SOLUTIONS MANUAL FOR Anatomy & Physiology 9th Edition. Kevin Patton

Anatomy & Physiology 9e Kevin Patton (Solutions Manual All Chapters, 100% Original Verified, A+ Grade) Instructor’s Resource Material for

1 Organization of the Body ANSWER KEYS Answers to Quick Check Questions 1. Science develops new principles by using detailed observations and vigorous tests, or experiments, to analyze each idea or hypothesis until a reasonable conclusion can be made. As more testing is done, eliminating outside influences or biases and ensuring consistent results, scientists begin to have more confidence in the principle and then call it a theory or law.

2. Anatomy is the study of the structure of an organism and the relationships of its parts. Physiology is the scientific study of the body functions of the living organism and its parts.

3. Physiology can be divided into (1) the type of organism involved, (2) the organizational level studied, and (3) a specific, or systemic, function being studied.

4. The study of the body that focuses on groups of organs that have a common function is called systemic anatomy.

5. An eponym is a term that is based on a person’s name.

6. Autopoiesis defines life; organisms are self-organizing or self-maintaining, and nonliving structures are not.

7. Metabolism is the sum of all physical and chemical reactions in the body. Each characteristic of life is related to these reactions.

8. The seven levels of organization are chemical, organelle, cellular, tissue, organ, system, and organism.

9. Answers may include any of the following: mitochondria, Golgi apparatus, nucleus, ribosome, endoplasmic reticulum, vacuole, and lysosome.

10. The four major tissue types are epithelial, connective, muscular, and nerve.

11. The 11 major organ systems are integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic, respiratory, digestive, urinary, and reproductive.

12. In the anatomical position, the body is in an erect, or standing, posture with the arms at the sides and palms turned forward. The head and feet are also pointing forward. This position is a reference position that gives meaning to the directional terms used to describe the body parts and regions.

13. The two major subdivisions of the body as a whole are axial and appendicular.

14. The two major body cavities and their subdivisions are (1) ventral cavity (thoracic and abdominopelvic cavities) and (2) dorsal cavity (cranial and spinal cavities).

15. The nine abdominopelvic regions are right hypochondriac, epigastric, left hypochondriac, right lumbar, umbilical, left lumbar, right iliac, hypogastric, and left iliac. The four abdominal quadrants are right upper, left upper, right lower, and left lower.

16. Superior is toward the head or upper or above; inferior: toward the feet or lower or below; anterior is front or “in front of;” posterior is back or “in back of;” medial is toward the midline of the body; lateral is toward the side of the body; dorsal is toward the back; and ventral is toward the belly.

17. Anatomical left is opposite of your left as you face the structure.

18. The rosette is used as a compass similar to those used on geographical maps. Rather than being labeled, N, S, E, and W, the anatomical rosette is labeled with abbreviated anatomical directions.

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Chapter 1 | Organization of the Body _________________________________________________________

19. The three major planes used to divide the body into parts are the sagittal, coronal (frontal), and transverse planes. A sagittal plane is any lengthwise plane running from front to back and top to bottom, dividing the body or any of its parts into right and left sides. A coronal (or frontal) plane is any lengthwise plane running from side to side and top to bottom, dividing the body or any of its parts into anterior and posterior portions.

A transverse plane is any crosswise plan that divides the body or any of its parts into upper and lower parts.

20. “Complementarity of structure and function” refers to the fact that anatomical structures seem “designed” (size, shape, form, or placement) to efficiently perform specific functions.

21. DNA “directs” the differentiation of specialized cells during development so that they can effectively contribute to a specific function. For example, in the lungs, the cilia, which cover the exposed surface of cells that form the tissues lining the respiratory passageways, help trap and eliminate inhaled contaminants.

Answers to Case Study Questions (p. 19) 1. b: The abdominopelvic cavity can be divided into quarters, or quadrants. Health care professionals commonly refer to these quadrants as a standard way to describe the location of pain or an injury on a patient.

2. c: The liver is a large organ that fills the majority of the right upper quadrant. A stab wound to this area will most likely affect the liver.

3. c: Proximal means closer to the trunk. So, the part of the lower extremity proximal to the knee would be the thigh region, also referred to as the femoral region. If the contusion is “just proximal” to the knee, it is just above the knee.

4. c: The proximal part of the upper extremity is referred to as the brachial region—the arm, which is where the humerus bone is located. (You’ll also find the brachial nerve and the brachial artery in this area.)

Answers to Review Questions (p. 22) 1. Anatomy is the study of the body’s structure and the relationship of its parts. Physiology is the study of functions of the living organism and its parts.

2. Chemical level: Atoms, molecules, and macromolecules that make up the body. The text uses cytoplasm as an example of the chemical level.

Organelle level: Collections of molecules organized in such a way that they can perform an individual function. Mitochondria, Golgi apparatus, endoplasmic reticulum, or any other organelles are examples.

Cellular level: Cells are the smallest units that possess and exhibit the basic characteristics of living matter.

Each cell is surrounded by a membrane and contains a single nucleus surrounded by cytoplasm. The cytoplasm contains numerous organelles. Muscle, bone, nerve, or any other cells are examples.

Tissue level: An organization of many similar cells specialized to perform a certain function. Epithelial, muscle, connective, and nervous tissues are examples.

Organ level: An organization of several different tissues arranged so that together they can perform a specialized function. Lung, heart, brain, or any other organs are examples.

System level: Varying numbers and kinds of organs arranged so that together they can perform complex functions for the body. Integumentary, skeletal, muscular, or any other organ systems are examples.

Organism level: An integrated assemblage of interactive structures able to survive and flourish. Human beings or any other organisms are examples.

3. Integumentary system: The primary function is protection. Other functions include regulating body temperature, synthesizing chemicals, and acting as a sense organ.

Skeletal system: The primary function is to support the body. Other functions include protection, allowance for movement, mineral storage, and blood cell formation.

Muscular system: The primary function is movement of the body. Muscles also generate heat for the body.

Nervous system: The primary functions are communication, integration, and control of body functions.

Endocrine system: The primary functions are also communication, integration, and control of body functions but in a slower, longer-lasting form than the nervous system provides.

Cardiovascular system: The primary function is the transport of substances to various parts of the body.

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Lymphatic/immune system: The primary function of the lymphatic system is the movement of tissue fluid and large molecules back to general circulation. The primary function of the immune system is conferring protection and resistance to disease.

Respiratory system: The primary function is the exchange of oxygen for carbon dioxide.

Digestive system: The primary function is the digestion of food, absorption of food, and elimination of undigested residue.

Urinary system: The primary function is to clean the blood of waste products. Other functions are to maintain the electrolyte, water, and acid-base balance of the body.

Reproductive system: The primary function is to ensure the survival of the genetic code and the species.

4. Anatomical position is a position in which the body is standing erect with arms at the side, palms forward, and the head and feet pointing forward. This is the reference position that gives meaning to the directional terms used to describe the body parts and regions.

5. Bilateral symmetry means that the right and left sides of the body are mirror images of each other, and only one plane can divide the body into left and right sides. Ipsilateral refers to a body part on the same side of the body. Contralateral refers to a body part on the opposite side of the body.

6. Somatotype is used to describe a particular category of body build or physique. The three major somatotype categories are endomorph, mesomorph, and ectomorph. Endomorphs are more round shaped, mesomorphs are more muscular, and ectomorphs are more lean and linear.

7. Anterior: The front or in front of Distal: Away from or farthest from the trunk or point of origin of a body part Sagittal plane: A lengthwise plane running from front to back, dividing the body into right and left sides Medial: Toward the midline of the body Dorsal: Toward the back Coronal plane: A lengthwise plane running from side to side, dividing the body into anterior and posterior sections Organ: Several different kinds of tissues arranged so that together they can perform a special function Parietal peritoneum: The membrane lining the inside of the abdominal cavity Superior: Toward the head or above Tissue: A group of similar cells specialized to perform a certain function 8. The mediastinum is located in the midpoint of the thoracic cavity between the right and left pleural cavities.

9. The principle of complementarity of structure and function states that each structure has a particular size, shape, form, or placement in the body that makes it especially efficient at performing a unique, specialized activity.

Answers to Critical Thinking Questions (p. 22) 1. Digestion is the process by which complex food particles are broken down into simpler substances. Through the circulatory system, these substances (nutrients) are transported from one body part to another. Growth occurs as a result of these nutrients increasing the size or number of cells.

2. An endomorph with a waist-to-hip ratio of 1:2 would be predisposed to heart disease, stroke, high blood pressure, and diabetes.

3. The abdominopelvic regions included in the x-ray would be right iliac, right lumbar, right hypochondriac, epigastric, left hypochondriac, and umbilical region. The more correct answer would include all nine regions.

4. From the largest to the smallest, the urinary bladder can be placed in the following cavities: ventral cavity, abdominopelvic cavity, and pelvic cavity.

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2 Homeostasis ANSWER KEYS

Answers to Quick Check Questions 1. The body’s internal environment is a watery fluid that surrounds the cells of the body.

2. Homeostasis is the relatively constant state maintained by the body.

3. In physiology, a set point value for a physiological variable is the value at which the body’s control systems have “set” as the normal value.

4. Because the human body is essentially a group of many living cells living in a bag (of skin) filled with body fluid, one can use the analogy of a fishbowl, where the cells living in body fluid are like fish living in water. Like the fishbowl accessories that maintain a stable environment for the health of fish, our organs maintain a stable fluid environment in our body.

5. The basic components of every feedback control system are the sensor mechanism, the integrator or control center, the effector mechanism, and the feedback. The variable is the physiology characteristic being controlled by the feedback loop and the set point value is the “normal” value for the variable.

6. Room temperature (variable) is kept stable by a thermostat (sensor-integrator) that feeds back information about room temperature to a controller that turns on the furnace (effector) if the room temperature dips below the value set on the thermostat (set point value).

7. A feedback loop is “negative” when its response reverses the direction of change (in the variable) detected by sensors.

8. Negative feedback control systems are inhibitory. They produce an action that is opposite to the change that activated the system. Negative feedback control systems stabilize physiological variables. Positive feedback control systems are stimulatory. Positive feedback tends to amplify or reinforce the change that is occurring.

Typically, such responses result in instability and disrupt homeostasis.

9. Examples of such circumstances include bacterial infection, when a higher temperature benefits the fight against infection, and when variables need to be higher or lower than average during particular times of the day in order to maintain normal function of the body.

10. A circadian rhythm is a daily pattern in body function, such as a daily drop in body temperature while sleeping.

11. Any time the body responds to a change that has not happened, but is likely to happen, is a feed-forward response—like when the stomach becomes active and begins producing digestive juices just before a meal.

12. Intracellular control mechanisms operate at the cell level. These mechanisms regulate functions within the cells. Intrinsic control mechanisms operate at the tissue and organ levels. They often make use of chemical signals. Extrinsic control mechanisms operate at the system and organism levels. These usually involve nervous and endocrine regulation.

Answers to Case Study Questions (p. 35) 1. b: An adrenaline boost causes a number of physical symptoms, including rapid pulse and breathing, which are all designed to urge the body into action. The term flight-or-flight response is used to describe an adrenaline release, because it addresses the body’s reaction to the increase in hormone production.

2. d: When Anniston ran her race, skeletal muscles (particularly her legs) worked extensively thus using energy at a very high rate. This increase in muscle contraction produced a substantial amount of heat, which raised her core body temperature. In attempt to cool the body down from this increase in temperature, her sweat glands were activated to produce/secrete sweat (water). This secretion of sweat reduced her body water levels.

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Chapter 2 | Homeostasis ___________________________________________________________________

3. b: This is an example of negative feedback. As the level of water in the blood falls, negative feedback ensures that the amount of ADH rises. As the level of water in the blood rises, negative feedback ensures that the amount of ADH falls.

Answers to Review Questions (pp. 36-37) 1. Homeostasis is the relatively constant state maintained by the body (relative uniformity of the normal body’s internal environment). Examples include the following: the body maintains a constant internal temperature, the blood and body fluid must maintain a constant chemical composition, or any other occurrence that demonstrates the body’s homeostatic regulation.

