’s disease and Addison’s disease.

V. The Endocrine System Throughout Life (pp. 572–573, Fig. 17.14) A. The endocrine glands have diverse developmental origins from all three germ layers.

B. Some hormonal secretions change little with aging, but others, such as GH, DHEA, and the sex hormones, show marked drops in secretion with age.

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Lecture Hints 1. Remind students of the specific characteristics distinguishing an endocrine gland and an exocrine gland.

2. Stress the anatomical and functional relationships between the endocrine and nervous systems, explaining how both work to maintain homeostasis and coordinate physiological functions throughout the body.

3. Emphasize the concept of feedback mechanisms for control of the synthesis and release of hormones; name several examples of hormonally regulated processes.

4. Explain the basic interaction between hormones and their target cells, noting that although hormones freely circulate through the body, all tissues are not affected by all hormones.

5. A flowchart structure is an ideal method to condense a large volume of complex material into a compact package. Suggest to the class that on a single, large sheet of paper or on a whiteboard, they map the entire endocrine system, flowchart style. Start at the top with the hypophysis, and trace the path of each hormone to its target tissue. If students are able to see the entire picture on a single sheet, they will easily master the concepts of endocrine function. Condensing content on one page is a far better learning tool than flashcards.

6. Emphasize that minute quantities of hormone are all that is necessary to produce dramatic effects in the body.

7. Students are often confused regarding the actual site of posterior pituitary hormone production. Remind students that the hypothalamus is the actual production site and that the axons from the hormone-producing neurons terminate in the posterior pituitary (where the neurohormones are released).

8. Point out the importance of receptor regulation in non-insulin-dependent diabetes.

9. The mechanism of hormone action is an ideal way to introduce some critical thought questions for the class. Ask the class: “Knowing the properties of steroids and proteins, how should these hormones be carried in the blood, and which mechanism (second messenger or intracellular receptor) demands what class of hormone?”

10. Some hormones are also neurotransmitters. Using an example such as norepinephrine, stress to students that there is no difference between the hormone and the neurotransmitter; the difference lies in the source of the chemical.

11. Use root-word definitions to emphasize the function of the parts of the pituitary: adeno = gland; neuro = nervous.

12. Point out the advantage of a portal system (like that in the digestive system) for the direct delivery of releasing and inhibiting hormones from hypothalamus to hypophysis.

13. Wherever possible, point out antagonistic hormone pairs (glucagon-insulin, calcitoninparathyroid hormone), and indicate direct control versus control by regulating factors (hormones).

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Classroom Discussion Topics and Activities 1. Use a model or a chart of a human torso to exhibit the major endocrine glands.

2. Demonstrate major endocrine glands using a dissected cat, rat, or human cadaver.

3. Use photographs as part of a PowerPoint presentation illustrating people affected with endocrine disorders such as goiter, gigantism, cretinism, and acromegaly.

4. Present the endocrine system with a global view, using the textbook’s Short Answer and Essay Questions 12–20 as a required assignment.

5. Diagram a feedback loop, beginning and ending with the anterior pituitary. The sequence will look like this: anterior pituitary → secretes → tropic hormone → stimulates → target endocrine gland → secretes → its hormone → inhibits → anterior pituitary.

6. Ask students to diagram the relationship of the pituitary to the hypothalamus in a similar diagram. It may look similar to this: hypothalamus |

|

V

V

releasing hormones

hormones

|

|

V

V

anterior pituitary

posterior pituitary

|

|

V

V |

hormones

V

|

|

V

V blood

7. Continue to discuss word origins with the students: a. Explain that the prefix nor- used in noradrenaline and norepinephrine describes the lack of a certain chemical radical that is part of the adrenaline (epinephrine) molecule. b. Explain that pituitary in Latin means “phlegm” because historically it was believed that this gland was the source of the mucus in the nasal cavity. c. Lact = milk, infundibulum = funnel, and so on.

8. Discuss why the pancreas, ovaries, testes, thymus, digestive organs, placenta, kidneys, and skin are considered to have endocrine functions. Relate the endocrine functions to the nonendocrine functions of these organs.

9. Discuss the role of the endocrine system in stress and stress responses.

10. Ask students to construct a list of all endocrine organs that are not controlled by the pituitary gland and the hypothalamus.

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11. Ask students to give examples of endocrine structures that are whole organs, others that are tissues within organs, and others that are isolated cells.

12. Discuss why the capillaries supplying all endocrine organs are either fenestrated capillaries or sinusoid capillaries but are never typical, continuous capillaries.

13. Ask students to explain how an adult could be a giant and have acromegaly as well.

14. It is known that students of human anatomy occasionally go out on Friday nights and drink beer with friends. Ask students how they explain to their uninformed friends the common repercussion of very frequent urination.

Clinical Questions 1. Mr. Swami made an appointment to see his doctor for pain in his loin area. Tests and x-ray exams revealed kidney stones and bones with a moth-eaten appearance throughout his skeleton. The lab technician botched the measurement of his blood calcium levels, and these are being remeasured, but the phosphate concentrations in his body fluids are very high. While waiting for the lab results, what tentative diagnosis does the doctor make?

Answer: The problem is probably hyperparathyroidism resulting from a tumor of the parathyroid gland. Hypersecretion of parathyroid hormone has probably stimulated a massive reabsorption of bone mineral (calcium and phosphate) from the skeleton, and blood calcium levels are expected to be as highly elevated as the phosphate levels. The treatment of Mr. Swami’s condition is removal of the tumorous parathyroid gland.

2. Butch, a high school wrestler who is trying to “make weight” before his wrestling match, buys diet pills off the shelf. He takes them as recommended and experiences a quick weight loss. What could cause his sudden loss of weight? (The label on the pill bottle lists a chemical known to be a strong diuretic.)

Answer: The diuretic antagonized the effect of antidiuretic hormone, causing water to be flushed from the body through excessive urination. The “weight loss” was simple water loss.

3. A woman with excessive body hair, a deep voice, and an enlarged clitoris shows the outward symptoms of which hormonal dysfunction?

Answer: The dysfunction is hypersecretion of androgens, possibly from a tumor of the adrenal cortex.

4. The parents of 14-year-old Megan are concerned about her height because she is only 4 feet tall, and they are both close to 6 feet tall. After tests by their doctor, certain hormones are prescribed for the girl. What are the probable diagnosis, hormones prescribed, and the reason why the girl might expect to reach normal height?

Answer: The diagnosis is hyposecretion of growth hormone. The prescription is commercial pituitary growth hormone. The reason the girl might reach her growth potential is that the epiphyseal plates of her bones have not yet closed, allowing additional growth of the skeleton and body in response to the hormone.

5. Paula, a 28-year-old woman, has been in the first stage of labor for 15 hours. Her uterine contractions are weak, and her labor is not progressing normally. Because Paula and her doctor desire a vaginal delivery, the physician orders that Pitocin (a synthetic oxytocin) be infused. What will the effect of this hormone be?

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Answer: Pitocin and oxytocin stimulate contraction of the smooth muscle of the myometrium, thus strengthening the uterine contractions to expel the baby.

Art Resources Figure 17.1 Figure 17.2 Figure 17.3 Figure 17.4 Figure 17.5 Figure 17.6 Figure 17.7 Figure 17.8 Figure 17.9 Figure 17.10 Figure 17.11 Figure 17.12 Figure 17.13 Figure 17.14 Table 17.1

Location of the major endocrine organs.

Three types of endocrine gland stimuli.

The pituitary gland (hypophysis).

Focus Figure: Hypothalamus and pituitary interactions.

The thyroid gland.

The parathyroid glands.

The adrenal gland, gross and microscopic structure.

Stress and the adrenal gland.

Axial CT of the brain through the diencephalon.

Photomicrograph of a pancreatic islet.

Disorders of pituitary growth hormone.

Thyroid disorders.

The effects of excess glucocorticoid.

Embryonic development of some major endocrine organs.

Pituitary Hormones: Summary of Target Organs and Effects

Teaching with Art Figure 17.4

Focus Figure: Hypothalamus and pituitary interactions.

Textbook pp. 560–561.

Checklist of Key Points in the Figure • Review examples of hormones secreted by the anterior lobe of the pituitary, mentioning why the anterior pituitary is no longer called the “master” gland.

• Stress that hormonal secretion by the anterior lobe of the pituitary is controlled from the hypophysis of the brain.

• Define and distinguish releasing hormones from inhibiting hormones.

• Explain that both releasing hormones and inhibiting hormones must travel through the hypophyseal portal system to control hormonal secretions from the anterior lobe of the pituitary.

• Compare and contrast the locations and functions of both sets of capillaries making up the hypophyseal portal system.

• Point out successive stages in which the releasing hormones signal secretion of anterior pituitary hormones.

Common Conceptual Difficulties Interpreting the Art • Distinguish functions of the anterior and posterior lobes of the pituitary.

• Explain the significance of capillary networks. ..

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• Explain the location of the median eminence.

• Identify the infundibulum.

Art Exercises 1. Provide unlabeled copies of Figure 17.4, and instruct students to label and color code arteries red, veins blue, and capillaries a third color, identifying the parts of the hypophyseal portal system.

2. Ask students to look at Figure 17.4 and list the successive steps in the pathway from the secretion of releasing hormones to anterior pituitary hormones to target organs, as can be deduced from this figure.

Critical Reasoning Ask students to study Focus Figure 17.4 again. Ask them to hypothesize why the anterior and posterior lobes of the pituitary, both of which are functionally unrelated, came to be so tightly mated together in the body, almost to the point that they appear to constitute a single organ.

What is the functional advantage of this configuration?

(Note: Before you ask this question, it is sometimes helpful to stress the different origins of both structures by pointing out that the anterior lobe of the pituitary originates in tissues that form the roof of the mouth and that the posterior lobe of the pituitary originates from brain tissue.)

Answer: The close proximity of the anterior and posterior lobes of the pituitary allows the hypophyseal portal system to be as short as possible, a situation that enables releasing hormones to travel rapidly to their target cells in the anterior lobe of the pituitary.

Supplemental Course Materials Library Research Topics 1. Research the inheritance aspect of certain endocrine disorders, such as diabetes mellitus, and certain thyroid disorders. Research the new treatments for type 1 diabetes.

2. Research the current information on the function of the diffuse neuroendocrine system (DNES) in the digestive tube and the DNES derivatives.

3. Just as some athletes abuse steroid hormones, other young athletes take growth hormone to increase their size. Investigate this illegal procedure and the effects of growth hormone on athletic performance.

4. Identify the various circadian rhythms in the body.

5. Research the roles, functions, and consequences of hormone replacement therapy (HRT).

6. Research the use of growth hormone to stimulate growth in children who are small for their age.

7. Research the ways in which taking melatonin as a nutritional supplement could help or harm natural circadian rhythms.

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Suggested Readings Gardner, David, and Dolores Shoback. Greenspan’s Basic and Clinical Endocrinology.

9th ed. McGraw-Hill Medical, 2011.

Greenstein, Ben, and Diana Wood. The Endocrine System at a Glance. 3rd ed. WileyBlackwell, 2011.

Melmed, Shlomo, and Kenneth S. Polonsky. Williams Textbook of Endocrinology. 12th ed.

Saunders, 2011.

Molina, Patricia, Endocrine Physiology. 4th ed. McGraw-Hill Medical, 2013.

Raloff, Janet. “Can Childhood Diets Lead to Diabetes?” Science News 159 (7) (February 2001): 111.

Saltiel, A. R., and C. R. Kahn. “Insulin Signaling and the Regulation of Glucose and lipid Metabolism.” Nature 414 (6865) (December 2001): 799–807.

Slight, Simon H. “Cardiovascular Steroidogenesis.” Science and Medicine 8 (1) (January/February 2002): 36–45.

Answers to Textbook Questions Answers for multiple-choice and matching questions 1–11 are located in the Answer Appendix of the textbook.

Short Answer and Essay Questions 12. (a) Pituitary: inferior to the diencephalon in the sella turcica, where the anterior lobe (pars distalis) lies anterior to the posterior lobe (pars nervosa). (p. 557) Pineal gland: roof of diencephalon. (p. 568) Thyroid gland: anterior neck. (p. 563) Parathyroid: on the posterior surface of, or embedded within, the lobes of the thyroid gland. (p. 565) Adrenal: on the superior surface of the kidney. (p. 566) (b) Pituitary: growth hormone, thyroid-stimulating hormone, adrenocorticotropic hormone, melanocyte-stimulating hormone, follicle-stimulating hormone, luteinizing hormone, antidiuretic hormone, and oxytocin. Pineal: melatonin. Thyroid gland: thyroid hormone and calcitonin. Parathyroid: parathyroid hormone. Adrenal: catecholamines, mineralocorticoids (aldosterone), glucocorticoids (e.g., cortisol), and sex hormones.

13. In a prolonged stressful situation, CRH, which is released by the hypothalamus, travels to the anterior pituitary where it stimulates the release of ACTH. Subsequently, ACTH enters the blood circulation and binds to target cells in the adrenal cortex to stimulate cortisol release. (pp. 567–568, Fig. 17.8) 14. Thyroid surgery may result in damaging the parathyroid gland located at the posterior surface of the thyroid gland. Parathyroid hormone is important as it helps to increase the blood concentration of Ca2+. If blood concentration of calcium falls, then the condition may be lethal, as maintaining a proper blood calcium level is important for neuromuscular functions, particularly signal transmission and muscle contractions. (p. 565) 15. (a) Hormones are messenger molecules that are secreted by endocrine cells and travel through the circulation to target cells elsewhere in the body. Hormones signal physiological responses in their target cells. (p. 555) (b) Renin is a hormone secreted by smooth muscle cells in the kidney, and atrial natriuretic hormone is secreted by cardiac muscle ..

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cells. (p. 569) Hormones secreted by neurons include all releasing hormones and inhibiting hormones from the hypothalamus as well as oxytocin and antidiuretic hormone. (pp. 556 and 561) 16. (a) thyroid gland. (b) pancreas. (c) anterior lobe of the pituitary. (d) anterior lobe of the pituitary. (e) pineal. (f) ovary. (g) adrenal cortex. (Fig. 17.1) 17. Students should draw lines and arrows from (a) skin (source) to liver to kidney to intestine (target). (p. 569) (b) pancreas to liver. (p. 568) (c) kidney to bone marrow. (p. 569) (d) posterior lobe of the pituitary (and hypothalamus) to breast, uterus, and all smooth musculature of the reproductive tract. (p. 560) 18. (a) anterior lobe of the pituitary. (b) posterior lobe of the pituitary (hypothalamus is also correct). (c) thyroid gland. (d) parathyroids and thymus. (e) adrenal medulla. (Fig. 17.1) 19. The pituitary gland has two basic divisions, an anterior lobe (adenohypophysis) composed of glandular tissue, and a posterior lobe (neurohypophysis) composed of neural tissue and a part of the brain. (p. 557) 20. The hormones secreted by the adrenal cortex are corticosteroids, which along with the sex hormones are the body’s major steroid hormones. Adrenal corticosteroids are of two main classes: mineralocorticoids (mostly from the zona glomerulosa) and glucocorticoids (mostly from the zona fasciculata and reticularis). A third type, the androgen hormone dehydroepiandrosterone, also known as DHEA is secreted from the zona reticularis.

Mineralocorticoids (mainly aldosterone) conserve water and sodium by increasing resorption of these substances by the kidney. Glucocorticoids (mainly cortisol) help the body cope with stress by stabilizing blood glucose levels, and in large quantities also inhibit inflammation and the immune system. DHEA is known to counteract stress, boost immunity and improve mood. (pp. 568)

Critical Reasoning and Clinical Applications Questions 1. In Clarissa’s case, the malfunctioning endocrine gland is her pancreas. Usually, people suffer from Type 1 diabetes because of an autoimmune destruction of their pancreatic beta cells, which results in little or no secretion of insulin. To control her blood glucose levels, Clarissa has to inject herself with insulin several times a day. She has to regularly and carefully manage her diet and exercise to ensure that her blood glucose levels remain stable. In the event of kidney failure because of diabetes, a pancreas transplant can be performed to halt the diabetes. In fact, a healthy kidney is transplanted to replace the patient’s failing kidneys in certain cases. (pp. 568, 572, 579) 2. George was talking about prolactinoma. This is the most common type of pituitary gland tumor, characterised by a hypersecretion of prolactin, excessive secretion of milk, and menstrual disturbances in women. In men, excess prolactin causes milk production, a loss of libido and impotence. (p. 574) 3. Dense particles of calcium in the pineal make this gland radiopaque and visible on x-ray images. (p. 568) 4. Oliver is suffering from pheochromocytoma, which is a disorder characterized by a tumor of the medullary chromaffin cells of the adrenal medulla. This results in increased production of the hormones, epinephrine and norepinephrine. The excessive secretion causes increased chronic sympathetic stimulation, leading to recurrent headaches, uncontrollable hypertension and palpitations. (p. 574) 216

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5. Obese man: People with abnormally low metabolic rates, caused by hyposecretion of thyroid hormone (hypothyroidism), use food energy slowly, gain weight easily, and may become obese. (p. 571) Dwarf and giant: Hyposecretion of growth hormone from the anterior pituitary during childhood leads to dwarfism, and a tumor that causes hypersecretion of this hormone during youth causes gigantism. (p. 570) Bearded lady: The zona reticularis cells of the adrenal cortex secrete androgens, and a tumor formed by these cells will secrete excess androgens into the blood, causing a beard to grow on a woman. (p. 568) Person with protruding eyes: Graves’ disease, characterized by an excessive secretion of thyroid hormone, causes the eyes to protrude, perhaps because of edema in the orbital tissue behind the eyes or perhaps through an effect on the extrinsic eye muscles. (p. 571) 6. Pharmaceutical companies seek to design drugs that either mimic ANP or slow the rate at which ANP is broken down in the body because ANP lowers blood pressure. Substances that mimic ANP or increase its longevity in the body might offer great clinical benefits in treating vascular hypertension (high blood pressure). Control of hypertension reduces the risks of strokes, heart failure, and aneurysms. (p. 569) 7. Melanie has steroid induced Cushing's disease (Cushing’s syndrome) characterized by truncal obesity, moon facies, hump neck and easy bruising of the skin. This condition occurs due to the excessive production of glucocorticoids either by excess secretion of ACTH from the pituitary gland or by increased ACTH secretion by ectopic tumors. Rare cases can occur from increased secretion of glucocorticoids from the adrenal cortex, or by iatrogenic abuse of steroids, as in Melanie's case. (p. 572) 8. Zona glomerulus – “glomerulus” – ball of yarn, named because of spherical clusters Zona fasciculata – “fascicle” – bundle, named because of parallel cords Zona reticularis – “reticulum” – network, named because of branching network of cells

Interpreting Medical Images Questions Answers to Interpreting Medical Images questions are provided in the Instructor Resources area of Mastering A&P. Figure 17.9: The third ventricle is located in the midline just anterior to the pineal gland, between the right and left portions of the thalamus in this axial section of the brain through the diencephalon. Anterior to the third ventricle, portions of the lateral ventricles separated by the septum pellucidum are also viewable.

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 17: The Endocrine System To the Student It’s Saturday night, and you and your friends go out and eat pizza and drink beer. During the course of the evening, a friend asks the question, “Why do I urinate more frequently after a couple of beers?” You confidently answer, “The alcohol in beer suppressed your ADH!” You are able to answer this question as well as celebrate because you understand the basics of how the endocrine system works. This chapter explores anatomical and functional relationships between the endocrine and nervous systems, explaining how both work to maintain homeostasis and coordinate physiological functions throughout your body. There are several organs that are purely endocrine in function as well as several other organs that have endocrine cells but belong to other organ systems. All these organs produce hormones that function as chemical messengers, going to specific target cells and causing specific effects.

You will also find that incorporating Practice Anatomy Lab 3.0 (PAL) (BC; DVD, Website) into your studies of the endocrine system will improve your understanding. For a good review of each of the endocrine glands, refer to the Endocrine System category within the Human Cadaver and Anatomical Models modules. Additionally, refer to the Histology module for a review of the histology of endocrine glands. You may access PAL 3.0 through the DVD or the www.myaandp.com website.

Step 1: Examine an overview of the endocrine system, describing glands and hormones. __ Define an endocrine gland in terms of its basic structure and function, listing all endocrine glands covered by your textbook. __ Define hormone. __ List several hormonally regulated processes. __ Explain similarities between the endocrine system and the nervous system. __ Describe how hormones are classified based on chemical structure. __ Explain the basics of hormonal action, defining target cells. __ Describe the mechanisms that control hormone secretion: humoral stimuli, neural stimuli, and hormonal stimuli.

Step 2: List and describe the major organs of the endocrine system, including hormones produced and hormonal effects. __ Using a chart format, list the location and structure (region/area) of the pituitary gland, including all the hormones secreted, their targets, and hormonal effects. __ Diagram a simplified feedback loop representing the endocrine interactions between the anterior lobe of the pituitary and a target endocrine gland. __ Explain how the hypothalamus controls the secretion of anterior pituitary hormones. __ Define hypophyseal portal system, explaining its significance. __ Define and distinguish releasing hormones and inhibiting hormones.

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__ Trace the path of releasing hormones through the pituitary gland. __ Describe the location and structure of the thyroid gland and the parathyroid glands, including hormones secreted, their targets, and hormonal effects. __ Describe the location and name the two divisions of the adrenal gland, explaining their structure (region/zone) and including hormones secreted, their targets, and hormonal effects. __ Describe the location and structure of the pineal gland, pancreas, thymus, and gonads, including hormones secreted, their targets, and hormonal effects.

Step 3: Describe disorders of the endocrine system, and describe changes associated with aging. __ Distinguish hyposecretion from hypersecretion of hormones, and name disorders associated with each. __ Describe diabetes mellitus. __ Describe the embryological development of major endocrine glands. __ Describe the effects of aging on some endocrine glands.

Step 4: Solve the Short/Answer and Essay Questions in the textbook for an excellent overall understanding of the endocrine system. __ Answer textbook questions 12–20, using photocopies of respective textbook diagrams.

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CHAPTER

18

Blood

Lecture and Demonstration Objectives 1. Name the basic components of blood, and define hematocrit.

2. List some of the molecules in blood plasma.

3. Describe the special structural features and functions of erythrocytes.

4. List the five classes of leukocytes, along with the structural characteristics and functions of each.

5. Describe the structure of platelets and their role in blood clotting.

6. Distinguish red bone marrow from yellow bone marrow.

7. Describe the basic histologic structures of red bone marrow.

8. Define hematopoiesis and blood stem cell.

9. Explain the differentiation of the various types of blood cells.

10. Consider some common disorders of erythrocytes, leukocytes, and platelets.

11. Describe the embryonic origin of blood cells.

12. List four different organs that form blood cells in the fetus.

13. Name some blood disorders that become more common as the body ages.

Suggested Lecture Outline I. Composition of Blood (pp. 578–585, Figs. 18.1–18.6, Table 18.1) A. The circulatory system is subdivided into the cardiovascular system and the lymphatic system.

1. Blood is the fluid in the vessels of the cardiovascular system.

2. The lymphatic system consists of vessels that return tissue fluid to blood (Chapter 21).

B. Blood is a specialized type of connective tissue consisting of formed elements suspended in plasma.

1. Functions of blood include transport of respiratory gases and nutrients, transport of hormones, and conveying leukocytes to sites where they fight infection.

2. Blood also helps regulate body temperature.

C. Blood makes up about 8% of body mass and is comprised of cellular and liquid components.

D. Hematocrit (or packed cell volume) is the percentage of blood composed of erythrocytes.

Average hematocrit is about 45% but varies with gender.

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E. The buffy coat is the percentage of centrifuged blood consisting of leukocytes.

1. Blood Plasma (pp. 579–580, Fig. 18.1) a. Blood plasma is about 90% water but contains respiratory gases, salts, hormones, and plasma proteins. Three important plasma proteins are albumin, globulins, and fibrinogen.

2. Formed Elements (pp. 580–585, Figs. 18.2–18.6, Table 18.1) a. Formed elements in blood include erythrocytes, leukocytes, and platelets. i. Erythrocytes measure about 7.5 µm and are the most numerous formed element.

Erythrocytes lack nuclei and organelles and are packed with the oxygen-carrying protein, hemoglobin. ii. Leukocytes are far less numerous than erythrocytes; white blood cells (WBCs) are crucial to the body’s defenses against diseases caused by bacteria, viruses, and parasites. iii. There are five types of leukocytes, which are divided into two groups (granulocytes and agranulocytes) based on the presence or absence of granules in the cytoplasm. iv. The five types of leukocytes, in order of relative percentages, are neutrophils, lymphocytes, monocytes, eosinophils, and basophils.

3. Platelets are cell fragments that break off from cells called megakaryocytes; platelets participate in the initial stages of blood clotting.

II. Blood Cell Formation (pp. 585–588, Figs. 18.7, 18.8) A. The process of blood cell formation begins in the embryo and continues throughout life; the process is called hematopoiesis or hemopoiesis.

1. Bone Marrow as the Site of Hematopoiesis (pp. 585–586, Fig. 18.7) a. Bone marrow, collectively the body’s second largest organ, is the site of hematopoiesis; there are two types of bone marrow: red and yellow. i. Red bone marrow actively generates red blood cells. ii. Yellow bone marrow is dormant and its color reflects the high content of fat cells.

B. Cell Lines in Blood Cell Formation (pp. 586–588, Fig. 18.8) 1. All blood cells continuously arise from blood stem cells; two types of progenitor cells arise directly from blood stem cells: lymphoid stem cells, which give rise to lymphocytes, and myeloid stem cells, which give rise to all other blood cells.

2. The genesis of erythrocytes begins with proerythroblasts and continues through various stages, during which hemoglobin accumulates and the nucleus and organelles are extruded.

3. Granular leukocytes begin as myeloblasts; monocytes and lymphocytes resemble stem cells with minimal structural changes.

III. Disorders of the Blood (pp. 588–589, Fig. 18.9) A. Disorders of Erythrocytes (pp. 588–589, Fig. 18.9) 1. Polycythemia, anemia, and sickle cell diseases are all disorders of erythrocytes.

B. Disorders of Leukocytes (p. 589)

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1. Leukemia is a form of cancer resulting from the uncontrolled proliferation of a leukocyte-forming cell line in the bone marrow.

C. Disorders of Platelets (p. 589) 1. Thrombocytopenia is an abnormally low concentration of platelets in the blood.

V. The Blood Throughout Life (pp. 589–591) A. In the embryo, blood stem cells develop in blood islands of the yolk sac during week 3; embryonic hematopoietic organs are the liver, spleen, and bone marrow.

B. The most common blood disorders that appear with aging are chronic leukemias, anemias, and clotting disorders.

Lecture Hints 1. Students often confuse the circulatory system and the cardiovascular system. Clearly describe and distinguish these terms.

2. Explain that the blood inside the blood vessels, together with interstitial fluid within the tissues and lymph contained in lymph vessels, constitute the internal environment of the body.

3. Remind students that blood is a specialized connective tissue with a fluid matrix (plasma).

4. Present a very brief overview of blood circulation: heart, arteries, veins, and capillaries.

5. Cite the mnemonic “Never Let Monkeys Eat Bananas” to aid students in learning the names and the relative percentages of leukocytes.

6. Emphasize that the hematocrit is an indirect measurement of the O2-carrying capacity of the blood. More red blood cells mean more O2 carried by the same volume of blood.

7. As a point of interest, mention that well-oxygenated blood is bright red; normal deoxygenated blood (at the tissue level) is dark red; and that under hypoxic conditions, hemoglobin becomes blue.

8. Spend some time with the feedback loop involved in erythropoiesis. This is a typical negative-feedback mechanism that allows the application of critical thought processes.

9. Mention that serum is essentially plasma without clotting proteins.

10. Explain why an incompatible ABO blood group will generate a transfusion reaction the first time a transfusion is given, whereas Rh incompatibility creates a problem the second time a transfusion is given.

Classroom Discussion Topics and Activities 1. Use photomicrographs from PAL 3.0 and other sources to exhibit blood cells.

2. a.

It is possible to have the students make their own blood smears and do WBC counts on their own blood. Strictly enforce safety procedures for proper care and handling of blood and lab materials if you attempt this in class. All that is needed are glass slides, cover-slips, a bottle of blood stain, methyl alcohol, microscopes, and sterile needles to prick fingertips. Closely follow safety guidelines for handling and disposing of blood and lab materials. Autoclaving is necessary to ensure sterility.

b. Provide blood-typing sera for typing students’ blood. Strictly follow safety guidelines.

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c.

Collect student data about WBC counts and blood types and compare data to expected frequencies.

3. Demonstrate a sample of centrifuged animal blood so students can examine the consistency, texture, and color of plasma. Use pH paper to determine the blood’s acidity or alkalinity. This is an excellent lead-in to a discussion about the composition and importance of plasma.

4. Use a magnet and iron filings to model the attraction between antibodies and antigens.

5. Use a lock and several keys (only one of which fits the lock) to demonstrate the specificity of antigens and antibodies.

6. Discuss the fears and facts associated with blood donation, blood transfusions, and AIDS. 7. Discuss the problems associated with injecting illegal drugs intravenously. What diseases are commonly spread in this manner?

8. Discuss the procedure of autologous transfusion.

9. Students are interested in discussion of anemias, leukemias, and hemophilia. Explain how classification schemes are used in the naming of anemias and leukemias.

10. Discuss the specific uses of donated blood, for example, for packed red cells, platelets, and serum.

11. Discuss blood groups. Explain the many varieties, the role of antigens and antibodies, donor and recipient compatibilities and incompatibilities, the genetics of ABO and Rh inheritance, and the importance of blood analysis in forensics or inheritance disputes.

12. Levels of cholesterol, triglycerides, and fatty acids in the blood are important indicators of possible heart attack or stroke. Ask students to explain the connection of these indicators to health problems.

Clinical Questions 1. A complete blood count and a differential WBC count have been ordered for Mrs. Ulevich. What information is obtained from the differential count that the total count cannot provide?

Answer: The differential count determines the relative proportions of the individual types of leukocytes (a valuable diagnostic tool). For example, elevated neutrophils indicate bacterial infections, and elevated eosinophils may indicate the patient is suffering from an allergy or parasitic worms. The complete blood count will reveal only the total number of leukocytes, which will allow one to recognize only that there is a systemic infection—without revealing any specifics about the type of infection.

2. List three blood tests that might be ordered if anemia is suspected, and one test that would be performed if infectious mononucleosis were suspected.

Answer: The tests for anemia are hematocrit, complete blood count, and microscopic study of the erythrocytes. A test for infectious mononucleosis is a differential WBC count (in which large lymphocytes that resemble monocytes are sought).

3. A bone marrow biopsy is ordered for two patients—one a small child and the other an adult. The specimen is taken from the tibia of the child but from the iliac bone of the adult. Explain why different sites are used for marrow samples in children versus adults.

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Answer: In adults, red marrow—the marrow that actively produces blood cells—occurs chiefly in the bones of the axial skeleton and limb girdles (e.g., iliac bone), but not in the tibia. In children, red marrow occurs throughout the skeleton.

4. A man of Greek ancestry goes to his doctor and tells the physician that he is very tired all the time and has difficulty catching his breath after even mild exercise. His doctor orders the following tests: complete blood count, hematocrit, and differential WBC count. The tests show small, pale, immature erythrocytes; fragile erythrocytes; and around 2 million erythrocytes per cubic millimeter. What is the tentative diagnosis?

Answer: The diagnosis is thalassemia. It can be treated with a blood transfusion.

Art Resources Figure 18.1 Figure 18.2 Figure 18.3 Figure 18.4 Figure 18.5 Figure 18.6 Figure 18.7 Figure 18.8 Figure 18.9 Table 18.1 A Closer Look

Major components of whole blood.

Blood cells.

Structure of erythrocytes.

Leukocytes.

Relative percentages of the different types of leukocytes.

Blood clot.

Red bone marrow.

Stages of differentiation of blood cells in the bone marrow.

Comparison of a normal erythrocyte with a sickled erythrocyte.

Summary of Formed Elements of the Blood Transplants of Bone Marrow and Cord Blood

Teaching with Art Figure 18.4

Leukocytes.

Textbook p. 582.

Checklist of Key Points in the Figure • Explain the pathway of how a blood stem cell gives rise to all blood cell types.

• Explain the differentiation of lymphoid stem cells into B or T lymphocytes.

• Explain that all other blood cells, including erythrocytes, derive from myeloid stem cells.

• Explain the life span and duration of development of each type of leukocyte.

• Describe the structural features and size of each type of WBC. • Describe the relative abundance of each type of WBC in the body.