2. Homeostatic control mechanisms are devices for maintaining or restoring homeostasis. Feedback control loops are systems that respond to changing internal environments and restore and maintain a healthy internal environment.

3. The four basic components of a control loop are (1) a sensor mechanism, (2) an integrator or control center, (3) an effector mechanism, and (4) feedback.

4. A negative feedback loop causes a reversal of a change that is occurring in the body, thus stabilizing a controlled variable near a set point value. A positive feedback loop, on the other hand, works in the opposite manner—amplifying a change in the controlled variable and thus promoting further movement away from the set point.

5. A drop in body temperature below the set point temperature acts as a stimulus, which promotes the response of muscle shivering. Shivering produces heat that moves the body temperature back toward the set point temperature.

6. Examples mentioned in this chapter include: regulation of body temperature, blood oxygen concentration, blood carbon dioxide concentration, blood acid levels (pH), and water content of body tissues.

7. Examples mentioned in this chapter include: regulation of labor contractions during childbirth, immune system response to infection, and formation of a blood clot.

8. A circadian rhythm is regular daily pattern in the body, such as highs and lows of temperature, blood pressure, or hormone concentrations in the blood.

9. Feed-forward is the concept that information may flow ahead to another process to trigger a change in anticipation of an event that will follow. It allows the body to react to anticipated changes in the body, rather than reacting only to changes after they have happened.

10. The three levels of homeostatic control in the body are intracellular, intrinsic, and extrinsic control mechanisms. Intracellular control mechanisms operate at the cell level. Intrinsic control mechanisms operate at the tissue and organ levels. Extrinsic control means “outside” control and operates at the system and organism levels.

11. Health usually involves an overall stability of the body maintained by homeostatic feedback loops. Disease is often the result of some disruption of homeostasis when abnormal changes to the body cannot be easily returned to normal ranges.

12. Risk factors mentioned in this chapter include: genetic factors, age, lifestyle, stress, environmental factors, microorganisms, and preexisting conditions.

13. A pathogen is an agent that causes disease. Examples mentioned in this chapter include: prions, viruses, bacteria, fungi, protozoa, and animals.

Answers to Critical Thinking Questions (p. 37) 1. Just as an aquarium filter removes toxic fish wastes, keeping the toxin levels relatively constant at a low, safe level, the kidneys remove toxic cellular wastes from the blood—thus keeping toxin levels in the blood at a relatively constant safe (low) level.

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2. Your eyes (seeing you are drifting out of your lane) are the sensory mechanism. Your brain is the integrator or control center. Your arms and hands are the effector mechanism. This is a negative feedback loop because the response opposes the change that stimulated it and returns it to set point (your own lane).

3. As blood glucose levels drop below the set point value, sensors detect this and provide the information to integrator mechanisms. Integrators respond by using regulatory mechanisms (such as, hormones) to push the glucose back up to normal concentrations.

4. This is negative feedback, because it reverses the drop in tissue oxygen levels by increasing the flow of blood to the local tissues (by dilating the nearby vessels). It is an example of intrinsic control, because it is happening at the tissue level, using cell-to-cell communication.

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3 Chemical Basis of Life ANSWER KEYS Answers to Quick Check Questions 1. Biochemistry is the specialized area of chemistry that deals with living organisms and life processes.

2. An element is a substance that cannot be broken down or decomposed into two or more different substances.

A compound is two or more elements joined to form chemical combinations.

3. Carbon, oxygen, hydrogen, and nitrogen make up 96% of the human body.

4. The three most important types of subatomic particles are proton, neutron, and electron. A proton is a subatomic particle with a positive charge located in the nucleus. A neutron is a subatomic particle with no charge located in the nucleus. An electron is a subatomic particle with negative charge located outside the nucleus.

5. The atomic number is the number of protons in the atom’s nucleus. Atomic weight refers to the mass of a single atom. It equals the number of protons plus the number of neutrons in the atom’s nucleus.

6. Energy levels are the shells or concentric circles with electrons surrounding each atom.

7. The tendency of atoms with fewer or more than eight electrons in the outer energy level to attempt to lose, gain, or share electrons with other atoms is called the octet rule.

8. Isotopes are atoms with the same number of protons, but differing numbers of neutrons. Isotopes have the same basic chemical properties as any other atom of the same element, and they also have the same atomic number. However, because they have a different number of neutrons, they differ in mass number.

9. The two types of chemical bonds between atoms are ionic and covalent bonds. Ionic bonds are formed by the transfer of electrons from one atom to another. Covalent bonds are formed when atoms share electrons.

10. Hydrogen bonds attract one molecule to another.

11. The three basic types of chemical reactions are as follows: Synthesis: A + B → AB. Decomposition: AB → A + B + energy. Exchange: AB + CD → AD + CB. 12. The term metabolism is used to describe all the chemical reactions that occur in the body’s cells.

13. Anabolism refers to the chemical reactions that join simple molecules together to form more complex biomolecules. Catabolism refers to chemical reactions that not only break down relatively complex compounds into simpler ones but also release energy from them.

14. ATP transfers energy to cell components, which makes it possible for them to do work.

15. Polar water molecules attract other polar compounds, causing them to dissociate. Hydrogen bonds absorb heat when they break and release heat when they form, minimizing temperature changes. Many hydrogen bonds must be broken before water can evaporate. Hydrogen bonds hold molecules of water together. The critical role that water plays as a solvent permits the transportation of many essential materials within the body.

Water has a high specific heat property. This means that water can lose and gain large amounts of heat with little change in temperature. Finally, water has a high heat of vaporization. This characteristic requires the absorption of significant amounts of heat to change water from a liquid to a gas.

16. Electrolytes are substances that break up in a solution to form charged particles or ions.

17. Acids and bases are chemical opposites. Although they both dissociate in solution, both release different types of ions. Acids release hydrogen ions, and bases are electrolytes that shift the H +/OH− balance in favor of OH−.

18. The term pH is a symbol used to mean the H+ ion concentration of a solution; pH stands for the negative logarithm of the H+ ion concentration.

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Chapter 3 | Chemical Basis of Life ___________________________________________________________

Answers to Case Study Questions (p. 52) 1. c: Your stomach contents are very acidic. When you vomit, you are “losing” that acid content to the outside.

Your overall body fluid is usually well balanced between acids and bases. (Your blood is just on the basic side at a pH of about 7.36 to 7.41.) A decrease in acid content body-wide (as with prolonged vomiting) could possibly lead to alkalosis or the body chemistry being too basic. Many reactions cannot occur when the pH is unbalanced, that is, the body cannot function properly, regardless of whether the imbalance is too acidic or too basic.

2. d: The concentration of hydrogen ions is reflected in the pH measure. More hydrogen ions translates to more acidic and a lower number on the pH scale. Fewer hydrogen ions translate to more basic and a higher number on the pH scale. A pH of 7.0 is neutral.

3. a: Remember your body is not simply a bag of water; it is a vessel containing specifically calibrated fluids in a number of different compartments. If you lose electrolytes (i.e., sodium, potassium, and chloride) through vomiting or sweating or any other means, you need to replace them in appropriate amounts.

4. b: Carbohydrates are the body’s primary source of energy. Simple sugars (monosaccharides) can be absorbed and used immediately by the body. Even polysaccharides can be easily broken apart. Proteins, on the other hand, require the body to expend much more energy to unwind and break down their component amino acids, which only then can be absorbed by the body. The same is true of lipids.

Answers to Review Questions (p. 54) 1. Element: A substance that cannot be broken down into two or more different substances.

Compound: A substance that can be broken down or decomposed into the elements within it.

Atom: The smallest particle of an element that retains the properties of that element.

Molecule: Two or more atoms sharing electrons to form a chemical bond.

2. In the nineteenth century, Dalton conceived of atoms as solid and indivisible particles. Today we know that atoms are divisible into smaller subatomic particles, some of which exist in a cloud around a dense central core called a nucleus.

3. Protons: Positively charged particles found in the nucleus.

Neutrons: Neutral particles found in the nucleus.

Electrons: Negatively charged particles that move around the nucleus in a cloud or field.

4. Atoms are not electrically charged particles, because they have an equal number of positively charged protons and negatively charged electrons, which neutralize each other.

5. About 96% of the body’s weight is made up of oxygen, carbon, hydrogen, and nitrogen.

6. Atomic number: The number of protons in an atom’s nucleus.

Mass number: The mass of the atom, which equals the number of protons plus the number of neutrons in the nucleus.

7. An atom can be listed as chemically inert and unable to react with another atom if the outermost electron shell has eight electrons.

8. An isotope is an atom that contains the same number of protons as other atoms of the same element but a different number of neutrons. The text includes examples of deuterium, tritium, and carbon-14.

9. Radioactivity is the emission of radiation from the atom’s nucleus.

10. When an atom is radioactive, it changes the chemical identity of the element. Chemical activity may change how two or more atoms are joined, but the chemical identity remains the same.

11. Alpha particles: Particles consisting of two protons and two neutrons.

Beta particles: Electrons formed in the nucleus of an atom by neutrons breaking down to a proton and an electron.

Gamma rays: A form of electromagnetic radiation.

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12. If an atom emits an alpha particle, it is transformed into the element with two fewer protons; it also has two fewer neutrons. If it emits a beta particle, it is transformed into an element with one more proton, and it has one fewer neutron.

13. A chemical reaction is an interaction between two or more atoms as a result of activity of electrons in their outermost shell.

14. In a synthesis reaction, two or more substances are combined to form a different, more complex substance. In a decomposition reaction, a complex substance is broken down into two or more simpler substances. In an exchange reaction, two different reactants exchange components and form two new products.

15. An inorganic compound is a compound that usually does not contain carbon but never contains C-C or C-H bonds.

16. Water is said to be polar because the molecule has a partial positive side and a partial negative side. The four functions of water that are crucial to survival are its strong polarity, its high specific heat, its high heat of vaporization, and the cohesion of the molecules.

17. Electrolytes are inorganic, charged particles that form when substances dissociate. An example would be NaCl dissociating into Na+ and Cl−. Any ionic compound that is water soluble would be an example.

18. A cation is a positive ion. (Any positive ion can be used as an example.) An anion is a negative ion. (Any anion can be used as an example.) An ion is a charged atom or molecule. (Any charged particle can be used as an example.)

19. Acid: A substance that will release a hydrogen ion when in solution.

Base: A substance that shifts the H+/OH− balance in favor of OH− by increasing the number of OH− ions or decreasing the number of H+ ions.

Salt: A substance that results from a reaction between an acid and a base.

Buffer: A substance that minimizes changes in the concentration of the H + and OH− ions. It maintains a constancy of pH. 20. A pH of less than 7.0 indicates the solution is an acid. The lower the value, the greater the hydrogen ion concentration. A pH of more than 7.0 indicates the solution is a base. The higher the value, the greater the concentration of the hydroxide ion. Each change of 1 unit on the pH scale represents a tenfold difference in the ion concentration.

21. Catabolism consists of chemical reactions that break down relatively complex compounds into simpler ones.

The function of catabolism is to release energy.

22. Catabolism breaks down large molecules that release energy. Anabolism builds large molecules from smaller molecules and requires energy. Metabolism encompasses all the reactions in the body—that is, the sum of anabolism and catabolism.

Answers to Critical Thinking Questions (p. 54) 1. Biochemists would have an interest in living organisms and life processes, such as growth, muscle contraction, transmission of nerve impulses, homeostatic processes, and control mechanisms.

2. Helium has two electrons in its outer shell. Hydrogen has only one electron in its outer shell. Because helium’s outer shell is filled, helium is unreactive. Hydrogen, however, has an incomplete outer shell and is very reactive.

3. In a single covalent bond, two electrons (one pair) are shared between two atoms. In a double covalent bond, four electrons (two pairs) are shared between two atoms. In an ionic bond, electrons are transferred from one atom to another, and the bond is formed by the attraction of opposite electrical charges.

4. In an adult with a body weight of 170 pounds, about 119 pounds would be water (170  0.70 = 119).

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4 Biomolecules ANSWER KEYS

Answers to Quick Check Questions 1. The four major groups of organic substances are proteins, carbohydrates, lipids, and nucleic acids.

2. Glucose is the most important monosaccharide in terms of body function.

3. Disaccharides and polysaccharides are carbohydrate compounds, or polymers, made of two or more simple sugars that are bonded together through a synthesis reaction. Monomers of glucose are joined together in a synthesis reaction that also involves the removal of water.

4. Fatty acids and glycerol are the building blocks of a triglyceride.

5. Phospholipids are fat compounds similar to triglycerides. They are modified, however, in that one of the three fatty acids attached to glycerol in a triglyceride is replaced in a phospholipid by another type of chemical structure containing phosphorus and nitrogen. Phospholipids form the backbone of the plasma membrane.

6. Cholesterol is the important steroid that stabilizes cellular structure.

7. Nitrogen is present in all proteins but not in carbohydrates.

8. Amino acids are the building blocks of proteins. An amino acid consists of a carbon atom to which are bonded an amino group, a carboxyl group, a hydrogen atom, and a side chain, or group of elements designated by the letter R. 9. The four levels of protein structure are as follows: primary refers to the number, kind, and sequence of amino acids that make up the polypeptide chain; secondary are polypeptide chains that are coiled or bent into pleated sheets; tertiary is a polypeptide chain that undergoes contortions and twisting to form a globular shape; and quaternary is protein that contains clusters of more than one polypeptide chain, all linked together into one giant molecule.

10. DNA and RNA are both important nucleic acids.

11. Nucleotides are small molecules of phosphates, sugar, and nitrogen bases that make up nucleic acids.

12. Base pair: Each nitrogen base in one chain of the DNA molecule is joined to a nitrogen base in the other chain by means of hydrogen bonds.

13. Besides joining together to form nucleic acids, nucleotides play a role in adenosine triphosphate (ATP) structure and energy-transferring molecule (nicotinic adenine dinucleotide [NAD +] and flavin adenine dinucleotide [FAD]) structure. They are also used as a signal inside the cell.

Answers to Case Study Questions (p. 72) 1. c: A high total cholesterol value is associated with a high risk of atherosclerosis. In particular, if that total cholesterol value includes a high blood concentration of low-density lipoprotein, an individual increases his/her risk for this and other coronary diseases.

2. d: High blood concentrations of high-density lipoproteins (HDLs) have been associated with a low risk of developing atherosclerosis and its many possible complications. HDL molecules are attracted to HDL receptors embedded in plasma membranes. Once they bind to their receptors, the cell is stimulated to release some of its cholesterol from storage. The released cholesterol migrates to the plasma membrane, where it may attach to the HDL molecule and then transported to the liver for excretion in bile.

3. a: Cholesterol is found only in foods of animal origin. It is particularly high in liver and the yolk of eggs.

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Chapter 4 | Biomolecules __________________________________________________________________

Answers to Review Questions (p. 74) 1. The building blocks of proteins are amino acids. The building blocks of carbohydrates are monosaccharides.

The building blocks of triglycerides are fatty acids and glycerol. The building blocks of DNA are nucleotides.

2. The binding site is the location on an enzyme with a unique shape that joins with a substrate. The binding site is the location on the enzyme where the reaction that the enzyme catalyzes takes place.

3. Proteins can perform some of the following functions: provide structure, catalyze chemical reactions (enzymes), transport substances in the blood (albumins), communicate information to cells (hormones), act as receptors (membrane binding sites), defend the body against harmful agents (immunoglobulins), and provide energy (protein catabolism).

4. Lipids are insoluble in water, contain nitrogen, and include prostaglandins and phospholipids.

5. Nucleotides are composed of a phosphate group; a pentose, or five-carbon, sugar; and a nitrogen base.

6. The pentose sugar deoxyribose is present in deoxyribonucleotide.

7. The DNA molecule is the largest molecule in the body. It is a polymer composed of many nucleotides. Two chains of nucleotides make up a single DNA molecule. The chains coil around each other to form a double helix.

8. Thymine is always paired with adenine, and guanine is always paired with cytosine in the DNA molecule.

9. The function of DNA is to act as the molecule of heredity—to pass the traits of one generation on to the next generation.

Answers to Critical Thinking Questions (p. 44) 1. Enzymes specifically catalyze one specific reaction (lock-and-key model). If amylase is altered in any way, it would not catalyze the starch, and it would not be broken down into a simpler, less complex molecule.

2. Amino acids are like letters of the alphabet. Just as the combinations of individual letters form words, different amino acid combinations form the many different protein chains.

3. ATP supplies the cells with energy by breaking the high-energy bonds between the second and third phosphate and releasing the energy from that bond. The outline should contain a representation of the ATPADP cycle.

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Instructor’s Resource Material for

5 Cell Structure ANSWER KEYS

Answers to Quick Check Questions 1. Schleiden and Schwann proposed the cell theory.

2. The answer may include one of the following examples: • Nerve cells have threadlike extensions over a meter in length. This structure allows the nerve cell to transmit nervous impulses from one area of the body to another.

• Muscle cells are specialized to contract or shorten.

• Red blood cells contain hemoglobin, which attracts oxygen.

• Gland cells release a secretion to the outside of the cell.

• Immune cells have outer membranes that allow them to engulf other cells.

3. Plasma membrane, cytoplasm, and the nucleus are the three main components of a typical cell.

4. The plasma membrane (1) serves as the boundary of the cell, maintaining its integrity; (2) it controls what goes in and out of the cell and (3) contains proteins and carbohydrate chains that serve as identifying markers and receptor molecules.

5. Organelles are “little organs” that are located within the cytoplasm. There are several types, each with a specific function for cell metabolism.

6. Answers will vary. Some examples of organelles and their functions include the following: Golgi apparatus, synthesizes carbohydrate; lysosome, cell’s “digestive system;” mitochondria, catabolism; ribosome, cell’s “protein factory;” and nucleus, houses genetic code.

7. The membranous organelles are the organelles that are specialized sacs or canals made of cell membrane.

The nonmembranous organelles are not made of membrane but are made of microscopic filaments or other nonmembranous materials.

8. Microfilaments are the smallest cell fibers; are made of thin, twisted strands of protein molecules; and usually form bundles that lie parallel to the long axis of the cell. They are found in muscle cells. Intermediate fibers are twisted protein strands that are slightly thicker than microfilaments. They are thought to form much of the supporting framework in many types of cells. Microtubules are the thickest of the cell fibers. They are tiny, hollow tubes made of protein subunits arranged in a spiral fashion. Microtubules often move things around in the cell or even cause movement of the entire cell.

9. The centrosome plays an important role during cell division, when a special “spindle” of microtubules is constructed for the purpose of moving chromosomes around the cell.

10. Desmosomes are the small “spot welds” that hold adjacent cells together. Gap junctions are formed when membrane channels of adjacent plasma membranes adhere to each other. Tight junctions occur in cells that are joined by “collars” of tightly fused membrane.

Answers to Case Study Questions (p. 94) 1. d: Hydrophilic molecules (represented by people in this case) can pass through channel proteins, which act as gates within the cell membrane “fence.” They cannot, however, pass through the phospholipid bilayer. Some proteins are transmembranous, meaning they stretch across the inside of the cell from one side to the other.

And cholesterol is part of the cell membrane, but it does not function as a passageway. Its main function is membrane stability.

2. b: Two organelles may look similar when a cell model is first examined. The endoplasmic reticulum truly is an interconnected “maze” of tubes. Reticulum means “network.” The other organelle that looks mazelike, the Golgi apparatus, is not connected. Rather, it is a series of closed-ended tubes, like a stack of curved pancakes.

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Chapter 5 | Cell Structure __________________________________________________________________

3. c: Ribosomes may be found floating free in the cytoplasm, but many of them are attached to the rough endoplasmic reticulum where they make proteins that are then transported through the network of canals.

4. a: Microtubules are the thickest of the cytoskeleton, made up of hollow tubes, like pipes. Microfilaments are the thinnest fiber, whereas intermediate filaments (as their name implies) are in between the two in size.

Answers to Review Questions (p. 97) 1. The range of human cell diameters is from 7.5 to 300 m.

2. The three main cell structures are the plasma membrane, the cytoplasm (with organelles), and the nucleus.

3. The plasma membrane is the outer boundary of the cell. It is a thin sheet, about 75 Å thick. The molecular structure includes lipids (such as, phospholipids and cholesterol) and proteins.

4. The communication function depends on membrane receptor proteins, which can respond to hormones or other regulatory chemicals, thereby triggering changes in cell functioning. The transport function depends on membrane proteins, which act as gates to let material in. The protein gates are selective. The identification function depends on glycoproteins, which identify the cell as “self.”

5. Endoplasmic reticulum: This consists of membranous-walled canals and flat, curving sacs arranged in parallel rows. If ribosomes are attached to their walls, they are called rough endoplasmic reticulum. If no ribosomes are attached, they are called smooth endoplasmic reticulum. The rough endoplasmic reticulum functions in both protein synthesis and intracellular transport of molecules. The smooth endoplasmic reticulum functions in the synthesis of membrane for use throughout the cell.

Ribosomes: These are non-membranous structures made of two parts: a large and small subunit composed of RNA and protein. The function of ribosomes is protein synthesis.

Golgi apparatus: This is a membranous organelle consisting of tiny sacs (cisternae) stacked on one another and located near the nucleus. Its function is the processing and packaging of protein for export from the cell.

Mitochondria: This is a sausage-shaped structure with an inner and outer membrane. The inner membrane has many folds called cristae. The mitochondria provide the cells with most of their energy.

Lysosomes: These are saclike structures that contain digestive enzymes. The function of lysosomes is to digest molecules or bacteria that are in the cell.

Proteasomes: These are cell structures that break down proteins.

Peroxisomes: These are small saclike structures containing peroxidase and catalase. Their function is to detoxify harmful chemicals in the cell.

Cytoskeleton: This is a name given to the rodlike structure of various sizes. The smallest are called microfilaments. The next larger fibers are called intermediate filaments, and the largest fibers are called microtubules. Their function is to form a three-dimensional lattice structure in the cell. The microtubules are also important in movement within the cell.

Cell fibers: These are intricate arrangements of fibers that form a three-dimensional lattice within the cell.

They appear to support parts of the cell formerly thought to float free in the cytoplasm—the endoplasmic reticulum, mitochondria, and “free” ribosomes.

Centrosome: This is composed of a cylinder made up of nine bundles of microtubules with three tubules in each bundle. There are two such structures at right angles to each other. Their function is to move chromosomes to the proper part of the cell during cell division.

Centrioles: These are a pair of cylindrical structures located near the nucleus. They play a role in cell division.

Cell extensions: These are special projections of cytoskeleton. There are three types: microvilli, cilia, and flagella. The microvilli are small fingerlike projections of the cell that allow for increased surface area for absorption. Cilia are short hairlike microtubule projections from the cell. Cilia function to move material in a particular direction. The flagella have a long microtubule structure that provides mobility of the sperm cell.

6. Desmosomes are analogous to spot welds that hold adjacent cells together. This allows cells to be held in place tightly. Gap junctions are formed when channels of adjacent cells adhere to each other. This provides tunnels from one cell to the next and also fuses two plasma membranes together. Tight junctions occur when cells are joined by collars of membranes tightly fused with neighboring cells. This prevents molecules from moving through sheets of cells.

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7. The nucleus holds the DNA, which is the molecule responsible for directing the production of proteins in the cell. The nucleoli functions to synthesize ribosomal RNA. 8. Light microscopy: This is used to look directly at the specimen. Stains can be used to differentiate cells.

Transmission electron microscopy: Using a thinly sliced specimen, this provides greater magnification with sharper images. All images are in black and white.

Scanning electron microscopy: The images are greatly magnified, but one can see only surface structures. All images are in black and white.