• Discuss the role each granulocyte and agranulocyte plays in the body.

• Give examples of illnesses that cause an increase or decrease in the number of each WBC type.

Art Exercises 1. Provide students with unlabeled color copies of Figure 18.4, and ask them to label each type of leukocyte.

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2. Ask students to use the figure to discern granulocytes from agranulocytes, to learn the specific function of each WBC, and to understand the clinical relevance of normal ranges for each type of WBC. Critical Reasoning 1. Ask the students to describe the location of action of each type of leukocyte.

Answer: All leukocytes function outside the bloodstream. Neutrophils migrate to a site of infection; lymphocytes function in lymphoid connective tissues, monocytes transform into macrophages in connective tissues; eosinophils attach to parasites and also release histamines; basophils direct later stages of parasitic infections.

2. How are the functional roles of B lymphocytes different from T lymphocytes?

Answer: T lymphocytes attack directly, whereas B lymphocytes mark bacterial cells for destruction by macrophages. (See Chapter 21 for more details.)

Supplemental Course Materials Library Research Topics 1. Research the blood disorders associated with the use of intravenous street drugs.

2. Research information about clinical uses of recombinant erythropoietin, colonystimulating factors, and tissue plasminogen activator.

3. How close is medical science to developing an effective blood substitute (artificial blood)?

4. Research the history of blood transfusions from the 1960s to the present.

5. Is allergy related to our body’s ability to fight parasitic worms?

6. Research the effects of sickle cell disease as well as the revolutionary drug for its treatment, hydroxyurea.

Suggested Readings Bain, B. Blood Cells: A Practical Guide. 4th ed. Wiley-Blackwell, 2006.

Cormack, D. H. Essential Histology. 2nd ed. Philadelphia: Lippincott Williams & Wilkins, 2001.

Gartner, L. P. Color Textbook of Histology. 3rd ed. Philadelphia: Saunders, 2006.

Gulati, G. Blood Cells: An Atlas of Morphology with Clinical Relevance. 1st ed. American Society for Clinical Pathology Hillman, R., K, Ault, and M. Leporrier. Hematology in Clinical Practice. 5th ed. McGrawHill Professional, 2010.

Junqueira, L. C., et al. Basic Histology. 12th ed. New York: McGraw-Hill Medical, 2009.

Kottke-Marchant, K., and B. Davis. Laboratory Hematology Practice. 1st ed. WileyBlackwell, 2012.

Lee, G. R., et al. Wintrobe’s Clinical Hematology. 12th ed. Baltimore: Lippincott Williams & Wilkins, 2008.

McKenzie, S. B. Clinical Laboratory Hematology. 2nd ed. Prentice Hall, 2009.

Rodak, B. F. Clinical Hematology Atlas. 4th ed. Saunders, 2012. ..

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Answers to Textbook Questions Answers to multiple-choice and matching questions 1–7 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 8. The percentage of the blood volume that consists of erythrocytes is known as the hematocrit. Normal hematocrit values vary but average around 45%. A decrease in hematocrit may be a sign of anemia, while an increase may be a sign of dehydration. (p. 579) 9. (a) The functional difference between red bone marrow and yellow bone marrow is that red marrow is actively producing blood cells, whereas yellow marrow is dormant. (b) Yellow marrow occupies the medullary cavity in the diaphysis of long bones of the adult limbs. (p. 585) 10. (a) Proerythroblasts accumulate iron and give rise to erythroblasts, then orthochromatic erythroblasts, stages in which hemoglobin is accumulating. Then the nucleus and organelles are ejected, and the reticulocyte stage is reached. (b) Reticulocytes are released into the circulation. (pp. 587–588) 11. A Thrombus is a blood clot that develops and persists within an intact blood vessel.

When a thrombus or a piece of a thrombus breaks off from a blood vessel’s wall and freely floats in the bloodstream, it is considered an embolism. However, in addition to blood clots, emboli can originate from air bubbles, fat masses, clumps of cells, or pieces of tissue, all of which are abnormal masses in the bloodstream. (pp. 585, 591) 12. Blood stem cells and committed cell types are both structurally undifferentiated cell types that appear almost identical. They differ functionally, however, in that the stem cell can produce any type of blood cell, whereas a committed cell can give rise to only one kind of blood cell (e.g., eosinophil, neutrophil, erythrocyte, basophil, or monocyte). (p. 587, Fig. 18.8) 13. The cytoplasm of megakaryocytes fragments to produce platelets. (p. 588) 14. The granulocytes Tina was seeing actually have single nuclei, but each nucleus has several lobes. Sometimes the connections between these lobes are not evident in blood smears, so a granulocyte may appear to have two nuclei. (pp. 582–584, Table 18.1) 15. (a) The circulatory system is composed of the cardiovascular system and the lymphatic system, which includes both lymphatic and blood circulatory components. The cardiovascular system is a subdivision of the circulatory system and is composed of the blood, heart, and blood vessels. Thus, the circulatory system and cardiovascular system are not exactly the same (p. 578). (b) The differential WBC count is just a part of a complete blood count. In a complete blood count, a sample of blood is taken, and the hematocrit, hemoglobin content, and overall concentrations of red and white cells and platelets are measured; a differential WBC count follows, in which the percentages of the different classes of leukocytes are counted on a blood smear. (p. 584) 16. Thrombocytes are platelets. They are not cells but disc-shaped plasma membrane, i.e., enclosed fragments of cytoplasm that form by breaking off from larger cells called megakaryocytes in the bone marrow. (p. 585)

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17. Yes. Although both lymphocytes and monocytes are agranular, lymphocytes are smaller in diameter (5–17 μm) than monocytes (14–24 μm). Moreover, lymphocytes have a spherical or indented nucleus and pale blue cytoplasm. Monocytes on the other hand, have a U- or kidney shaped nucleus and grey-blue cytoplasm. (pp. 583–584) 18. An eosinophil is a white blood cell that contains larger, pink-staining granules in contrast to the purple-staining granules of the basophil. Eosinophils have a two-lobed nucleus shaped like a barbell, whereas the basophil nucleus is U- or S-shaped. Basophils mediate the late stages of allergic inflammation, whereas eosinophils stop this allergic response (among other functions). (pp. 583–584) 19. Typically, graft-versus-host disease affects the recipients of hematopoietic cell transplants. In this condition, the transplanted cells attack the recipient’s tissues as these cells are the immune system’s cells. (See A Closer Look on p. 590) 20. Globulins include antibodies and blood proteins that transport lipids, iron, and copper.

Albumin helps keep water from diffusing out of the bloodstream into the extracellular matrix of tissues. Fibrinogen is one of the several proteins involved in a series of chemical reactions that achieve blood clotting. (p. 579) 21. Serum is plasma with all the clotting factors removed. (p. 579) 22. (a) They stain red or pink because they are basic and eosin binds to them. (b) They stain purple or black because they are acidic and hematoxylin binds to them.

Critical Reasoning and Clinical Applications Questions 1. Janie’s cancerous leukocytes are immature or abnormal and are incapable of defending against infection in the usual way. Furthermore, the nonfunctional cancer cells become so abundant in the bone marrow that they crowd out the healthy lines of leukocyte-forming cells. (p. 589) 2. Band cells are immature neutrophils that are produced in the bone marrow. During infection, there is an increased release of immature neutrophils in the blood. Renzo's peripheral smear shows increased band cells because he is suffering from infection, most probably of bacterial origin, since neutrophils are the main innate immune cells active in bacterial infection. (p. 588) 3. Blood eosinophil levels increase when one has parasitic worms, and the daughters’ eosinophil counts were about 10 times greater than normal. The daughters must have gotten tapeworms from the dog, which picked up the worms from infected sheep. (pp. 583–584) 4. Sickle cell disease (formerly sickle cell anemia) is a common inherited condition exhibited primarily in people of Central African descent. It is caused by a genetic mutation in the hemoglobin of red blood cells, causing them to crystallize during hypoxia or dehydration. The red blood cells assume a sickled phenotype, are more fragile and prone to damage. Sickled red blood cells fail to pass through capillaries and induce painful ischemic attacks. (p. 589–589) 5. Marco’s erythrocytes are not producing one of the four polypeptide chains of hemoglobin. Because hemoglobin is essential for transporting oxygen in blood, he will need blood replacements (containing normal hemoglobin) for the rest of his life. (p. 581)

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6. High numbers of neutrophils may indicate the presence of a major bacterial infection in the child’s body. (p. 582–583) 7. Anemia – “an” – without, “emia” – blood, red blood cells (erythrocytes) Thrombocytopenia – “thrombo” – clot, platelets Leukemia – “leuko” – white, white blood cells (leukocytes) Lymphoma – “lymph” – water, lymphocytes

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 18: Blood To the Student Blood is the fluid of the cardiovascular system and plays many vital interactive roles within the body, including delivery of oxygen and nutrients, removal of carbon dioxide and other waste products, and transport of plasma proteins. Blood interacts with the respiratory system in delivering oxygen to cells and removing waste from tissues of the body. Nutritive interactions result in the transport of food molecules from the small intestine to the liver and, ultimately, to the cells of the body. Blood carries metabolic wastes and excess water to the kidneys, resulting in urine production and excretory interaction. Regulatory interaction involves the transport of hormones from the site of production to target tissues. Other functions involve the regulation of body heat and protection against foreign invaders, such as microbes and toxins. Blood is essential for survival, and any region of the body deprived of blood dies in minutes. Obviously, it is important for you to understand the nature of blood because with every succeeding topic you study in anatomy, blood is featured and is a focal point in some way.

You will also find that incorporating Practice Anatomy Lab 3.0 (PAL) (BC; DVD, Website) into your studies of blood will help you differentiate the five types of leukocytes.

For an excellent review of leukocytes and erythrocytes, refer to photomicrographs 10–21 in the Cardiovascular System tab of the Histology module. You may access PAL 3.0 through the DVD or the www.myaandp.com website.

Step 1: Distinguish the circulatory system from the cardiovascular system. __ Define circulatory system, including functions of blood. __ Define cardiovascular system. __ Define lymphatic system.

Step 2: Describe the composition of blood, including functions of its components. __ Define and describe plasma. __ Distinguish plasma from serum. __ Define hematocrit. __ List the formed elements of blood. __ Describe the structure, function, and life span of erythrocytes. __ Summarize the role of hemoglobin in the blood. __ Discuss the function of leukocytes. __ Distinguish granulocytes from agranulocytes, listing examples of each. __ Describe similarities and differences between lymphocytes and monocytes. __ Distinguish antigen from antibody. __ Distinguish T cells from B cells, describing how they attack cells. __ Define apoptosis.

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__ Define and describe macrophage and phagocytosis. __ Define platelet, and describe its functions. __ Distinguish thrombus from embolus.

Step 3: Explain blood cell formation. __ Define hematopoiesis, and describe bone marrow as a site of blood cell formation. __ Distinguish yellow bone marrow from red bone marrow, both structurally and functionally. __ Define blood stem cell. __ Describe the formation of red blood cells. __ Describe the formation of white blood cells and platelets.

Step 4: Describe common blood disorders and embryological development of blood. __ Name and describe symptoms of blood disorders, such as anemia, polycythemia, sickle-cell disease, and leukemia. __ Name four hematopoietic organs in the fetus.

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The Heart

Lecture and Demonstration Objectives 1. Describe the orientation, location, and surface anatomy of the heart in the thorax.

2. Describe the layers of the pericardium and the tissue layers of the heart wall.

3. List the important structural features of each heart chamber: right and left atria, and right and left ventricles.

4. Name the heart valves, and describe their locations and functions. Indicate where on the chest wall each of the valves is heard.

5. Describe the cardiac skeleton, and explain its functions.

6. Describe the path of a drop of blood through the four chambers of the heart and the systemic and pulmonary circuits.

7. Describe the structure of cardiac muscle tissue.

8. Describe the structure of intercalated discs, and discuss their importance in the contraction of cardiac muscle.

9. Name the components of the conducting system of the heart, and describe the conduction pathway.

10. Describe the locations of the coronary arteries and cardiac veins on the heart surface.

11. Define coronary artery disease, heart failure, and atrial and ventricular fibrillation.

12. Explain how the heart develops, and describe some congenital heart defects.

13. List some effects of aging on the heart.

Suggested Lecture Outline I. Location and Orientation Within the Thorax (pp. 594–596, Figs. 19.1, 19.2) A. The heart is a double pump; the right side pumps blood to the lungs for oxygenation (i.e., the pulmonary circuit); the left side pumps blood throughout the body to nourish tissues (i.e., the systemic circuit).

B. The four chambers are the right and left atria (receiving chambers) and the right and left ventricles (pumping chambers).

C. The cone-shaped heart lies obliquely in the mediastinum; it is the size of a fist, it weighs approximately 250–350 grams, its apex points toward the left hip, and the broad posterior base is directed toward the left shoulder.

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II. Structure of the Heart (pp. 597–603, Figs. 19.3–19.5) A. Coverings (p. 597, Fig. 19.3) 1. The pericardium is a three-layered sac enclosing the heart. a. The fibrous pericardium is made up of dense connective tissue and acts as a protective outer layer that holds the heart in place and prevents its overfilling with blood. b. The serous pericardium lies deep to the fibrous pericardium and is composed of two layers: the parietal layer of serous pericardium, which adheres to the inner layer of the fibrous pericardium, and the visceral layer of serous pericardium (epicardium). c. The pericardial cavity is the slit-like space between the parietal and visceral layers of the serous pericardium.

2. Layers of the Heart Wall (pp. 597–598, Fig. 19.4) a. The wall of the heart is composed of three distinct layers: a superficial epicardium (same as the visceral layer of the serous pericardium), the middle myocardium (composed of cardiac muscle tissue), and the deep endocardium (lining of the heart composed of endothelium and a thin layer of connective tissue).

3. Heart Chambers (pp. 598–603, Fig. 19.5) a. The heart has four chambers: the right and left atria, and the right and left ventricles. Each chamber has special identifying structures. i. The right atrium receives blood from the systemic circuit through the superior and inferior vena cava and receives blood from the heart through the coronary sinus. ii. The left atrium receives blood from the lungs through the pulmonary veins. iii. The right ventricle pumps blood into the pulmonary circuit to the lungs. iv. The left ventricle pumps blood into the systemic circuit via the aorta.

III. Heart Valves (pp. 603–605, Figs. 19.6–19.9) A. Valve Structure (p. 603, Figs. 19.5, 19.6) 1. Each of the four heart valves is composed of endocardium reinforced with a core of connective tissue. a. The atrioventricular (AV) valves are located at the junctions of the atria and ventricles. The right AV valve is the tricuspid valve, and the left AV valve is the bicuspid (mitral) valve. b. The aortic semilunar valve and pulmonary semilunar valve are located at the junctions of the ventricles and the great arteries of the heart.

2. The cardiac skeleton lies between the atria and ventricles and surrounds each of the four heart valves. Functions of the cardiac skeleton include anchoring the valve cusps, preventing overdilation of valve openings, serving as the points of attachment for cardiac muscle, and blocking the direct spread of electrical impulses from the atria to the ventricles.

B. Valve Function (p. 603, Figs. 19.7, 19.8) 1. Heart valves open to allow blood to flow and close to prevent backflow in response to differences in blood pressure on each side of the valves.

C. Heart Sounds (pp. 603–605, Fig. 19.9) 1. Heart sounds (the familiar “lub-dup”) are produced by the closing of the valves.

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IV. Pathway of Blood Through the Heart (pp. 605–607, Figs. 19.10, 19.11) A. The pathway of blood through the heart begins with a drop of oxygen-poor systemic blood arriving at the right atrium and terminates with an oxygen-rich drop of blood leaving the left ventricle.

B. A sequence of atrial contractions and ventricular contractions (called a heartbeat) propels blood through the heart.

C. The muscular walls of the right and left ventricles reflect differential pressures in the pulmonary and systemic circuits.

V. Cardiac Muscle Tissue (pp. 607–609, Figs. 19.12, 19.13) A. Structure of Cardiac Muscle (pp. 607–608, Figs. 19.12, 19.13) 1. Cardiac muscle tissue forms the myocardium of the heart wall.

2. Cardiac muscle cells are short, branching cells with one or two centrally located nuclei.

3. Intercalated discs are complex cell junctions joining cardiac muscle cells.

B. Mechanism of Contraction (pp. 608–609) 1. Cardiac muscle cells are triggered to contract by ionic calcium.

VI. Conducting System and Innervation (pp. 609–611, Figs. 19.14, 19.15) A. Conducting System (pp. 609–610, Fig. 19.14) 1. Heart muscle generates and conducts electrical impulses; the intrinsic production of impulses can be altered by extrinsic neural controls.

2. The conducting system of the heart is a series of specialized cardiac muscle cells that carries impulses throughout the heart; among the several components are the sinoatrial (SA) node and the AV node.

B. Innervation (pp. 610–611, Fig. 19.15) 1. Innervation to the heart is served by visceral sensory fibers, parasympathetic fibers, and sympathetic fibers; parasympathetic fibers slow the heart rate, and sympathetic fibers increase the heart rate.

VII. Blood Supply to the Heart (pp. 611–612, Fig. 19.16) A. Coronary Arteries (pp. 611–612, Fig. 19.16) 1. Coronary arteries supply oxygenated blood to the heart muscle.

B. Cardiac Veins (p. 612, Fig. 19.16) 1. Cardiac veins drain the deoxygenated blood from the heart.

VIII. Disorders of the Heart (pp. 612–614) A. Coronary Artery Disease (p. 612) 1. Coronary artery disease is caused by atherosclerotic blockage of the coronary arteries.

B. Heart Failure (pp. 612–614) 1. Heart failure is a progressive weakening of the heart as it fails to keep pace with the demands of pumping blood and thus cannot meet the body’s need for oxygenated blood.

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C. Disorders of the Conduction System (p. 614) 1. Disorders of the conduction system include atrial and ventricular fibrillation.

IX. The Heart Throughout Life (pp. 614–616, Figs. 19.17, 19.18) A. Development of the Heart (pp. 614–615, Figs. 19.17, 19.18) 1. The embryonic heart starts pumping around day 22, and four chambers are apparent; four final chambers are defined during month 2.

2. Congenital heart defects mostly are traced to month 2 of development.

B. The Heart in Adulthood and Old Age (pp. 615–616) 1. Age-related changes that affect the heart are the hardening and thickening of the cusps of the heart valves and fibrosis of cardiac muscle.

Lecture Hints 1. Emphasize the two-pump concept and that arteries carry blood away from the heart, whereas veins carry blood toward the heart. You could state: “Arteries ALWAYS Away.”

2. When discussing heart orientation, explain that the base of the heart is directed toward the right shoulder, and the apex points toward the left hip.

3. Consider the structural similarities of a blood vessel wall to the walls of the heart, relating the heart-wall layers to the tunics (layers) of a blood vessel. Expressly state that cardiac muscle tissue forms the muscular walls of the heart and that smooth muscle tissue forms the muscular walls of blood vessels.

4. Emphasize the importance of thoroughly understanding the pathway a drop of blood travels through the heart. Stress that the only function of the heart valves is to ensure one-way conduction of the blood.

5. Point out that the visceral layer of the pericardium (epicardium) is the same as the outermost layer of the heart wall and is composed of simple squamous epithelial tissue.

6. Display Figure 19.3 to show both the pericardium and the heart wall so that students get an overall perspective of construction.

7. Clearly distinguish that atria and auricles are different structures: The atria are the upper chambers of the heart, whereas the auricles are a part of the atria.

8. Point out that blood flows through the right and left side of the heart simultaneously and that the direction of flow in both sides progresses from atrium to ventricle, with both sides of the heart pumping the same volume of blood.

9. Describe the construction differences between the atrioventricular valves and the semilunar valves, and explain why the construction of each type of valve works best in its location. Stress that the valves are not rigid structures but flexible flaps of endocardium reinforced with dense connective tissue.

10. Describe the mechanisms by which cardiac muscle cells function.

11. Emphasize that the pacemaker cells are cardiac muscle cells, just modified so that they spontaneously depolarize.

12. Clearly distinguish the basic rate set by the conduction system of the heart from the acceleratory or inhibitory controls (sympathetic and parasympathetic) set by the medulla.

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13. Stress the relationship between pressure changes in the heart chambers and the flow of blood through the heart. The concepts of pressure gradients and flow are often new to students.

14. Note that although the ventricles have both a passive and an active phase to filling, the atria only fill passively.

15. Relate the heart sounds to specific points in the discussion of the cardiac cycle so that students integrate these ideas.

16. Explain that most blood volume bypasses the fetal lungs. Discuss the importance of this, highlighting the roles of the foramen ovale and ductus arteriosus as shunts away from pulmonary circulation. Explain the significance of the closure of these structures after birth.

17. Explain that coronary arteries are actively delivering blood to the myocardium when the heart is relaxed; when the ventricles are contracting, the coronary arteries are compressed and ineffective.

18. Tell students there are several synonyms in heart terminology; prepare a list of terms and their synonyms to help alleviate student confusion.

Classroom Discussion Topics and Activities 1. Use a model of a human torso to show the position of the heart in the chest cavity.

2. Use a model of a human heart to show the structures of the heart.

3. Demonstrate a dissected fresh cow or sheep heart obtained from a butcher to show the gross anatomy of the heart. Students (or family and friends) who hunt deer are an additional potential source for a fresh heart. Tell students who wish to bring a deer or bovine heart to class that they must freeze the heart before bringing it to you; thaw later for demonstration. This is an excellent way to demonstrate the thin and delicate nature of valves and other gross anatomical features.

4. To show that the long axis of the human heart is not located simply in the midsagittal plane of the body like the heart of other animals, do the following demonstration: Orient a sharpened pencil vertically in front of you with the point down, then rotate the point 45 degrees (halfway) anteriorly and 45 degrees (halfway) to the left. The point represents the heart’s apex, and you will have angled the heart into its proper position. If your class is in a large lecture hall, a pencil may be too small to use as a demonstration tool. In a large lecture hall, you could use an empty paper towel roll to which you have taped a small piece of paper curved into a cone.

5. Show a DVD or YouTube clip of a beating heart, ideally with heart sounds. Stress that although the right side of the heart is a pulmonary pump and the left side is a systemic pump, both atria contract at the same time and both ventricles contract at the same time.

6. Although the left side of the heart generates more pressure than the right side, approximately the same volume of blood is ejected from each side per beat. Ask students to think about what would happen if this were not the case. Follow up with a discussion of congestive heart failure.

7. Provide stethoscopes and instruct students to identify the first and second “lub-dup” heart sounds produced by the individual valves. Define auscultation.

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8. Discuss the significance of the heart’s pacemaker, including the use and roles of artificial pacemakers.

9. Discuss the steps in recovery from a heart attack.

10. Discuss the role of cardiac muscle in ejecting blood from the ventricles as opposed to ejecting blood from the atria.

11. Explore the topic of heart transplants, and ask students why transplanted hearts are not often reinnervated.

Clinical Questions 1. Eleanor, an older woman, complains of shortness of breath and intermittent fainting spells. Her doctor runs various tests and finds that her AV node is not functioning properly. What is the suggested treatment?

Answer: The suggested treatment is surgery to implant an artificial pacemaker.

2. Linda, a 14-year-old girl undergoing a physical examination before being admitted to summer camp, was found to have a loud heart murmur at the second intercostal space on the left side of the sternum. The murmur creates a swishing sound with no high-pitched whistle. What, exactly, is producing the murmur?

Answer: Incompetence (not stenosis) of the pulmonary semilunar valve. Incompetent valves produce swishing sounds, and the pulmonary semilunar valve is heard at the superior left corner of the heart, as indicated in this question.

3. A 48-year-old man enters the hospital complaining of chest pain. His history includes chain smoking, a high-stress job, a diet heavy in saturated fats, lack of exercise, and high blood pressure. Although he is not suffering from a heart attack, his doctor explains to him that a heart attack is quite possible. What did the chest pain indicate? Why is the man a prime candidate for a heart attack? (Note: It might be best to have the students read A Closer Look in the next chapter of the textbook, p. 651, before answering this question.)

Answer: His symptoms indicate angina pectoris, a transient ischemia attack from severe narrowing (or spasms) of his coronary arteries. A narrowed coronary artery is likely to become fully occluded, causing the heart muscle to die from oxygen deprivation a fullblown heart attack.

Art Resources Figure 19.1 Figure 19.2 Figure 19.3 Figure 19.4 Figure 19.5 Figure 19.6 Figure 19.7 Figure 19.8 Figure 19.9 236

The heart as a double pump.

Location of the heart in the thorax.

The layers of the pericardium and of the heart wall.

The circular and spiral arrangement of cardiac muscle bundles in the myocardium of the heart.

Gross anatomy of the heart.

Heart valves.

Function of the atrioventricular valves.

Function of the semilunar valves.

Areas on the thoracic surface where heart sounds are heard most clearly.

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Figure 19.10 Figure 19.11 Figure 19.12 Figure 19.13 Figure 19.14 Figure 19.15 Figure 19.16 Figure 19.17 Figure 19.18 A Closer Look

Focus Figure: Blood flow through the heart.

Anatomical differences between the right and left ventricles.

Microscopic anatomy of cardiac muscle.

Electron micrograph of a portion of a cardiac muscle cell.

The intrinsic conducting system of the heart.

Autonomic innervation of the heart.

Coronary circulation.

Heart development.

Congenital heart defects.

Coronary Artery Disease

Teaching with Art Figure 19.5

Gross anatomy of the heart. In diagrammatic views, vessels carrying oxygen-rich blood are red; those carrying oxygen-poor blood are blue. (a) Photograph of the anterior aspect (pericardium removed). (b) Anterior view (see A Brief Atlas of the Human Body, Figure 47). (c) Anterior view of the internal aspect of the right atrium. The anterior wall of the atrium has been opened and reflected superiorly. (d) Inferior view; the surface shown rests on the diaphragm (posterior aspect is at the top of this figure; see A Brief Atlas of the Human Body, Figure 49).

Textbook pp. 599–601.

Checklist of Key Points in the Figure • Describe the surface anatomy of the heart.

• Distinguish atria from ventricles.

• Indicate the important structural features of each chamber.

• Point out that the view in part (e) is a frontal section specially cut to show the valves as well as the chambers.

• Identify the valves.

• Identify the great vessels associated with the heart.

• Identify the layers of the heart wall.

Common Conceptual Difficulties Interpreting the Art • Explain that the pericardial sac surrounding the heart has been removed.

• Clarify the difference between atrium and auricle.

• Stress that an artery carries blood away from the heart and veins carry blood toward the heart.

• Explain that it is a visual convention to depict red-colored vessels carrying oxygen-rich blood and blue-colored vessels carrying oxygen-poor blood.

• Distinguish the pulmonary circulation from the systemic circulation. (Show Figure 19.1 to reinforce the distinction.)

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Art Exercises 1. Provide unlabeled copies of the (e) part of Figure 19.5. Instruct students to draw a representation of systemic and pulmonary circulation, including the flow of blood through the heart as well as labels of chambers, valves, and great vessels. Ask students to color oxygen-rich vessels red and oxygen-poor vessels blue.

2. Instruct students to sketch the adult heart and associated vessels. Referring to Figure 19.17, Heart development, in their textbook, color and label the adult regions derived from each embryonic heart chamber: (a) sinus venosus, (b) embryonic atrium, (c) embryonic ventricle, and (d) bulbus cordis.

Note: An additional exercise involving the conduction system also is suggested.

Critical Reasoning Instruct students to look at the atrioventricular valves in part (e) of Figure 19.5, and ask them to explain the role of the AV valves when the ventricles contract (ventricular systole). After explaining the one-way flow of blood, ask the question, What is the exact role of the papillary muscles during contraction of the ventricles?

Answer: Papillary muscles contract along with the rest of the ventricle, pulling the chordae tendineae and anchoring the valve to prevent eversion of the AV valves into the atria. Papillary muscles do not act to open AV valves.

Supplemental Course Materials Library Research Topics 1. Research the alternatives to coronary bypass operations. (This also applies to material covered in Chapter 20 of the textbook, p. 651.)

2. Research the effects of smoking on the heart and heart function.

3. Research the criteria used for heart transplants and their success rate.

4. Research the status of artificial hearts and their use as a temporary solution until a heart donor can be found.

5. Research the effects of exercise on heart function.

6. Research the various types of heart block and their significance and treatment.

7. Research the procedures and types of artificial valves currently used in valvereplacement surgery.

8. Research new innovations in coronary artery bypass graft surgery (CABG).

9. Research “keyhole” valve replacement surgery. This surgery is also called minimally invasive valve replacement surgery.

10. Research types of heart surgery used as temporary solutions for a person waiting for a heart transplant.

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Suggested Readings Abe, Y., et al. “Present Status of the Total Artificial Heart at the University of Tokyo.”

Artificial Organs 23 (March 1999): 221–228.

Anversa, P., and B. Nadal-Ginard. “Myocyte Renewal and Ventricular Remodeling.” Nature 415 (6868) (January 2002): 240–243.

Bloom, J. M. “Prevention of Sudden Death in Patients with Coronary Artery Disease.”

New England Journal of Medicine 342 (April 27, 2000): 1291–1292.

Bonetta, Laura. “New Study on Aging Heart.” Nature Medicine 8 (3) (March 2002): 201.

Fuster, V., R. Walsh, and R. Harrington. Hurst’s the Heart. 13th ed. McGraw-Hill Professional, 2010.

Hoffman-Kim, Diane. “Tissue Engineering: Heart valves.” Science and Medicine 8 (March/April 2002): 62–64.

Iaizzo, P. Handbook of Cardiac Anatomy, Physiology, and Devices. 2nd ed. Springer, 2009.

Moore, K. L. Clinically Oriented Anatomy. 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2009.

Nattel, S. “New Ideas about Atrial Fibrillation 50 Years On.” Nature 415 (6868) (January 2002): 219–226.

Rockman, H. A., W. J. Koch, and R. J. Lefkowitz. Seven Transmembrane-Spanning Receptors and Heart Function.” Nature 415 (6868) (January 2002): 206–212.

Saremi, F., S. Achenbach, and E. Arbustini. “Revisiting Cardiac Anatomy: A Computed Tomography-based Atlas and Reference.” 1st ed. Wiley-Blackwell, 2010.

Williams, P. L., et al. Gray’s Anatomy. 38th ed. New York: Churchill Livingstone, 1995.

Answers to Textbook Questions Answers for multiple-choice and matching questions 1–11 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 12. The pericardium is a triple-layered sac that encloses the heart. The fibrous pericardium is the outer most layer that adheres to the diaphragm inferiorly, and superiorly it is fused to the roots of the great vessels that leave and enter the heart. It acts as a tough outer coat that holds the heart in place. It also keeps the heart from overfilling with blood.

(Figure 19.3, p. 597) 13. The heart lies in the mediastinum, posterior to the sternum and costal cartilages, and rests on the superior surface of the diaphragm. Its four corner points, as projected onto the anterior thoracic wall, are indicated in Figure 19.2.

14. Blood flow through the heart, beginning with the superior vena cava, inferior vena cava, and coronary sinus: SVC/IVC → Right atrium → through the tricuspid valve → Right ventricle → through the pulmonary semilunar valve → Pulmonary trunk → Pulmonary arteries → Lungs → Pulmonary veins → Left atrium → through the bicuspid (mitral) valve → Left ventricle → through the aortic semilunar valve → Aorta → to the body. (Note that

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pulmonary arteries are the only arteries carrying deoxygenated blood and that pulmonary veins are the only veins carrying oxygenated blood.) (pp. 605–607, Fig. 19.10) 15. (a) From the sinoatrial node through atrial musculature to atrioventricular (AV) node, through AV bundle and its bundle branches, through the subendocardial conducting network (Purkinje fibers) through ventricular musculature. (b) No. It consists of cardiac muscle cells. (c) The conducting system initiates each heartbeat, sets the basic rate of the heartbeat, and ensures that the heart chambers contract in the proper sequence. (pp. 609–610, Fig. 19.14.)