Answers to Critical Thinking Questions (p. 97) 1. Students should describe the nerve cell and explain how its processes (dendrites and axons) allow it to receive and send nerve impulses. The muscle cell’s elongated shape allows it to contract or shorten.

2. Ribosomes are structures that form polypeptides, which are released into the endoplasmic reticulum (ER) for processing into proteins. Vesicles move the processed proteins from the ER to Golgi apparatus for final steps of processing. Vesicles move the finished proteins to the plasma membrane where the vesicle membrane fuses with the plasma membrane—thus releasing the proteins by exocytosis.

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Instructor’s Resource Material for

6 Cell Function ANSWER KEYS

Answers to Quick Check Questions 1. Diffusion, dialysis, osmosis, filtration, and facilitated diffusion—not all of these transport processes require cell energy to move substances across the membrane. They differ in how the substances move across the membrane. Dialysis is a form of diffusion in which the selectively permeable nature of the membrane causes the separation of smaller solute particles from larger solute particles. Osmosis is the diffusion of water across a semipermeable membrane. Filtration differs in that it moves substances across a membrane by the force of hydrostatic pressure. Facilitated diffusion uses carrier molecules that attract a solute, change its shape, and then release it to the other side of the membrane.

2. Osmotic pressure develops in the cell that originally had the higher concentration of impermanent solute.

Osmotic pressure arises from the tendency of a pure solvent to move through a semipermeable membrane and into a solution containing a solute to which the membrane is impermeable.

3. The three active processes that transport substances across a cell membrane are sodium-potassium pump, endocytosis, and exocytosis. The sodium-potassium pump operates in the plasma membrane by actively transporting sodium ions and potassium ions but in opposite directions. In endocytosis, the plasma membrane “traps” some extracellular material and brings it into the cell. Exocytosis is the process by which large molecules, notably proteins, can leave the cell even though they are too large to move out through the plasma membrane. All of these processes require cell energy.

4. Enzymes are proteins and have the chemical properties of proteins. They are usually tertiary or quaternary proteins of complex shape. Enzymes often contain a nonprotein part called a cofactor. An important structural attribute of enzymes is the active site. The active site is the portion of the enzyme molecule that chemically “fits” the substrate molecule(s). This structure allows the enzymes to bind substrates together or unbind components of a substrate.

5. An allosteric effector is a molecule or other agent that alters enzyme function by changing its shape.

Examples include certain antibiotic drugs, changes in pH, or changes in temperature.

6. Glycolysis, citric acid cycle, and the electron transport system are the three catabolic pathways that together make up the process of cellular respiration.

7. The aerobic pathway extracts more energy.

8. Energy must be transferred to adenosine triphosphate (ATP) before it can be used by most cell processes.

9. Glycolysis is a catabolic pathway that begins with glucose and ends with two molecules of pyruvic acid. Two ATP molecules and nicotinamide adenine dinucleotide (NADH) are generated in this pathway. The citric acid cycle converts pyruvic acid to acetyl coenzyme A and moves into a sequence of reactions that generate ATP, NADH, FADH2, and carbon dioxide. The electron transport system uses the NADH and FADH 2 to transfer energized electrons to a set of special molecules embedded in the cristae of the inner mitochondrial membrane. Additional ATP molecules are formed along with molecules of water.

Answers to Case Study Questions (p. 117) 1. b: Just as some molecules need a facilitator (either a channel or carrier) to allow them to enter a cell, the subway car doors acted as a channel through which the people could move into the train. The people were moving from a high concentration to a low concentration, so their movement was passive.

2. d: Because sodium is moving from low concentration to high concentration, the movement requires energy.

This example would be a form of active transport. Sodium molecules are small enough to be transported across the cell membrane by a protein pump.

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Chapter 6 | Cell Function ___________________________________________________________________

3. b: The input of water (with no solutes) into Tobie’s system would make his blood more dilute (i.e., more water increase than solute increase). That would make the fluid part of his blood hypotonic (hypo = low), a potentially dangerous situation (see Figure 6-5).

Answers to Review Questions (p. 119) 1. Diffusion is the natural tendency of small particles to spread out evenly within any given space.

Dialysis is a form of diffusion in which a selectively permeable membrane causes the separation of small solute particles from larger ones.

Facilitated diffusion occurs when movement of molecules is facilitated or made more efficient by the action of carrier mechanisms in a cell membrane.

Osmosis is the diffusion of water through a selectively permeable membrane.

Filtration is the passing of water and permeable solutes through a membrane by the force of hydrostatic pressure.

2. A concentration gradient is a measurable difference in concentration from one area to another. Because molecules spread from a high concentration to a low concentration, they spread down a concentration gradient.

3. A membrane channel is a pore in the cell membrane through which specific ions or other small water-soluble molecules can pass. The text specifically names sodium and chloride channels.

4. Isotonic means that two solutions have the same potential osmotic pressure because they have the same concentration of impermeable solutes.

Hypotonic means that a solution has a lower concentration of impermeable solutes and a higher concentration of water than does a reference solution.

Hypertonic means that a solution has a higher concentration of impermeable solute and a lower concentration of water than does a reference solution.

5. Osmotic pressure develops in the solution that originally has the higher concentration of impermeable solute.

6. Active transport is a carrier-mediated process that uses cellular energy to move molecules “uphill;” that is, from an area of lower concentration to an area of higher concentration.

7. The sodium-potassium pump operates in the plasma membrane. It actively transports sodium ions out of the cell and potassium ions into the cell.

8. In endocytosis, the plasma membrane receptors bind to a specific molecule in the intracellular fluid, causing a portion of the plasma membrane to be pulled inward by the cytoskeleton. This forms a small pocket around the material. The edges of the pocket fuse, forming a vesicle in the cell. In exocytosis, the material to leave the cell is enclosed by a membranous vesicle and is moved to the plasma membrane by the cytoskeleton. The vesicle then fuses to the plasma membrane, which releases the material outside the cell.

9. Oxidation-reduction enzymes allow energy release for the cells.

Hydrolyzing enzymes are digestive enzymes that break down molecules.

Phosphorylating enzymes add or remove phosphate groups.

Carboxylases add or remove carbon dioxide.

Mutases or isomerases rearrange atoms in a molecule.

Hydrases add water to molecules but do not break them down.

10. Answers should include three of the following principles: • Enzymes are specific in their action; they act on only one substance.

• Various physical and chemical agents activate or inhibit the enzyme by changing its shape. These include allosteric effectors, pH, and temperature.

• Enzymes are able to catalyze a reaction in both directions.

• Enzymes are not used up by the reaction, but they are continually wearing out and need continual synthesis.

• Many enzymes are synthesized as inactive proenzymes.

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11. Metabolism is the complete set of chemical reactions in the living organism.

Catabolism is the breaking down of large molecules into smaller molecules to release energy.

Anabolism is the building up of large molecules from smaller ones, which requires energy.

12. Glycolysis releases a small portion of the energy in glucose. This occurs in the cytosol and releases adenosine triphosphate (ATP) and reduced nicotinamide adenine dinucleotide (NADH). The end product is pyruvic acid. This process can occur without oxygen.

Citric acid cycle uses the pyruvic acid from glycolysis and converts it into acetyl coenzyme A (CoA). The cycle occurs in the mitochondria. The acetyl CoA enters the cycle and is broken down, releasing carbon dioxide, ATP, NADH, and a reduced form of flavin adenine dinucleotide (FADH 2).

The electron transport system uses energized electrons, which are carried by the NADH and FADH 2 to electron-acceptors in the mitochondria. The electrons are passed along a chain of electron-accepting molecules. Their energy is used to pump hydrogen ions between the spaces of the mitochondrial membranes.

When they flow back, the energy they provide is used to form ATP. The hydrogen eventually joins with oxygen to form water.

Answers to Critical Thinking Questions (p. 119) 1. Dialysis is the diffusion of small solute particles, but not large particles, through a selectively permeable membrane that separates the larger from smaller solutes. It is a passive transport process. Phagocytosis is the process of moving large particles or bacteria into the cell by trapping them in a section of plasma membrane that pinches off to form an intracellular vesicle. It is an active transport process.

2. Because potential osmotic pressure is a prediction rather than a measurement of what has already developed, actual osmotic pressure is more easily measured.

3. Because osmotic pressure is based on the number of particles, it is important to determine how many particles are being added to the solvent. If the solvent is a nonelectrolyte (such as, sugar), 1 mole of sugar will produce 1 mole of particles. If it is an electrolyte (such as, NaCl), 1 mole of NaCl will produce 2 moles of particles—1 mole of each ion. If the solution is not isotonic, the cells may burst (if solution is hypotonic) or shrink in size (if solution is hypertonic).

4. The engulfing of bacteria is phagocytosis, which is the endocytosis of solid material. The engulfing of the dissolved proteins is pinocytosis, which is the endocytosis of liquid material.

5. The shape of the enzyme determines what substrate the enzyme fits and, hence, the chemical reaction that it catalyzes. The allosteric effector can inhibit the enzyme by changing its shape so that it no longer fits the substrate. Conversely, the allosteric effector can activate the enzyme by changing its shape so that it does fit the substrate.

6. Aerobic (oxygen-requiring) respiration is a catabolic process that produces the maximum amount of energy available from each glucose molecule. Anaerobic respiration is a catabolic process that does not require the immediate use of oxygen. Besides its ability to produce ATP without oxygen, anaerobic respiration has the advantage of being rapid. Cells having difficulty getting oxygen may rely on anaerobic respiration to resynthesize their ATP molecules.

7. Mitochondria are necessary so that enough energy can be released to keep the cell functioning. Cells that are active (e.g., skeletal muscle cells) require more mitochondria to keep up with the energy demands.

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Instructor’s Resource Material for

7 Cell Growth and Development ANSWER KEYS Answers to Quick Check Questions 1. The sequence of nitrogen base pairs is a code or blueprint that controls the activity of each cell and the genome of the individual.

2. Transcription occurs in the nucleus. Editing (splicing) also occurs in the nucleus. Translation occurs in the ribosomes (cytoplasm).

3. Transfer RNA determines the sequence.

4. Cell growth and reproduction are the two major phases of the cell life cycle. Mitosis occurs during cell reproduction.

5. Protein synthesis and an increase in size of the membranous organelles and plasma membrane cause the cytoplasm to grow.

6. Mitosis (mitotic cell division) is a process of organizing and distributing nuclear DNA during cell division. It results in two gametes, each with the identical number of chromosomes as the parent cell. Meiosis (meiotic cell division) occurs only in primitive sex cells. It results in four gametes, each having half of the number of chromosomes of the parent cell.

Answers to Case Study Questions (p. 134) 1. a: If the body loses its ability to control mitosis normally, abnormal hyperplasia may occur. The new mass of cells thus formed is a tumor or a neoplasm. Neoplasms may be relatively harmless growths, which are called benign.

2. b: Apoptosis is a type of programmed cell death in which organized biochemical steps within the body lead to fragmentation of the cell and removal of the pieces by phagocytic cells. Apoptosis occurs frequently in the cells of your body when cells are no longer needed or when they have certain malfunctions that could lead to cancer or some other potential problem.

3. c: Anaplasia is a condition in which cells fail to differentiate into a specialized cell type. Cells in malignant neoplasms often exhibit this characteristic.

Answers to Review Questions (p. 136) 1. DNA is one of the largest molecules in the body. It has the shape of a twisted ladder, a double helix.

2. DNA is located in the nucleus of the cell.

3. Protein synthesis begins with the DNA molecule opening up and attracting a messenger ribonucleic acid (mRNA) molecule. The mRNA separates from the DNA and moves out of the nucleus and to a ribosome. The ribosome “reads” the mRNA and attracts a specific transfer RNA (tRNA) molecule with a nucleotide sequence opposite to that of the mRNA. The tRNA is carrying with it a specific amino acid, which is added to the growing protein. This process repeats with more tRNA molecules bringing specific amino acids until the complete protein is formed.

4. Additional material is added as a cell grows by way of protein synthesis, the synthesis of more organelles and plasma membrane, and the replication of more mitochondria. This increases the amount of cytoplasm and, therefore, the size of the cell.

5. The DNA molecule “unzips” to expose the nucleotide bases, and through the mechanism of obligatory base pairing, new nucleotides pair with either side of the DNA molecule, forming a new half to each of the original strands of DNA. This process is catalyzed by DNA polymerase. After all the bases have been paired, two new DNA molecules have been formed. This process occurs in the synthesis, or S, phase of the cell cycle.

6. Mitosis is the process of organizing and distributing nuclear DNA during cell division.

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Chapter 7 | Cell Growth and Development _____________________________________________________

7. Prophase: Chromosomes shorten and thicken, centrioles move to opposite poles of the cell, and spindle fibers appear and begin to orient between opposing poles. The nuclear membrane and the nucleolus disappear.

Metaphase: Chromosomes align across the equator of spindle fibers. Each pair of chromatids is attached to a spindle fiber at its centromere.

Anaphase: Each centromere splits, detaching the chromosomes. Each chromosome moves to an opposite pole.

Telophase: Chromosomes uncoil, the nuclear membrane and nucleolus reappear, and the spindle fibers disappear.

8. Meiosis is the process of nuclear division that produces gametes with half the usual number of chromosomes.

The two stages are meiosis I and meiosis II. In meiosis I, the DNA replication occurs before division. The number of chromosomes is halved, but the chromatid pairs remain together. In meiosis II, the DNA is not replicated and the chromatids split apart, providing the haploid number of chromosomes to each of the new cells.

9. The reduction from diploid to haploid number takes place in meiosis II. 10. A normal example of hyperplasia occurs in the milk-producing glands in the female breast during pregnancy.

Abnormal hyperplasia can occur when the body loses control over mitosis and a tumor forms.

Answers to Critical Thinking Questions (p. 136) 1. The loss of ribosomes would not affect transcription; this process occurs in the nucleus. However, the loss of ribosomes would have a great impact on translation, because it is at the ribosome where translation, the building of the protein molecule, occurs.

2. The nitrogen bases are like letters of the alphabet. The sequence of these bases forms a code, much like forming words in a text. These coded sequences of nucleotides dictate the genetic structure of the individual and the metabolic function of the individual’s cells.

3. The process of protein synthesis is responsible for the production of enzymes for the cell. Enzymes regulate all the anabolic and catabolic reactions in the cell. Without a sufficient number of the correct enzymes, the cell would not stay alive.

4. Atrophy caused the change in the muscles of the limb. When muscles are out of use, the muscle cells decrease in size.

5. Hypertrophy refers to an increase in cell size. Hyperplasia refers to cells increasing their rate of reproduction.

6. This question can be answered in a variety of ways. The correct answer should include the role of the nucleus in the formation of the cytoplasm, the directions for protein synthesis for making enzymes and new organelles, the regulation of anabolic and catabolic reactions, and the role of DNA in mitosis and genetic continuity.

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Instructor’s Resource Material for

8 Introduction to Tissues ANSWER KEYS Answers to Quick Check Questions 1. The four basic tissue types are epithelial tissue, connective tissue, muscle tissue, and nervous tissue.

Epithelial tissue covers and protects the body surfaces, lines body cavities, specializes in moving substances into and out of the blood, and forms many glands. Connective tissue is specialized to support the body and its parts, to connect and hold them together, to transport substances through the body, and to protect it from foreign invaders. Muscle tissue produces movement. Nervous tissue specializes in communication between various parts of the body and the integration of their activities.

2. A primary germ layer is an orderly arrangement of cells that develop within 2 weeks after the blastocyst has implanted itself in the uterus.

3. ECM is the extracellular matrix. ECM is made up mostly of proteins, proteoglycans, and water.

4. Elastic fibers are flexible and not very strong, but they are also stretchy and rebound after stretching.

Collagenous fibers, on the other hand, are not stretchy, but they are very strong when pulled by movement of surrounding tissues.

5. Epithelial and connective tissues have the greatest capacity to regenerate after an injury.

6. Damaged muscle is sometimes replaced with fibrous connective tissue instead of muscle tissue. This results in the muscle losing some or all of its ability to function.

7. Cutaneous, serous, and mucous and connective are the four principal types of body membranes. Cutaneous, serous, and mucous are epithelial membranes.

8. Mucus is a watery secretion that contains a mixture of mucins, which are a group of about two dozen different proteoglycans. Mucus coats and protects the underlying cells of the mucous membrane. It also acts as a lubricant for food as it moves along the digestive tract and serves as a sticky trap for contaminants in the respiratory tract.

Answers to Case Study Questions (p. 152) 1. c: Muscle and nerve tissue have limited capacity to regenerate. Damaged muscle is sometimes replaced with fibrous connective tissue instead of muscle. When this happens, the muscle loses some or all of its ability to function. Neurons can sometimes regenerate but very slowly and only if certain neuroglia are present to “pave the way.”

2. a: The skin is also known as the cutaneous membrane, composed of stratified squamous epithelium and underlying connective tissue. The superficial layer of the cutaneous membrane is the epidermis. Mucous membranes are found lining cavities open to the outside (e.g., the mouth, nose, and urinary tract). Serous membranes line cavities that are closed (e.g., thoracic cavity).

3. b: A material called the basement membrane exists between epithelial and connective tissues. It is composed of secretions from both the epithelial and the connective cells.

4. c: When a break in the connective tissue occurs, collagen fibers usually form a dense fibrous mass (scar). An atypical and unusually thick scar may develop in the lower layer of the skin (keloid).

Answers to Review Questions (p. 154) 1. Tissue is defined as a group of similar cells that perform a common function. The four principal tissue types are epithelial tissue, connective tissue, nervous tissue, and muscle tissue.

2. The three germ layers are the endoderm, mesoderm, and ectoderm. These germ layers are a result of cells moving and regrouping within the early embryo. The function of these layers is to differentiate to form specific tissues (histogenesis).

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Chapter 8 | Introduction to Tissues ___________________________________________________________

3. Muscle has a limited capacity to regenerate itself, and damaged muscle is often replaced by connective tissue.

Nervous tissue also has a limited capacity to regenerate itself. Nerves outside the central nervous system can regenerate slowly and only if certain neuroglia cells can pave the way. Normal brain and spinal cord neurons do not grow back when injured.

4. Epithelial tissue and connective tissue are the major categories of body membranes. Some examples of epithelial tissue membranes are cutaneous, serous, and mucous. An example of connective tissue membrane is synovial.

5. Neoplasm (new matter) or tumor refers to any abnormal growth of cells. Neoplasm is often classified as benign (does not spread to other tissues) or malignant (tends to spread to other regions of the body).

Answers to Critical Thinking Questions (p. 154) 1. The skeletal and muscular systems arise from the mesoderm. The earliest time in development when only these tissue types would be affected is during or shortly after gastrulation.

2. A proper amount of fat in the body is necessary. Fat is used to protect various body organs, such as the kidneys. It acts as an insulator to help maintain body temperature and acts as a source of stored energy for the body. Too little fat affects the athlete’s health by compromising these functions.

3. The student should construct a flowchart or diagram on tissue healing that includes the following: All answers should include the fact that an injury is followed by phagocytotic cells removing dead or injured cells and an attempt at regeneration. If the tissue is epithelial or connective and if the injury is small, it will heal completely. If the injury is deep or large, it may leave a scar. A larger scar called a keloid may form. Muscle tissue has a limited ability to heal itself and is often replaced by connective tissue. Nervous tissue has the most limited ability to heal itself. Neurons outside the central nervous system may heal, but cells in the central nervous system usually do not heal.

4. The skin will probably heal faster and more completely. It is made up of epithelial tissue, which heals faster and more completely than muscle tissue.

5. The fluid is synovial fluid. It is produced by the synovial membrane surrounding the joint; its function is to reduce the friction between bones in movable joints.

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Instructor’s Resource Material for

9 Tissue Types ANSWER KEYS

Answers to Quick Check Questions 1. The answer may include any three of the following: protection, sensory functions, secretion, absorption, and excretion.

2. Squamous, cuboidal, and columnar are the three basic shapes of epithelial cells.

3. Simple squamous epithelium tissue consists of only one layer of flat, scalelike cells. Stratified epithelium tissue is characterized by multiple layers of cells.

4. Exocrine glands discharge their secretion products into ducts.

5. The three kinds of fibers that may be present in a connective tissue ECM are collagenous fibers, reticular fibers, and elastic fibers. Collagenous fibers are white fibers made up of collagen and often occur in bundles.

Reticular fibers are made up of a specialized type of collagen called reticulin. Elastic fibers are made up of a protein called elastin.

6. The four types of fibrous connective tissue are loose, adipose, reticular connective, and dense connective.

Loose connective tissue is stretchable and one of the most widely distributed of all tissues. The matrix is a soft, thick gel. It contains many fibroblasts and macrophages. Adipose connective tissue contains predominantly fat cells and many fewer fibroblasts, macrophages, and mast cells. Reticular connective tissue is a dense, net-like tissue with branching reticulin fibers with reticular cells. It filters injurious substances out of blood and lymph. Dense connective tissue has fibers packed densely into a matrix that contains relatively few fibroblast cells. It is designated regular or irregular.

7. The inorganic (bone salt) portion of bone makes it hard.

8. Blood tissue exists in a liquid state.

9. The two types of involuntary muscle are smooth and cardiac. Smooth muscle is found in the walls of the viscera. Cardiac muscle makes up the wall of the heart.

10. The two principal types of cell in nervous tissue are neurons and neuroglia. Neurons are conducting units of the nervous system. The function of neuroglia is connecting and supporting cells.

Answers to Case Study Questions (p. 174) 1. c: Adipose tissue contains mainly fat cells (adipocytes) and many fewer fibroblasts, macrophages, and mast cells. Each adipocyte typically has one large vesicle filled with stored triglycerides. This fat cell is so large that it pushes the cytoplasm of the cell outward toward the plasma membrane as it stores more and more fat.

2. b: This tissue sample of dense fibrous tissue predominantly characterized by bundles of collagenous fibers is found in structures that anchor muscle to bone, such as tendons. Tendons provide great strength because of the arrangement of collagen fibers.

3. a: This calcified tissue sample is cancellous (spongy) bone. The thin beams (trabeculae) form a framework that supports a softer tissue (red bone marrow). The lattice of trabeculae also give internal support to the bone—much as the crisscrossing pattern of the roof trusses of a building help support the weight of the roof.

4. b: This tissue sample is hyaline cartilage. Hyaline cartilage takes its name from the Greek word hyalos or “glass.” The name is appropriate because the low amount of collagen in the matrix gives hyaline cartilage a shiny and translucent appearance. This is the most prevalent type of cartilage and is found covering the ends of bones that articulate at joints. The external ear is composed of elastic cartilage.

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Chaper 9 | Tissue Types ___________________________________________________________________

Answers to Review Questions (p. 178) 1. The five most important functions of epithelial tissue are protection, sensory function, secretion, absorption, and excretion.

2. None. The epithelial tissues have no blood vessels.

3. Epithelial cells are classified based on cell shape into four categories: squamous, cuboidal, columnar, and pseudostratified columnar. Squamous cells are flat and platelike. Cuboidal cells are cube shaped. Columnar epithelial cells are higher than they are wide and appear narrow and cylindrical. Pseudostratified columnar cells are oddly shaped columnar cells. Although each cell touches the basement membrane, the tops of the cells do not fully extend to the surface of the membrane.

4. Arrangement of epithelial cells in a single layer is called simple epithelium. If the epithelial cells are layered one on another, the tissue is called stratified epithelium. If the epithelial cells are layered in a relaxed state but can form a single layer when stretched, the tissue is called transitional epithelium.

5. Simple squamous epithelium: Examples include alveoli; the lining of blood and lymph vessels; and the surfaces of pleura, pericardium, and peritoneum.

Simple cuboidal epithelium: Examples include glands and their ducts and tubules and ducts of the kidney.

Simple columnar epithelium: Examples include the cells that line the stomach, intestine, uterus, uterine tubules, and parts of the respiratory tract.