16. See Figs. 19.5b and d and 19.16.

17. The cardiac skeleton should be shown in the coronary sulcus between the atria and the ventricles. (p. 601, Fig. 19.5e) 18. (a) The anterior surface of the heart is formed by the right atrium, the right ventricle, the auricle of the left atrium, and the left ventricle. (Fig. 19.5b, p. 599) (b) The left atrium is the most posterior chamber of the heart. (Fig. 19.5d, p. 600) 19. (a) from sinus venosus: posterior, smooth-walled part of the right atrium; coronary sinus; sinoatrial node. (b) from embryonic atrium: anterior, ridged parts of the right and left atria. (c) from embryonic ventricle: left ventricle. (d) from embryonic bulbus cordis: right ventricle, pulmonary trunk, and the first part of the aorta. (pp. 614–615, Fig. 19.17) 20. Coronary artery diseases are treated by bypass grafts. While grafting, a portion of a vessel elsewhere in the body is removed and grafted between the aorta and heart wall in such a way that the new vessel provides an alternate route for the blood to enter the heart, thus bypassing the blockage in a specific coronary artery. (See A Closer Look on p. 613) 21. Cardiac muscle is more resistant to fatigue. The anatomical basis for cardiac muscle’s enduring nature is its abundant mitochondria making large amounts of ATP by an aerobic metabolism. It is important for cardiac muscle to be fatigue resistant because death would quickly ensue if the heart muscle failed. (pp. 607–608) 22. The connective tissues surrounding the cardiac myofibers merge with the cardiac skeleton, and thus, function to anchor the muscle cells and transmit the contractile forces produced by the muscle cells. This arrangement is similar to the tendinous origins and insertions of skeletal muscles (p. 608) 23. Cardiac muscle tissue and skeletal muscle tissue resemble each other in that both are striated and contract by the sliding filament mechanism. Skeletal muscle cells are extremely long, cylindrical, and multinucleate. Cardiac muscle cells are shorter, branching, and contain one or two centrally located nuclei. Unlike skeletal muscle tissue, not all cells of cardiac muscle are innervated. Additionally, cardiac muscle tissue is involuntary, whereas skeletal muscle tissue is under voluntary control. (p. 608, Fig. 19.12)

Critical Reasoning and Clinical Applications Questions 1. (1) Mixing of oxygenated with deoxygenated blood: ventricular septal defect and tetralogy of Fallot; (2) Increased workload for ventricles: coarctation of the aorta, tetralogy of Fallot; (3) Both: tetralogy of Fallot. (pp. 614–615, Figs. 19.17, 19.18) 2. Shaun suffers from hypertrophic cardiomyopathy, an inherited condition in which the wall of the left ventricle (especially the interventricular septum) is abnormally thick, and is composed of disorganized muscle cells. Increased thickness of the ventricular wall

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obstructs blood flow and predisposes to ischemia, especially during exercise. Symptoms include dizziness, fainting and even sudden death. (p. 607) 3. (a) All sounds of the aortic semilunar valve are best heard near the superior right corner of the heart on the anterior thoracic wall: the second intercostal space at the right sternal margin. (b) All sounds of the mitral valve are best heard at the apex point of the heart: the fifth left intercostal space in line with the middle of the clavicle. (pp. 603 and 605, Fig. 19.11) 4. Cardiac tamponade is the condition in which excess fluid in the pericardial cavity compresses the heart; therefore, the heart cannot expand during diastole and cannot propel blood effectively. In the man’s case, excess blood has leaked into the pericardial cavity from the heart itself, through a puncture in the heart wall caused by the knife. With the heart unable to pump blood effectively, the drainage of blood from the great veins of the head to the heart is slowed considerably, and blue, deoxygenated, venous blood accumulates in the face and brain. The man’s cardiac tamponade will be treated by draining the excess blood from the pericardial cavity (and by surgically closing the hole in his heart wall). (p. 597) 5. Ameena suffers from Mitral valve prolapse. The weak collagen of the mitral valve and chordae tendineae makes one or both cusps of the mitral valve to ‘flop’ into the left atrium during ventricular systole. Being the most common disorder of the heart, it is characterized by a clicking sound followed by a swish. This is actually the sound of the backflow of the blood. (p. 604) 6. Stenosis of a heart valve occurs when the valve has a narrowed opening, as when its cusps are fused or stiffened. An incompetent valve, by contrast, is one that fails to close tightly. Both lead to abnormal heart sounds. (See “Clinical Applications: Valve Disorders,” p. 604.)

7. Mrs. Peterson is suffering from atrial fibrillation, which is associated with an irregular heartbeat. Multiple waves of impulses originating from the atria, randomly stimulating the AV node, signal the ventricles to contract quickly and irregularly. The lack of coordinated ventricular movements may predispose to the formation of blood clots that might break and reach the brain, causing strokes. Hence, anticoagulants were prescribed as a prophylaxis for Mrs. Peterson. (p. 614) 8. Blockage of the circumflex branch affects the left atrium and the posterior part of the left ventricle. (p. 611, Fig. 19.16) 9. The pumping arrangement of the ventricles is comparable to simultaneously squeezing and rolling up the end of a tube of toothpaste. The distance between the base and the apex, and the diameter of the left chamber, both decrease when the left ventricle contracts. The powerful force sends blood through the aortic semilunar valve, and the pumping efforts of the right ventricle are improved because the left ventricle bulges into the chamber of the right ventricle. (pp. 605–607)

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Interpreting Medical Images Questions Answers to Interpreting Medical Images questions are provided in the Instructor Resources area of Mastering A&P. Figure 19.2:

a) b) Upper right corner at the sternal end of rib #3; upper left corner at the sternal end of rib #2; lower right corner at the sternal end of rib #6; lower left corner at ICI #6. This heart is in the normal boundaries. The lower left corner is slightly lower than typical, likely because the x-ray image was taken from a standing position.

Figure 19.16: The right coronary artery shows stenosis just proximal to the branching of the marginal artery; see circled region in associated image. The stenosis occurs before the right coronary artery gives off its major branches that supply the majority of the right ventricle and some of the posterior region of the left ventricle. These areas will have poor blood supply and thus poor perfusion due to the stenosis. Vessels off the right coronary artery that supply the right atrium branch off prior to the area of stenosis, so the right atrium should receive adequate blood supply.

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 19: The Heart To the Student Place your hand over your heart. As you feel the beat of this muscular organ, think about what it does to sustain life for you. It is the force behind the pumping of blood to the lungs to pick up oxygen and the pumping of blood to deliver oxygen and nutrients to your entire body. In one year, the heart pumps an estimated 1 million gallons of blood and beats approximately 40 million times. A daily estimate is 2,700 gallons of blood pumped and 100,000 beats! Add the fact that blood is pumped through an estimated 60,000 miles of vessels in your body, and the heart becomes even more phenomenal. The heart has fascinated and intrigued man for centuries and still today is linked with human emotions. [The resemblance to the popular valentine is unmistakable.] Your goal in this chapter is to learn the gross anatomy and functions of the heart and its structures, how blood moves through the heart, and circulation patterns. Don’t forget the availability of PAL 3.0 and other resources at myaandp.com as you study the heart.

Step 1: Explain the orientation and location of the heart in the human body. __ Describe the physical characteristics, orientation, and location of the heart in the mediastinum. __ Distinguish the apex from the base. __ Name the structure that the heart contacts inferiorly. __ Define mediastinum.

Step 2: Explain systemic, pulmonary, and coronary circuits. __ Define artery and vein. __ Describe the heart as being organized into two pumps. __ Define and summarize the pathway of systemic circulation. __ Define and summarize the pathway of pulmonary circulation. __ Define and summarize the pathway of coronary circulation.

Step 3: Describe the gross anatomy of the heart. __ Define pericardium, and distinguish visceral pericardium, parietal pericardium, and pericardial sac. __ Name the layers of the heart wall, from external to internal, including tissue components of each layer. __ Describe the surface anatomy of the heart. __ Name the four chambers of the heart, and list structural features of each. __ Draw the heart in an anterior view and cut open, and label as many parts as you can. __ Distinguish between the following: • Atrium and auricle • Atrium and ventricle ..

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• Pectinate muscle and trabeculae carneae • Trabeculae carneae and papillary muscle • Bicuspid valve and tricuspid valve Step 4: Describe blood flow through the heart and include valves and heart sounds. __ Trace a drop of blood from the right atrium back to the right atrium. __ Review pulmonary and systemic pathways. __ Define and describe heartbeat. __ Name the four valves; describe locations, structures, and functions. __ Explain the cause of the first and second heart sounds—“lub” and “dup”—indicating the location on the anterior chest wall for best observations using a stethoscope. __ Describe the cardiac skeleton structural support of the AV valves, including functions.

Step 5: Describe cardiac muscle tissue. __ Discuss the structure of cardiac muscle tissue. __ Describe the function of cardiac muscle tissue, including the role of intercalated discs. __ Describe the role of calcium ions in cardiac muscle cell contraction. __ Compare cardiac muscle tissue to skeletal muscle tissue.

Step 6: Describe the conduction system, and explain innervation to the heart. __ Discuss the initiation of the heartbeat. (Is innervation needed?) __ Distinguish heartbeat from heart rate. __ Draw a frontally sectioned heart, and label parts of the conduction system. __ List the sequence of events in conduction of an electrical impulse from the SA node to the subendocardial conducting network (Purkinje fibers), including contraction of chambers. __ Name the kind of tissue that composes the conduction system. __ Describe the effects on the heart of innervation by parasympathetic and sympathetic fibers.

Step 7: Describe blood supply to and from the heart muscle. __ Name the vessels that supply the heart with oxygenated blood. __ Name the vessels that drain the heart muscle of deoxygenated blood. __ Indicate where venous blood of the heart muscle joins systemic venous blood. __ Trace the pathway of a drop of blood from the myocardium back to the myocardium.

Step 8: Examine common disorders of the heart. __ Describe conditions, causes, and symptoms of disorders of the heart: coronary artery disease, heart failure, and disorders of the conduction system.

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Step 9: Examine embryonic development of the heart and effects of old age on the heart. __ Summarize the stages in heart development evident in week 4 of gestation, naming the four embryonic chambers. __ Draw an adult heart and its great vessels, indicating regions derived from each embryonic heart chamber. __ Give examples of congenital heart defects. __ List several age-related changes that affect the heart.

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CHAPTER

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Blood Vessels

Lecture and Demonstration Objectives PART ONE: GENERAL CHARACTERISTICS OF BLOOD VESSELS

1. Describe the three tunics that form the wall of an artery or vein.

2. Define vasa vasorum.

3. Compare and contrast the structure and functions of elastic arteries, muscular arteries, and arterioles.

4. Describe the structure and function of capillaries, sinusoids, and capillary beds, and explain the structural basis of capillary permeability.

5. Explain how to distinguish a vein from an artery in histological sections.

6. Describe the structural features of arteries and veins that help maintain the flow of blood through these vessels.

7. Define vascular anastomoses and explain their functions.

PART TWO: BLOOD VESSELS OF THE BODY

1. Define pulmonary and systemic circuits.

2. Name the major vessels of the pulmonary circuit.

3. Name the three vessels that arise from the aortic arch. Describe the routes of arterial blood supply from these vessels to the head and neck, the brain, the thorax, and the upper limb.

4. Describe the pathways and the organs supplied by the midline arteries and by the paired arteries branching off the abdominal aorta.

5. Describe the pathway of arterial supply to the pelvis and the lower limb.

6. Identify the location of pulse points in the limbs, head, and neck.

7. Trace the veins that empty into the superior vena cava as you describe the routes of venous return from the brain, the head and neck, and the thorax and upper limbs.

8. Trace the veins that empty into the inferior vena cava as you trace venous return from the abdominal organs and from the pelvis and lower limbs.

9. Describe the structure and special function of the hepatic portal system and explain the significance of portal-systemic anastomoses.

10. Define atherosclerosis, deep vein thrombosis, venous disease of the lower limb, aneurysm, microangiopathy of diabetes, and arteriovenous malformation.

11. Trace the cardiovascular circuit in the fetus, and explain how it changes at birth.

12. List some effects of aging on the blood vessels.

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Suggested Lecture Outline PART ONE: GENERAL CHARACTERISTICS OF BLOOD VESSELS (pp. 621–628, FIGS. 20.1–20.6)

The main types of blood vessels are arteries, capillaries, and veins. Arteries carry blood away from the heart and toward the capillaries; veins carry blood away from the capillaries and toward the heart. Arteries “branch,” whereas veins “serve as tributaries.”

I. Structure of Blood Vessel Walls (p. 621) A. Except for capillaries, blood vessel walls have three tunics: tunica intima, tunica media, and tunica externa; tunica media is thicker in arteries than in veins.

B. Vasa vasorum are small arteries, capillaries, and veins that serve walls of larger vessels, such as the aorta.

II. Types of Blood Vessels (pp. 621–627, Figs. 20.1–20.6, Table 20.1) A. Arteries (pp. 621–624, Figs. 20.1, 20.2, Table 20.1) 1. The passage of blood through arteries proceeds from elastic arteries (the largest) to muscular arteries (middle-sized, distributing arteries) to arterioles (the smallest).

B. Capillaries (pp. 624–626, Figs. 20.1 and 20.3–20.5, Table 20.1) 1. Capillaries are the smallest blood vessels. They have a diameter of 8–10 µm, just large enough to permit the passage of erythrocytes in single file; the wall is a single layer of endothelium. a. Sinusoids are wide, leaky capillaries that occur in bone marrow, spleen, and liver tissues. b. Capillary permeability permits the exchange of nutrients and wastes between blood and tissue fluid; four routes of capillary permeability allow molecules to pass into and out of capillaries. c. The blood-brain barrier is an example of low-permeability capillaries; all but the most vital molecules are prevented from leaving the blood and entering the brain tissue. d. A capillary bed is a network of the body’s smallest vessels; beds run through almost all tissues, especially loose connective tissues. e. Sometimes blood is shunted straight through a capillary bed (from arteriole to metarteriole to thoroughfare channel to venule) and does not enter the true capillaries surrounding the tissue.

C. Venous Vessels (pp. 626–627, Figs. 20.1, 20.16) 1. Veins are formed from the smallest veins called venules; the smallest venules are postcapillary venules.

2. Venous blood is under less pressure than arterial blood; compared to arteries, veins have thinner walls, a wider lumen, a thinner tunica media, a thicker tunic externa, and valves.

III. Vascular Anastomoses (pp. 627–628) A. Vascular anastomoses occur where vessels unite or interconnect; arterial anastomoses serve a common organ, such as the brain or a joint; venous anastomoses are much more common than anastomoses between arteries. ..

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PART TWO: BLOOD VESSELS OF THE BODY (pp. 628–655, Figs. 20.7–20.25)

There are several important patterns of circulation; the two basic patterns are pulmonary circulation and systemic circulation; other examples are myocardial circulation and hepatic portal circulation.

IV. The Pulmonary Circulation (pp. 628–629, Fig. 20.7) A. Oxygen-poor blood leaves the heart, and oxygen-rich blood returns to the heart via the following vessels: pulmonary trunk, pulmonary arteries, lobar arteries, lung capillaries, and pulmonary veins.

V. The Systemic Circulation (pp. 629–650, Figs. 20.8–20.23) A. Not all vessels on the right and left sides of the body are mirror images.

1. Systemic Arteries (pp. 629–640, Figs. 20.8–20.15) a. Systemic arteries carry oxygenated blood from the heart to the capillaries of organs throughout the body. b. The aorta is the largest artery in the body; three parts of the aorta are the ascending aorta, the aortic arch, and the descending aorta. c. Arteries that supply the head and neck are the single brachiocephalic and paired common carotids, internal and external carotids, and vertebrals; the neck is also supplied by the thyrocervical and costocervical trunks. d. Arteries that supply the thoracic wall are the internal thoracic and intercostal arteries; thoracic visceral organs are supplied by branches of the thoracic aorta. e. The upper limbs are supplied by arteries that arise from the subclavian arteries: axillary, brachial, radial, ulnar, and palmar arch. f. Arterial supply to the abdomen arises from the abdominal aorta; abdominal arteries include the inferior phrenics, the unpaired celiac trunk that branches into the left gastric, splenic, and common hepatic, the unpaired superior mesenteric, suprarenals, renals, gonadals, the unpaired inferior mesenteric, lumbars, median sacral, and the common iliac arteries. g. The following arteries supply the pelvis and lower limbs: common iliac, internal iliac, femoral popliteal, anterior tibial, posterior tibial, and plantar arch.

2. Systemic Veins (pp. 642–650, Figs. 20.16–20.23) a. Systemic veins carry deoxygenated blood from the capillaries of organs throughout the body toward the heart; the superior and inferior venae cavae are the body’s main veins. b. The superior vena cava receives venous blood from all body regions superior to the diaphragm, excluding the heart wall; the inferior vena cava receives venous blood from all body regions inferior to the diaphragm. c. Most blood draining from the head and neck enters three pairs of veins: the internal jugulars, the external jugulars, and the vertebrals; the venous dural sinuses drain the brain and empty into the internal jugulars. d. Veins of the thorax are the azygos, the hemiazygos, and the accessory hemiazygos.

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e. Veins of the upper limb are deep or superficial; deep veins have companion names and locations of the upper limb arteries; superficial veins of the upper limb are the cephalic, median cubital, and basilic. f. Most veins of the abdomen share companion names of the abdominal arteries and drain into the inferior vena cava: lumbar, gonadal, renal, suprarenal, and hepatic veins. g. The hepatic portal system delivers nutrient-laden blood from the intestines to the liver; tributaries of the hepatic portal system are the superior mesenteric, splenic, inferior mesenteric, and portal vein. h. Portal-systemic anastomoses provide emergency pathways through which backup portal blood can return to the heart; overloads result in esophageal bleeding, hemorrhoids, and caput medusae. i. Deep veins of the pelvis and lower limb share the names of the arteries they accompany: plantar arch, posterior and anterior tibials, fibular, popliteal, femoral, external iliac, internal iliac, and common iliac veins; superficial veins are the great saphenous and small saphenous veins.

VI. Disorders of the Blood Vessels (pp. 650–651, Fig. 20.24) A. Examples of blood vessel disorders are atherosclerosis, aneurysm, deep vein thrombosis of the lower limbs, venous disease, microangiopathy of diabetes, and arteriovenous malformation.

VII.Blood Vessels Throughout Life (pp. 654–655, Fig. 20.25) A. Embryonic blood vessels form during week 3.

1. Fetal Circulation (pp. 654–655, Fig. 20.25) a. All major fetal circulation vessels are in place by the third month. b. Unique fetal anatomical vessels and structures are the umbilical arteries, the single umbilical vein, ductus venosus, foramen ovale, and the ductus arteriosus.

2. Blood Vessels in Adulthood (p. 655) a. The most important aspect of the aging of the vascular system is the progression of atherosclerosis.

Lecture Hints 1. Stress that arteries carry blood away from the heart and “branch” or “fork.” Stress that veins carry blood toward the heart and “join” or “serve as tributaries.”

2. When describing blood vessel wall structure, emphasize the relationship of structure to function. The tunica interna reduces friction between the vessel walls and blood; the tunica media controls vasoconstriction and vasodilation of the vessel; the tunica externa protects, reinforces, and anchors the vessel to the surrounding structures.

3. Explain that arterioles, as the smallest arteries, regulate blood flow into capillary beds through vasoconstriction and vasodilation.

4. Students find interesting the concept that the heart is “a big blood vessel.” Explain how the endocardium corresponds to the tunica intima, the myocardium corresponds to the tunica media, and the connective tissue portion of the epicardium corresponds to the tunica externa. ..

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5. Explain that the degree of vascularity varies throughout the body; compare a highly vascular part, such as the brain, with examples that are poorly vascular, such as ligaments and tendons, and avascular examples, such as the cornea and lens.

6. When discussing circulatory pathways, emphasize the important differences between arteries and veins: (1) there is one terminal systemic artery, the aorta, but two terminal systemic veins, the superior and inferior venae cavae; (2) arteries run deep and are well protected, but veins are both deep, which run parallel to the arteries, and superficial, which run just beneath the skin; (3) arterial pathways tend to be clear and distinct, but there are often many interconnections in venous pathways, making them difficult to follow; and (4) there are at least two areas where venous drainage does not parallel the arterial supply: the venous dural sinuses draining the brain, and the hepatic portal system draining from the digestive organs to the liver before entering the main systemic circulatory pathway.

7. Review the basics of pulmonary and systemic circulation before introducing the major blood vessels of the body.

8. Incorporate schematic drawings to help students master the function of the cardiovascular system.

9. Point out that vessels in the head and limbs are mostly bilaterally symmetrical, but some vessels on the right side and left side of the body are not always mirror images of each other, and some deep trunk vessels are asymmetrical.

10. Explain how to “trace a drop of blood” from one location in the body to another, beginning and ending in capillaries.

Classroom Discussion Topics and Activities 1. Display a model of a human torso, a model of the circulatory vessels, and/or a wall chart to exhibit the major blood vessels of the body. Point out major blood vessels and have students name them.

2. Use a short piece of cloth-wrapped garden hose to show the layers (tunics) of arteries and veins. Wrap the hose with one color (red) to represent the tunica media and another color (white) to represent the tunica externa (adventitia).

3. Use a short piece of soaker hose to illustrate a capillary as the “functional unit” of the circulatory system.

4. Blow up a long balloon to imitate an aneurysm or a varicose vein.

5. Direct the class in solving blood-tracing problems using a flowchart format. Assign several blood-tracing problems, or allow students to make up their own. A few examples include tracing a drop of blood from the: a. brain to the kidney b. left foot to the right thumb c. small intestine to the posterior knee d. left testis to the spleen e. myocardium to the liver f. left thorax to the face g. placenta back to the placenta 250

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6. Discuss the significance of a healthy diet low in saturated fat in maintaining normal blood flow.

7. Discuss why some coronary bypass surgeries have to be repeated after a few years.

8. Discuss what occurs when an artery loses its elasticity.

9. Ask students to think about answers to the following questions for a class discussion: a. What factors or events retard venous return? b. Why do water and dissolved solutes leave the bloodstream at the arteriole end of a capillary bed and enter the bloodstream at the venule end of the bed? c. Why is the elasticity of the large arteries so important? Or, why is arteriosclerosis such a threat? (Refer to A Closer Look: Atherosclerosis? Get Out the Cardiovascular Drano, p. 651) 10. Project unlabeled copies of Figures 20.8 and 20.16, and instruct students to name the vessels.

Clinical Questions 1. Atherosclerosis is a stealthy killer. Describe the disease process, noting the involvement of specific cells and tissue types.

Answer: See “A Closer Look” on p. 651 of the textbook and the articles on atherosclerosis in the Suggested Readings that follow.

2. A woman in her early 50s showed up at the walk-in clinic complaining of an aching pain in her right leg following a fall. Visual examination revealed that the medial aspect of that leg was red and swollen. A diagnosis of phlebitis was made. What is phlebitis, and what more serious condition may follow if proper healing does not occur?

Answer: Phlebitis is an inflammation of a vein, accompanied by painful throbbing and redness of the skin over the inflamed vein. If proper healing does not occur, stagnant blood may clot within the vein (this is thrombophlebitis). The danger is that the clot could detach and form an embolus.

3. The day after Spike returned from winning a boxing match, he heard that the boxer who lost suffered a ruptured middle meningeal artery from the knockout blow. Where is this artery located, and what are some likely consequences of its rupture?

Answer: The middle meningeal artery, a branch of the external carotid and maxillary arteries, runs along the broad internal surfaces of the parietal bone and squamoustemporal bone of the cranium. A rupture of this artery is likely to cause a large hematoma, which exerts pressure on the underlying cerebral cortex of the brain, interfering with the conscious, cortical functions.

4. One way that clinicians check patients for the advanced stages of alcoholism is to look for the caput medusae and hemorrhoids. Explain why these may be symptoms of advanced alcoholism.

Answer: Both the superficial veins around the navel and the hemorrhoidal veins are anastomoses between portal blood and systemic blood (see the discussion of portalsystemic anastomoses). Chronic alcoholics often have cirrhosis of the liver, which obstructs the flow of portal blood through the liver sinusoids. This blood backs up and overfills the portal-systemic anastomoses around the navel (causing the Medusa head) and overfills the hemorrhoidal veins (causing hemorrhoids). ..

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Art Resources Figure 20.1 Figure 20.2 Figure 20.3 Figure 20.4 Figure 20.5 Figure 20.6 Figure 20.7 Figure 20.8 Figure 20.9 Figure 20.10 Figure 20.11 Figure 20.12 Figure 20.13 Figure 20.14 Figure 20.15 Figure 20.16 Figure 20.17 Figure 20.18 Figure 20.19 Figure 20.20 Figure 20.21 Figure 20.22 Figure 20.23 Figure 20.24 Figure 20.25 Table 20.1 A Closer Look

Generalized structure of arteries, veins, and capillaries.

Comparison of arterial wall structure.

Red blood cells passing through a capillary.

Capillary structure.

Anatomy of a capillary bed.

Blood flow through veins.

Pulmonary circulation.

Major arteries of the systemic circulation.

The great vessels that exit and enter the heart.

Arteries of the head, neck, and brain.

Arteries of the thorax and right upper limb.

Major branches of the abdominal aorta.

Midline branches off the abdominal aorta supplying the organs of the digestive tract.

Arterial supply to the pelvis.

Arteries of the right pelvis and lower limb.

Major veins of the systemic circulation, anterior view.

Venous drainage of the head, neck, and brain.

Veins of the head and neck, right superficial aspect.

Veins of the thorax and right upper limb, anterior view.

The superficial veins of the right upper limb.

Tributaries of the inferior vena cava.

The hepatic portal system.

Veins of the right lower limb and pelvis.

Sixty-four-slice CT angiogram of an abdominal aortic aneurysm.

Fetal and newborn circulation.

Summary of Blood Vessel Anatomy Atherosclerosis? Get Out the Cardiovascular Drano.

Teaching with Art Figure 20.25

Fetal and newborn circulation.

Textbook p. 652.

Checklist of Key Points in the Figure • Explain that major vessels are in place by the embryonic third month and that blood flows in the same direction as the adult.

• Describe the placenta as the organ of transport between the fetus and the mother, functioning as the fetal respiratory organ.

• Explain that fetal lungs and liver receive very little blood; define shunt.

• Define umbilical cord, stressing that there are two umbilical arteries and one umbilical vein.

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• Describe the location and function of the ductus venosus, foramen ovale, and ductus arteriosus; identify future adult derivatives.

Common Conceptual Difficulties Interpreting the Art • Stress that an umbilical artery carries blood away from the fetal heart and that an umbilical vein carries blood to the fetal heart. It is the fetal heart that is the point of reference, not the maternal heart.

• Describe the mixing of oxygenated and deoxygenated blood.

• Explain why shunts away from pulmonary circulation are necessary in the fetal heart.

• Point out that the prenatal circulatory pattern must be able to rapidly convert to the postnatal circulatory pattern.

Art Exercises Using Figure 20.25, instruct students to design a flowchart that traces a drop of blood from the placenta back to the placenta. Include all shunts and color code high, moderate, low, and very low regions of blood oxygenation.

Critical Reasoning Looking at Figure 20.25, ask students to identify the adult (“newborn”) structures derived from the following fetal structures and to describe their locations in the adult using additional figures from the textbook: a. Umbilical vein b. Umbilical arteries c. Ductus venosus d. Foramen ovale e. Ductus arteriosus Answer: a. The ligamentum teres (“round ligament”), the remnant of the umbilical vein, is contained in the anterior margin of the falciform ligament of the liver. Refer to Figure 23.25. b. The umbilical arteries become the medial umbilical ligaments in the anterior abdominal wall inferior to the navel. Refer to Figure 20.25. c. The ligamentum venosum on the liver’s inferior surface is the fetal remnant of the ductus venosus. Refer to Figure 23.26. d. The fossa ovalis is the fetal remnant of the foramen ovale and appears as a depression in the interatrial septum. Refer to Figure 19.5e. e. Postnatally, the ductus arteriosus becomes the ligamentum arteriosum, a fibrous interconnection between the pulmonary trunk and aortic arch. Refer to Figure 19.5b.

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Supplemental Course Materials Library Research Topics 1. Research the congenital defects of circulation that result from differences between the fetal and adult circulations.

2. Research the risk factors implicated in atherosclerosis and what can be done to minimize the risk.

3. Research procedures and the types of valves currently used in valve replacement surgery.

4. Research data from the past three years to the present concerning vascular health and components of a healthy diet.

5. Research methods by which one can effectively lower LDL cholesterol while raising HDL cholesterol.

Suggested Readings Arampatzis, C. “Coronary Atherosclerosis: Current Management and Treatment.” 1st ed.

Informa Healthcare, 2012.

Ballantyne, Christie. Dyslipidemia and Atherosclerosis Essentials. 4th ed. Jones & Bartlett Publishers, 2008.

Foley, Natalia. Anatomy and Physiology of the Blood Vessels. Liberty Soldier, 2007.

(Audio CD) Fuster, V., R. Walsh, and R. Harrington. Hurst’s the Heart. 13th ed. McGraw-Hill Professional, 2010.

George, Sarah Jane. Atherosclerosis. 1st edition. Wiley-VCH, 2010.

Hoffman-Kim, Diane. “Tissue Engineering: Heart valves.” Science and Medicine 8 (March/April 2002): 62–64.

Iaizzo, P. Handbook of Cardiac Anatomy, Physiology, and Devices. 2nd ed. Springer, 2009.

Moore, K. L. Clinically Oriented Anatomy. 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2009.

Wick, Georg, and Cecilia Grundtman. Inflammation and Atherosclerosis. Springer, 2012.

Answers to Textbook Questions Answers for multiple-choice and matching questions 1–16 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 17. Vital molecules such as glucose pass through the barrier by highly selective transport mechanisms in the plasma membranes of the endothelial cells. The blood brain barrier does not prevent the passage of uncharged and lipid-soluble molecules such as oxygen, carbon dioxide, and some anesthetics, which may simply diffuse through the endothelial cells and enter the brain tissue freely. (p. 625) 18. Elastic arteries are the large, thick-walled arteries close to the heart. These arteries contain many layers of elastin in their walls, especially in the tunica media. This large 254

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amount of elastin enables the arteries to withstand large pressure fluctuations by expanding when the heart contracts, forcing blood into them, and recoiling as blood flows forward into the circulation during heart relaxation. The tunica media of elastic arteries contains substantial amounts of smooth muscle, but these vessels are not as active in vasoconstriction as are the muscular arteries. (pp. 621–623, Fig. 20.2) Muscular arteries are medium- and smaller-sized arteries farther along the circulatory pathway that carry blood to specific body organs. Their tunica media contains proportionately more smooth muscle and less elastic tissue than that of elastic arteries. Muscular arteries are most active in vasoconstriction, although the elastin in their walls continues to dampen the pulsatile force produced by the heartbeat. (p. 623, Fig. 20.2) Arterioles are the smallest of the arterial vessels, feeding directly into the capillary beds.

Larger arterioles exhibit all three tunics, with tunica media being the thickest of these.

The walls of the smaller arterioles are little more than smooth muscle cells that coil around the endothelium of the tunica intima. When arterioles constrict, the tissues served are largely bypassed. When the arterioles dilate, blood flow into the local capillaries increases dramatically. (pp. 623–624, Fig. 20.2) 19. (a) A sinusoid is a wide, twisty, leaky capillary. (b) Sinusoids occur wherever there is an extensive exchange of large materials (such as proteins or cells) between the blood and surrounding tissue. For example, they occur in the bone marrow and spleen, where many blood cells move through their walls. (p. 625) 20. The sketch of the cerebral arterial circle (of Willis) should resemble that in Figure 20.10c.

21. (a) The two tributaries of the hepatic portal vein are the superior mesenteric vein and the splenic vein. (b) The function of the hepatic portal circulation is to deliver blood laden with nutrients from the stomach and intestine to the liver, where the nutrients are processed. (pp. 645 and 648) 22. The azygos vein ascends along the right surface, or the center, of the bodies of the thoracic vertebrae. It drains most systemic blood from the thorax region of the body. (p. 643, Fig. 20.18) 23. Ascending aorta, aortic arch, thoracic aorta, and abdominal aorta (a combination of the thoracic and abdominal aorta forms the descending aorta). (p. 631) 24. In a fetus, blood is oxygenated at the placenta because the fetal lungs are not functional.