Pseudostratified columnar epithelium: Examples include air passages of the respiratory system and certain parts of the male reproductive system, such as the urethra.

Stratified squamous (keratinized) epithelium: An example is the skin.

Stratified squamous (nonkeratinized) epithelium: Examples include the lining of the vagina, mouth, and esophagus.

Stratified cuboidal epithelium: Examples include sweat gland ducts, the pharynx, and parts of the epiglottis.

Stratified transitional epithelium: An example is the wall of the urinary bladder.

6. Glandular epithelium is specialized for secretory activity. Glandular epithelial cells may function singly as unicellular glands or in groups or clusters of solid cords or follicles as in multicellular glands. If the glands empty into ducts, they are exocrine glands. If they empty into the blood, they are endocrine glands.

7. Exocrine glands can be classified by their structure using the shape and complexity of their ducts. They can be tubular or alveolar (saclike); they can have one duct leading out of a simple gland or more than one duct leading out of a complex gland. Examples of tubular simple glands are intestinal glands, sweat glands, and gastric glands. Examples of alveolar simple glands are sebaceous glands. Mammary glands can be either tubular compound glands or alveolar compound glands. Salivary glands can be either tubular or alveolar compound glands.

8. Loose fibrous connective tissue has a matrix of soft viscous gel because it contains hyaluronic acid. The matrix also contains collagen and elastic fibers, which allow it to stretch.

9. Dense fibrous connective tissue consists mainly of fibers packed densely in the matrix. In dense (irregular) fibrous tissue, the fibers intertwine in irregular, swirling arrangements. Dense (regular) fibrous tissue contains fibers that are arranged in regular, parallel rows. One form of dense (regular) fibrous tissue is predominantly bundles of collagenous fibers (collagenous dense [regular] fibrous tissue). Another form of dense (regular) fibrous tissue contains mostly elastin fibers (elastic dense [regular] fibrous tissue).

10. Bone on the microscopic level is organized into osteons or Haversian systems. Bone cells are located in small spaces called lacunae. They are arranged in concentric layers of bone matrix called lamellae. Small canals called canaliculi connect each lacuna and bone cell with the nutrient blood vessels found in the central Haversian canal. Like bone cells, cartilage cells (chondrocytes) are found in lacunae. Cartilage is avascular, and blood must move through the cartilage by diffusion.

11. The three major types of cartilage tissue are hyaline, fibrocartilage, and elastic. Hyaline cartilage is shiny and translucent. It is found in support rings of the respiratory tubes and covering the ends of bones. Fibrocartilage is a durable cartilage with a rigid matrix filled with strong white fibers. It serves as shock absorbers between

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vertebrae and in the knee joint. Elastic cartilage has a large number of fine elastic fibers that give it strength and flexibility. This is found in the external ear and the larynx.

12. Blood is composed of plasma and blood cells. The blood cells are erythrocytes, leukocytes, and thrombocytes. The erythrocytes transport respiratory gases. The leukocytes destroy harmful microorganisms, and thrombocytes assist in blood clot formation. The plasma transports nutrients and waste products, regulates the pH of body fluids, and helps maintain body temperature.

13. The three major types of muscle tissue are skeletal muscle tissue, smooth muscle tissue, and cardiac muscle tissue.

14. The two basic types of cells in the nervous system are the neurons, which are the conducting cells, and neuroglia cells, which are support cells.

Answers to Critical Thinking Questions (p. 136) 1. Epithelial tissues have limited amounts of intercellular material. They can form continuous sheets of tightly packed cells. Epithelial cells in the skin and in mucous and serous membranes are attached firmly to the connective tissue under them by forming a basement membrane. The cells in an epithelial sheet are held together by desmosomes, or tight junctions. The secretory function is accomplished by epithelial cells grouped in solid cords of specialized follicles.

2. Oil production does the most damage. It comes from holocrine glands; the cells rupture to release the oil from the gland, killing the cell that produced it.

3. Connective tissue contains one or more of the following fibers: collagenous fibers, which are tough and strong; reticular fibers, which are delicate; or elastic fibers, which are extensible and elastic. Fibrous tissues (such as, areolar, adipose reticular, and dense fibrous) have extracellular fibers as their predominant feature.

The type and arrangement of these fibers are what distinguishes one type of tissue from another.

4. Calcium and other inorganic material are responsible for about 66% of the extracellular matrix of bone tissue.

Insufficient amounts of calcium would compromise normal growth and weaken the bone and thus make it susceptible to injury and disease. To ensure normal development of bone, calcium is a necessary part of an individual’s diet.

5. A tendon is made up of collagen fibers. This gives density and flexibility with great tensile strength but no elasticity. Ligaments are made up of predominantly elastic fibers, which give the ligaments less strength but more elasticity. Because of this structural difference, the ligament is not able to function as a tendon.

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Instructor’s Resource Material for

10 Skin

ANSWER KEYS Answers to Quick Check Questions 1. Epidermis and dermis are the primary skin layers. Epithelium dominates the epidermal layer, and connective tissue dominates the dermis.

2. Most of the body surface is covered by thin skin. Skin covering the palms of the hands, soles of the feet, and other body areas subject to friction is classified as thick skin. In thin skin, the number of cell layers in each epidermal stratum is less than that in thick skin. Raised parallel ridges are not present in the dermis of thin skin.

3. Keratinocytes and melanocytes are the two main cell types in the epidermis.

4. Stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale are the five layers of the epidermis.

5. The dermal-epidermal junction separates the dermis and epidermis.

6. The dermal papillae form the bumps that produce ridges.

7. The dermis layer is vascular.

8. The hypodermis forms a connection between the skin and the underlying structures of the body.

9. Metabolism of foods is the source of body heat. Muscles and glands produce more heat than any other tissues.

10. The answer should be any three out of the following: evaporation, radiation, conduction, and convection.

11. Varying amounts of melanin determine hair color.

12. The seven functions of the skin are: (1) protection, (2) sensation, (3) growth, (4) synthesis of important chemicals and hormones, (5) excretion, (6) temperature regulation, and (7) immunity.

13. The surface film is produced by the mixing of residue and secretions from sweat and sebaceous glands, with the epithelial cells constantly being cast off from the epidermis.

14. Hair, nails, and skin glands are the appendages of the skin.

15. The two types of sweat glands are eccrine and apocrine. Eccrine are the most numerous and widespread of the sweat glands in the body. They are small and function throughout life to produce perspiration rich in salts, ammonia, uric acid, urea, and other wastes. Apocrine glands are located deep in the subcutaneous layer. They are much larger than eccrine glands and are connected with hair follicles. Apocrine glands enlarge and begin to function at puberty, producing a more viscous and colored secretion.

16. Sebum (1) keeps the hair supple and (2) keeps the skin soft and pliant.

17. Surface film of the skin is produced by the mixing of residue and secretions from sweat and sebaceous glands with epithelial cells.

Answers to Case Study Questions (p. 204) 1. a: The epidermis is composed of only epithelial tissue. Epithelial tissue is avascular (meaning it has no blood vessels). The dermis has many blood vessels. If Aidan's finger is not bleeding, then the splinter could not have penetrated down to the dermis. So, the correct answer must be “a. Epidermis only.” In case you were still considering “d. Stratum basale only,” look again at the layers in the epidermis. The stratum basale is the deepest layer (farthest from the surface); so, the splinter would have to pass through the upper layers first.

2. d: The skin on the palms (and fingertips) is thick skin, whereas the skin on the arm is thin skin. Only the thick skin contains the stratum lucidum layer. All of the other layers listed are found in both thick and thin skin.

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Chapter 10 | Skin _________________________________________________________________________

3. c: Epidermal dendritic cells (Langerhans cells) are the “first responders” that identify a protein on an invading organism and show that protein to other immune system cells. By showing the immune cells the invader’s protein, the dendritic cells are saying, “This is your target!” which is sort of like giving a bloodhound a scent.

Answers to Review Questions (p. 208) 1. The skin has several functions: Protection: The skin protects the body from microorganisms, harmful chemicals, and mechanical injuries. It protects the body from dehydration and from ultraviolet light by forming melanin.

Sensation: The skin can respond to pain, heat, cold, pressure, and touch.

Movement and growth without injury: The skin is supple and elastic so that the body can move and grow without injury.

Vitamin D production: The skin allows a precursor substance to be converted to vitamin D on exposure to ultraviolet light.

Excretion: The skin excretes water, urea, ammonia, and uric acid.

Immunity: Specialized cells that attach to and destroy microorganisms are found in the skin. Also, Langerhans cells function with T cells to trigger immune reactions.

Temperature regulation: Production of sweat and regulation of blood flow to and away from the skin surface helps regulate body temperature.

2. The cell types found in the epidermis are keratinocytes, melanocytes, Langerhans cells, and helper T cells.

3. Stratum corneum: This is the outermost layer composed of a thin sheet of squamous cells that are dead and continuously being replaced. The cytoplasm in these cells has been replaced by keratin. The cells are water repellent and chemical resistant. They are held together by desmosomes.

Stratum lucidum: The keratinocytes are tightly packed together in this layer. Nuclei are absent, and the cells are filled with a soft gel-like substance called eleidin, which will be transformed into keratin.

Stratum granulosum: Keratinization begins here. Cells are arranged into sheets, two to four layers deep, and filled with intensely staining granules called keratohyalin. This is necessary for keratin formation. Cells in this layer have begun to degenerate as a result of lysosomal enzymes. Nuclei are missing or degenerate.

Stratum spinosum: This is composed of 8 to 15 layers of irregularly-shaped cells with very prominent intercellular bridges or desmosomes. Microscopically, the desmosomes give the layer a spiny appearance.

Cells are rich in RNA to initiate protein synthesis.

Stratum basale: This is a single layer of columnar cells. Only the deepest cell layer undergoes mitosis.

Because of this, the cells push up through the other layers.

4. The stratum corneum is sometimes called the barrier area.

5. There are a number of correct answers, but they all should include the following: The cells of the stratum basale continue to go through mitosis at the same rate that the cells are shed from the surface of the skin.

Injury stimulates an increased rate of mitosis, and continued abrasion will form a thickening of the stratum corneum called a callus.

6. Keratin is a protective, water-repellent protein in skin cells in the stratum corneum. Cells in the stratum granulosum contain keratohyalin, which is necessary for the formation of keratin. The cells in the stratum lucidum contain eleidin, which will eventually become keratin.

7. The dermis of the skin contains blood vessels.

8. A blister is the result of injury to the epidermis or the dermoepidermal junction. This can damage the desmosomes, which hold the skin cells together. Blisters can form following burns, friction injuries, exposure to irritants, or accumulation of toxic products after cell injury or death. Typically, these break disulfide linkages or hydrogen bonds, which are the links in the desmosomes. This is an example of the relationship between the skin’s structure and function.

9. The two layers of the dermis are the papillary layer and the reticular layer. The reticular layer makes the skin stretchable and able to rebound.

10. The arrector pili muscles are small bundles of involuntary muscles attached to each hair follicle. Contraction of these muscles makes the hair stand on end. The skin around them rises in what is called “goose pimples.”

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11. The appendages of the skin are nails, hair, and skin glands.

12. Hair papilla: Contains the blood capillaries, which nourish the germinal matrix of the hair.

Germinal matrix: A cup-shaped cluster of cells that forms in the stratum germinativum, which is the follicle’s innermost layer at the bottom.

Hair root: The part of the hair that remains hidden in the follicle.

Hair shaft: The visible part of the hair.

Follicle: The small tube of epidermal cells that spreads down into the dermis. It forms two layers: the outer dermal root sheath and the epithelial root sheath.

13. The three primary types of skin glands are sweat glands, sebaceous glands, and ceruminous glands.

14. Eccrine glands are small and distributed over almost the entire body surface. They are simple coiled, tubular type of glands that produce a transparent watery liquid rich in salts, ammonia, uric acid, and urea. They play an important role in regulating body temperature. Apocrine glands are found in the axilla, in the areola of the breast, and around the anus. They are larger than the eccrine glands and are connected to hair follicles. They are simple branched tubular glands that enlarge and begin functioning at puberty. They produce a more viscous and colored secretion than do the eccrine glands. In females, apocrine glands show cyclic changes linked to the menstrual cycle.