Fetal circulation has two routes to bypass the pulmonary circuit. These include the foramen ovale, an opening in the interatrial septum, and the ductus ateriosus, a shunt between the pulmonary trunk and the aorta. In a newborn, the foramen ovale and the ductus ateriosus is closed. As a result, the heart becomes functionally divided. The right side of the heart receives and pumps poorly oxygenated blood, while the left side of the heart receives and pumps highly oxygenated blood. In the fetus, most of the blood in the umbilical vein bypasses the liver capillaries and is delivered to the inferior vena cava via the ductus venosus. In a newborn, the umbilical vein and ductus venosus are closed, so blood enters the liver via the portal veins and is collected by hepatic veins into the IVC. (Fig. 20.25, pp. 652–653)

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25. Arteriosclerosis (“hardening of the arteries”) is a general term for the pathological thickening and loss of elasticity of the arterial walls. Atherosclerosis is a specific term for the thickening of the tunica intima that narrows the arterial lumen because of deposits of atheromas in coronary arteries, resulting in strokes and heart attacks. (p. 651, A Closer Look) 26. 1. The superficial temporal artery is a branch of the external carotid artery. 2. The facial artery is a branch of the external carotid artery. 3. The left common carotid artery branches from the aortic arch and the right common carotid artery branches from the brachiocephalic artery. 4. The brachial artery is a continuation of the axillary artery. 5. The radial artery branches from the brachial artery. 6. The femoral artery is a continuation of the external iliac artery. 7. The popliteal artery is a branch of the femoral artery. 8. The posterior tibial artery is a branch of the popliteal artery. 9. The dorsal pedis artery is the inferior continuation of the anterior tibial artery. (p. 630, Figs. 20.8a, b)

Critical Reasoning and Clinical Applications Questions 1. Zachary is suffering from ruptured esophageal varices because of portal hypertension.

Chronic alcoholism causes cirrhosis of the liver and elevated blood pressure in the portal venous system. Esophageal varices are one of the sites of portal-caval anastomoses that get engorged and become prone to rupture with increasing portal hypertension. When these anastomosing veins start to fail, as Zachary’s case, a person may vomit blood due to torn esophageal veins. (p. 648) 2. Closing a patent foramen ovale is much more difficult and dangerous because it requires opening the heart—and open-heart surgery is always difficult, especially in a small child. (p. 655, “Related Clinical Terms”) 3. The blood brain barrier (BBB) is a unique system where the endothelial cells in the brain capillaries have complete tight junctions with no intercellular clefts and are usually impermeable to most cells and large molecules. It is believed that extreme stress, as during war conditions, may cause damage to these tight junctions and can expose the brain tissue to potential toxic substances. This mechanism has been implicated in the neurological symptoms associated with the Gulf War syndrome, marked by numerous chronic symptoms including severe depression, fatigue, and memory loss. (p. 625) 4. The aneurysm was a balloon widening or outpocketing of a brain artery with weak walls that was compressing nearby nervous structures and in danger of bursting. The surgeons removed the aneurysm and replaced this arterial segment with a strong tube that will not burst. (p. 650, Fig. 20.24) 5. In the absence of the pressure-dampening effect of the elastic arteries, the wall of arteries throughout the body must withstand pulses of higher maximum pressure. (pp. 621 and 623) Battered by higher than normal pressures, the arteries may eventually rupture, as occurs in some strokes, or may weaken and form an aneurysm. Atherosclerosis, a common type of arteriosclerosis, is described in detail in the A Closer Look box on p. 651.

6. Because it is an artery, the internal thoracic artery (p. 634, Fig. 20.11) has a thicker wall than the saphenous vein (pp. 648–649. Fig. 20.23), so it is less likely to be damaged by the pressure of the heartbeat or to develop atherosclerosis. As a result, the arterial graft lasts longer and leads to higher long-term rates of survival than the venous graft. Another advantage of using the internal thoracic artery is that it lies near the heart, so it need not be transplanted from some distant site in order to be grafted.

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7. Because both the ductus arteriosus and foramen ovale lead to a mixing of oxygen-rich pulmonary blood with oxygen-poor systemic blood after birth, the blood reaching the tissues is not fully oxygenated. In such cases, the baby is blue from cyanosis. Still, the affected babies can survive, and surgeons usually wait until the child is a few years old (and can better withstand the risks of thoracic surgery) before repairing the defects. (p. 650, Fig. 20.25) 8. (a) The venous blood in the legs has to travel the farthest distance to return to the heart, all “uphill” against gravity. Thus, the drainage of this blood may be slowed or halted, especially in people who stand still for long periods. Pooling of blood in the veins of the lower limb puts backpressure on the valves and walls of these veins, so that the valves may fail and the walls may stretch. (pp. 626–627) (b) Valves prevent backflow of blood, and they direct the flow of venous blood to the heart. In the neck, gravity directs venous blood in the proper direction anyway, so few valves are necessary—unlike in the lower limbs. (pp. 626–627)

Interpreting Medical Images Questions Answers to Interpreting Medical Images questions are provided in the Instructor Resources area of Mastering A&P.

Figure 20.17: The right and left internal jugular veins exit the skull via the right and left jugular foramina, respectively.

Figure 20.24: a. celiac trunk; note the twisting splenic artery extending toward the left side of the body. b. right renal artery; the paired renal arteries branch to supply the nephrons that make up the kidney. c. right common iliac artery; the aorta bifurcates into the right and left common iliac artery. Recall that in identifying right or left, you are referring to the individual’s right or left side. d. left internal iliac artery; the common iliac artery bifurcates into the external and internal iliac arteries.

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 20: Blood Vessels To the Student Arteries, veins, and capillaries are dynamic structures that accomplish the delivery of blood throughout your body. The pulmonary circuit carries blood to the lungs for gas exchange, oxygen is picked up, and carbon dioxide is removed. The systemic circuit delivers oxygenated blood to the tissues of the body in exchange for carbon dioxide. As you study the vascular system, keep in mind that many arteries and deep veins are named the same and parallel with each other. Arteries always carry blood away from the heart, and veins always carry blood toward the heart. Regardless of type, vessels carrying oxygen-rich blood are colored red, and vessels carrying oxygen-poor blood are colored blue. First, learn the specific characteristics of blood vessels. Second, practice numerous blood-tracing problems to truly understand the “circuit” of blood circulation.

You will also find that incorporating Practice Anatomy Lab 3.0 (PAL) (BC; DVD, Website) into your studies of the blood vessels will help you differentiate arteries from veins and learn the details of pulmonary and systemic circulation. For an excellent review of blood vessels, refer to the Cardiovascular System section of the Cadaver module. You may access PAL 3.0 through the DVD or the www.myaandp.com website.

Step 1: Describe the general characteristics of blood vessels. __ Name the main types of vessels, describing the directional flow of blood within each type. __ Describe the structure and function of three types of arteries, and name a body location for each. __ Name the tunics of a blood vessel. __ Clearly distinguish capillaries from sinusoids, naming body locations for each. __ Explain the structural basis of capillary permeability. __ Describe four routes involved in capillary permeability. __ Distinguish a metarteriole from a thoroughfare channel. __ Define precapillary sphincter, and describe its function. __ Compare postcapillary venules to capillaries. __ Explain how to histologically distinguish a vein from an artery, including comments on lumina and tunics. __ Explain the function of valves in veins, and describe them on varicose veins. __ Define vascular anastomoses, explain their functions, and identify body locations. __ Define vasa vasorum, explain their functions, and name a couple of their locations.

Step 2: Review the heart and the great vessels. __ Identify the major vessels associated with the heart. __ Review how blood moves through the heart.

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Step 3: Describe pulmonary circulation. __ Name the major vessels of the pulmonary circuit. __ Trace a drop of blood in the pulmonary trunk back to the left atrium. __ Explain why pulmonary arteries are colored blue and pulmonary veins are colored red in Figure 20.7 in your textbook.

Step 4: Describe systemic circulation. __ List the major arteries, and name the part of the body they supply. __ List the major veins that serve as tributaries for the superior and inferior venae cavae, naming the parts of the body that they drain. __ Describe the special function of the hepatic portal system, and explain the significance of the portal-systemic anastomoses. __ Diagram the pathway of the hepatic portal system using a flowchart format. __ Name each part of the body drained by a vessel of the hepatic portal system. __ Explain what makes a portal system extremely unique, and answer the question, “Does the human body have other portal systems and, if so, where?” __ Trace a drop of blood from the kidney to the spleen. __ Trace a drop of blood from the descending colon to the right hand. __ Formulate several blood-tracing problems, and check your answers with your professor.

Step 5: Describe blood vessel disorders. __ Distinguish atherosclerosis from arteriosclerosis (see A Closer Look). __ Describe deep vein thrombosis of the lower limb. __ Describe venous disease and the population it affects most. __ Describe microangiopathy of diabetes. __ Describe the various arteriovenous malformations.

Step 6: Describe fetal circulation. __ Name fetal vessels that carry blood to and from the placenta, and describe the concentration of oxygen contained in them. __ Define shunt. __ Explain how the ductus venosus, ductus arteriosus, and foramen ovale function as fetal circulatory shunts. __ Describe what happens to the ductus arteriosus and foramen ovale at birth. __ Identify the adult structures derived from the ductus venosus, ductus arteriosus, foramen ovale, umbilical arteries, and umbilical vein. __ Trace a drop of fetal blood from the placenta back to the placenta, including shunts.

Indicate regions of oxygen concentration (high, moderate, low, and very low) along the pathway.

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Lecture and Demonstration Objectives 1. Describe the structure and distribution of lymphatic vessels.

2. Explain how lymph forms and the mechanisms by which it is transported.

3. List and explain the important functions of the lymphatic vessels.

4. Describe how lymph nodes function as lymphatic organs.

5. Describe the function, recirculation, and activation of lymphocytes.

6. Relate the structure of lymphoid tissue to its infection-fighting function.

7. Describe the locations, histological structure, and immune functions of the following lymphoid organs: thymus, lymph nodes, spleen, tonsils, aggregated lymphoid nodules in the intestine, and appendix.

8. Describe the basic characteristics of two disorders of the lymphatic vessels: chylothorax lymphangitis; and three disorders of lymphocytes and lymphoid organs: mononucleosis, Hodgkin’s lymphoma, and non-Hodgkin’s lymphoma.

9. Outline the development of the lymphatic vessels and lymphoid organs.

Suggested Lecture Outline I. The Lymphatic System (pp. 660–664, Figs. 21.1–21.4) A. Tissue fluid arises from blood filtered through capillary walls.

B. Lymph flows only toward the heart. Lymphatic vessels form a one-way system rather than a full circuit.

1. Lymphatic Capillaries (pp. 660–661, Fig. 21.1) a. Lymphatic capillaries are highly permeable vessels that collect excess tissue fluid.

2. Collecting Lymphatic Vessels (p. 661) a. Collecting lymphatic vessels accompany blood vessels. b. Lymph is propelled through lymphatic vessels by the bulging of skeletal muscles, the pulsations of nearby arteries, the muscular tunica media of the lymphatic vessels themselves, and the normal movement of the limbs and trunk.

C. Lymph Nodes (pp. 661–662, Figs. 21.2, 21.3)

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a. Lymph nodes are specialized structures designed to cleanse the lymph of pathogens. There are approximately 500 lymph nodes in the body. b. Superficial lymph nodes are located in the cervical, axillary, and inguinal regions.

Deep lymph nodes are located in the thorax, abdomen, and pelvis.

D. Lymph Trunks (p. 662, Fig. 21.4) 1. Lymph trunks converge from the collecting lymphatic vessels. There are five major lymphatic trunks: the lumbar, intestinal, bronchomediastinal, subclavian, and jugular.

E. Lymph Ducts (pp. 662–664, Figs. 21.2, 21.4) 1. Lymph ducts are the largest lymphatic vessels. These are the thoracic duct and the right lymphatic duct. The thoracic duct rejoins venous circulation at the junction of the left internal jugular and left subclavian veins.

II. The Immune System (pp. 664–673, Figs. 21.5–21.12) A. Lymphocytes (pp. 665–666, Figs. 21.5, 21.6) 1. Lymphocytes are white blood cells whose main function is to recognize and fight a specific foreign molecule. Two major categories of lymphocytes are T cells and B cells. a. T cells fight invaders directly. b. B cells differentiate into plasma cells that secrete antibodies.

B. Lymphocyte Differentiation and Activation (pp. 667–668, Fig. 21.6) 1. Immature lymphocytes go through several stages before they are able to attack antigens.

C. Lymphoid Tissue (pp. 667–669, Fig. 21.7) 1. Lymphoid tissue is the most important tissue of the immune system. It is a specialized connective tissue in which lymphocytes gather to fight invading microorganisms.

D. Lymphoid Organs (pp. 669–673, Figs. 21.8–21.12) 1. The bone marrow and thymus are the primary lymphoid organs, and the lymph nodes, spleen, tonsils, and aggregated lymphoid nodules are the secondary lymphoid organs.

III. Disorders of the Lymphatic System (p. 673) A. The major disorders of the lymphatic and immune systems include chylothorax, lymphangitis, mononucleosis, Hodgkin’s lymphoma, and non-Hodgkin’s lymphoma.

IV. The Lymphatic and Immune Systems Throughout Life (pp. 673–674) A. The lymphatic vessels and lymph nodes develop from lymphatic sacs, which are projections from large vessels in the embryo.

B. The thymus originates from the pharynx, whereas all nonthymic lymphoid organs derive from mesodermal mesenchyme.

Lecture Hints 1. Students often do not make the fluid connection between blood, lymph, and interstitial fluid. Clearly explain their relationships.

2. Identify areas of the body that lack lymph capillaries, particularly the central nervous system, and remind students how the CNS deals with excess tissue fluid. ..

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3. Summarize the lymph drainage patterns, naming major trunks and ducts and stressing locations where lymph ducts empty into major veins. Refer to Figures 21.2 and 21.4.

4. Remind students that the body’s first line of defense is the skin and mucous membranes, performing nonspecific resistance to disease, whereas the immune system provides specific resistance.

5. Explain how the blood-thymus barrier is analogous to the blood-brain barrier.

6. Emphasize the differences between lymphatic capillaries and blood capillaries. Students often raise the question: “Given that both are capillaries, why does interstitial fluid flow from blood capillary to lymphatic capillary?”

7. Point out that the same factors that help venous return also aid lymph movement.

Because both are structurally similar and follow the same general pathways, logic dictates that factors affecting fluid movements should also be similar.

8. Mention that buboes (inflamed lymph nodes) are the “swollen glands” seen in infectious processes.

9. Point out that the structure and locations of lymph nodes are ideal for filtering the interstitial fluid (containing tissue proteins, metabolic wastes, and pathogenic microorganisms) flushed from tissue spaces.

Classroom Discussion Topics and Activities 1. Use a model and chart of the human torso to demonstrate lymphatic organs.

2. Demonstrate lymphatic organs using a human cadaveric donor, a dissected cat, or a dissected rat.

3. Use a soaker hose to emphasize the leakiness of lymph capillaries.

4. Ask students why a body region develops edema after the lymphatics are removed from that area, possibly using the example of severe edema in the upper limb of a woman recovering from a radical mastectomy.

5. Use a visual aid that shows a person with elephantiasis to illustrate the edema that results from obstruction of the lymphatic vessels.

6. Survey the class to determine how many students have had their palatine tonsils removed. Explain that in the 1950s, a tonsillectomy was a routine operation, and almost 100% of the children in North America had their tonsils taken out. In the 1960s, this operation was recognized to be largely unnecessary, so your current survey should indicate that only a minority of students have had a tonsillectomy. (The textbook authors’ surveys indicated a 50% rate among their own students in 1980, fewer than 20% in 1991, and fewer than 5% in 1995.)

7. Assign A Closer Look: AIDS: The Modern-Day Plague? as required reading. Instruct students to look up newspaper and popular magazine articles that concern the social, medical, and economic problems surrounding AIDS for class discussion and/or reports.

8. Discuss why a physician checks for swollen lymph nodes in the neck when examining a patient who shows symptoms of ventilatory disorder.

9. Discuss the ramifications of removing the spleen or tonsils.

10. Discuss the role of the thymus in the body’s immune response, including newborns and the elderly. What is the immune status of a person born without a thymus?

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11. Discuss the pros and cons surrounding laws that require universal immunization of American children against diseases such as tuberculosis, smallpox, measles, and mumps.

Although many of the listed diseases are not common in the United States any longer, what consequences could result if children are not vaccinated against these diseases?

12. Discuss allergy, explaining that it is an abnormally vigorous immune response to an otherwise harmless antigen. Ask students to explain allergic symptoms and the role of T cells in some responses.

Clinical Questions 1. What is the consequence of obstruction of the lymphatic vessels of a body region?

Answer: Obstruction of the lymphatic vessels results in severe, localized edema.

2. How does the lymphatic system both help and hinder the spread of cancer through the body?

Answer: Cancer cells can easily enter the “leaky” lymphatic capillaries and therefore travel in the lymph stream through the body. Lymph nodes, located along the collecting lymph vessels, filter and help destroy the cancer cells.

3. A pregnant woman complains to her doctor that her ankles and feet stay swollen all the time. She is very worried about this. As her doctor, what would you tell her?

Answer: She has edema, an accumulation of excess tissue fluid in the extracellular spaces of the areolar connective tissues of her lower limbs. This is caused by her pregnancy and the fact that the enlarged uterus is pressing on the lymphatic vessels in the pelvis (which drain the lower limb). (It also results from the fact that blood volume increases during pregnancy; this increases the hydrostatic pressure at capillaries, resulting in the formation of more tissue fluid.) She should be monitored for edema until she delivers, but it should clear up at the end of pregnancy.

4. A woman has a modified radical mastectomy with removal of the axillary lymph nodes on her left side. What can she expect to happen to her left arm, and why?

Answer: The large lymph vessels draining the upper limb are inevitably removed along with the axillary nodes. Therefore, she can expect chronic edema in the left upper limb, although lymph drainage will eventually be reestablished by regrowth of the vessels.

5. A man involved in a traffic accident is rushed to the emergency room of a hospital with severe internal bleeding. Examination reveals that his spleen has ruptured. What is the treatment of choice and the prognosis?

Answer: Surgical removal of the spleen, with tying off of the splenic vessels, is indicated.

If the splenectomy is performed quickly enough to avoid massive loss of blood through internal bleeding, the prognosis is very good because most functions of the spleen will be taken over by macrophages in the liver and bone marrow.

6. Why do the elderly tend to develop cancer more frequently than younger people?

Answer: One reason is that as one ages, the efficiency of the immune system declines.

T cells become less effective at killing cancer cells.

7. James, a 36-year-old engineer, appeared at the clinic in an extremely debilitated condition. He had purple-brown lesions on his skin and a persistent cough. A physical examination revealed swollen lymph nodes. Laboratory tests revealed a low lymphocyte count. Information taken during the personal history revealed that James was upwardly ..

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mobile economically and homosexual in sexual orientation. The skin lesions proved to be evidence of Kaposi’s sarcoma. What is James’s problem, and what is his outlook?

Answer: James is suffering from AIDS. At the present time, AIDS is a treatable disease, but it remains 100% fatal.

8. Children born without a thymus must be kept in a germ-free environment if they are to survive. Explain why this is necessary.

Answer: If the thymus fails to develop, the T cells will not form. If there are no T cells to recognize foreign antigens, there is no resistance to disease. Furthermore, there will be no helper T cells, and because helper T cells are necessary to activate B cells, there will be no active B lymphocytes, either.

Art Resources Figure 21.1 Figure 21.2 Figure 21.3 Figure 21.4 Figure 21.5 Figure 21.6 Figure 21.7 Figure 21.8 Figure 21.9 Figure 21.10 Figure 21.11 Figure 21.12 A Closer Look

Distribution and special features of lymphatic capillaries.

General distribution of collecting lymphatic vessels and regional lymph nodes.

Structure of a lymph node.

The lymph trunks and ducts.

Lymphocyte function.

Differentiation, activation, and recirculation of lymphocytes.

Mucosa associated lymphoid tissue (MALT).

Lymphoid organs.

The thymus.

Structure of the spleen.

Histology of the palatine tonsil.

Aggregated lymphoid nodules.

AIDS: The Modern-Day Plague?

Teaching with Art Figure 21.5

Lymphocyte function.

Textbook p. 665.

Checklist of Key Points in the Figure • Discuss the role of lymphocytes in the body’s immune system.

• Distinguish T cells from B cells.

• Describe the direct role of antigen attack by the T cell and the indirect role of antigen attack by the B cell.

• Give examples of target cells attacked by T cells and B cells.

• Define apoptosis, and distinguish apoptosis from phagocytosis.

Common Conceptual Difficulties Interpreting the Art • Emphasize that the events depicted occur in infected tissue, not in the blood.

• Point out that the macrophage in the figure is not a transformed B lymphocyte.

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• Clearly distinguish an antigen from an antibody.

• Stress that although agranulocytes (lymphocytes and monocytes) resemble each other structurally, they are distinct functionally and thus are different cell types.

• Explain what “B” and “T” stand for in T lymphocytes and B lymphocytes.

Art Exercises 1. Provide students with unlabeled diagrams of Figure 21.5, and instruct them to color and label the following: a. Color and label the antigen and antibody representations in both the (a) and (b) parts of the figure. b. Label the sites of apoptosis and phagocytosis.

2. Instruct students to make a table that compares the similarities and differences (structural and functional) between B and T lymphocytes.

Critical Reasoning Ask the students the following questions about Figure 21.5: 1. Identify the class of specific target cells represented in Stage 2 of part (a).

Answer: Eukaryotic cells, such as human cells introduced in transplants.

2. Identify the class of specific target cells represented in Stage 3 of part (b).

Answer: Bacterial cells.

3. Lymphocytes represent 20–45% of all leukocytes in the blood, yet lymphocytes do not function in the blood. Where is the activity in the figure occurring?

Answer: Lymphocytes function in the connective tissues, especially lymphoid connective tissues.

4. Where did the macrophage in the figure come from?

Answer: A macrophage is a phagocytic monocyte and uses the bloodstream to reach connective tissues, like all leukocytes.

Supplemental Course Materials Library Research Topics 1. Chronic fatigue syndrome, in which people suffer extreme fatigue and flulike symptoms for years, has recently received much media attention. Research this condition, and evaluate the evidence that it is an immune deficiency disease.

2. Research the differences between lymph nodes swollen due to infection and those swollen due to cancer.

3. Research the changes that appear in the thymus with age, and relate these changes to the body’s immune response.

4. Research the difficulties involved in organ transplant surgeries. How is the drug cyclosporine used?

5. Research the possible side effects of vaccines.

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Suggested Readings Alberts, B., et al. Molecular Biology of the Cell. 4th ed. New York: Garland, 2002, Chapter 24.

Hanninen, A., and L. C. Harrison. “Gamma Delta T cells as Mediators of Mucosal Tolerance: The Autoimmune Diabetes Model.” Immunology Review 173 (February 2000): 109–119.

Junqueira, L. C., et al. Basic Histology. 12th ed. Stamford, CT.: McGraw-Hill, 2009.

Murray, P. R. and K. S. Rosenthal. Medical Microbiology 6th ed. Mosby, 2008.

Parham, P., The Immune System. 3rd ed., Stanford: Garland Science, 2009.

Paul, W. “Reexamining AIDS Research Priorities.” Science 267 (February 3, 1995): 633–636.

Sompayrac, L. M., How the Immune System Works 3rd ed. Wiley-Blackwell, 2008.

Answers to Textbook Questions Answers for multiple-choice and matching questions 1–11 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 12. Lymph nodes cleanse antigens from the lymph, whereas the spleen cleanses antigens from the blood. (pp. 661 and 670) 13. In order to recognize the distinctive appearance of the lymph trunks and lymph ducts in X-ray films, physicians inject lymphatic vessels with a radiopaque dye. This procedure is called lymphangiography. (p. 661) 14. The thoracic duct originates at the cisterna chyli on the bodies of lumbar vertebrae L1 and L2 and ascends along the thoracic vertebral bodies. In the superior thorax, it turns to the left and empties into the venous circulation in the root of the neck—at the junction of the left internal jugular and left subclavian veins. (pp. 662–663, Fig. 21.2) 15. (1) Lymph vessels return excess tissue fluid to the blood. (Slightly more tissue fluid is produced by blood capillaries than returns directly to them.) (2) Lymph vessels return leaked proteins to the blood. (Plasma proteins slowly but continually leak from the blood capillaries and must be returned in order to maintain normal circulatory dynamics.) (3) Lymph vessels carry absorbed fats from the intestine to the blood. (These lipids are absorbed into intestinal lymph capillaries called lacteals.) (pp. 661–662) 16. The axillary nodes, inguinal nodes, and cervical nodes are superficially located and easily palpated. (pp. 661–662, Fig. 21.2) 17. Both T and B lymphocytes produce memory cells when they are activated by specific antigens. These cells wait within the lymphoid tissue until the body encounters the specific antigen again. When memory lymphocytes bind to this antigen, they proliferate and rapidly and vigorously attack the antigen-bearing microorganism. Thus, through acquired immunity, these memory cells guard a person from subsequent infections or prevent one from getting certain diseases more than once. (p. 667)

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18. Lymph is propelled by the bulging of contracting skeletal muscles and the pulsations of nearby arteries pushing on the lymphatic vessels, squeezing lymph through them; the muscular tunica media of the lymphatic vessels contract to help propel the lymph; and the normal movements of the limbs and trunk help to keep the lymph flowing. (p. 661) 19. The spleen lies in the left superior quadrant of the abdominal cavity just posterior to the stomach. It is bound by the false ribs with its long axis along the tenth rib. During accidents, the ribs can be easily fractured and may pierce through the relatively thin capsule of the spleen. (Fig. 21.8, pp. 670) 20. She is mistaken. Although the thymus atrophies with age and becomes impregnated with fat, it continues to produce T cells throughout adulthood. (p. 669)

Critical Reasoning and Clinical Applications Questions 1. His swollen “glands” are inflamed cervical lymph nodes. Bacteria have spread from lymph vessels that drain the region of the cut in his face and have lodged in the lymph nodes of the neck, infecting these nodes. (pp. 661–662) 2. Lucas is suffering from chylothorax because of damage to the thoracic duct. Surgical restoration of the thoracic duct is necessary to prevent further lymph leakage. Lymph leakage can lead to several complications, including pleural effusion leading to collapse of the lungs, protein and fatty nutrient wasting, and diminished blood volume following the loss of fluid from the circulation. (p. 673) 3. In portal hypertension, the flow of blood through the liver sinusoids is impeded, and venous blood backs up through the veins of the portal system, including the splenic vein.

With this backup, large amounts of blood accumulate in the spleen, enlarging it. (Recall that splenic sinusoids are leaky, so blood can leak out of them into the substance of the spleen.) Notice that this particular question has nothing to do with infection or the immune function of the spleen. (pp. 670–671 and Chapter 20, p. 648) 4. Molly is suffering from infectious mononucleosis, which is caused by the Epstein Barr virus and specifically targets B lymphocytes. This attack leads to a massive activation of T lymphocytes, which in turn attack virus affected B cells. Infectious mononucleosis is commonly transmitted by the saliva (thus known as the “kissing disease”), and would indicate intimacy between both partners. Splenomegaly is a common complication. (p. 673) 5. You should explain to Pedro that HIV spreads through unprotected sexual intercourse, drug abuse, and from infected mothers to their children during delivery or through breast milk. HIV primarily affects the T helper cells that are CD4 positive. It can also affect dendritic cells, macrophages, and microglial cells.

HIV mutates frequently creating problems in discovering an efficient vaccine. (p. 668) 6. Simi had splenomegaly because only an enlarged spleen can be felt protruding anterior to the costal margin. Microorganisms from all three of her blood infections had been filtered by the spleen and were infecting that organ, causing its enlargement. (pp. 670–671)

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 21: The Lymphatic and Immune Systems To the Student Your eyes itch; your nose is runny; you break out in hives, and hives itch, too. What happened to your otherwise feeling of perfect comfort? Your body initiated a vigorous immune response to a specific foreign molecule, usually a protein, to which you are allergic.

Daily, your body is subjected to cuts, scrapes, bumps, bruises, burns, bites, stings, and a multitude of disease-causing microorganisms such as bacteria and viruses; any one of these has significant potential to cause harm to your body. Usually you stay healthy because of the tremendous effort of the all-important lymphatic and immune systems.

Lymphatic vessels collect tissue (interstitial) fluid, which is called lymph once it enters the lymphatic vessels. Specialized white blood cells traveling in blood and lymph provide protection to tissues and clean up tissue debris, such as dead cells. And, interestingly, an additional function of the lymphatic system aids in the absorption of fats. Whether or not your career goal involves the health profession, this chapter is of paramount importance to you because it explains how disease organisms travel throughout the body and how your body mounts an attack to contain and eradicate these organisms.

You will also find that incorporating Practice Anatomy Lab 3.0 (PAL) (BC; DVD, Website) into your studies of the lymphatic system will give you an excellent opportunity to review the organs of the lymphatic system. You will find the Lymphatic System sections of the Cadaver and Anatomical Models modules particularly helpful. For a review of photomicrographs of lymphoid tissues, study the slides in the Histology Module, Lymphatic System.

You may access PAL 3.0 through the DVD or the Mastering A&P Website.

Step 1: Perceive clearly and fully the structure and function of the lymphatic vessels and lymph. __ Describe the structure and distribution of lymphatic vessels. __ Define lymph, explaining the formation process and its contents. __ Describe lymph, comparing and contrasting it to both interstitial fluid and blood. __ Identify each type of lymphatic vessel, indicating important functions and specialized structural features. __ Define lacteal, explaining its location and function. __ Explain why it is possible for disease-causing organisms and cancer cells to gain easy access to the lymphatic stream. __ Describe the structural features of collecting lymph vessels, explaining how to distinguish a lymph vessel and blood vessel if you observe them side by side. __ Describe the mechanics of lymph flow, including how flow is maintained. __ Identify two main lymph ducts, and explain the drainage pathway of each. __ Describe the entire course of the thoracic duct. __ Trace a drop of lymph from its point of formation to its return to the bloodstream.

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Step 2: Understand the structure and function of lymph nodes. __ Identify the primary locations of lymph nodes in the body. __ Explain how lymph nodes function as lymphatic organs. __ Diagram a simple flowchart of the pathway of lymph into, through, and out of a lymph node. __ Define and distinguish the anatomical terms afferent and efferent, hilum, and sinus and sinusoid.

Step 3: Understand the structure and function of lymphocytes in the immune system. __ Define and describe lymphocytes. __ Distinguish T cells from B cells, explaining how each attacks antigens. __ Explain the recirculation of lymphocytes, including its function. __ Explain the three stages in the activation of lymphocytes: origination, development of immunocompetence, and antigen encounter. __ Distinguish effector lymphocytes from memory lymphocytes. __ Explain the important difference between natural killer cells and cytotoxic T cells. __ Explain why helper T cells can be called “managers of the immune system.”

Step 4: Understand the structure and function of lymphoid tissues. __ Identify the type of tissue that makes up lymphoid tissue. __ Summarize the basic characteristics of lymphoid tissues, including their locations. __ Relate the structure of lymphoid tissue to its infection-fighting function. __ Define MALT. __ Relate the structure of a lymphoid nodule to its immune function. __ Distinguish lymph nodes from aggregated lymphoid nodules.

Step 5: Understand the structure and function of lymphoid organs. __ List structures classified as lymphoid organs. __ Describe the anatomical location of each of the listed lymphoid organs. __ Describe the significant histological features of each of the listed lymphoid organs. __ Describe the immune functions of each of the listed lymphoid organs. __ Compare the functions of a lymph node to the functions of the spleen. __ Distinguish the red pulp from the white pulp of the spleen. __ Identify lymphoid organs described as parts of MALT.

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Step 6: Identify some specific disorders of the lymphatic and immune systems and explain the effects of aging. __ Read A Closer Look: AIDS: The Modern-Day Plague? in Chapter 21 of the textbook and summarize the social, medical, and economic implications of the disease. __ Explain a simple way to identify an enlarged spleen, and describe the ramifications of a ruptured spleen. __ Outline the development of the lymphatic vessels and lymphoid organs. __ Explain why the effectiveness of the immune system declines with age.

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The Respiratory System

Lecture and Demonstration Objectives 1. Identify the respiratory passageways in order, from the nose to the alveoli in the lungs.

Distinguish the structures of the conducting zone from those of the respiratory zone.

2. List and describe the numerous structures that protect the respiratory system from dust, bacteria, food particles, and other foreign matter.

3. Identify and describe the functions of the respiratory structures located in the skull.

4. Identify the boundaries of the three regions of the pharynx and the structures located in each region.

5. Describe the structure and functions of the larynx.

6. Describe the macroscopic and microscopic structure of the trachea.

7. Explain how the walls of the upper respiratory passages differ histologically from those in the lower parts of the respiratory tree.

8. Describe the structure of a lung alveolus and of the respiratory membrane.

9. Describe the gross structure of the lungs and the pleurae.

10. Explain the relative roles of the respiratory muscles, pleural cavity, and lung elasticity in the act of ventilation.

11. Define surfactant, and explain its function in ventilation.

12. Explain how the brain and peripheral chemoreceptors control the ventilation rate.

13. Consider the causes and consequences for respiration of asthma, cystic fibrosis, chronic bronchitis, emphysema, and lung cancer.