15. The skin surface film has a variety of functions, including antibacterial and antifungal activity. It provides lubrication and hydration of the skin surface, acts as a buffer for skin irritants, and provides a block to toxic agents.

16. The “rule of nines” divides the total body surface into 11 areas of 9% (or multiples of 9%). The front and back of the trunk are 18% each. The front and back of each leg are 9% each. Each arm is 9%, and the head is 9%. The perineum makes up the additional 1%. By determining the parts of the body involved in the burn, one can make a rough estimate as to the percentage of body surface involved.

17. First-degree burns cause minor discomfort and reddening of the skin. Skin may peel, but tissue destruction is minimal and there are no blisters.

Second-degree burns injure the upper layer of the dermis, which may include the sweat glands, sebaceous glands, and hair follicles. Tissue death is not complete. Blisters, severe pain, swelling, and edema characterize this type of burn. Scarring is common.

Third-degree burns destroy both epidermis and dermis. Tissue death extends below hair follicles and sweat glands and may involve muscle or bone. Third-degree burns are insensitive to pain immediately after the injury; scarring is serious.

Answers to Critical Thinking Questions (p. 208) 1. The hair follicle, nail, sweat glands, and oil glands are part of the integumentary system only. The stratum corneum and the stratum basale are part of both the integumentary system and the integument. The skin is the integument. The skin and its appendages make up the integumentary system.

2. In thick skin, all layers of skin are present and each is several layers thick. In thin skin, the layers are less thick and one or more layers may be absent entirely. The thickness of the hypodermis depends on the amount of fat in this layer.

3. The dermoepidermal junction (DEJ) is the attachment point of the epidermis to the dermis. It has a basement membrane, special fibrous elements, and a polysaccharide gel. This allows it to hold the two parts of the skin together.

4. To leave as small a scar as possible, the incision should be made parallel to the Langer cleavage lines. These lines are different from the front and rear of the thigh; so, the incision should be made at a different angle.

5. This might hamper the skin’s ability to produce vitamin D. This function can occur only when the skin is exposed to ultraviolet (UV) light, which as a rule would be sunlight.

6. Light-skinned individuals are more likely to sunburn easily. It has been recently theorized that blistering sunburns may trigger the development of malignant melanoma.

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Chapter 10 | Skin _________________________________________________________________________

7. During a period of increased body temperature, the brain signals the sweat glands within the layer of skin to secrete sweat. The evaporation of sweat cools the body and is essential in keeping the body temperature in balance. To avoid dehydration, it is important to increase fluid consumption before, during, and after any type of exercise.

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Instructor’s Resource Material for

11 Skeletal Tissues ANSWER KEYS

Answers to Quick Check Questions 1. Bone and cartilage are the major types of connective tissue in the skeletal system.

2. Compact and cancellous (spongy) bones are two types of bone tissue.

3. The six structural components of a typical long bone that are visible to the naked eye are the (1) diaphysis, (2) epiphysis, (3) articular cartilage, (4) periosteum, (5) medullary cavity, and (6) endosteum.

4. Inorganic salts and organic matrix are the two principal chemical components of bone matrix.

5. The resiliency of cartilage cushions jolts and blows.

6. Lamellae, lacunae, canaliculi, and Haversian canals are the main structures of the osteon.

7. Volkmann canals connect blood vessels between adjacent, parallel osteons.

8. Trabeculae are tiny branches of hard bone found in cancellous bone.

9. Osteoblasts, osteoclasts, and osteocytes are the three major types of bone cells.

10. The types of bone marrow are red marrow and yellow marrow.

11. The five functions of bone are (1) support, (2) protection, (3) movement, (4) mineral storage, and (5) hematopoiesis.

12. Intramembranous and endochondral ossification are the two types of bone formation.

13. The three major types of cartilage are (1) hyaline, (2) elastic, and (3) fibrocartilage.

14. Chondrocyte is the primary type of cartilage cell.

15. The two mechanisms of cartilage growth are interstitial growth and appositional growth.

Answers to Case Study Questions (p. 229) 1. c: An older female patient fracturing her hip is a typical case of osteoporosis (osteo = bone; porosis = porous). Rickets is found only in children (before the bones have fully matured). Osteosarcoma is a form of cancer (sarcoma = malignant tumor, or literally “fleshy growth”), but it is found more often in young males.

Osteomyelitis (-itis = inflammation) is a bacterial infection, which is painful but not likely to cause the hip fracture.

2. a: The femur is longer than it is wide, which is pretty much the definition of a “long bone.”

3. d: The articular cartilage, found at the ends of long bones, is hyaline cartilage. This cartilage is part of the original model formed during fetal development. The rest of the cartilage is replaced by bone tissue as the body matures.

4. b: Although increasing her intake of calcium and vitamin D will help, diet alone may not be enough to counter the effects of osteoporosis. Calcitonin stimulates the action of osteoblasts, which will take calcium from the bloodstream and build more bone matrix, hopefully making Eleanor’s bones less susceptible to fracture.

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Chapter 11 | Skeletal Tissues _______________________________________________________________

Answers to Review Questions (p. 232) 1. The microscopic structure of compact bone is centered around the osteon, or Haversian system. Concentric layers of calcified matrix (lamellae) surround the osteon, which contains blood and lymph vessels and nerves.

The bone cells are located in small spaces in the lamellae called lacunae. The cells are connected to the other cells and the osteon by small canals called canaliculi. In cancellous bone the microscopic structure is based on trabeculae, which consist of needlelike bone spicules. Bone cells are found in the trabeculae, nutrients are delivered to the cells, and waste products are removed by diffusion through tiny canaliculi that extend to the surface of the spicules. The microscopic structure of cartilage consists of many collagenous fibers embedded in a firm gel, rather than a calcified matrix. Cartilage is more flexible. No canal system or blood vessels exist in cartilage. Cartilage cells also lie in lacunae, but nutrients must diffuse through the matrix to get to them.

2. The long bone contains six structures. The diaphysis is the main shaft of the bone. The epiphyses are the two ends of the bone. The articular cartilage is a thin layer of cartilage that covers the joint surfaces of the epiphyses. The periosteum is a dense, white fibrous membrane that covers the bone. The medullary cavity is a tubelike hollow space in the diaphysis. The endosteum is a thin epithelial layer that lines the medullary cavity.

3. The function of the periosteum is to cover the bone and provide an attachment point for muscle tendon fibers.

It contains bone-forming and bone-destroying cells and contains the blood vessels that supply the bone.

4. The two components are inorganic salts and organic matrix. Inorganic salts consist of calcium and phosphate crystals called hydroxyapatite. Other inorganic substances, such as magnesium and sodium, are also found in bone. The organic matrix consists of a mixture of protein and polysaccharides. The organic matrix gives the bone some resiliency to help resist fracture.

5. An osteon consists of lamellae, which are concentric cylinder-shaped layers of calcified matrix; lacunae, which are spaces in which bone cells lie; and canaliculi, which are small canals radiating in all directions from the lacunae, connecting them to one another and to the large central canal. The central canal is a large canal in the center of the osteon containing blood vessels, lymph vessels, and nerves.

6. The three major cell types found in bone are osteoblasts, osteoclasts, and osteocytes. Osteoblasts are small cells that synthesize and secrete a specialized organic matrix called osteoid, which is the important part of the bone matrix. Osteoclasts are large, multinucleated cells responsible for the active erosion of bone minerals.

They allow bone to undergo continuous change and remodeling. Osteocytes are mature, nondividing osteoblasts that have become surrounded by matrix and now lie in the lacunae.

7. Vascular damage occurring immediately after a fracture results in hemorrhage and pooling of blood that forms the fracture hematoma. As the hematoma resorbs, a bone callus forms, which serves to bind the ends of the broken bone together and stabilizes the fracture. If the fracture is properly aligned and immobilized, the callus tissue will be actively modeled and replaced with normal bone.

8. Both bone and cartilage have a matrix that consists of collagen fiber. Both tissues consist of more extracellular substances than cells. In bone, however, the fibers are embedded in a calcified matrix, whereas in cartilage they are embedded in a more flexible material. Bone is a vascular tissue, and cartilage has no blood vessels in it.

9. The three types of cartilage are hyaline, elastic, and fibrocartilage. Hyaline cartilage resembles milk glass. It is semitransparent and has a bluish cast. The two principal chemical compounds that make up hyaline cartilage are chondroitin sulfate and a gel-like polysaccharide secreted by chondrocytes. Hyaline cartilage forms articular cartilage of bones, costal cartilage, the rings of the trachea and bronchi, and the tip of the nose.

Elastic cartilage has fewer collagen fibers than hyaline cartilage and a large number of elastic fibers. It is yellowish and is found in the external ear, the epiglottis, the eustachian tube, and the nasal cavity.

Fibrocartilage has a small quantity of matrix and abundant fibrous elements. It is strong and rigid and usually is associated with regions of dense connective tissue. Fibrocartilage is found in the symphysis pubis, in the intervertebral disks, and near the point of attachment of some large tendons and bones.

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Answers to Critical Thinking Questions (p. 232) 1. The two bone functions are hematopoiesis and mineral storage. Normally hematopoiesis is responsible for the formation of blood cells. This function is carried out by the myeloid tissue or bone marrow. Normally mineral storage is responsible for maintaining the homeostatic level of blood calcium. If there is too much calcium in the blood, calcium is stored in the bone. If there is too little calcium in the blood, calcium is removed from the bone.

2. In intramembranous ossification, groups of cells in a membrane differentiate into osteoblasts. They secrete matrix material and collagenous fibers. The Golgi apparatus of these osteoblasts secretes a compound called mucopolysaccharide, and the endoplasmic reticulum secretes collagen. Large amounts of ground substance accumulate around each osteoblast, and numerous collagen fibers become embedded in the ground substance.

This constitutes the organic matrix. As the matrix calcifies, the trabeculae join in a network to form spongy bone. Eventually, the spongy bone will be covered by plates of compact bone. In endochondral ossification, the pattern of the bone has been formed by cartilage. This cartilage model develops a periosteum, which produces a ring or collar of bone. Soon after the collar of bone appears, the cartilage begins to calcify. A primary ossification center forms when blood vessels enter the rapidly changing cartilage at the midpoint of the diaphysis. Ossification progresses from the diaphysis toward each epiphysis, and the bone grows in length. Secondary ossification centers appear in the epiphyses, and growth begins toward the diaphysis until bone length is complete. A layer of cartilage called the epiphyseal plate remains between the epiphysis and the diaphysis. The epiphyseal plate allows the bone to grow in length by thickening, and ossification occurs on the side nearest the diaphysis.

3. There are two forms of cartilage growth: interstitial and appositional. Interstitial growth occurs when the cartilage cells in the substance of the tissue mass divide and begin to secrete additional matrix. This is possible because of the soft and pliable nature of the matrix. Appositional growth occurs when the cells in the inner layer of the perichondrium begin to divide and secrete matrix on the surface of the cartilage, causing an increase in size. Bone growth can occur by apposition in intramembranous bone when the cells of the periosteum add matrix to the outside of the bone. In endochondral bone, a type of interstitial growth occurs when the epiphyseal plate lays down more cartilage, and ossification occurs from the diaphysis of the bone outward, adding length to the bone.

4. Until bone growth is complete, the epiphyseal plate remains between the diaphysis and the epiphysis. The epiphyseal plate allows the diaphysis of a long bone to increase in length. Any serious trauma to this area may affect a child’s or young adult’s normal bone growth.

5. Degeneration of bone and cartilage tissue may lead to a loss of bone density. This can make a person prone to fractures. This is particularly a concern among women who suffer from osteoporosis. The loss of bone density may also result in compression of weight-bearing bones, which negatively affects posture.