14. Trace the development of the respiratory system in the embryo and fetus.

15. Describe the normal changes that occur in the respiratory system from infancy to old age.

Suggested Lecture Outline I. Functional Anatomy of the Respiratory System (pp. 678–696, Figs. 22.1–22.13, Table 22.1) A. Respiration involves the following processes: pulmonary ventilation, external respiration, transport of respiratory gases, and internal respiration.

B. The function of the respiratory system is to supply the body with oxygen and dispose of carbon dioxide. (p. 678) 1. The Nose and Paranasal Sinuses (pp. 679–683, Figs. 22.1–22.4, Table 22.1) ..

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2. The nose and paranasal sinuses are functional organs of the respiratory system. a. The nose and nasal cavity provide an airway for respiration and house olfactory receptors. b. Respiratory mucosa lines the nasal cavity and paranasal sinuses. c. Nasal conchae increase turbulence as air passes through the nasal cavity. d. Paranasal sinuses drain into the nasal cavity.

B. The Pharynx (p. 683, Figs. 22.1, 22.3, Table 22.1) 1. The funnel-shaped pharynx connects the nasal cavity and the oral cavity to the larynx and esophagus; three parts of the pharynx are the nasopharynx, the oropharynx, and the laryngopharynx.

C. The Larynx (pp. 683–686, Figs. 22.5, 22.6, Table 22.1) 1. The larynx is the voice box and entryway into the trachea. a. The larynx contributes significantly to voice production. b. The vocal folds of the larynx may act as a sphincter to prevent the passage of air. c. Innervation of the larynx is served by recurrent laryngeal nerves that are branches of the vagus.

D. The Trachea (pp. 686–688, Fig. 22.7, Table 22.1) 1. The trachea is the “windpipe” connecting the larynx to the primary bronchi.

E. The Bronchial Tree (pp. 688–691, Figs. 22.8–22.10, Table 22.1) 1. The right and left primary bronchi are the largest conduits for air in the conducting zone of the bronchial tree. a. Secondary bronchi (lobar bronchi) enter each lobe of the right and left lung. b. Segmental bronchi branch from the secondary bronchi to serve each lung segment.

2. Important changes in connective tissues, epithelium, and smooth muscle occur along the length of the conducting zone of the bronchial tree.

3. The respiratory zone is the distal end of the respiratory tree and contains respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli. Additionally, alveoli contain type 2 alveolar cells, which secrete surfactant and alveolar macrophages and trap and remove inhaled particles.

F. The Lungs and Pleurae (pp. 691–696, Figs. 22.11–22.13) 1. Lungs, the primary organs of respiration, are covered by pleurae. a. Parietal pleura lines the thoracic cavity, and visceral pleura is in direct contact with the surface of the lung.

2. Gross anatomical features of the lung include the base and apex, lobes and fissures, hilum and root, and cardiac notch of the left lung.

II. Ventilation (pp. 696–699, Figs. 22.14–22.16) A. The Mechanism of Ventilation (pp. 696–698, Fig. 22.14) 1. The mechanism of breathing (pulmonary ventilation) consists of two phases: inspiration and expiration.

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a. Inspiration is the active process by which the diaphragm and intercostal muscles contract, increasing thoracic volume and decreasing pressure within the lungs.

Deep inspiration additionally involves the actions of the scalenes and sternocleidomastoid muscles, the pectoralis minor, the quadratus lumborum, and the erector spinae muscles. b. Quiet expiration is chiefly a passive process involving the relaxation of intercostal muscles and the diaphragm, decreasing thoracic volume and increasing pressure within the lungs. Forced expiration is an active process that involves the actions of the oblique and transverse abdominis muscles.

B. Neural Control of Ventilation (pp. 698–699, Figs. 22.15, 22.16) 1. The brain’s most important respiratory center is in the reticular formation of the medulla oblongata, but it receives modification from receptors that sense the chemistry of the blood.

III. Disorders of the Respiratory System (pp. 699–702, Figs. 22.17, 22.18) A. Bronchial Asthma (pp. 699–702, Figs. 22.17, 22.18) 1. Asthma is a type of allergic inflammatory response that occurs in people who are hypersensitive to irritants in the air or to stress.

B. Cystic Fibrosis 1. Cystic fibrosis is an inherited disease in which the functions of exocrine glands are disrupted throughout the body.

C. Chronic Obstructive Pulmonary Disease 1. Chronic obstructive pulmonary disease is a category of disorders in which the flow of air into and out of the lungs is difficult or obstructed.

IV. The Respiratory System Throughout Life (pp. 702–703, Fig. 22.19) A. Embryologically, the nasal cavity develops from the olfactory placodes; the pharynx forms as part of the foregut; and the lower respiratory tubes grow from an outpocketing of the embryonic pharynx.

B. As humans age, the nose becomes dryer and the thorax becomes more rigid; lungs become less elastic.

Lecture Hints 1. Introduce the respiratory system as the first one of four internal organ systems lined by mucosa and possessing openings to the external surface of the body; the other systems with external openings and mucosae are the digestive, urinary, and reproductive systems.

2. Distinguish external (systemic) respiration from internal (cellular) respiration. (Refer to basic texts covering general biology, cell biology, or physiology for details of cellular respiration.)

3. Using Figure 7.11, review the locations of the paranasal cavities in the skull, and remind students that the paranasal cavities not only open into the nasal cavity but also are lined with the same mucosa and perform similar air-processing functions.

4. Comment on the location of the maxillary paranasal sinus opening; explain the significance of the opening’s not being optimally positioned for easy drainage into the nasal

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cavity when the head is upright as well as the unfortunate drainage of the frontal and ethmoidal sinuses into the maxillary sinus.

5. Explain the passageways and openings between the ears, nose, and throat that invading bacteria may travel. (Refer to the Art Exercises for several examples.)

6. Define Valsalva’s maneuver, explaining how closing of the glottis along with abdominal muscle contraction aid in urination, defecation, and childbirth.

7. Stress the anatomical structure and function of the trachea, explaining its relationship to the esophagus and the vertebral column, and explain the significance of the C-shaped rings of cartilage and the trachealis.

8. Construct a flowchart diagram showing the air pathway from a primary bronchus to the terminal bronchioles, explaining the transition from gross anatomical structures to microscopic anatomical structures and summarizing changes in bronchial wall tissue composition as the conducting tubes become smaller.

9. Stress the difference between ventilation and respiration.

10. Describe the differences in muscles used for quiet inspiration and forced inspiration and the differences in quiet expiration and forced expiration. Ask students for examples of when they use each type of inhalation and exhalation.

11. Show slides of the bones of the skull to illustrate the relationship between the bony and soft tissue structures of the respiratory system.

12. Spend some time with diagrams and photographs of the conducting zone, reinforcing the three-dimensional anatomy of the upper-airway structures.

13. Point out the characteristics of the epithelia that line the conducting airways, explaining why those epithelia are the correct choice for that particular area. This will reinforce epithelial types and gradually establish an intuitive sense in the students so they can predict epithelia for any location in the body.

14. Students often have the misconception that the oxygen level is the principal stimulant of respiration. Emphasize that the carbon dioxide level is the most important factor.

Classroom Discussion Topics and Activities 1. Demonstrate the respiratory organs using a model of a human torso and/or a model of the respiratory system.

2. Display preserved human respiratory structures.

3. Demonstrate respiratory structures using a dissected cat or mink.

4. Identify a source for fresh lung tissue, and, if possible, obtain a fresh thoracic pluck (lungs plus attached trachea and heart). Make a small incision in the trachea, insert a straw, pinch off the trachea, and blow through the straw to demonstrate the elasticity and inflation of fresh lung tissue. An alternative to the straw is compressed air and an attached hose. Students are amazed at the difference between preserved tissue and fresh tissue. Fresh lung tissue may be frozen and thawed several times before it “expires.”

5. Demonstrate the cohesive effect that exists between the two pleural layers (parietal pleura lining the thoracic wall and visceral pleura covering the lungs) by placing a drop of water on a glass slide and then covering it with a second glass slide. Demonstrate the slides moving easily from side to side and the difficulty pulling them apart directly.

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6. Demonstrate the changing pressures in the thorax as the diaphragm contracts and relaxes, using a “model lung.” Use a bell jar with balloon “lungs” attached to a glass “Y” tube inserted into a one-hole stopper in the top of the bell jar. Cover the bottom of the jar with flexible elastic sheeting to simulate the diaphragm.

7. Instruct students to relax, close their eyes, and take a few deep breaths. Ask them to focus on breathing and to identify the nostril through which air is flowing faster.

8. Compare the vocal cords to guitar strings to explain pitch and intensity of sound. Ask students to explain why men have deeper voices than boys or women.

9. Enter class one day with a toilet seat (which in itself is quite an attention getter!). Put the toilet seat on a table in front of the students, stand an open book upright on the back part of the ringlike seat, lift up the toilet lid, and say, “This lid is the epiglottis.” Ask the students to identify the laryngeal structures represented by the open book (thyroid cartilage) and the ringlike seat (cricoid cartilage).

10. Demonstrate the locations of the paranasal sinuses using a midsagittal-cut half skull.

Tell students to observe their own frontal paranasal sinuses by shining a flashlight on their faces just below the eyebrows while they are looking in a mirror in a darkened room. Maxillary sinuses also are evident by shining light into the oral cavity and closing the mouth around the flashlight.

11. Obtain fresh animal blood from a veterinary science facility. Using rubber tubing, bubble air through the blood to demonstrate the color change that occurs when hemoglobin is well oxygenated.

12. Display visual aids comparing healthy lung tissue and cancerous or emphysematous lung tissue, and discuss with the class how an individual who has never smoked can get lung cancer.

13. Ask students why respiratory infections are more common than infections of most other organ systems.

14. Discuss with students how the pseudostratified ciliated columnar epithelium in the respiratory tract is adapted for its function of filtering air, and explore the effects of nicotine from cigarette smoke on the lining of the respiratory tract.

15. Instruct students to prepare an answer for the following question: Why is it desirable (and smart) to practice a sport at high altitudes (such as Denver) for a few weeks before an athletic event held in the high mesa of Mexico City?

16. Demonstrate how to perform the Heimlich maneuver to alleviate choking.

17. Invite a health professional to class to demonstrate and discuss artificial respiration (mouth-to-mouth/nose resuscitation).

18. Ask students to explain what fills the space when a lung is removed surgically.

Clinical Questions 1. Why do asthmatic people have difficulty breathing? How does epinephrine provide relief?

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2. Yvonne had been suffering through a severe cold and was complaining of a frontal headache and a dull, aching pain at the side of her face. What regions have become sites of secondary infection following respiratory infection of Yvonne’s nasal cavity?

Answer: Following nasal infection, the paranasal sinuses can become infected. Yvonne’s frontal and maxillary sinuses were hurting.

3. Mr. Rowel has tuberculosis of the right lung. In an effort to rest his lung and promote recovery, the doctor injects a measured amount of air into the pleural cavity, a procedure called “artificial pneumothorax.” How does this rest the lung? Is it permanent? Explain.

Answer: In artificial pneumothorax, the pressure of the air in the pleural cavity causes the lung to collapse, making it unable to expand and recoil, so its ventilatory movements cease. No longer subjected to the stresses of expansion and contraction, the lung can rest and recover. The pneumothorax is not permanent because air can be drawn out of the pleural cavity with chest tubes, permitting the lung to reinflate and resume its normal function.

4. Alvin, a smoker, sees his doctor because he has a persistent cough and becomes short of breath after very little exertion. He has a barrel chest and a red face, and he explains that it is difficult for him to exhale but not to inhale. What diagnosis will the doctor make?

Answer: Alvin has the symptoms of emphysema.

5. Mr. Rasputin agitated a bee’s nest while making repairs to his roof. As expected, he promptly was stung several times. Because he knew he was allergic to bee stings, he rushed to the hospital. While waiting, he went into a state of shock and had extreme difficulty breathing. Examination showed his larynx to be edematous, and a tracheotomy was performed. Why is edema of the larynx likely to obstruct the airway? What is a tracheotomy, and what purpose does it serve? Why will Mr. Rasputin remain in the hospital for a while?

Answer: The larynx functions to provide an open airway to the trachea and lungs. Edematous swelling of the mucosa of the larynx will close the airway, blocking all air entering the trachea. Tracheotomy is a surgical incision into the trachea through the anterior neck. It allows air to reach the lungs when the larynx is blocked. Mr. Rasputin will have to remain in the hospital until the swelling subsides and the larynx once again becomes patent, for a tracheotomy is only a temporary measure.

Art Resources Figure 22.1 Figure 22.2 Figure 22.3 Figure 22.4 Figure 22.5 Figure 22.6 Figure 22.7 Figure 22.8 Figure 22.9 Figure 22.10 276

The major respiratory organs.

External nose.

The upper respiratory tract.

Nasal conchae and paranasal sinuses.

Anatomy of the larynx.

Movement of the vocal cords.

Tissue composition of the tracheal wall.

The bronchi in the conducting zone.

Structures of the respiratory zone.

Alveoli and the respiratory membrane.

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Figure 22.11 Figure 22.12 Figure 22.13 Figure 22.14 Figure 22.15 Figure 22.16 Figure 22.17 Figure 22.18 Figure 22.19 Table 22.1 A Closer Look

Anatomical relationships of organs in the thoracic cavity.

Bronchopulmonary segments.

Position of the lungs and the pleural cavities in reference to the thoracic cage.

Changes in thoracic volume and sequence of events during inspiration and expiration.

Respiratory centers in the brain stem.

Location and innervation of the peripheral chemoreceptors in the carotid and aortic bodies.

The pathogenesis of chronic obstructive pulmonary disease.

Alveolar changes in emphysema.

Embryonic development of the respiratory system.

Principal Organs of the Respiratory System Lung Cancer: The Facts Behind the Smoke Screen

Teaching with Art Figure 22.3

The upper respiratory tract.

Textbook p. 681.

Checklist of Key Points in the Figure • Identify conducting-zone structures, distinguishing upper respiratory structures from lower respiratory structures, explaining their functions, and stressing differences between the pharynx and larynx.

• Distinguish the external nose from the internal nasal cavity.

• Point out precise locations of tonsils forming a ring of protection for the pharynx entrance, reminding students of their immune system function.

• Distinguish the hard palate from the soft palate.

• Discuss the mechanics of preventing food from entering the trachea during swallowing.

• Explain the anatomy of the larynx, and point out the structures that aid in sound production.

• Compare the structure of the trachea to the esophagus.

• Distinguish respiratory mucosa from olfactory mucosa, explaining that different types of epithelium are located along the respiratory tract.

Common Conceptual Difficulties Interpreting the Art • Remind students that some respiratory tract openings are very evident, whereas others are not, such as those of the paranasal sinuses.

• Clearly distinguish the external nares from the internal nares (choanae).

• Clearly distinguish choanae from fauces.

• Identify each region of the pharynx, explaining where and how air and food share a common passageway.

• Continue to reinforce the concept of structures functioning as organs.

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Art Exercises Provide students with several unlabeled copies of Figure 22.3. Instruct students to do the following exercises: 1. Epithelium Exercise: Color code the regions of different types of epithelium in the respiratory mucosa lining the structures in the figure. Provide students with the names of different types of epithelium and color assignments (or instruct students to identify epithelial types on their own as part of the exercise). Ideally, students will identify the following: a. Vestibule of the nasal cavity (lined with skin)—keratinized stratified squamous epithelium of the epidermis b. Roof of the nasal cavity (and covering of the superior nasal conchae and the superior part of the nasal septum)—specialized olfactory epithelium (composed of pseudostratified columnar epithelium) c. Rest of the nasal cavity—pseudostratified ciliated columnar epithelium d. Paranasal sinuses—pseudostratified ciliated columnar epithelium e. Nasopharynx—pseudostratified ciliated columnar epithelium f. Oropharynx—stratified squamous epithelium g. Laryngopharynx—stratified squamous epithelium h. Larynx, superior to the vocal folds (true vocal cords)—stratified squamous epithelium i. Larynx, inferior to vocal folds—pseudostratified ciliated columnar epithelium j. Trachea—pseudostratified ciliated columnar epithelium 2. Openings Exercise: Using an unlabeled copy of Figure 22.3, instruct students to identify all openings and passageways that provide a method of communication from the nasal cavity and the pharynx to some other place in the body. Explain to students that some of the openings are obvious, such as the opening of the pharyngotympanic tube, and that others are not obvious, such as those of the paranasal sinuses. Ideally, students will identify the following openings: perforations of the cribriform plate of the ethmoid, all the paranasal sinuses, the opening of the nasolacrimal duct, internal nares (choanae), external nares (nostrils), the pharyngotympanic tube, fauces, the laryngeal entrance, and the esophageal entrance.

3. Passageway Exercise: Using an unlabeled copy of Figure 22.3, instruct students to trace the movement of air from the nostrils to the larynx, labeling the structures air passes through.

Critical Reasoning 1. Instruct students to look at their colored figure of the Epithelium Exercise (1) and to determine the direction the cilia propel dusty mucus in the following regions: a. Nasopharynx Answer: Mucus is propelled downward. b. Larynx, inferior to the vocal folds Answer: The power stroke of cilia is directed upward, toward the pharynx.

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2. Instruct students to look at their labeled figure of the Openings Exercise (2) and to construct a flowchart identifying all possible channels of communication for disease organisms from the nasal cavity to other places in the body.

Answer:

nasal cavity → cranial cavity nasal cavity → paranasal sinuses nasal cavity → nasolacrimal duct → orbit nasal cavity → pharynx → oral cavity nasal cavity → nasopharynx → middle ear nasal cavity → pharynx → larynx → (lungs) nasal cavity → pharynx → esophagus → (digestive tract)

3. Referring students to the labeled Passageway Exercise (3), ask why it is possible for a feeding tube inserted into a patient’s nostril to end up in the stomach.

Answer: The laryngopharynx is a common passageway for food and air with an opening into the esophagus, and when the patient swallows the tube during insertion, it is directed into the esophagus (not the larynx) and ultimately enters the stomach.

Supplemental Course Materials Library Research Topics 1. Research and list the respiratory diseases caused by inhalation of toxic particles associated with specific occupations, such as coal mining and working in an asbestos factory.

2. Research the incidence of cancer in smokers versus nonsmokers and in people working in respiratory-hazard areas versus those working in safe respiratory areas.

3. Research the current status of heart-lung transplants and the circumstances under which such a transplant is possible.

4. Research the causes, known and supposed, of sudden infant death syndrome.

5. What treatments are used to keep infants with respiratory distress syndrome alive?

Suggested Readings Beall, Cynthia M., et al. “Pulmonary Nitric Oxide in Mountain Dwellers.” Nature 414 (November 2001): 411–412.

Christensen, Damaris. “The Persistent Problem of Cystic Fibrosis.” Science News 161 (4) (January 2002): 59–60.

Fawcett, D. W. A Textbook of Histology. 12th ed. New York: Chapman & Hall, 1997, Chapter 29.

Moore, K. L. Clinically Oriented Anatomy. 6th ed. Baltimore: Lippincott Williams & Wilkins, 2009.

Ward, J. P. T, J. Ward, and R. M. Leach. The Respiratory System at a Glance. 3rd ed.

Hoboken, NJ: Wiley-Blackwell, 2010.

West, J. B. Respiratory Physiology: The Essentials. 9th ed. Baltimore: Lippincott Williams, & Wilkins, 2012.

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Answers to Textbook Questions Answers to multiple-choice and matching questions 1–10 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 11. Expired air travels from an alveolus in an alveolar sac, alveolar duct, or respiratory bronchiole to a terminal bronchiole, larger bronchioles, many orders of bronchi, trachea, larynx, pharynx (laryngopharynx, oropharynx, nasopharynx), choanae, nasal cavity, and external nares. The first four of these structures, which have alveoli, are in the respiratory zone (alveolus, alveolar sac, alveolar duct, respiratory bronchiole); all the other, larger structures are in the conducting zone. (pp. 679–691) 12. All these cilia propel sheets of mucus that trap dust from the inhaled air. The beat directions propel the mucus down to the pharynx from upper respiratory passages and up to the pharynx from lower respiratory passages. In both cases, this dusty mucus is swallowed and disposed of through the digestive tract. (p. 680) 13. These elastin fibers are largely responsible for quiet expiration. At the end of inhalation, the recoil of the elastin fibers helps decrease the volume of the lungs and thorax. This raises the pressure within the lungs, and air moves along its pressure gradient out of the lungs (= expiration). (pp. 691 and 697) 14. The three main functions of the nose are: (1) providing an airway for respiration; (2) filtering inhaled air to cleanse it of foreign particles; (3) housing the olfactory (smell) receptors. (pp. 679–680) 15. Accidentally inhaled objects are likely to be lodged in the right lung. This is because the right main bronchus is wider, shorter, and more vertical than the left (p. 694, Fig. 22.12) 16. A choana is an internal nostril, an opening between nasal cavity and nasopharynx (p. 680). A concha is a mucosa-covered, scroll-shaped bone that projects into the nasal cavity (p. 682). The carina is a mucosa-covered ridge on the last tracheal cartilage that is sensitive to irritation. (p. 687) 17. Softness or loudness of the voice depends on the force with which air rushes across the vocal folds. The greater the amount of force, the stronger the vibrations are, and louder the sound. The entire length of the pharynx acts as a resonating chamber to amplify the quality of sound. Moreover, the oral cavity, nasal cavity, and paranasal sinuses also contribute to vocal resonance. (p. 686) 18. The picture should resemble that in Figure 22.11 and should show the following: Right lung: upper, middle, and lower lobes; horizontal and oblique fissures. Left lung: upper and lower lobes; oblique fissure and cardiac notch.

19. The pulmonary arteries deliver oxygen-poor blood to the lungs for oxygenation across the pulmonary capillaries (a part of the respiratory membrane) before it is returned back to the heart. The bronchial arteries deliver oxygen-rich blood to the lung tissue itself. (pp. 691, 694) 20. Macrophages phagocytize the finest suspended particles in the inhaled air. (p. 691)

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Critical Reasoning and Clinical Applications Questions 1. (a) Normally, during swallowing, the soft palate reflects superiorly to seal the nasopharynx and prevent food or drink from entering the nasal cavity. During giggling, however, this sealing mechanism sometimes fails to operate (because giggling demands that air be forced out of the nostrils), and swallowed fluids may enter the nasal cavity and then exit through the nostrils. (b) Even though standing on his head, the boy made certain that he swallowed carefully so that his soft palate did correctly seal the entrance to his nasal cavity. Then, his swallowing muscles directed the milk through his esophagus to the stomach, against gravity. (p. 683) 2. Adjacent bronchopulmonary segments are separated from one another by partitions of dense connective tissue, which no major vessels cross. Therefore, it is possible for a surgeon to dissect adjacent segments away from one another. The only vessels that had to be cauterized were the few main vessels to each bronchopulmonary segment. (p. 691) 3. Olivia delivered a premature baby suffering from respiratory distress syndrome (RDS).

Prematurity is associated with inadequate production of surfactant in the lungs of the baby. Surfactant, produced by type II alveolar cells, helps in reducing surface tension in the alveoli and prevents the inner walls of the alveolus from sticking together during exhalation. (p. 698) 4. (a) The increase in blood acidity will be detected by chemoreceptors, located in the medulla oblongata and the aortic and carotid bodies. (b) The increase in carbon dioxide levels will cause a reflex via the respiratory centers to increase the rate and depth of respiration. With increased respiration, the body tries to get rid of the extra carbon dioxide in the blood. (p. 698) 5. Loren is suffering from post-pneumonia pleurisy (pleuritis) which is caused by inflammation of the two layers of the pleura. During breathing, the friction produced by the rubbing of the two layers of the inflamed pleura causes a sharp stabbing chest pain. Pain is produced mainly from the parietal pleura, as the visceral pleura are relatively pain insensitive. (p. 695) 6. Mr. Smith is suffering from emphysema because of chronic smoking-induced inflammation of the lungs. Smoking causes increased activity of lung macrophages and neutrophils, which produce enzymes that destroy alveolar walls. It is also accompanied by increased lung fibrosis that makes the lungs less elastic and results in the trapping of air during exhalation. This causes the characteristic barrel chest appearance. (p. 701)

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Interpreting Medical Images Questions Answers to Interpreting Medical Images questions are provided in the Instructor Resources area of Mastering A&P.

Figure 22.3: Figure 22.4: The middle nasal concha (ethmoid bone) and the inferior nasal conchae (inferior nasal conchae bones) are viewable in the MRI in Figure 7.15a.

Figure 22.11: The black structures in the CT shown in Figure 1.11 are the right and left lungs. The diaphragm, separating the thoracic cavity from the abdominal cavity, is attached to the xiphoid process of the sternum anteriorly, the costal cartilages of vertebrae T6–T12 anterolaterally, and the bodies of the upper lumbar vertebra posteriorly. A section through the T10 region will show abdominal organs (anteriorly) and the inferior portions of the lungs (posteriorly).

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 22: The Respiratory System To the Student The respiratory system is responsible for delivery of air to your lungs, where gas exchange occurs. Within lung tissue, oxygen is picked up by the bloodstream, and the waste product, carbon dioxide, is removed from the bloodstream for disposal via the same air tubes. This life-sustaining interaction between the cardiovascular system and the respiratory system provides the oxygen that every cell needs for its survival. If your cells are deprived of oxygen and die, tissues die, and ultimately you “suffocate” in a matter of minutes. The use of oxygen by cells for obtaining energy from food molecules such as glucose is termed cellular respiration, and this is a completely different topic from systemic respiration covered in this chapter.

Do not confuse the two concepts.

This chapter has several key concepts and focal points explaining how the respiratory system interacts with other organ systems in your body, not just the cardiovascular system.

Additionally, the mucosal lining of the respiratory system provides an excellent avenue for disease organisms to travel along, and the many openings and passageways of the nasal cavity to other parts of the body provide disease organisms with a ready-made entry to those regions.

You will find that incorporating Practice Anatomy Lab 3.0 (PAL) (BC; DVD, Website) into your studies of the respiratory system will give you an excellent opportunity to review the organs of the respiratory system. You will find the Respiratory System sections of the Cadaver and Anatomical Models modules particularly helpful. For a review of photomicrographs of respiratory tissues, study the slides in the Respiratory System section of the Histology module. You may access PAL 3.0 through the DVD or the Mastering A&P Website.

Step 1: Describe the functional anatomy of the principal organs of the respiratory system. __ For each of the following principal organs of the respiratory system, provide a general anatomical description, and note any distinctive features: nose, pharynx, larynx, trachea, bronchial tree, alveoli, lungs, and pleurae. __ Describe the function of each of the listed principal organs of the respiratory system. __ Distinguish the structures of the conducting zone from the structures of the respiratory zone.

Step 2: Describe the mucosa of the respiratory tract. __ Identify the lining of the respiratory tract, name the major type of epithelium associated with the tract, discuss its functions, and define goblet cells. __ Distinguish respiratory mucosa from olfactory mucosa.

Step 3: Describe the nose and nasal cavity. __ Describe the bony framework of the nasal cavity, including the functions of conchae. __ Discuss locations and functions of the paranasal sinuses. ..

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__ Define and distinguish choanae and fauces.

Step 4: Describe the pharynx, larynx, and trachea. __ Describe the structure and function of the pharynx, including regions, openings, tonsils, and location. __ Describe the structure and function of the larynx, including cartilages, sound (voice) production, sphincter functions, and innervation. __ Explain the mechanics of swallowing and how food is prevented from entering the nasopharynx and larynx. __ Relate the sphincter functions of the larynx, that is, the closing of the glottis and abdominal muscle contractions (Valsalva’s maneuver), to the functions of the urinary, digestive, and reproductive systems. __ Describe the structure and function of the trachea, including its anatomical relationship to the esophagus and vertebral column, trachealis, and wall tunics. __ Define carina (and be careful not to confuse it with concha or choana).

Step 5: Describe the bronchial tree. __ Discuss the structure and function of the bronchial tree, beginning with primary bronchi and ending with terminal bronchioles, distinguishing bronchi in the conducting zone from bronchi in the respiratory zone. __ Describe the anatomy of the alveoli, and discuss gas exchange, the blood-air barrier, and other significant features. __ List tissue changes that occur in the bronchial wall as air tubes progressively become smaller.

Step 6: Describe the lungs and pleurae. __ Review the difference between the serous membrane and the mucous membrane. __ Distinguish visceral pleura from parietal pleura, pleural cavity, and pleural fluid, and draw and label a diagram of these structures in the thoracic cavity. __ Draw a right lung and a left lung, labeling gross anatomical features. __ Define mediastinum, and explain the anatomical relationships of organs in the thoracic cavity. __ Review pulmonary circulation, and describe blood supply to the lung tissue itself. __ Name the plexus of innervation to the lungs.

Step 7: Explain the mechanism of ventilation (breathing). __ Describe the mechanical aspects of inspiration and expiration, summarizing changes in the thoracic volume, the action of the diaphragm, and the action of intercostal muscles. __ Explain why surface tension of the alveolar fluid does not collapse the microscopic alveoli after each breath. (Hint: Do you remember the role of surfactant?) __ Explain the neural control of ventilation, including the location of the respiratory center in the brain and the types of monitoring chemoreceptors.

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Step 8: Read about the major disorders of the respiratory system covered in your textbook, study in detail disorders assigned by your instructor, and consider changes in the respiratory system throughout life. __ Read this chapter’s A Closer Look: Lung Cancer: The Facts Behind the Smoke Screen. __ Describe the symptoms and causes of bronchial asthma. __ Describe the symptoms and causes of cystic fibrosis. __ Explain the significance of a nosebleed from the posterior nasal cavity as opposed to a nosebleed from the anterior part of the nasal cavity. __ Summarize prenatal, postnatal, and aging changes that occur in the respiratory system.

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CHAPTER

23

The Digestive System

Lecture and Demonstration Objectives 1. Describe the overall function of the digestive system, and differentiate the alimentary canal from the accessory digestive organs.

2. Draw the major subdivisions of the anterior abdominal wall, and identify the organs located in each region.

3. Explain the location and function of the peritoneum and peritoneal cavity. Define mesentery.

4. Differentiate between intraperitoneal and secondarily retroperitoneal digestive organs.

Name the mesenteries associated with the intraperitoneal digestive organs.

5. List the major processes that occur during digestion.

6. Describe the four layers of the wall of the alimentary canal.

7. Describe the structure and appearance of smooth muscle fibers, and describe how smooth muscle cells are joined together to form a sheetlike tissue.

8. Discuss the different stimuli that can initiate the contraction of smooth muscle tissue.

9. Describe the innervation of the muscle and glands in the alimentary canal.

10. Describe the gross and microscopic anatomy and the basic functions of the mouth, teeth, salivary glands, and pharynx.

11. Describe the gross and microscopic anatomy of the esophagus.

12. Describe the gross and microscopic anatomy of the stomach.

13. Relate the histological modifications in the wall of the stomach to the digestive activities that occur there.

14. Describe the gross and microscopic anatomy of the small and large intestine.

15. Relate the individual histological modifications in the wall of the intestines to the digestive activities of these regions.

16. Describe the gross and microscopic anatomy and functions of the liver, gallbladder, and pancreas.

17. Describe some disorders of the digestive organs.

18. Explain how the digestive organs develop in the embryo, and define the foregut, midgut, and hindgut.

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Suggested Lecture Outline I. Overview (pp. 708–715, Figs. 23.1–23.6, Table 23.1) A. The digestive system is divided into two anatomical and functional groups: the alimentary canal and the accessory organs of digestion.

1. Abdominal Regions (p. 709, Fig. 23.2) B. The abdominopelvic cavity is divided into nine regions or, by another scheme, into four quadrants. These divisions aid in describing the locations of abdominopelvic organs.

1. The Peritoneal Cavity and Peritoneum (pp. 712–714, Figs. 23.3, 23.4, Table 23.1) a. The digestive organs in the peritoneal cavity developed surrounded by peritoneum.

Visceral peritoneum covers most abdominal organs and is continuous with the parietal peritoneum. b. Mesenteries are formed from a double layer of peritoneum and function to hold abdominal organs in place, store fat, and allow passage of blood vessels and nerves to and from digestive organs.

C. Digestive Processes (pp. 714–715, Figs. 23.5, 23.6) 1. Digestive processes of the digestive system are ingestion, propulsion, mechanical breakdown, digestion, absorption, and defecation.

II. Anatomy of the Alimentary Canal (pp. 715–738, Figs. 23.6–23.24) A. Histology (pp. 715–717, Fig. 23.7) 1. Histologically, the walls of the alimentary canal have the same four tissue layers. a. The mucosa is a mucous membrane and the innermost layer of the alimentary canal. b. The submucosa is a layer of fibrous connective tissue external to the mucosa that contains blood vessels, lymph vessels, and nerves. c. The muscularis externa contains two layers of smooth muscle: the circular and longitudinal layers. d. The serosa is the visceral peritoneum.

B. Smooth Muscle (pp. 717–719, Figs. 23.8–23.10) 1. Smooth muscle layers form the muscularis externa in the wall of the alimentary canal.

Smooth muscle cells are elongated, with tapering ends and one central nucleus.

Smooth muscle in the alimentary canal is arranged in sheets: usually an outer longitudinal layer and an inner circular layer. The stomach contains an additional oblique layer of smooth muscle. Smooth muscle contracts more slowly than skeletal muscle and is under the control of involuntary nerve fibers.

2. The myenteric plexus and submucosal nerve plexus are the visceral nerve plexuses supplying the wall of the alimentary canal. Parasympathetic, sympathetic, visceral sensory fibers, and enteric neurons comprise these plexuses.

C. The Mouth and Associated Organs (pp. 719–724, Figs. 23.11–23.15, Focus Figure 23.24) 1. The mouth is a mucosa-lined cavity whose boundaries are the lips anteriorly, the palate superiorly, the cheeks laterally, and the tongue inferiorly.

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a. The lining of the mouth is stratified squamous epithelium, with some keratinization on the tongue, palate, lips, and gums. b. The lips and cheeks are formed primarily by the orbicularis oris and buccinator muscles, respectively. c. The palate has two distinct parts: the hard palate and the soft palate. d. The tongue is composed of intrinsic muscles that function in changing the shape of the tongue and extrinsic muscles that act to extend, protract, retract, and move the tongue laterally. The fungiform and vallate papillae on the dorsal surface of the tongue contain taste buds. e. The teeth tear and grind food. Humans have two sets of dentition, the primary dentition (deciduous teeth) and the permanent dentition. Humans have a specific dental formula, a shorthand way of indicating the numbers and relative positions of the different classes of teeth. f. Major salivary glands are compound tubuloalveolar glands that produce saliva and salivary enzymes to initiate digestion and moisten the mouth.

D. The Pharynx (p. 724, Fig. 23.11, Focus Figure 23.24) 1. The pharynx is a common passageway for food and air.

E. The Esophagus pp. 724–725, Figs. 23.1, 23.11, 23.16, Focus Figure 23.24) 1. The esophagus is a collapsible tube that connects the pharynx to the stomach; microscopic anatomy reveals several unique histological features.

F. The Stomach (pp. 726–729, Figs. 23.17, 23.18, Focus Figure 23.24) 1. The stomach extends from the distal esophagus to the duodenum. Its functions include churning food into chyme and beginning protein digestion. a. Gastric glands contain three types of secretory cells: mucous neck cells, parietal cells, and chief cells. b. Two other epithelial cell types, enteroendocrine cells and undifferentiated stem cells, are found in gastric glands as well as elsewhere in the stomach.

G. The Small Intestine (pp. 729–732, Figs. 23.19, 23.20, Focus Figure 23.24) 1. The small intestine is the longest part of the alimentary canal; its subdivisions are the duodenum, the jejunum, and the ileum; microscopic anatomy reveals modifications for nutrient absorption and typical wall structure.

H. The Large Intestine (pp. 732–738, Figs. 23.21–23.23, Focus Figure 23.24) 1. The large intestine has several subdivisions: cecum, appendix, colon, rectum, and anal canal; superior and inferior mesenteric blood vessels serve the large intestine; sympathetic and parasympathetic fibers, and some somatic nerves innervate this organ; defecation occurs when rectal wall muscles contract; microscopic anatomy reveals the lack of villi.

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III. Anatomy of the Accessory Organs (pp. 738–743, Figs. 23.25–23.28) A. The Liver (pp. 738–742, Figs. 23.25–23.27) 1. The liver is the largest gland in the body, and it performs hundreds of essential functions. Its digestive function is to produce bile. Important gross features of the liver are the right and left lobes and the quadrate and caudate lobes and the falciform ligament.

The microscopic anatomy reveals the classic liver lobule. The functional cells of the liver are hepatocytes.

B. The Gallbladder (p. 742, Fig. 23.19) 1. The gallbladder functions to store and concentrate bile produced by the liver. The cystic duct and common hepatic duct join to form the bile duct, which empties bile into the duodenum.

C. The Pancreas (pp. 742–743, Figs 23.19, 23.28) 1. The pancreas is both an endocrine gland and an exocrine gland. Its digestive functions include producing most of the enzymes that digest food in the small intestine.

IV. Disorders of the Digestive System (pp. 744–745, Fig. 23.29) A. Peptic Ulcers (p. 744) 1. Ulcers are craterlike erosions of the mucosa in any region of the alimentary canal that is exposed to stomach secretions.

B. Intestinal Obstruction (p. 744) 1. Any hindrance to the movement of chyme or feces through the intestine is called intestinal obstruction.

C. Inflammatory Bowel Disease (p. 744) 1. Inflammatory bowel disease is a noncontagious, periodic inflammation of the intestinal wall characterized by chronic leukocyte infiltration of this wall.

D. Viral Hepatitis (pp. 744–745) 1. Upon infection, most types of viral hepatitis lead to flulike symptoms and jaundice (yellow skin and mucous membranes, an indication that the liver is not removing bile pigments from the blood to make bile).

E. Cystic Fibrosis and the Pancreas (p. 745) 1. Cystic fibrosis disrupts secretions in the respiratory system, but most of the body’s other secretory epithelia are affected as well, including the pancreas.

V. The Digestive System Throughout Life (pp. 745–746, Fig. 23.30) A. Embryonic Development (pp. 745–746, Fig. 23.30) 1. The week 3 primitive gut is a tube of endoderm covered by splanchnic mesoderm; the embryonic gut is divided into a foregut, midgut, and hindgut, which form distinct regions of the digestive system.

B. The Digestive System in Later Life (p. 746) 1. In later life, many disorders of the digestive system include appendicitis, gastroenteritis, food poisoning, ulcers, and gallstones; the efficiency of digestive processes declines in the elderly.

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Lecture Hints 1. Explain why the alimentary canal is shorter in a living person than in a cadaver.

2. Discuss the concept that food inside the alimentary canal is technically outside the body because the mouth and anus both open to the external environment.

3. Point out that tooth enamel is the hardest substance in the body, explain caries, and ask students whether they recall the type of joint that exists between a tooth and its socket.

4. Review the mechanics of swallowing, reminding students that the tongue is skeletal muscle and that the action is voluntary.

5. Emphasize that the esophagus has an adventitia rather than a serosa and that its muscularis externa is skeletal muscle for the first third of its length.

6. Explain why the stomach does not digest itself.

7. Stress the duodenum as the site where the bile duct and the main pancreatic duct empty their contents.

8. Stress features of the small intestine that increase its surface area, reminding students of the importance of the concept of surface area for processes such as absorption or gas exchange.

9. Emphasize structural modifications in each area of the GI tract that permit optimum digestion and absorption.

10. Present an overall summary statement about secretions made in various parts of the alimentary canal, the major salivary glands, the liver, and pancreas as derivatives from blood plasma, emphasizing the role of the large intestine in reabsorption of water and the consequences of diarrhea.

11. Remind students that the liver receives blood from two sources. Spend some time reviewing the hepatic portal system; this is an example of blood entering a capillary bed, feeding into a vein, and then another capillary bed before it returns to the general systemic circulation.

12. Caution students that some mesenteries are termed “ligaments” and not to confuse that usage with fibrous ligaments that connect bone to bone.

13. Emphasize that the amount of time the contents of the large intestine are in contact with the mucosa determines fecal water content. Too little time in the large intestine means a watery stool, and too much time results in constipation.

Classroom Discussion Topics and Activities 1. Use a dissectible model of a human torso to exhibit the digestive organs.

2. Demonstrate the digestive organs of a dissected cat or rat, or display actual human specimens, if available. Displaying a preserved cat is an excellent way to demonstrate mesenteries as well. (Students gain a greater appreciation of “gross” in gross anatomy when viewing the greater omentum and realizing they have one, too.)

3. Instruct students to touch the lateral folds of tissue immediately posterior to their lower teeth with their tongue. Ask them to identify the salivary ducts they are touching.

(Answer: Ducts of the submandibular salivary glands.)

4. Display a human skull to demonstrate different tooth shapes, types, and numbers.

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5. Demonstrate the emulsifying action of bile. Mix oil and water together and allow the layers to separate. Add bile salts and shake vigorously, explaining that oil disperses into hundreds of tiny fatty spheres because of the action of bile salts.

6. When describing the mechanics of swallowing, instruct students to touch their larynx and feel it rise when they swallow.

7. Obtain gallstones from a surgeon, and show them to the class, explaining how they form and why they are very painful.

8. Use a long, not quite fully blown-up balloon to demonstrate peristalsis, and provide a stethoscope for students to listen to sounds of digestive peristalsis.

9. Use a vacuum-cleaner hose to demonstrate gut rotation in the embryo.

10. Use a thick paperback book, opened 360 degrees so that its pages radiate out from its spine, as a model of a classic liver lobule.

11. Bring a washcloth to class, and use its nap to model intestinal villi.

12. To help students remember the important structures on the visceral surface of the liver, point out a large H on that surface. The left limb of that H is formed by the liver’s fissure, the crossbar of the H by the porta hepatis, and the right limb by the inferior vena cava superiorly and the gallbladder inferiorly. (Reinforcement of the “H” for “hepatic” also prevents careless confusion of terms hepatic and renal.)

13. Survey your class, asking students who have had their wisdom teeth removed to raise their hands. (In the textbook authors’ classes, the vast majority had undergone this operation.)

14. Discuss why it is necessary for someone with ulcer-like symptoms to consult a physician rather than just using antacids.

15. Discuss the reasons why elderly people should be checked for colorectal cancer.

16. Ask students why rabbits make “pellets” and people don’t. (A haustrum in rabbits is capable of setting up churning action independently of neighboring haustra. The human intestine does not have this capability.)

17. Ask students whether it is possible to survive without a stomach. It is. Note that vitamin B production depends on the secretion of a special polypeptide by the stomach and that B12 is needed for maturation of red blood cells, so patients with gastrectomies may develop pernicious anemia.

Clinical Questions 1. Colleen had a growth in her left parotid gland, which her physician feared might be cancerous. Surgery was done to remove the growth, which turned out to be solidified saliva that had blocked some ducts within the parotid. After the operation, some of the left side of Colleen’s face was paralyzed. Why is it difficult to avoid paralyzing the face in this kind of operation?

Answer: The facial nerve, which innervates the muscles of facial expression, radiates within the substance of the parotid gland. Some branches of this nerve are inevitably cut when surgery is performed on this gland.

2. An attorney with a severe gastric ulcer started complaining of back pain. The physician discovered that the back pain was due to damage to the pancreas. How could a perforating gastric ulcer damage the pancreas?

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Answer: The ulcer perforated through the posterior wall of the stomach, leaking stomach acids and pepsin onto the pancreas. These caustic fluids damaged the pancreas.

3. What is a hiatal hernia? What are its causes and symptoms?

Answer: A hiatal hernia is a structural abnormality in which the fundus of the stomach protrudes superiorly into the thorax through the esophageal hiatus of the diaphragm.

Gastric juices regurgitate superiorly into the esophagus. Symptoms include heartburn, inflammation of the esophagus, or esophageal ulcers.

4. A 53-year-old woman enters the emergency room complaining of severe pain in her left iliac region. She claims previous episodes (but this one is the most painful) and says that the condition is worse when she is constipated and is relieved by defecation. A large tender mass is palpated in the left iliac fossa, and a barium study reveals a large number of diverticula in her descending and sigmoid colon. What are diverticula, and what is believed to promote their formation? Does this woman have diverticulitis or diverticulosis?

Explain.

Answer: Diverticula are small herniations of the mucosa through the colon wall, a condition called diverticulosis. They are believed to form when the diet lacks bulk and the volume of residue in the colon is small. The colon narrows, and contractions of its circular muscle become more powerful, increasing the pressure on its walls and inducing the herniations. Diverticulitis is a condition in which the diverticula become infected and inflamed. The great severity of her pain suggests that the woman’s diverticulosis has developed into diverticulitis.

5. Trish goes to the emergency room with the following symptoms: severe pain in the umbilical region, loss of appetite, nausea, and vomiting. While she is waiting to see a doctor, the pain moves to her lower right abdominal quadrant. What is her probable condition?

Answer: Trish probably has appendicitis, although this condition is notoriously difficult to diagnose without more extensive testing. The treatment for appendicitis is surgical removal of the appendix.

6. The health department closed a restaurant because, for the second time in three years, more than a dozen customers who ate there developed hepatitis. How did this happen?

Answer: Restaurants occasionally have trouble with hepatitis when an infected employee transmits it to the food via a fecal route. This occurs when an employee fails to thoroughly clean hands after using the washroom.

Art Resources Figure 23.1 Figure 23.2 Figure 23.3 Figure 23.4 Figure 23.5 Figure 23.6 Figure 23.7 Figure 23.8 Figure 23.9 292

The alimentary canal and the accessory digestive organs.

Divisions of the anterior abdominal wall.

Focus on the peritoneum.

The mesenteries.

Activities of the gastrointestinal tract.

Peristalsis and segmentation.

Histological layers of the alimentary canal.

Arrangement of smooth muscle in the walls of hollow organs.

Cytoskeletal elements involved in the contraction of smooth muscle.

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Figure 23.10 Figure 23.11 Figure 23.12 Figure 23.13 Figure 23.14 Figure 23.15 Figure 23.16 Figure 23.17 Figure 23.18 Figure 23.19 Figure 23.20 Figure 23.21 Figure 23.22 Figure 23.23 Figure 23.24 Figure 23.25 Figure 23.26 Figure 23.27 Figure 23.28 Figure 23.29 Figure 23.30 Table 23.1

Innervation of smooth muscle.

Anatomy of the mouth.

The dorsal surface of the tongue.

Human dentition.

Longitudinal section of a canine tooth within its bony tooth socket.

The major salivary glands.

Microscopic structure of the esophagus.

Gross anatomy of the stomach.

Microscopic anatomy of the stomach.

The duodenum of the small intestine, and related organs.

Structural modifications of the small intestine that increase the surface area for digestion and absorption.

Gross anatomy of the large intestine.

Defecation reflex.

The mucosa of the large intestine.

Focus on digestive processes.

Anterior view of the liver.

Visceral surface of the liver (posteroinferior view).

Microscopic anatomy of the liver.

The gross and microscopic anatomy of the pancreas.

Peptic ulcers.

Development of the digestive system.

Summary of Intraperitoneal and Secondarily Retroperitoneal Digestive Organs in the Abdomen and Pelvis

Teaching with Art Figure 23.26

Visceral surface of the liver (posteroinferior view).

Figure 23.27

Microscopic anatomy of the liver.

Textbook pp. 740–741.

Checklist of Key Points in the Figure • Identify anatomical features on the visceral surface of the liver using Figure 23.26.

• Discuss and point out the various ducts bile travels through from the liver, to the gallbladder for storage, and finally to the duodenum via the common bile duct.

• Explain that bile in the common bile duct may continue directly to the duodenum or enter the cystic duct of the gallbladder for storage.

• Review the function of bile as an emulsifier of fats, not a digestive enzyme.

• Using Figure 23.27, explain how bile drains through a liver lobule, indicating its site of production, bile canaliculi, and bile ducts in the portal triads.

• Correlate the relationship of the bile ducts in the microscopic view with the hepatic ducts at the porta hepatis in the gross view.

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Common Conceptual Difficulties Interpreting the Art • Explain the location of the hepatopancreatic sphincter at the duodenum; it controls the entry of bile into the duodenum. Refer students to Figure 23.19.

• Point out that the cystic duct accommodates the flow of bile into the gallbladder for storage as well as the flow out of the gallbladder on its way to the common bile duct.

Art Exercises Provide students with unlabeled diagrams of Figures 23.19, 23.26, and 23.27. Instruct students to trace the movement of bile from its point of origin to its entry into the duodenum, including its storage in the gallbladder. Students should label all parts of the pathway. Additionally, a flowchart summarizing the same pathway may be of benefit so that coordination between diagrams is evident.

Critical Reasoning After your students study the figures, ask them to propose a sequence of events that may evolve if the cystic duct or a bile duct becomes blocked because bile became too concentrated and formed gallstones.

Answer: The first event is severe pain as the gallbladder becomes swollen and inflamed.

If the blockage does not work its way to the duodenum, the gallstones must be removed surgically, or the gallstones must be reduced in size by a procedure such as lithotripsy to ensure their passage to the duodenum. In some cases, the gallbladder must be removed as well.

Supplemental Course Materials Library Research Topics 1. Research the causes and treatments of ulcers.

2. Research the benefits of fiber in the diet.

3. Research liver transplants in terms of the rationale for the transplant, the procedure, and the prognosis.

4. Research the histological changes in the liver that accompany cirrhosis. Also research vascular changes to the hepatic portal system and other venous drainage that accompany cirrhosis of the liver.

5. Research pancreatic transplants, partial pancreatic transplants, and nanotechnology that allows turning digestive secretions on and off.

6. Research Crohn’s disease and ulcerative colitis. How are the conditions similar? How are they different?

7. Research the effects that cystic fibrosis has on the digestive system.

8. Research new methods of treating, managing, and curing gastroesophageal reflux disease (GERD).

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Suggested Readings Cormack, D. H. Essential Histology. 2nd ed. Philadelphia: Lippincott Williams & Wilkins, 2001.

Ferber, Dan. “Cracking Gut Bugs’ Cell-Skewing Strategy.” Science 294 (5550) (December 2001): 2269.

Harder, Ben. “Germs That Do a Body Good. “Science News 161 (5) (February 2002): 72–74.

Johnson, L. R. Gastrointestinal Physiology. 7th ed. St. Louis: Mosby, 2006.

Johnson, L. R., F. K. Ghishan, and J. D. Kaunitz. Physiology of the Gastrointestinal Tract, Two-Volume Set. 5th ed. Academic Press, 2012.

Junqueira, L. C., et al. Basic Histology. 12th ed. Stamford, CT: Appleton & Lange, 2009.

Moore, K. L. Clinically Oriented Anatomy. 9th ed. Philadelphia: Lippincott Williams & Wilkins, 2012.

Robbins, S. L., V. Kumar, and R. Cotran. Basic Pathology. 8th ed. Philadelphia: W. B. Saunders, 2007.

Seppa, N. “Immune Cells Rush to Gut in Food Allergy.” Science News 159 (14) (April 2001): 214.

Williams, P. L., et al. Gray’s Anatomy. 38th ed. New York: Churchill Livingstone, 1995.

Answers to Textbook Questions Answers for multiple-choice and matching questions 1–18 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 19. A labeled drawing of the digestive organs can be found on p. 708, Figure 23.1.

20. Enteric neurons are located in the myenteric nerve plexus and the submucosal nerve plexus. The myenteric nerve plexus is in the muscularis externa between the circular and longitudinal smooth muscle layers. The activation of the neurons in the myenteric nerve plexus plexus causes these smooth muscle layers to contract and control peristalsis and segmentation. The submucosal nerve plexus lies within the submucosal layer of the gut wall. The activation of nerve fibers in the submucosal plexus stimulates secretion from the mucosal glands and the contraction of the muscularis mucosae. (pp. 718–719) 21. (a) Deciduous teeth: 2I, 1C, 2M/2I, 1C, 2M. Permanent teeth: 2I, 1C, 2P, 3M/2I, 1C, 2P, 3M. (pp. 721–722, Fig. 23.13) (b) Pulp is a loose connective tissue that fills the hollow center of each tooth (the pulp cavity) and contains the tooth’s vessels and nerves. (p. 722, Fig. 23.14) 22. (a) Rectal valves are in the rectum, whereas anal valves are located more inferiorly, in the anal canal. Although both are transverse folds of mucosa, the anal valves are smaller. See Figure 23.21b. (b) The pyloric part of the stomach (consisting of the pyloric antrum and pyloric canal) lies next to the pylorus (which contains the pyloric sphincter), but they are not the same. See Figure 23.17a. (c) The anal canal is the last part of the digestive tube, whereas the anus is the hole at the end of the anal canal (p. 733 and Fig. 23.21a). (d) Intestinal villi (finger-shaped projections of the mucosa) are much larger than intesti..

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nal microvilli (tiny projections from the apical membranes of individual absorptive enterocytes). See Figure 23.20 on p. 731. (e) The hepatic portal vein enters the liver, whereas the hepatic veins leave the liver. See Figure 23.25. These distinct veins lie on opposite sides of the liver sinusoids. See Chapter 20. (f) The narrow gastric glands open into the wide gastric pits in the wall of the stomach. See Figure 23.18b.

23. (a) The sketch of the visceral surface of the liver should resemble that in Figure 23.26. (b) The exercise is self-explanatory. The two lobes within the H are the caudate and quadrate. The left lobe is divided from the right lobe at the right limb of the H. 24. The small intestine is about 2.7 to 5 metres long. It has three subdivisions: the duodenum, jejunum, and the ileum. Characteristic features of the small intestine are circular folds (plicae circulares), villi, and extensive microvilli (Fig. 23.20, pp.731–732). The large intestine is about 1.5 metres long. It has five subdivisions: the cecum, appendix, colon, rectum, and anal canal. Over most of its length, the large intestine exhibits three special features: teniae coli (longitudinal strips), haustra (sacs), and epiploic appendages (fatfilled pouches of visceral peritoneum that hang from the intestine.) (p. 732, Fig. 23.21) 25. (a) The three major vessels in a portal triad are (1) venule branch of the portal vein, (2) arteriole branch of the hepatic artery, and (3) bile duct. Triads lie at the external corners of the liver lobules (p. 739). (b) Organelles that are abundant within hepatocytes are (student should list any three of these): (1) rough ER, which makes the blood proteins; (2) smooth ER, which detoxifies and metabolizes many poisons and compounds from the blood, and also helps make bile; (3) Golgi apparatus, which packages secretory products of the ER; and (4) mitochondria, which provide the energy for the many activities carried out by the hepatocyte. (pp. 739 and 742) 26. Intrinsic (minor) salivary glands are scattered within the mucosa of the tongue, palate, lips, and cheeks. They do not have ducts. By contrast, the extrinsic (major) salivary glands, lie external to the mouth, but connect to it through their ducts. The parotid gland is located anterior to the ears. Its parotid duct opens into the mouth, lateral to the second upper molar. (Fig. 23.15) The submandibular gland lies along the medial surface of the mandibular body, just anterior to the angle of the mandible. Its duct opens at the floor of the mouth, directly lateral to the tongue’s lingual frenulum (Fig. 23.11b). The sublingual gland lies at the floor of the oral cavity, inferior to the tongue. Its duct opens into the mouth, directly superior to the gland. (pp. 723–724) 27. See Figure 23.19 on p. 730.

28. Foregut/midgut boundary: duodenum where the bile duct enters. Midgut/hindgut boundary: two-thirds of the way along the transverse colon. (pp. 745–746) 29. In the alimentary canal, digestion of starches begins in the mouth; digestion of proteins begins in the stomach; and the small intestine is the sole site for fat digestion. (pp. 723, 727, and 729–731) 30. The sphincters of the gastrointestinal tract and their locations are as follows: 1. The cardiac sphincter is located at the junction of the esophagus and stomach. (p. 724) 2. The pyloric sphincter is located at the junction of the stomach and small intestine. (p. 727, Fig. 23.18) 3. The ileocecal valve is located at the junction of the ileum and cecum. (Note that the sphincter is actually located at the distal end of the ileum.) (p. 732, Fig. 23.21a) 4. The internal anal sphincter is a thickening of the circular layer of smooth muscle. (p. 734, Fig. 23.21b) 5. The external anal sphincter is skeletal muscle under voluntary control. (p. 734, Fig. 23.21b) 296

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31. Mary’s claim is not correct. Chewing is performed by the mouth, while food is churned in the stomach. These actions are classified as mechanical processes, and include chewing in the mouth, the churning of food in the stomach, and segmentation (the rhythmic local constrictions of the intestine). (p. 714)

Critical Reasoning and Clinical Applications Questions 1. (a) The abdominal regions that overlap the upper right quadrant are the right hypochondriac, epigastric, right lumbar, and umbilical. (b) The abdominal regions that overlap the lower left quadrant are the left iliac, hypogastric (pubic), left lumbar, and umbilical.

(Fig. 23.2) 2. Meckel's diverticulum is caused by a failure of the vitelline duct to close completely during development and can result in an outpocketing of the ileum. The presence of ectopic gastric or pancreatic tissue can lead to ulceration and blood in stool. (p. 746).

3. The grandfather, a simple man of few words, said that when he was in his 40s, his gums started getting sore. The gums pulled away from the teeth, and his teeth loosened and fell out. (p. 723) 4. Gallstones easily show up when using ultrasound imaging. Gallstones are formed when there is either too much cholesterol or too little bile salt in the gallbladder, causing the cholesterol to crystallize into gallstones. These stones can plug the cystic duct, which not only blocks the flow of bile from the gallbladder but also results in extreme pain when either the gallbladder or cystic duct contracts. Gallstones can also block the pancreatic duct and result in pancreatitis. (pp. 742–743) 5. Mitch is suffering from pancreatitis as a result of chronic alcoholism. Chronic alcohol ingestion causes necrosis of pancreatic tissue and precipitation of proteins in the pancreatic ducts. Loss of pancreatic enzymes can impair fat absorption and lead to foul greasy stools. It can also lead to nutritional deficiencies, diabetes, pancreatic abcesses and even sepsis. (pp.743).

6. The janitor had ascites, resulting from alcohol-induced cirrhosis of the liver. Obstruction of venous flow through the liver raised the blood pressure in the capillaries of the visceral peritoneum of the intestine, causing large quantities of tissue fluid (serous fluid) to leave these capillaries and accumulate in the man’s peritoneal cavity. (p. 747) 7. Because cancer chemotherapy treatments preferentially destroy all the body’s most rapidly dividing cells, chemotherapy usually obliterates the dividing cells of the intestinal epithelium in addition to cancer cells. The resulting destruction of the lining of the alimentary tract disrupts digestion and causes nausea, diarrhea, and vomiting. (pp. 730–731 and A Closer Look, Chapter 4) 8. The endoderm not only gives rise to the lining epithelium of the alimentary canal, but to the secretory cells of the digestive glands; the liver and pancreas arise as buds from the distal foregut. (pp. 745–746) 9. Mr. Chen could be suffering from diverticulosis, colon malignancies, or internal hemorrhoids, which are common causes of painless bleeding in the elderly. (p. 734).

10. Rebound tenderness of the right lower quadrant of the abdominal surface indicates appendicitis. (p. 733)

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Interpreting Medical Images Questions Answers to Interpreting Medical Images questions are provided in the Instructor Resources area of Mastering A&P. Figure 23.2: The MRI shown in Figure 1.4c is a section through the lower portion of the hypochondriac (left and right) regions and the epigastric region. This plane of section is just superior to the subcostal plane shown in Figure 23.2.

Figure 23.20: The mucosal layer of the stomach contains longitudinal folds (rugae) that have a smooth surface texture. The mucosal layer of the small intestine contains circular folds that run transversely through the length of the small intestine. Extending from these circular folds are the fingerlike villi (shaggy hairs) that extend into the lumen of the small intestine, giving the luminal surface of the mucosa of the small intestine a velvety texture and greatly increasing the surface area for nutrient absorption.

Figure 23.21: The pouches are called haustra. They are normal features of the large intestine. The haustra form from the muscle tone of the longitudinal layer of the muscularis externa, especially the thickened teniae coli, which causes the large intestine to pucker, forming the haustra.

Clinical Application: Diverticulosis: Diverticulosis results when the mucosal layer of the colon herniates, creating saclike protrusions from the wall of the colon known as diverticula. If these protrusions rupture, the contents of the colon can leak into the peritoneum, causing the complications of peritonitis.

Figure 23.25: To view the gallbladder, the ultrasound probe is placed in the right upper quadrant, below the subcostal plane. Thus, the probe would be scanning in the right lateral region of the abdomen. The gallbladder is located at the intersection where the right hypochondriac, epigastric, right lateral, and umbilical regions meet.

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 23: The Digestive System To the Student The digestive system is responsible for the food-processing activities of ingestion, digestion, absorption, and elimination of feces. Because of the external openings, you will be presented with the unique concept that food “inside” the alimentary canal (the GI tract) is actually “outside” the body. The structural plan of the alimentary canal includes digestive organs: the mouth, pharynx, esophagus, stomach, small intestine, and large intestine. In addition, it contains several accessory digestive organs: the teeth, tongue, gallbladder, major salivary glands, liver, and pancreas. A clear understanding of the peritoneum, peritoneal cavity, and associated mesenteries is essential to your study. The general arrangement, location, gross anatomy, microscopic anatomy, and functions of all the aforementioned structures are part of your study of the digestive system.

Incorporating Practice Anatomy Lab 3.0 (PAL) (BC; DVD, Website) into your studies of the digestive system will give you an excellent opportunity to review organs of the alimentary canal and accessory organs of digestion. You will find the Digestive System sections of the Cadaver and Anatomical Models modules particularly helpful. For a review of photomicrographs of digestive system tissues, study the slides in the Histology Module, Digestive System. You may access PAL 3.0 through the DVD or the Mastering A&P Website.

Step 1: Describe an overview of the digestive system. __ Identify the anatomical abdominal regions and quadrants, locating the positions of the abdominopelvic organs. __ Differentiate the alimentary canal from the accessory digestive organs. __ List and describe specific and essential food-processing activities of the digestive system. __ Draw a simple diagram distinguishing peristalsis from segmentation.

Step 2: Explain the peritoneum and peritoneal cavity. __ Review the differences and similarities between serous membranes and mucous membranes. __ Define peritoneum, distinguishing among visceral peritoneum, parietal peritoneum, and the peritoneal cavity. __ Define mesentery. (Note: Refer to the items below for more details.) __ Explain the difference between retroperitoneal organs and intraperitoneal organs, and give several examples. __ Name several specific examples of mesenteries, describing their locations and functions, and indicating whether each example is dorsal or ventral. (Note: Some mesenteries are called “ligaments”; do not confuse this terminology with fibrous ligaments that connect bone to bone.) __ Refer to Figure 23.6 and apply specific names to the two ventral mesenteries indicated in the diagram.

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Step 3: Describe the general characteristics of the alimentary canal. __ Describe the histology of the alimentary canal wall, including the structure and function of smooth muscle. __ Draw a cross-section and label the four layers of the alimentary canal wall at the level of the esophagus. __ Draw a cross-section and label the four layers of the alimentary canal wall at the level of the small intestine. __ Name the visceral nerve plexuses that occur in the wall of the alimentary canal, and list the types of fibers and neurons present. __ Describe the effects of sympathetic and parasympathetic innervation to the stomach.

Step 4: Describe the mouth (oral cavity) and its associated organs. __ Describe the gross anatomy and histology of the oral cavity. __ Identify the type of epithelium that lines the oral cavity. __ Explain the functions of lips and cheeks, also explaining why lips are reddish. __ Describe the structure and function of the tongue, including papillae and taste buds. __ Name and identify locations of major salivary glands. __ Describe the structure and function of teeth, distinguish permanent from deciduous teeth, and identify classification types of teeth.

Step 5: Describe the gross anatomy and histology of the pharynx, esophagus, and stomach. __ Explain the role of the pharynx during swallowing. __ Describe the location and gross anatomy of the pharynx, including openings. __ Describe the location, gross structure, and function of the esophagus. __ Explain how the outer layer of the wall of the esophagus differs from the rest of the digestive tract. __ Describe the location, gross anatomy, and functions of the stomach. __ Compare and contrast the microscopic structure of the esophagus and stomach.

Step 6: Describe the small intestine and the large intestine and their roles in digestion. __ Describe the location and functions of the small intestine, identifying its individual segments. __ Explain why the duodenum is retroperitoneal. __ Identify major ducts and their contents that empty into the duodenum. __ Describe the features of the small intestine that increase its surface area. __ Describe the location and functions of the large intestine, identifying its subdivisions. __ Describe and identify special anatomical features on the external surface of the colon. __ Compare the lining of the large intestine to the lining of the small intestine. __ Describe defecation.

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Step 7: Describe the liver, gallbladder, pancreas, and blood flow through the liver. __ Identify the location, and list the functions of the liver. __ Describe the gross anatomy of the liver, including its lobes, mesenteries, and vessels. __ Describe liver lobules, including the components of a portal triad. __ Outline the flow of blood through the liver. (Reminder: It has two blood-supply sources.) __ Explain the functions of hepatocytes. Discuss the role of each cellular organelle within hepatocytes. __ Explain the functions of hepatic macrophages. __ Identify the location, structure, and function of the gallbladder. __ Trace the movement of bile from its point of secretion all the way to the duodenum. __ Explain the function of bile. __ Identify the location, structure, and function of the pancreas.

Step 8: Describe diseases and disorders of the digestive system. __ Discuss the causes and symptoms of a peptic ulcer, intestinal obstruction, inflammatory bowel disease, viral hepatitis, and cystic fibrosis.

Step 9: Discuss the development of the digestive system and the consequences of aging to the digestive system. __ Describe the embryonic development of the digestive system. __ Discuss the embryonic origin of regions of the digestive system. __ Define allantois, cloaca, oral membrane, stomodeum, and proctodeum. __ Discuss how aging affects digestive processes and diseases associated with aging and the digestive system.

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CHAPTER

24

The Urinary System

Lecture and Demonstration Objectives 1. Describe the location, coverings, and external gross anatomy of the kidney.

2. Describe the internal gross anatomy and the macroscopic blood vessels of the kidney.

3. Identify the portions of the nephron, and explain the role of each in the formation of urine.

4. Describe the location and functions of the arterioles and capillaries surrounding the nephron.

5. Describe the location, histology, and function of the ureters.

6. Describe the shape, location, histology, and function of the bladder.

7. Describe the structure and function of the urethra in both sexes.

8. Define micturition, and explain its neural control.

9. Describe the basic causes, symptoms, and treatment of urinary tract infections, kidney stones (calculi), and bladder and kidney cancers.

10. Trace the embryonic development of the urinary organs.

11. List several effects of aging on the structure and function of the urinary system.

Suggested Lecture Outline I. Kidneys (pp. 753–763, Figs. 24.1–24.10) A. Gross Anatomy of the Kidneys (pp. 753–756, Figs. 24.1–24.4) 1. Kidneys cleanse the blood of many unnecessary or undesirable substances, such as nitrogenous wastes, while forming urine; the purity and chemical constancy of the blood and other extracellular body fluids is maintained. The main waste products excreted in urine are urea, uric acid, and creatinine.

2. Kidneys are located retroperitoneally and extend from the 11th or 12th thoracic vertebra to the 3rd lumbar vertebra. An adult kidney is about 12 cm x 6 cm x 3 cm. a. Externally, kidneys appear reddish brown and bean-shaped. b. Several layers of supportive tissue surround the kidneys: the fibrous layer, perirenal fat capsule, and renal fascia. c. Internal gross anatomy of a kidney reveals two distinct regions: the cortex and the medulla.

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d. Gross vasculature of the kidneys involves the renal arteries, renal veins, and a complicated vascular pathway; the nerve supply of the kidney is supplied by the renal plexus.

B. Microscopic Anatomy of the Kidneys (pp. 756–763, Figs. 24.5–24.10) 1. The nephron is the main structural and functional unit of the kidney.

2. Mechanisms of urine production by the nephron involve three processes: filtration, resorption, and secretion.

3. The nephron is composed of the renal corpuscle and a tubular section consisting of the proximal convoluted tubule, the nephron loop, and the distal convoluted tubule. a. The renal corpuscle (located in the cortex) is the site of filtration. The renal corpuscle consists of the glomerulus and glomerular capsule. The filtration membrane lies between the blood in the glomerulus and the capsular space. b. After forming in the renal corpuscle, the filtrate continues through the tubular section to join the collecting tubule; resorption and secretion occur along the way. c. After passing through the renal tubules, urine passes into the collecting ducts.

The most important role of the collecting ducts is conservation of body fluids.

4. There are two classes of nephrons: cortical nephrons and juxtamedullary nephrons; 85% of nephrons are cortical nephrons. Juxtamedullary nephrons help with concentrating urine and have long nephron loops.

5. Microscopic blood vessels associated with nephrons form two capillary beds: the glomeruli and the peritubular capillaries.

6. Vasa recta are capillary-like vessels around the nephron loop. The vasa recta function as part of the kidney’s urine-concentrating mechanism.

7. The juxtaglomerular complex is a structure near the glomerulus that functions in the regulation of blood pressure.

II. Ureters (pp. 763–764, Figs. 24.1–24.3, 24.11, 24.12, 24.14) A. Gross Anatomy (p. 763, Fig. 24.1) 1. Ureters are slender, retroperitoneal tubes of about 25 cm each. The ureters continue from the renal pelvis to enter the urinary bladder at an oblique angle.

B. Microscopic Anatomy (pp. 763–764, Fig. 24.11) 1. The ureter walls are composed of mucosa, muscularis, and adventitia. The epithelium of the mucosa is transitional epithelium. The muscularis of the ureter is unlike the digestive tract because the inner layer is longitudinal and the external layer is circular.

The inferior one-third of the ureter contains an additional external layer of muscularis, which is longitudinal.

III. Urinary Bladder (pp. 764–765, Figs. 24.12–24.15) A. Gross Anatomy (pp. 764–765, Figs. 24.12, 24.14) 1. The urinary bladder is a collapsible muscular sac that stores and expels urine. It lies on the pelvic floor inferior to the peritoneal cavity.

2. An empty urinary bladder is shaped like an upside-down pyramid. At the anterior angle is a fibrous band called the urachus, which is the closed vestige of the allantois.

3. Arteries supplying the urinary bladder are branches of the internal iliac arteries.

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B. Microscopic Anatomy (p. 765, Figs. 21.13, 24.14) 1. The walls of the urinary bladder are composed of mucosa, a thick muscular layer, and adventitia. The epithelium of the mucosa is transitional epithelium. The muscular layer, called the detrusor, is made up of intermingled smooth muscle fibers arranged in inner and outer longitudinal layers and a middle circular layer.

2. A full adult urinary bladder can contain about 500 ml of urine.

IV. Urethra (pp. 766–767, Fig. 24.14) A. The urethra is a thin-walled tube that drains urine from the urinary bladder and conveys it out of the body.

B. In males, the smooth muscle layer of the urethra becomes very thin toward its distal end.

The epithelium of the urethra in males changes from transitional epithelium to stratified and pseudostratified columnar, and finally stratified squamous epithelium at the urethra’s distal end.

C. The internal urethral sphincter is a thickening of the detrusor. This sphincter is an involuntary one, which prevents dribbling of urine between voiding. The external urethral sphincter is under voluntary control.

D. The length and functions of the urethra differ in males and females. The female urethra is approximately 4 cm long (Fig. 24.14b), whereas in males the urethra is about 20 cm long.

The male urethra has three named regions. From internal to external, the regions are: the prostatic urethra, the intermediate part of the urethra, and the spongy urethra.

V. Micturition (pp. 767–768, Fig. 24.15) A. Micturition, also called urination or voiding, is the act of emptying the urinary bladder.

VI. Disorders of the Urinary System (pp. 768–769) A. Urinary Tract Infections (p. 768) 1. Most urinary tract infections (UTIs) occur in sexually active young women.

B. Renal Calculi (pp. 769–769) 1. In 12% of men and 5% of women in North America, calcium, magnesium, or uric acid salts in the urine crystallize and precipitate in the calices or renal pelvis, forming kidney stones, or renal calculi.

C. Cancer of Urinary Organs (p. 769) 1. Bladder cancer and kidney cancer account for 3% and 2%, respectively, of cancer deaths.

VII. The Urinary System Throughout Life (pp. 769–771, Fig. 24.16) A. Three sets of kidneys develop in sequence in the embryo: pronephric, mesonephric, and metanephric.

B. Kidneys of newborns cannot concentrate urine.

C. Urinary infections are the most common problem through middle age; incontinence is a problem with the elderly.

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Lecture Hints 1. Explain that the kidneys are not only the primary organs for the elimination of metabolic waste but also are responsible for several important functions. List these functions.

2. Point out that the kidneys work with other organs, such as lungs, skin, and digestive organs, to accomplish the overall elimination of waste from the body.

3. Clearly distinguish ureter from urethra.

4. Remind students of the concept of surface area and its application to the urinary system, including how much filtrate is generated per minute.

5. Emphasize the retroperitoneal location of urinary structures.

6. Students will confuse the different capillary beds of the kidney; stress the differences among glomerulus, peritubular capillaries, and the vasa recta.

7. Mention the similar function of the rugae in the urinary bladder to the rugae in the stomach.

8. Emphasize that the urinary system is one of the few locations in the body that contain transitional epithelium.

Classroom Discussion Topics and Activities 1. Display a model of a dissectible human torso or urinary system model to exhibit the urinary organs.

2. Display preserved human kidney and urinary bladder specimens if possible, or display a dissected cat or rat showing gross urinary structures. Additionally, if available, a sheep kidney corrosion cast specimen illustrates beautifully the rich vascular nature of the kidney.

3. Obtain cow or pig kidneys from the market, and demonstrate their structure.

4. Use a funnel and filter paper to demonstrate the filtration process in the renal corpuscle.

Represent the relationship between the glomerulus and glomerular capsule with a head of lettuce in a bowl or a baseball in a baseball glove.

5. Have each student form a pyramid of clay as a model for the empty bladder. Ask them to insert pipe cleaners into each corner of the pyramid to represent the ureters, urethra, and urachus.

6. Students realize that kidneys are primary excretory organs, but they forget the other functions. Ask students what problems a dialysis patient may encounter.

7. When discussing filtration and tubular resorption, make an analogy to cleaning closets.

One effective way to clean out a closet is to remove everything (filtration) and then put back into the closet only what you want to keep (resorption). The rest is thrown away.

8. Ask students to deduce why physicians tell a sick person to drink plenty of fluids and why fluid intake and output are so carefully monitored in hospital settings.

9. Discuss how kidney stones are formed and how they can be treated.

10. A “logical” design for kidney function would be to directly and actively remove all the undesirable molecules from the blood, yet the kidney does not operate this way at all.

Instead, it forms a blood filtrate, then reabsorbs all the desirable molecules, letting the undesirable molecules exit passively in the urine. Discuss the benefits of such an indirect mechanism of ridding the body of wastes.

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11. Both the spleen and kidney “cleanse” the blood. What are some similarities and differences between these two blood-cleansing organs?

12. Ask students to list the basic substances that compose normal urine, and then ask for suggestions of abnormal substances that may be in urine. Include a laboratory copy of a urinalysis report in the discussion, and ask students to interpret the findings.

13. Ask students to review gout in Chapter 9, and recall that uric acid crystals are deposited around joints.

Clinical Questions 1. Infants and many elderly people are incontinent. Define incontinence.

Answer: Incontinence is the inability to voluntarily control micturition.

2. Richard, an older man, sees his doctor for severe pain in his lower abdominal or flank area. He also has an elevated temperature and nausea. Exhaustive tests rule out abdominal obstructions and infections. X-rays indicate a shadow in his right ureter. Diagnose his problem. Give a suggested treatment and prognosis.

Answer: The symptoms suggest that a large kidney stone is lodged in the ureter. Treatment would be surgical removal, or ultrasound or shock waves to shatter the calculus.

The prognosis is for complete recovery. However, there is a possibility that renal calculi will form again.

3. Eleven-year-old Brian is complaining of a severe sore throat and gets to stay home from school. His pediatrician prescribes a course of broad-spectrum antibiotics, and Brian feels much better within a few days. He stops taking his medicine five days earlier than the doctor had told him. Two weeks later Brian’s throat still feels fine, but he experiences dull, bilateral pain in his lower back, and his urine is a smoky brown color. On the basis of Brian’s signs and symptoms, diagnose his condition, and indicate the relationship (if any) between his present condition and his earlier sore throat.

Answer: Brian is showing the symptoms of a severe kidney infection. The smoky brown color of his urine indicates the presence of blood or bile. Apparently, infectious bacteria have spread from the sore throat, through the blood, to lodge and multiply in both kidneys.

4. Whenever Frank, a young father, changed his infant daughter’s diaper, he wiped her from back to front. The child developed a urinary tract infection. Why? Answer: Frank unknowingly was spreading fecal bacteria anteriorly from the region of the anus to the external urethral orifice. From there, the bacteria spread superiorly through the girl’s urinary tract.

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Organs of the urinary system.

Position of the kidneys abutting the posterior abdominal wall.

Internal anatomy of the kidney.

Blood vessels of the kidney.

Basic mechanism of urine formation.

Renal corpuscle and the filtration membrane.

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Figure 24.7 Figure 24.8 Figure 24.9 Figure 24.10 Figure 24.11 Figure 24.12 Figure 24.13 Figure 24.14 Figure 24.15 Figure 24.16

Location and structure of nephrons.

Histology of the nephron.

Cortical and juxtamedullary nephrons and their blood vessels.

Juxtaglomerular complex.

Microscopic structure of the ureter, cross section.

Position of the urinary bladder in reference to the pelvic organs.

Histology of the bladder.

Structure of the urinary bladder and urethra.

Micturition.

Development of the urinary organs in the embryo.

Teaching with Art Figure 24.9

Cortical and juxtamedullary nephrons and their blood vessels.

Textbook p. 761.

Checklist of Key Points in the Figure • Explain that both cortical and juxtamedullary nephrons are represented.

• Trace the uriniferous tubule (nephron and collecting duct) through the diagram, reminding students of the role of urine production.

• Stress the association of the kidney with a rich blood supply, and comment on how much blood is filtered daily (or by the minute or hour).

• Review the basics of arterial blood supply and venous blood drainage.

• Trace the blood vessel route, beginning with the interlobular artery and ending with the interlobular vein; name the vessel sequence.

• Explain the blood vessel route from the aorta to the interlobular artery and from the interlobular vein to the inferior vena cava.

• Stress the relationship of the microscopic structures to the gross structures, explaining the cortex and medulla.

Common Conceptual Difficulties Interpreting the Art • Clearly distinguish the diagrammatic blood vessels from the diagrammatic uriniferous tubular structures.

• Explain that there are two beds of capillaries in the kidney as well as the capillary-like vasa recta.

• Relate the diagram to the overall gross structure of the kidney.

• Explain why the blood pressure in the glomerulus is extraordinarily high and results in forcing filtrate into the glomerular capsule.

Art Exercises Provide each student with two (or more) copies of unlabeled Figure 24.9. Instruct students to identify and color code all the parts of the nephron on one copy. Permit them to use the textbook for reference to several chapter diagrams. On the second copy, instruct students to look at Figure 24.4 in their textbooks and to identify and label all vessels represented in their

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copies of Figure 24.9. Request that they color arteries red, veins blue, and capillaries any third color. Additionally, it is possible to instruct students to indicate structures located in the cortex and medulla as well as to identify locations of filtration, resorption, and secretion.

Critical Reasoning Ask students to recall their study of blood vessels and name another place in the body where two beds of capillaries are significant. Instruct students to look at Figure 24.9, identify the two beds of capillaries, and explain why the renal system is not a portal system.

Answer: The hepatic portal system involves two beds of capillaries in the venous drainage of the body. In the kidneys, vasa recta are continuations of efferent arterioles of juxtamedullary glomeruli, whereas the peritubular capillaries are continuations of efferent arterioles of cortical glomeruli. The renal system is not a true portal system because the two sets of capillaries are not associated with the same type of nephron, and thus are not continuous with each other.

Supplemental Course Materials Library Research Topics 1. Research the treatments that are available for kidney stones and how kidney stones can be prevented.

2. Research the complications that can arise from chronic infections of the urinary tracts.

3. Research the process of dialysis.

4. What are the effects of atherosclerosis on the kidney?

5. What causes kidney failure in many people who suffer from diabetes mellitus?

6. Research new advancements in care and treatments for kidney cancers.

7. Research the process by which kidney donors are matched with recipients. What advances have been made in kidney transplantation?

Suggested Readings Eaton, D. and J. Pooler. Vander’s Renal Physiology. 8th ed. McGraw-Hill Medical, 2013.

George, A. L., Jr., and E. G. Neilson. “Genetics of kidney disease.” American Journal of Kidney Disease 35 (4 Suppl 1) (April 2000): S160–169.

Kelly, C. R., and J. Landman. The Netter Collection of Medical Illustrations—Urinary System: Volume 5. 2nd ed. Saunders, 2012.

McDougal, W. S., A. J. Wein, A. C. Novick, et. al. Campbell-Walsh Urology. 10th ed.

Saunders, 2011.

Robbins, S. L., V. Kumar, and R. Cotran. Basic Pathology. 9th ed. Philadelphia: W.B. Saunders, 2012.

Scheinman, S. J. “New Insights into Causes and Treatments of Kidney Stones.” Hospital Practice 35 (Off Ed) (March 15, 2000): 49–50, 53–56, 62–63.

Shankland, S. J., and G. Wolf. “Cell Cycle Regulatory Proteins in Renal Disease: Role in hypertrophy, proliferation, and apoptosis.” American Journal of Renal Physiology 278 (April 2000): 515–529.

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Answers to Textbook Questions Answers for multiple-choice and matching questions 1–14 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 15. The kidneys are protected by several layers of supporting tissues. Directly adhered to a kidney’s surface is a thin, tough layer of dense connective tissue called the fibrous capsule. It forms a barrier that can inhibit the spread of infection from the surrounding regions. Just external to the renal capsule is the perirenal fat capsule, and external to that is an envelope of renal fascia. The renal fascia contains an external layer of pararenal fat.

These fat layers cushion the kidneys against blows and help hold them in place. In addition, the kidneys are protected by the erector spinae muscle and the 11th or 12th ribs posteriorly. (Figure 24.2a, pp. 753–755) 16. The ureters lead into the bladder, whereas the urethra leads out of the bladder (see Fig. 24.1). The perirenal fat lies internal to the renal fascia, whereas the pararenal fat lies external to the renal fascia (Fig. 24.2). The renal sinus is a space in the medial region of the kidney that contains the renal pelvis (expanded first part of the ureter) as well as fat, nerves, and branches of renal blood vessels. (pp. 754–755) 17. From the glomerulus through the filtration membrane into the interior of the glomerular capsule, to the proximal convoluted tubule, to the nephron loop, to the distal convoluted tubule, to the collecting tubule (to papillary ducts), into the minor calyx, to the major calyx, to the renal pelvis, through the ureter, to the bladder, to the urethra. (pp. 757–760, Figs. 24.6, 24.7, 24.9) 18. (a) The kidneys do not act by directly removing wastes from the blood. Instead, they form a filtrate that contains all the small molecules of blood, and then they reclaim all the beneficial molecules and return them to the blood. This leaves the remaining filtrate (including undesirable wastes) to pass as urine. The reclaiming of the beneficial molecules is called resorption (p. 757). (b) The peritubular capillaries surround the proximal and distal tubules within the cortex of the kidney. They readily absorb solutes and water from the tubule cells. They arise from the efferent glomerular arterioles draining the glomeruli. (p. 762) 19. The glomerulus is both fed and drained by arterioles, namely, the afferent and efferent glomerular arterioles. Because these arterioles are high-resistance vessels and the efferent arteriole has a smaller diameter than the afferent arteriole, the blood pressure in the glomerulus is much higher than that in any other capillary bed. This higher than normal blood pressure in the glomerulus helps in filtration and forces the filtrate out of the blood and into the capsular space. (p. 762) 20. (a) and (b): The urachus attaches to the anterior angle of the bladder, the urethra attaches to the inferior angle, and the paired ureters enter the two posterolateral angles. (c) The trigone is defined by the openings of the two ureters superiorly and the opening of the urethra inferiorly. (Technically, these are called ureteric orifices and the internal urethral orifice.) (pp. 764–765, Fig. 24.14) 21. Micturition is the act of emptying the bladder. It is controlled by the micturition center in the pons of the brain, which responds to distension of the bladder wall by signaling a parasympathetic contraction of the bladder’s detrusor to squeeze out urine. At the same ..

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time, the pons inhibits sympathetic pathways to the bladder (pathways that would otherwise prevent micturition). (pp. 767–768, Fig. 24.15) 22. The male urethra has three regions: (1) the prostatic urethra which runs through the prostate gland; (2) the intermediate part of the urethra, or membranous urethra, which runs through the urogenital diaphragm; (3) the spongy urethra, which passes through the entire penis, and opens at the tip of the penis via the external urethral orifice. When the prostate is enlarged, the patient may have difficulty in urination and urine retention in the bladder.

(Fig. 24.14, pp. 766–767) 23. The ureters pass obliquely through the posterior wall of the bladder, so that they are pressed shut when the bladder fills with urine. This prevents reflux of urine into the ureters and kidneys when the bladder is full. That is, it prevents hydronephrosis, an accumulation of urine within the kidney that exerts crushing pressure on the kidney tissue. (pp. 763–764, 770, and 771) 24. There are several types of epithelium throughout the structures of the urinary system.

The nephrons are lined throughout with simple cuboidal epithelium reflecting the function of secretion and absorption (pp. 757–760). The ureter and urinary bladder both are lined with transitional epithelium with mucosa; transitional epithelium stretches readily and permits distension (pp. 763–765). The urethra is lined partly with transitional epithelium (near the urinary bladder) and progresses to stratified and pseudostratified columnar epithelium in mid urethra (sparse in females) that functions in mucous production. Near the end of the urethra, the epithelium is stratified squamous, and it protects underlying tissues from abrasion. (pp. 766–767)

Critical Reasoning and Clinical Applications Questions 1. Mrs. Patel is suffering from a condition called cystocele, which occurs when the urinary bladder pushes on the vagina and bulges into the anterior superior vaginal wall. This is a result of weakened pelvic muscles, a condition that may occur in a woman who has experienced multiple pregnancies, as in Mrs. Patel’s case. If the cystocele is not corrected, it might lead to urinary obstruction or incontinence. (p. 771) 2. Cystitis is inflammation (and infection) of the urinary bladder, generally resulting from the spread of fecal bacteria up the urethra. Women contract cystitis more often than men because their urethra is short and its external orifice lies closer to the anal opening. (p. 768) 3. The best surgical approach to the kidney is through the posterolateral abdominal wall, where it is nearest from the surface and is easily accessible without having to cut through a lot of muscle, vessels, or nerves. Care must be taken to make an incision below the 12th rib since the superior third of the kidney lies anterior to the pleura. Injury to the pleura may cause pneumothorax. (p. 754) 4. The pleural cavity lies directly posterior to the superior third of each kidney (and to the superior third of the fat that surrounds the kidney). While removing this fat, the surgeon accidentally cut through the parietal pleura, causing a pneumothorax that collapsed the lung. (p. 754) 5. Mr. Rubin is suffering from bladder cancer that occurs due to a neoplasm in the transitional epithelium of the urinary bladder. Risk factors include smoking, working in industrial chemical environments, and exposure to artificial sweeteners. Blood in the urine is a common symptom of bladder cancer. (p. 769) 310

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6. Urinary incontinence refers to the general lack of voluntary control over urination. During stress incontinence, the urethral sphincter mechanisms malfunction and everyday actions such as coughing, sneezing, laughing, and jumping can cause urine to leak out.

Often during childbirth, the tearing or weakening of the external urethral sphincter can result in loss of the voluntary control of this muscle. (pp. 768, 771)

Interpreting Medical Images Questions Answers to Interpreting Medical Images questions are provided in the Instructor Resources area of Mastering A&P. Figure 24.2 The right kidney is located slightly inferior to the left kidney because of the position of the liver on the right side. This section runs through the hilum of the left kidney and the superior portion of the right kidney.

Clinical Application: Pyelography:

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 24: The Urinary System To the Student Perhaps a nice, juicy steak is one of your favorite foods. Why mention food in a chapter titled “The Urinary System?” When your body processes food, metabolic wastes are produced. For example, steak is meat, meat contains protein, protein is made of amino acids, amino acids contain nitrogen, and nitrogen-containing substances are poison to your cells if they accumulate in your tissues and blood. Kidneys filter organic wastes from the blood and help maintain the purity and chemical constancy of the blood with, of course, the production of urine as a vital excretory result. Thoroughly review all the functions of the kidneys because removal of nitrogenous waste is only one of many important functions. There are more than 1 million structural and functional units of the kidney called nephrons, consisting of renal corpuscles plus renal tubules. Collectively, in one kidney, nephrons are an estimated 85 miles long and filter approximately 1200 ml (about 5 cups) of blood per minute. The number of nephrons is constant from birth, and new ones do not form in the event of injury or disease—hence, the significance of kidney transplants and dialysis.

You will also find that incorporating Practice Anatomy Lab 3.0 (PAL) (BC; DVD, Website) into your studies of the urinary system will give you an excellent opportunity to review these organs. You will find the Urinary System sections of the Cadaver and Anatomical Models modules particularly helpful. For a review of photomicrographs of the nephron, urinary bladder, ureters, and urethra, study the slides in the Histology module, Urinary System. You may access PAL 3.0 through the DVD or the Mastering A&P Website.

Step 1: Describe the gross structure and function of the kidneys. __ List all functions accomplished by the kidneys during the formation of urine. __ Identify all organs associated with the transport and storage of urine. __ Describe the external gross anatomy of the kidneys, including location and hili. __ Name the structures that enter and leave the kidney through the renal hilum. __ Distinguish perirenal fat from pararenal fat, describing their respective functions. __ Distinguish the renal capsule from the renal fascia, describing their respective functions. __ Describe the internal gross anatomy of the kidney, defining renal cortex, renal medulla, renal pyramids, renal pelvis, renal sinus, and major and minor calyces. __ Explain the nerve supply to the kidneys. __ Draw a flowchart representing the vascular pathway through a kidney, beginning with the renal artery and ending with the renal vein. (Hint: Refer to Figs. 24.8 and 24.9, if needed.)

Step 2: Describe the microscopic anatomy of the kidneys and urine formation. __ Identify the main structural and functional unit of the kidney, naming its two major parts, and explain their orientation within the kidney. __ Define each of the kidney functions during urine production: filtration, resorption, and secretion.

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__ Name the parts of the nephron, and explain how “each region” or “each of the regions” contributes to urine formation. __ Identify the part of the filtration barrier that prevents the passage of red blood cells into the capsular space. (Hint: Refer to Fig. 24.6.) __ Explain how the unique structure of podocytes contributes to filtration. __ Draw a single, generalized nephron, showing its basic relationship to blood vessels and sites of filtration, resorption, and secretion. (Hint: Refer to Figs. 24.5, 24.7.) __ Explain how the kidney acts to conserve water and prevent dehydration. __ Identify two major categories of nephrons, pointing out their major differences. __ Describe the association of microscopic blood vessels and the nephron, being very observant of the interlobar and interlobular vessels. __ Name specific beds of capillaries, and identify their roles in urine production. __ Explain the structure and function of the juxtaglomerular complex, and describe its location with respect to the gross structure of the kidney.

Step 3: Describe the gross structure and microscopic structure of the other organs of the urinary system: ureters, urinary bladder, and urethra. __ Describe the location and function of the ureters. __ Explain the histological structure of the ureteral (ureteric) wall. __ Explain how urine moves through the ureter. __ Describe the location of the urinary bladder, explaining the positions and shapes of full and empty urinary bladders. __ Define urachus, indicating its embryonic origin. __ Define trigone, explaining the relationship of openings located there. __ Describe the histological structure of the urinary bladder, explaining why distensibility is unique for this organ. __ Describe the location and function of the urethra, including the sphincters. __ Explain the gross anatomical differences of the urethra between males and females. __ Explain how urine moves through the urethra. __ Define micturition.

Step 4: Describe disorders of the urinary system and changes that occur with aging. __ List basic symptoms and features of specific disorders such as urinary tract infections, kidney stones, and cancer of the urinary bladder or kidney. __ Trace the embryonic origin of the organs of the urinary tract. __ List several effects of aging on the organs of the urinary tract.

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CHAPTER

25

The Reproductive System

Lecture and Demonstration Objectives 1. Describe the location, gross and microscopic structure, and function of the testes.

2. Describe the location, structure, and functions of the ducts and accessory glands of the male reproductive system.

3. Describe the structure of the penis, and explain the mechanism of erection.

4. Outline the events of spermatogenesis.

5. Describe the location, structure, and function of the ovaries.

6. Describe the anatomy of the uterine tubes in terms of their function.

7. Explain the location, regions, supportive structures, and layers of the uterus.

8. Explain the structure of the vagina in terms of its functions.

9. Describe the anatomy of the female external genitalia.

10. Describe the structure and location of the mammary glands.

11. Explain the phases of the ovarian cycle and the stages of oogenesis.

12. Outline the three phases of the uterine cycle.

13. Describe the processes of implantation and placenta formation.

14. Define a placental (chorionic) villus, and explain its functions.

15. List the three phases of labor.

16. Consider various cancers of the reproductive organs.

17. Compare and contrast the prenatal development of the male and female sex organs.

18. Note the anatomical changes that occur during puberty and menopause.

Suggested Lecture Outline I. The Male Reproductive System (pp. 776–787, Figs. 25.1–25.10) A. The male and female reproductive systems function to produce offspring; the primary sex organs, the gonads, produce gametes: sperm in males and ova in females.

1. The Testes (pp. 776–779, Figs. 25.1–25.3) a. The testes are paired organs located in the scrotum. The testes are the male primary sex organ and the site of sperm production. b. Two muscles, the dartos muscle and the cremaster muscle, respond to changes in the temperature of the testes.

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3. Each testis is approximately 2.5 cm in width and 4 cm in height. Within the scrotum, the tunica vaginalis partially encloses each testis.

4. Each testis contains seminiferous tubules called “sperm factories.” a. Spermatogenic cells are in the process of forming sperm. b. Sustenocytes surround the spermatogenic cells and provide a variety of important functions. c. Myoid cells contract rhythmically to help sperm and testicular fluid through the tubules. d. Interstitial cells secrete the male sex hormones, the androgens.

B. Male Reproductive Ducts (pp. 779–782, Figs. 25.3–25.6) 1. The reproductive duct system in males traces the pathway that sperm cells follow, beginning with the seminiferous tubules and ending with the urethra.

2. The epididymis is the site where sperm mature.

3. The ductus deferens stores and transports sperm during ejaculation.

4. The spermatic cord contains the ductus deferens, blood vessels, and nerves; the inferior part lies in the scrotum, and the superior part runs through the inguinal canal.

5. The urethra carries sperm from the ejaculatory duct to outside the body.

C. Accessory Glands (pp. 782–783, Figs. 25.1, 25.6, 25.7) 1. Accessory glands in males include the seminal glands, the prostate, and the bulbourethral gland; accessory glands produce secretions that contribute to semen formation.

2. The paired seminal glands secrete a sugar-rich fluid that forms 60% of the ejaculate.

3. The prostate surrounds the prostatic urethra; its secretions constitute about one-third of the volume of semen and function to clot and liquefy ejaculated semen.

4. The bulbo-urethral glands produce mucus that lubricates the urethra for sperm passage.

D. The Penis (pp. 783–784, Figs. 25.1, 25.6) 1. The penis is the male organ of intercourse and delivers sperm into the female reproductive tract.

E. The Male Perineum (p. 784, Fig. 25.8) 1. The male perineum contains the scrotum, the root of the penis, and the anus; the bony landmarks are the coccyx, the ischial tuberosities, and the pubic symphysis.

F. Spermatogenesis (pp. 784–787, Figs. 25.9, 25.10) 1. Spermatogenesis is the formation of sperm, which occurs within seminiferous tubules from puberty until death. a. Formation of spermatocytes begins with spermatogonia, which divide by mitosis.

Type B cells move toward the lumen to become primary spermatocytes. b. Primary spermatocytes undergo meiosis I, resulting in the production of two secondary spermatocytes. The two secondary spermatocytes undergo meiosis II, which results in the production of a total of four spermatids. c. Spermiogenesis is the process by which spermatids differentiate into sperm.

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II. The Female Reproductive System (pp. 787–800, Figs. 25.12–25.21) A. The female reproductive system differs from the male system in several important ways; the gametes are eggs, female organs prepare to support developing offspring, and female organs undergo changes according to the reproductive cycle called the menstrual cycle. (p. 787, Fig. 25.12) 1. The Ovaries (pp. 787–789, Figs. 25.12, 25.13, 25.15) a. The ovaries are the female primary sex organs and the site of egg cell production.

2. The Uterine Tubes (pp. 789–790, Figs. 25.11, 25.12, 25.14, 25.15) a. The uterine tubes (also called fallopian tubes or oviducts) receive the ovulated oocyte and provide a site for fertilization.

3. The Uterus (pp. 790–792, Figs. 25.11, 25.12, 25.15, 25.16) a. The uterus is a hollow thick-walled organ whose functions are to receive, retain, and nourish a fertilized egg, embryo, and fetus throughout pregnancy. b. Supports of the uterus are several ligaments, mesenteries, and muscles of the pelvic floor. c. The uterine wall is composed of three basic layers: an outer perimetrium, a middle myometrium, and an inner endometrium.

4. The Vagina (pp. 792–793, Figs. 25.11, 25.12, 25.17) a. The vagina is the distensible, muscular tube that connects the uterus to the body’s exterior; it receives the penis and semen during intercourse and acts as the birth canal.

5. The External Genitalia and Female Perineum (pp. 793–794, Fig. 25.17) a. The external genitalia, also called the vulva, are the female reproductive structures that lie external to the vagina in the diamond-shaped perineum.

6. Oogenesis and the Female Menstrual Cycle (pp. 794–798, Figs. 25.18–25.20) a. Oogenesis, the production of female gametes, starts before birth and takes decades to complete. b. The ovarian cycle is the monthly menstrual cycle as it relates to the ovary; the ovarian cycle has three phases: (1) the follicular phase, (2) ovulation, and (3) the luteal phase. i. During the follicular phase (first half of the ovarian cycle, days 1–14), 6–12 primordial follicles start to grow. ii. Ovulation is the midpoint of the ovarian cycle; an oocyte is released from a follicle at the surface of the ovary. iii. In the luteal phase (second half of the ovarian cycle, days 15–28), the ruptured follicle becomes the corpus luteum. c. The uterine cycle is the menstrual cycle as it involves the endometrium.

7. The Mammary Glands (pp. 798–800, Fig. 25.21) a. The mammary glands are modified sweat glands that are present in both sexes but function only in lactating females.

III. Pregnancy and Childbirth (pp. 800–806, Figs. 25.22–25.27) A. Pregnancy (pp. 800–805, Figs. 25.22–25.26) 1. Pregnancy begins with a fertilized oocyte and ends with production of offspring nine months later.

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2. Events leading to fertilization are the acrosomal and cortical reactions that accomplish the sperm penetration of an oocyte.

3. Implantation occurs in the uterus about six days after fertilization.

4. Formation of the placenta involves both embryonic (trophoblastic) and maternal (endometrial) tissues.

5. The anatomy of the placenta ensures no mixing of maternal and fetal blood occurs; the placenta is an organ of transport between the mother and fetus.

B. Childbirth (pp. 805–806, Fig. 25.27) 1. Childbirth or parturition, the act of giving birth, occurs an average of 266 days after fertilization and 280 days after the last menstrual period; the stages of labor include dilation, expulsion, and the placental stage.

IV. Disorders of the Reproductive System (pp. 806–808, Fig. 25.28) A. Reproductive System Cancers in Males (p. 806) 1. Reproductive system cancers in males include testicular cancer and prostate cancer.

2. Testicular cancer affects approximately 1 of 50,000 males, most often in the age bracket of 15–35 years; this cancer is cured in 95% of all cases.

3. Prostate cancer is a slow-growing cancer that is the second most common cause of cancer death in men; lung cancer is first.

B. Reproductive System Cancers in Females (pp. 806–808, Fig. 25.28) 1. Reproductive cancers in females include ovarian cancer, endometrial cancer, cervical cancer, and breast cancer. a. Ovarian cancer affects 1.4% of women and is the fifth most common cause of cancer death in women. b. Endometrial cancer affects 2% of women and is the fourth most common cause of cancer death in women (after lung, breast, and colorectal cancers). c. Cervical cancer occurs in 1% of women between ages 30–50; survival rates improve with early detection. d. Breast cancer, the second most common cause of cancer deaths in women, kills 3% of the women in the United States.

V. The Reproductive System Throughout Life (pp. 808–811, Figs. 25.29–25.31) A. Embryonic Development of the Sex Organs (p. 808, Figs. 25.29, 25.30) 1. Embryonic development of the sex organs of both males and females begins during week 5.

B. Descent of the Gonads (pp. 808–810, Fig. 25.31) 1. The gonads descend in both sexes after forming in the dorsal abdomen; testes descend into the scrotum, and ovaries descend into the pelvis.

C. Puberty (p. 811) 1. Puberty generally occurs between ages 10 and 15, when reproductive organs mature and reproduction is possible.

D. Menopause (p. 811) 1. Menopause in women occurs normally between ages 46–54 and marks the end of ovulation and menstruation.

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Lecture Hints 1. Continue stressing word origins. (Testes is a wonderfully classical example. Historically, men did not “testify,” or witness, by placing their hands over their hearts or on the Bible, but by placing their hands elsewhere.… And women were not permitted to testify at all.

Wonder why?)

2. Explain the tunica vaginalis as a serous membrane.

3. Remind students of the unique relationship of a mucous membrane (the lining of the tube) meeting a serous membrane (visceral peritoneum) at the infundibulum.

4. Point out that although FSH and LH are named for female structures, they have male functions as well.

5. Emphasize the difference between mitosis and meiosis. Students are often confused by similar-sounding names; be sure to clearly distinguish spermatogenesis from spermiogenesis.

6. Stress that the secondary oocyte (even when initially ovulated) does not complete meiosis II until it is penetrated and therefore should technically not be called an ovum until fertilization has occurred.

7. Mention that germinal epithelium has nothing to do with ovum formation; it is a misnomer.

8. Explain the functional significance of the large amount of cytoplasm in the oocyte compared to the insignificant amount of cytoplasm in the polar bodies; mention that polar bodies are tiny nucleate cells that cannot be fertilized.

9. Present the uterine cycle and ovarian cycle in a manner that clearly distinguishes the two.

The ovarian cycle is the menstrual cycle as it pertains to the ovaries, and the uterine cycle is the menstrual cycle as it pertains to the uterus. Regardless of the sequence of presentation, emphasize that both cycles occur concurrently and that both should be visualized as one continuous process, even though different events occur at different times.

10. Emphasize the difference between menstrual phase and menstrual cycle. Students often confuse the two.

11. Stress the importance of the blood-testis barrier in preventing immune action against sperm antigens.

12. Point out that erection is a parasympathetic response and that ejaculation is due to sympathetic reflex action.

Classroom Discussion Topics and Activities 1. Use a dissectible model of the human torso to exhibit male and female reproductive organs.

2. Demonstrate dissected cats or rats of both sexes. Try to obtain a pregnant female cat.

3. Use a “pregnant” torso model or chart to illustrate the most desirable positioning of the placenta and the vertex presentation of a fetus.

4. Use a chart showing a pregnant and nonpregnant uterus, sagittal view, pointing out the relationship between the uterus, urinary bladder, and pelvic bone. Explain why a pregnant female frequently has to urinate.

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5. If available, show preserved specimens of human embryos and/or fetuses in various stages of development. Include a placenta and attached umbilical cord, if possible.

6. Display preserved human male and female reproductive system specimens, if possible.

Students are always surprised at how small an ovary or a never-been-pregnant uterus actually is.

7. Display models showing the process of meiosis in spermatogenesis and oogenesis.

8. Tie a long string around a softball to model the male duct system and the testis. Blow up a balloon, and push the softball into the balloon to represent the testis surrounded by the tunica vaginalis. The leather cover of the softball represents the tunica albuginea.

9. Use a doll, a drawstring sack (uterus), and a model of the bony pelvis to illustrate the placement of the fetus for vaginal delivery and the turning movements that allow the baby to move through the pelvis during the delivery. (For more information, see the discussion of the female bony pelvis in Chapter 7.)

10. Discuss the need for mammograms and self-examination for early diagnosis of breast cancers. Discuss the self-examination procedure, and distribute a handout showing the correct breast examination procedure. Ask the students whether it is possible for males to develop breast cancer. Discuss the current treatments for breast cancer.

11. Discuss the need for self-exams for testicular cancer. Discuss how the procedure is done, and distribute handouts showing the correct testicular examination procedure.

12. Discuss the various causes of, and treatments for, infertility.

13. Discuss similarities and differences between the blood-brain barrier and the blood-testis barrier.

14. Multiple births have always attracted attention. Instruct students to find out the difference between fraternal and identical twins and to illustrate what events occur by combining information from Chapter 3 with Chapter 25.

15. Draw a schematic diagram of the human life cycle, incorporating the following concepts: meiosis and mitosis, spermatogenesis and oogenesis, haploid and diploid, fertilization and implantation, and embryo and fetus as well as differentiation, growth, and time of sexual maturity.

Clinical Questions 1. Blaine and Andrew were best friends who, during their youth, had held similar beliefs about preventing world overpopulation. Both had received vasectomies on the same day in the same clinic, and both regretted it later, after they were married. Blaine’s vasectomy proved to be surgically reversible, whereas Andrew’s was not. Explain why many vasectomies lead to permanent sterility.

Answer: Following some vasectomies (e.g., Andrew’s), lymphocytes are able to enter the cut-open end of the ductus deferens, reach the testis, attack the sperm, and cause sterility. (The lymphocytes go around the blood-testis barrier that normally keeps lymphocytes away from sperm.) In other vasectomies (e.g., Blaine’s), lymphocytes do not enter the tied end of the ductus deferens, do not reach the testes, and do not cause sterility; thus, Blaine’s vasectomy was successfully reversed when the two ends of his ductus were surgically reunited. (A newer explanation is that the sperm may leak out the open end of the ductus deferens after a vasectomy, leading to lymphocyte activation.)

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2. A man in an isolated rural area called his physician and said that his 3-year-old son had several openings along the underside of his penis. The father and mother had not noticed this when the child was an infant in diapers, but now that the boy was being toilet trained, it was obvious that urine dribbled out the wrong part of the penis. What was the boy’s condition, and what is its embryological origin? Is the condition correctable?

Answer: The boy had hypospadias, a condition in which the right and left urethral folds do not fuse completely, leaving openings along the ventral midline of the penis. It is easy to correct surgically.

3. An alcoholic woman had ascites (a buildup of excess serous fluid in the peritoneal cavity). Her physician inserted a syringe into her vagina and drained out most of this excess fluid. Exactly where was the tip of the syringe needle inserted?

Answer: The tip of the needle was in the rectouterine pouch, which lies directly posterior to the posterior vaginal fornix. This is the most inferior point of the peritoneal cavity, so gravity causes the fluid of ascites to accumulate here.

4. Assume that a woman could be an “on-demand” ovulator like a rabbit, in which copulation stimulates the hypothalamus and anterior pituitary to release a surge of LH—and that an oocyte was ovulated on day 26 of the woman’s 28-day cycle. Why would a successful pregnancy be unlikely at this time?

Answer: A successful pregnancy would be unlikely so late in the cycle because progesterone levels would have fallen, depriving the uterine endometrium of hormonal support.

The endometrial cells would have begun to die, and menstruation would be about to start. The fertilized egg would not be able to implant in the shedding wall of a menstruating uterus.

5. A 30-year-old woman is admitted to the emergency room. Her husband, who rode in the ambulance with her, said that she had suddenly complained of severe pain in the right iliac region of her abdomen and then had collapsed. Upon examination, she showed signs of internal hemorrhage, and her abdominal muscles were rigid. Her menstrual history revealed that she had missed her last menstrual period. A diagnosis of ruptured tubal pregnancy was made, and surgery was scheduled. What is an ectopic tubal pregnancy, and why does it cause problems?

Answer: An ectopic pregnancy occurs when the embryo implants in any site other than the uterine endometrium. In a tubal pregnancy, the embryo implants in the thin wall of the uterine tube. This tube is unable to establish a placenta or accommodate growth, and it ruptures. Severe internal bleeding results.

Art Resources Figure 25.1 Figure 25.2 Figure 25.3 Figure 25.4 Figure 25.5 Figure 25.6 Figure 25.7 320

Reproductive organs of the male, sagittal view.

Relationships of the testis to the scrotum and spermatic cord (anterior view).

Structure of the testis.

Histology of the epididymis and ductus deferens.

Spermatic cord in the inguinal canal (at left) and an inguinal hernia (at right).

Male reproductive structures.

The prostate.

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Figure 25.8 Figure 25.9 Figure 25.10 Figure 25.11 Figure 25.12 Figure 25.13 Figure 25.14 Figure 25.15 Figure 25.16 Figure 25.17 Figure 25.18 Figure 25.19 Figure 25.20 Figure 25.21 Figure 25.22 Figure 25.23 Figure 25.24 Figure 25.25 Figure 25.26 Figure 25.27 Figure 25.28 Figure 25.29 Figure 25.30 Figure 25.31 A Closer Look

The male perineum.

Spermatogenesis (sperm formation).

Spermiogenesis: transformation of a spermatid into a sperm.

Internal organs of the female reproductive system, midsagittal section.

Internal female reproductive organs.

Photomicrograph of a mammalian ovary.

Photomicrograph through the uterine tube.

Peritoneal reflections around the female pelvic organs, anterior view.

The endometrium of the uterus and its blood supply.

The external genitalia (vulva) of the female.

Oogenesis.

The ovarian cycle.

The menstrual cycle: structural and hormonal changes.

Structure of a lactating (milk-secreting) mammary gland.

Events leading to fertilization: the acrosomal and cortical reactions.

Fertilization.

Implantation of the blastocyst.

Placenta formation.

Vascular relationships in the placenta.

Stages of labor.

Mammograms.

Development of the internal reproductive organs in both sexes.

Development of homologous structures of the external genitalia in both sexes.

Descent of the testes.

Contraception: To Be or Not To Be

Teaching with Art Figure 25.1

Reproductive organs of the male, sagittal view.

Figure 25.12

Internal female reproductive organs. (a) Posterior view.

Textbook pp. 776 and 788.

Checklist of Key Points in the Figure • In Figure 25.1, describe the location, structure, and function of the testes.

• In Figure 25.1, trace the route traveled by sperm, naming ducts, describing the male accessory organs, describing the structure of the penis, and explaining the formation of semen.

• In Figure 25.12, describe the location, structure, and function of the ovaries.

• In Figure 25.12, trace the movement of an ovulated oocyte to the lumen of the uterus, describing the anatomy of the uterine tube and explaining the location, regions, supportive structures, and layers of the uterus.

• Identify the most inferior part of the peritoneal cavity, the rectouterine pouch.

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Common Conceptual Difficulties Interpreting the Art • Remind students of the difference between meiosis and mitosis.

• Review the basics of spermatogenesis and oogenesis.

• Explain how sperm and oocytes move through their respective ducts.

• Describe how ovaries and testes are both retroperitoneal, although peritoneal membranes are associated with each.

Art Exercises Provide students with several unlabeled copies of Figures 25.1 and 25.11.

1. Pathway Exercise: a. Instruct students to color code the route sperm travel, from the testis to the external urethral meatus, naming all structures along the way. b. Instruct students to color code the route an ovulated oocyte travels, from the surface of the ovary to the lumen of the uterus, naming all structures along the way. c. Instruct students to color code and trace the path a sperm cell follows, from the testis all the way to the location of possible fertilization, naming all structures along the way.

2. Male and Female Homologies Exercise: Review the meaning of the term homology with students, referring students to Figure 25.30 on p. 810. Provide the following list of the male and female reproductive homologies, and instruct students to identify and color code each pair of structures using provided copies of Figures 25.1 and 25.11.

Male

Female

a. scrotum

labia majora

b. testes

ovaries

c. penis

clitoris

d. spongy urethra

vestibule

e. bulbo-urethral glands

vestibular glands (located deep to vaginal orifice, see Figure 25.20 on p. 798)

3. Membrane Exercise: Using unlabeled copies of Figures 25.1 and 25.12, color all surfaces covered by peritoneum.

Critical Reasoning 1. Two students expressed opposing views as to whether ejaculation comes directly from the testes or directly from the epididymis. Which one is correct?

Answer: The latter is correct because the sperm must first spend weeks in the epididymis.

(Many students do not realize this.)

2. Two students also expressed opposing views as to whether an ovulated oocyte is initially deposited directly into the end of the uterine tube or deposited initially into the peritoneal cavity. Which one is correct?

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Answer: The latter is correct. There is essentially no direct contact between the uterine tube and the ovary. The uterine tube receives the oocyte only as a result of complex movements of the infundibulum and fimbriae, which generate currents in the peritoneal cavity that carry the oocyte into the uterine tube. (There is evidence that one little fimbria of the uterine tube always attaches to the ovary!)

3. Ask students to answer the question, “Are the internal male ducts homologous to those in the female, and why or why not?”

Answer: The answer is no because male ducts develop from the embryonic mesonephric duct, and female ducts develop from the embryonic paramesonephric duct.

Supplemental Course Materials Library Research Topics 1. Research procedures involved with artificial insemination, including sperm storage, sperm banks, and sperm bank donors.

2. Research the current treatments for disorders of the prostate. What is the mechanism of the new pills and surgically implanted drugs that can shrink a hyperplastic prostate?

3. Research the disorders associated with the menstrual cycle.

4. Research the latest advances in birth control. Evaluate the evidence that the pill increases one’s likelihood of developing breast cancer. How soon will a male oral contraceptive be available?

5. Research the incidence of and reasons for hysterectomies in the United States, and evaluate whether this operation is overperformed.

6. Research current information on gender. How has the concept of gender changed in recent years?

7. Research data on transgender and sexual reassignment surgeries.

Suggested Readings Christensen, Damaris. “Mammograms on Trial.” Science News 161 (17) (April 2002): 264–266.

Coustan, D. R. Human Reproduction: Growth and Development. Boston: Little, Brown, 1995.

Garbers, David L. “Ion Channels: Swimming with sperm.” Nature 413 (6856) (October 2001): 579–582.

Greer, J. Mosby’s Color Atlas and Text of Obstetrics and Gynecology. St. Louis: Mosby, 2001.

Hayes, D. F., et al. Atlas of Breast Cancer. 2nd ed. St. Louis: Mosby, 2000.

Heffner, L. J. and D. J. Schust. The Reproductive System at a Glance. Boston: WileyBlack-well, 2010.

Kirby, R. S., et al. Prostate Cancer: Principles and Practice. 1st ed. London, CRC Press, 2006.

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Moore, K. L. Clinically Oriented Anatomy. 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2012.

Muramatsu, Takashi. “Carbohydrate Recognition in Spermatogenesis.” Science 295 (5552) (January 2002): 53–54.

Sanio, R. L. Gender Identity and Sexual Orientation: Research, Policy, and Personal Perspectives. Danvers, MA: Jossey-Bass, 2005.

Smith, R. P, et. al. The Netter Collection of Medical Illustrations: Reproductive System, 2nd edition. Philadelphia: Elsevier (Saunders), 2011.

Answers to Textbook Questions Answers for multiple-choice and matching questions 1–18 are located in the Answers Appendix of the textbook.

Short Answer and Essay Questions 19. The structures that regulate the temperature of the testes (important for producing viable sperm) are the dartos muscle, the cremaster muscles, and the pampiniform venous plexus.

The dartos muscle is responsible for wrinkling the scrotal skin. The cremaster muscles are responsible for elevating the testes. Under hot conditions, these muscles relax, so the scrotal skin is flaccid and loose. The pampiniform venous plexus absorbs heat from the arterial blood, cooling it before it enters the testes, thereby keeping the testes cool. Together, these muscles help to produce viable sperm by keeping the testes cool as sperm can only be produced at a temperature of 3°C. (pp. 777–779) 20. (a) Each ductus deferens ascends through the scrotum and inguinal canal to enter the pelvic cavity through the deep inguinal ring. From there, it extends posteriorly along the lateral wall of the true pelvis, arches medially over the ureter, and descends along the posterior wall of the bladder. Its expanded end, the ampulla, then joins with the duct of the seminal gland to form the ejaculatory duct. Each ejaculatory duct runs within the prostate gland inferior to the bladder, where it empties into the urethra. (p. 780) (b) An ejaculated sperm is squeezed from the epididymis through the ductus deferens, the ejaculatory duct, and the urethra to exit the penis and enter the female vagina. From there, the sperm swim through the lumen of the uterus to a uterine tube and fertilize an oocyte in the ampulla of this tube. (pp. 779–784 and 800–802) 21. If fertilization fails to occur in a particular menstrual cycle, the corpus luteum in the ovary degenerates and stops secreting progesterone. Blood progesterone levels fall, depriving the endometrium of hormonal support. Cells in the functional layer leak lysosomal enzymes (which initiate tissue necrosis) and release prostaglandins (which signal the spinal arteries to constrict spasmodically). Denied oxygen, the endometrial cells die and release still more lysosomal enzymes until the functional layer starts to “self-digest.” The spinal arteries then constrict one final time and suddenly open wide.

As blood gushes into the weakened capillary beds, these vessels fragment, causing the functional layer to slough off. This is menstruation. (Fig. 25.20) 22. (a) Please see stages 1–6, as described on pp. 793 and 795 and in Figure 25.19. (b) Middle of the cycle, around day 14. (p. 797)

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23. The greater vestibular glands are the paired, pea-sized glands lateral to the vaginal orifice (Figure 25.20b). They lie deep to the posterior part of the labia on each side and secrete lubricating mucus into the vaginal orifice during sexual arousal, thereby facilitating the entry of the penis. (p. 793) 24. His cremaster muscles had reflexively pulled his testes superiorly, closer to the warmth of his body. (p. 777) 25. The uterine tube is the site of 90% of all ectopic pregnancies. As the uterine tube cannot establish a placenta or accommodate the growing fetus, it ruptures. This is why the condition must be diagnosed on time. (p. 803) 26. On reaching an oocyte, a sperm undergoes the acrosomal reaction. During this process, digestive enzymes are released from the acrosome (cap-like structure covering the nucleus) as they are required to create (digest) a slit in the zona pellucida, which would allow the sperm to reach the oocyte plasma membrane and fuse with it. (pp. 800–801, Fig. 25.22) 27. (a) Spermatids differentiate into sperm during spermiogenesis, which is the third and final stage of spermatogenesis. Sperm are composed of head, midpiece, and tail. Sperm enter the seminiferous tubules and travel to the epididymis. Spermatocytes are the immature male gametes that develop through the process of spermatogenesis into sperm. (pp. 786–787). (b) The epididymis is a large, comma-shaped structure superior and lateral to the testis; it contains both the coiled duct of the epididymis and the efferent ductules (pp. 779–780). (c) The ovarian ligament is a fibrous band extending medially from the ovary, whereas the suspensory ligament is a fold of mesentery extending superiorly and laterally from the ovary. (Fig. 25.15). (d) The vulva is all the female external genitalia, but the vestibule is just the space between the two labia minora (p. 799). (e) Spermatogenesis is the entire process of sperm formation, the transformation of spermatogonia stem cells to complete sperm cells. Spermiogenesis is merely the final stage of spermatogenesis, in which spherical spermatids transform into tadpole-shaped sperm cells. (pp.

784–787) 28. FSH and LH influence both the male and female reproductive systems. In females, FSH stimulates maturation of follicles in the ovaries and helps signal production of estrogens by these follicles; in males, FSH stimulates sperm production and the production of androgen-binding protein by sustentacular cells in the testes. In females, LH triggers ovulation and signals the ovarian follicles to produce androgens (which are converted to estrogens) and progesterone; in males, LH signals the secretion of androgens by interstitial cells in the testes. (pp. 787 and 795, Fig. 25.20) 29. Oogenesis is gametic meiosis in females; spermatogenesis is gametic meiosis in males.

(1) An individual primary oocyte produces a single functional gamete, the ovum (along with three nonfunctional polar bodies); an individual primary spermatocyte produces four functional sperm cells. (2) Mitosis of female stem cells, the oogonia, occurs in the fetus; mitosis of male stem cells, the spermatogonia, begins at puberty. (Figs. 25.9, 25.18)

Critical Reasoning and Clinical Applications Questions 1. Matthew had cryptorchidism, a congenital condition where one of the testes fails to descend into the scrotum from the abdomen. The undescended testis can be located in either the inguinal canal or the pelvic cavity. It fails to produce sperm because of the higher temperature in the abdomen. The undescended testis is also prone to malignant transformation and should therefore be removed surgically to prevent future malignancy. (p. 810) ..

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2. Henry was suffering from hypospadias, a congenital abnormality of the male urethra, where the two urethral folds fail to close properly, leading to openings on the undersurface of the penis. During urination, urine dribbles from the undersurface of the penis more than from the tip. Surgical correction is usually the treatment of choice. (p. 808) 3. The man probably has a tumor of the prostate, and the enlargement of the prostate is constricting his prostatic urethra. In the rectal exam, a physician is feeling the prostate for swelling and lumps. (pp. 783 and 806) 4. Sheila is suffering from a ruptured tubal pregnancy. The abdomen is usually full of blood that causes decreased blood pressure, and tenderness of the abdomen to touch. Ectopic tubal pregnancies occur when the fertilized ovum implants in the fallopian tube instead of the uterus. As the ectopic pregnancy progresses, the fallopian tube ruptures, causing severe hemorrhage. This is a medical emergency, and surgical intervention accompanied by aggressive fluid therapy is necessary to stop the hemorrhage and correct the hypotension. (p. 798 and 803) 5. Doctors recommend that men not wear tight underwear or tight jeans if they want to father children because tight clothing holds the testes close to the warmth of the body, where higher temperatures inhibit sperm production. (p. 777) 6. A female with an ovary removed from one side and a uterine tube removed from the other side possibly can get pregnant if the surgeon repositions the existing uterine tube closer to the existing ovary. In any event, uterine tubes have little or no contact with the ovaries. The ovulated oocyte is released into the peritoneal cavity and the uterine tube performs a series of complex movements to capture the oocyte. (pp. 786–790) 7. Sandra is suffering from a type of ectopic pregnancy, which is caused by the embryo’s implantation in one of her uterine tubes. Because the uterine tube is unable to establish a placenta and accommodate the fetus’ growth, the tube can rupture and cause internal bleeding (could be fatal if not diagnosed early). Thus, in Sandra’s case, she will not be able to have a full-term pregnancy. (p. 803) 8. In a mastectomy, the surgeon must cauterize (1) the lateral thoracic artery, and the cutaneous branches of (2) the internal thoracic artery and (3) the posterior intercostal arteries that supply the breast. (See pp. 798–800, “Mammary Glands.”)

Interpreting Medical Images Questions Answers to Interpreting Medical Images questions are provided in the Instructor Resources area of Mastering A&P.

Figure 25.28: The thin thread-like structures in part (b) are the lactiferous ducts that drain the alveoli of the lactiferous glands. Malignancies typically begin in the duct system within the breast. The most common types of cancers are carcinomas, cancers of epithelial tissues. The tissue lining the lactiferous ducts is epithelia.

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Supplemental Student Materials to Human Anatomy, Ninth Edition Chapter 25: The Reproductive System To the Student Up to this point, along with the structure and function, you have studied the embryology, growth, and development of all the systems that make you unique from other organisms.

Your study of male and female reproductive systems provides the information you need to understand how you, as a species, physically survive from one generation to the next.

In terms of the human life cycle, this is the last topic to explore. The reproductive system includes the study of the phenomenal mechanisms that result in the production of gametes by the testes and ovaries, and the supporting roles of the many male and female organs that ultimately accomplish the overall reproductive goal, production of offspring. The amount of information is vast and decidedly complicated because of the vital roles played by hormones in processes such as the menstrual cycle and pregnancy.

You will also find that incorporating Practice Anatomy Lab 3.0 (PAL) (BC; DVD, Website) into your studies of the male and female reproductive systems will give you an excellent opportunity to review organs of these systems. You will find the Reproductive System sections of the Cadaver and Anatomical Models modules particularly helpful. For a review of photomicrographs of the testes, male accessory glands, ovaries, uterine tubes, and uterus, study the slides in the Histology module, Reproductive System. You may access PAL 3.0 through the DVD or the Mastering A&P website.

Step 1: Describe the structure and function of the organs of the male reproductive system. __ Define sexual reproduction. __ Identify the primary sex organs or gonads of the male, and comment on their delayed development compared to other organ systems of the human. __ Describe the scrotum, and explain the associated structures that aid in regulation of temperature for the testes. __ Define testis, identifying its primary functions and structural features, and explain the origin of the word. __ Explain completely the details of spermatogenesis, using diagrams and time lines, including the formation of spermatocytes, meiosis, and spermiogenesis. __ Explain how meiosis differs from mitosis, and indicate how many functional sperm result from one diploid cell. __ Distinguish the structure and function of spermatogenic cells, sustentocytes, myoid cells, and interstitial cells. Identify whether each type of cell identified is haploid or diploid.

Step 2: Describe the reproductive duct system in males. __ List the individual parts of the system of ducts through which sperm travel from their point of origin in the testis to the external urethral orifice, explaining the location of each part. __ Explain the location, histology, and functions of the epididymis.

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__ Explain how sperm move through the ductus (vas) deferens. __ Describe the anatomical path of the ductus deferens through the pelvic cavity. __ Describe the spermatic cord, and clearly distinguish it from the ductus deferens. __ Identify the location, structure, and function of the male urethra, relating to its three parts.

Step 3: Describe the male accessory glands, their secretions, and their functions. __ Describe the location, structure, secretions, and functions of the seminal glands, prostate, and bulbo-urethral gland.

Step 4: Describe the penis and male perineum. __ Describe the gross anatomy of the penis, explaining its function. __ Identify the types of erectile tissues, explaining the mechanism of erection and why the erect penis does not buckle or kink during intercourse. __ Distinguish erection from ejaculation. __ Draw the diamond-shaped region of the male perineum, and label the bony landmarks, structures, and openings contained there.

Step 5: Describe the structure and function of the female gonads, including ovum production and associated hormonal events. __ Identify the primary sex organs or gonads of the female and comment on their delayed development compared to other organ systems. __ Describe the location, structure, and function of the ovaries, including their supporting mesenteries and ligaments. __ Define and describe the menstrual cycle, summarizing structural and hormonal changes occurring to the ovary. __ Define and describe the follicular phase, ovulation, and the luteal phase of the ovarian cycle, including the names of hormones and hormonal functions. __ Distinguish clearly FSH from LH, listing functions associated with the menstrual cycle.

(Hint: Do not forget that although these hormones are named for female structures, they also have male functions.) __ Explain how the corpus luteum functions as an endocrine gland. __ Explain completely the details of oogenesis, using flowchart diagrams and timelines, including the formation of oogonia, meiosis, and ova. __ Identify which cells in the oogenesis flowchart are haploid and which are diploid. __ Explain how many functional ova result from one diploid cell. __ Identify the structure from which an oocyte ovulates and the precise space into which it is released. __ Define fertilization.

Step 6: Describe the accessory ducts and organs associated with the female reproductive system. __ Describe the location, structure, and function of the uterine tubes, including specific regions and the histology of the tubular wall.

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__ Explain how the ovulated oocyte is propelled into the infundibulum from the peritoneal cavity. __ Note the characteristics of the uterine tube that aid movement and help sustain the oocyte or possible embryo on its journey to the uterus. __ Describe the location, structure, and function of the uterus, including its gross anatomical features and the function of cervical mucus. __ Name and describe the uterine-supporting ligaments and mesenteries. __ Name the tunics of the uterine wall, explaining their functions. __ Describe the uterine structural and hormonal changes associated with the menstrual cycle, identifying three phases. __ Explain what happens if fertilization and implantation occur as well as what happens physically if those events do not occur. __ Relate the structure of the vagina to its function, including the layers of the vaginal wall. __ Distinguish the fornix of the vagina from the cervix of the uterus.

Step 7: Describe the vulva and female perineum. __ List, locate, and describe the structures of the female external genitalia. __ Define the term homologue, and identify four male and female homologous structures. __ Diagram the female perineum as a diamond-shaped region, and label its bony landmarks, openings, and associated structures. __ Describe the structure and function of the mammary glands, distinguishing mammary glands from breasts.

Step 8: Describe the events that occur in the female reproductive tract during pregnancy and childbirth. __ Review the stages of basic embryology in Chapter 3. __ Define fertilization, and discuss events leading to sperm penetration of an oocyte. __ Describe the process of implantation. __ Explain the formation of the placenta, including its structure and function. __ Explain the three successive stages of labor involved in childbirth.

Step 9: Explore the disorders of the reproductive system and changes that occur with aging. __ Read about reproductive system cancers in males: testicular cancer and prostate cancer. __ Read about reproductive cancers in females: ovarian cancer, endometrial cancer, cervical cancer, and breast cancer. __ Describe the embryonic development of the sex organs, and explain why the male ducts and female ducts are not homologous. __ Describe the descent of the gonads, naming termination points. __ Note the anatomical changes that occur during puberty and menopause.

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