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Instructor’s Resource Material for

12 Axial Skeleton ANSWER KEYS

Answers to Quick Check Questions 1. The eight bones of the cranium are frontal bone, two parietal bones, two temporal bones, occipital bone, sphenoid bone, and ethmoid bone. The frontal bone forms the forehead and part of the top of the cranium and joins to parietal bones in an immovable joint called a suture; the two parietal bones form immovable joints with several bones by sutures; the two temporal bones house the middle and inner ear structures and contain the mastoid sinuses; the occipital bone forms immovable joints with the parietal, temporal, and sphenoid bones; the sphenoid bone is in the central portion of the cranial floor, where it anchors the frontal, parietal, occipital, and ethmoid bones; the ethmoid bone is a complex irregular bone that helps make up the anterior portion of the cranial floor, medial wall of the orbits, upper parts of the nasal septum, and sidewalls and part of the nasal roof; lies anterior to the sphenoid and posterior to the nasal bones.

2. The 14 bones of the face are two maxillae, mandible, two nasal bones, two zygomatic bones, two lacrimal bones, two palatine bones, two inferior conchae, and a vomer. The two maxillae form part of the floor of the orbits, part of the roof of the mouth, and part of the floor and sidewalls of the nose; the mandible articulates with the temporal bone; the two nasal bones form the upper part of the bridge of the nose; the two zygomatic bones form the outer margin of the orbit, and they articulate with the maxillary, temporal, frontal, and sphenoid bones; the two lacrimal bones help form the sidewall of the nose, and they join the maxilla, frontal bone, and ethmoid bone; the two palatine bones join each other in the midline forming the posterior part of the hard palate; the two inferior conchae form the upper and middle ledges of the nasal cavity; and the vomer completes the septum posteriorly.

3. Only the hyoid bone does not normally form a joint with any other bone.

4. The three types of vertebrae are the cervical (with 7 in the vertebral column), thoracic (with 12), and lumbar (with 5).

5. Ribs, vertebral column, and sternum form the thorax. Each rib articulates with both the body and the transverse process of the corresponding thoracic vertebra, and the tubercle of each rib articulates with the vertebrate’s transverse process. Anteriorly, each rib of the first seven pairs joins a costal cartilage that attaches to the sternum.

6. A floating rib is one that does not attach even indirectly to the sternum.

Answers to Case Study Questions (p. 261) 1. d: The shape of the sphenoid bone resembles a bat with its wings outstretched and legs extended down and back.

2. c: The occipital bone is missing. The cranium is formed by eight bones: the frontal, two parietal, two temporal, the sphenoid, the ethmoid, and the occipital.

3. b: The skulls of both a fetus and a newborn infant have unique anatomical features not seen in an adult. The face at birth forms a relatively smaller proportion of the cranium (about ⅛ than in the adult. The fontanels (spaces between the skull bones) are unique features in the infant skull.

Answers to Review Questions (p. 263) 1. The bones are the individual organs that make up the skeletal system. There are 206 bones in the adult skeleton. These are divided into two subdivisions: the axial skeleton and the appendicular skeleton.

2. The bones of the cranium make up the brain case of the skull; most of these bones are unpaired. The facial bones make up the front of the skull. Most of the bones of the face are paired. The bones of the cranium are the frontal, two parietal, two temporal, the occipital, the sphenoid, and the ethmoid. The bones of the face are two maxilla, two zygomatic, two nasal, the mandible, two lacrimal, two palatine, two inferior nasal conchae, and the vomer.

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Chapter 12 | Axial Skeleton _________________________________________________________________

3. The fontanels are the frontal, which is found at the intersection of the sagittal and coronal sutures; the occipital, which is found at the intersection of the sagittal and lambdoidal sutures; the sphenoid, which is found at the junction of the frontal, parietal, temporal, and sphenoid bones; and the mastoid, which is found at the juncture of the parietal, occipital, and temporal bones. The sutures of the skull are the squamous, which is the line of articulation along the curved edge of the temporal bone; the coronal, which is the joint between the parietal bones and the frontal bone; the lambdoidal, which is the joint between the parietal and occipital bones; and the sagittal, which is the joint between the right and left parietal bones.

4. The five sinuses of the skull are the mastoid, frontal, sphenoid, ethmoid, and maxillary sinuses.

5. The clinical importance of the cribriform plate is that it separates the nasal cavities from the brain. Any infection or damage to the cribriform plate would expose the brain to infection or injury. The clinical importance of the mastoid air cells is that an infection in this area can be caused by spread of infection from the middle ear. Because this air space does not drain, infection may erode the bone and cause the infection to spread to the brain.

6. There is a single primary curve of the spine at birth. To support the body in the upright position, the secondary curves of the spine—the cervical curvature and the lumbar curvature—develop. The remaining primary curves are the thoracic curvature and the sacral (pelvic) curvature.

7. The bony components of the thorax consist of the thoracic vertebrae, the sternum, and the ribs.

8. Vertebroplasty is a new experimental orthopedic procedure that involves the injection of a “super glue” type of bone cement to repair fractured and compressed vertebrae.

Answers to Critical Thinking Questions (p. 263) 1. The fontanels allow the skull to pass through the birth canal without fracturing one or more of the cranial bones.

2. Foramina are round holes in the skeleton. They provide passageways for blood vessels and nerves.

3. The air spaces in the skull bones reduce the weight of the skull without sacrificing strength. However, these spaces (lined with mucous membranes) are susceptible to infections, leading to headaches and general discomfort.

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Instructor’s Resource Material for

13 Appendicular Skeleton ANSWER KEYS Answers to Quick Check Questions 1. The shoulder girdle is made of the clavicle and scapula. The sternoclavicular joint is formed between the sternum and clavicle.

2. The radius and ulna are the forearm bones. The radius is lateral.

3. The hand bones are metacarpals. The wrist bones are carpals.

4. The ilium, ischium, and pubis fuse to form the coxal (hip) bone.

5. The bones of the lower extremity are the femur, patella, tibia, fibula, tarsals, metatarsals, and phalanges. The femur is the thigh bone. The patella is the kneecap, which is located in the tendon of the quadriceps femoris muscle as a projection to the underlying knee joint. The tibia is the largest of the lower leg bones. The fibula is the smaller of the two lower leg bones and more laterally and deeply placed. The tarsals are the ankle bones. The metatarsals are the bones of the foot. The phalanges are the toe bones.

6. Arches furnish more supporting strength per given amount of structural material.

7. Answers may include differences in general form, skull, and pelvis (cavity, sacrum, coccyx, pubic arch, symphysis pubis, ischial spine, ischial tuberosity, anterior superior iliac spine, and greater sciatic notch).

Answers to Case Study Questions (p. 280) 1. d: Vertebrae are named according to their location in the spine. There are 12 in the thoracic, or chest, region.

2. c: The superior seven pairs of ribs are called “true ribs” because each one has its own piece of costal cartilage that attaches directly to the sternum.

3. b: The mandible is the lower jaw bone. Robert will not be able to chew food.

4. a: The tibia is the “shin” bone and supports the body weight when a person stands or walks.

Answers to Review Questions (p. 282) 1. A compound (or open) fracture is one in which the broken bone projects through the surrounding tissue. A simple (or closed) fracture does not produce a break in the skin. A complete fracture involves a break across the entire section of bone. An incomplete fracture involves only a partial break where bone fragments are still partially joined. Clinical signs include loss of function, false motion, pain, soft tissue edema, and deformity.

Treatment includes realignment of the bone, immobilization, and rehabilitation to restore function.

2. The bones of the shoulder are the clavicle and the scapula. The bones of the pelvic girdle are the coxal bones and the sacrum.

3. The false pelvis is the structure above the pelvic inlet and is bordered by muscle in the front and by bone along the sides and back. The true pelvis creates the boundary of another imaginary plane called the pelvic outlet.

4. The bones of the upper and lower limbs are similar. The bone of the upper arm is the humerus; the bone of the thigh is the femur. The forearm has two bones: the ulna and radius. The lower leg also has two bones: the tibia and fibula. There are eight bones of the wrist: the pisiform, triquetrum, lunate, scaphoid, hamate, capitate, trapezoid, and trapezium. There are seven bones of the ankle: three cuneiforms and the cuboid, navicular, talus, and calcaneus. The hand consists of five metacarpals and fourteen phalanges. The foot consists of five metatarsals and fourteen phalanges. The leg has the patella, or kneecap; there is no corresponding bone in the arm.

5. The largest sesamoid bone in the body is the patella.

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Chapter 13 | Appendicular Skeleton __________________________________________________________

6. There are three arches in the foot—two longitudinal arches and one transverse arch. The medial longitudinal arch is composed of the calcaneus, talus, navicular, and cuneiforms of the tarsals and three medial metatarsals. The lateral longitudinal arch is composed of the calcaneus and cuboid of the tarsals and the lateral two metatarsals. The transverse arch is formed by the cuneiforms and cuboid bones of the tarsals and the five metatarsals. The function of the arches is to supply increased strength and support to the foot and to provide a springy cushion for the foot.

7. Despite its apparent rigidity, the symphysis pubis softens during delivery, allowing the expansion of the pelvic outlet. This accommodates the newborn’s head as it passes out of the birth canal.

Answers to Critical Thinking Questions (p. 282) 1. The anatomical structure of the thumb metacarpal with the carpal bones allows a wide range of movement, particularly the ability to oppose the thumb to the fingers. This allows for a much greater dexterity than the forepaw of any animal and enables humans to manipulate even small objects in their environment effectively.

2. In males, the bones are heavier and thicker, muscle attachment sites are more massive, and joint surfaces are relatively large. These features allow for general form and support of a generally larger body frame than females. In females, the pelvic cavity is wider, the pubic arch has an angle that is greater than 90 degrees, and the pelvic cavity is shorter and more expansive than the male pelvis. These features accommodate childbearing.

3. The shoulder girdle consists of only two bones on each side, the clavicle and scapula. The scapula is broad and has many attachment sites for muscles, which attach on all sides to hold the bones in place during the stress it undergoes. The attachment points to the upper extremity are fairly loose. This provides for a great deal of flexibility but also makes the joint fairly easy to dislocate. The pelvic girdle serves as a stable, circular base that supports the trunk and attaches the lower extremities to it. Strong ligaments bind each coxal bone to the sacrum posteriorly and to each other anteriorly. This framework provides support and flexibility at the hip.

4. The prominent bumps on many of the bones fit into fossae on other bones to form joints. These bumps also provide attachment points for muscles.

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Instructor’s Resource Material for

14 Articulations ANSWER KEYS

Answers to Quick Check Questions 1. An articulation, or joint, is a point of contact between bones.

2. The three major classes of joints according to a structural scheme are fibrous, cartilaginous, and synovial.

The three major classes of joints according to a functional scheme are synarthroses, amphiarthroses, and diarthroses.

3. The three types of fibrous joints are syndesmoses, sutures, and gomphoses. Syndesmoses: Joint between distal ends of the radius and ulna. Sutures: Found only in skull. Gomphoses: Found between the tooth and the alveolar process of the mandible or maxilla.

4. The two types of cartilaginous joints are synchondroses and symphyses. Synchondroses: Between the first rib and sternum; and the joint present during the growth years between the epiphysis of a long bone and its diaphysis. Symphyses: Symphysis pubis and the articulation between the bodies of adjacent vertebrae.

5. Synovial joints are characterized by the (1) joint capsule, (2) synovial membrane, (3) articular cartilage, (4) joint cavity, (5) menisci, (6) ligaments, and (7) bursae.

6. The three main categories of synovial joints grouped according to axial movement are uniaxial, biaxial, and multiaxial. The subtypes of uniaxial joints are hinge and pivot joints. The subtypes of biaxial joints are saddle and condyloid joints. The subtypes of multiaxial joints are ball and socket and gliding joints.

7. Hinge joint: Elbow, knee. Pivot joint: Projection (dens) of the second cervical vertebra that articulates with a ring-shaped portion of the first cervical vertebra and the head of the radius that articulates with the radial notch of the ulna. Saddle joint: The thumb’s metacarpal bone articulates in the wrist with a carpal bone (trapezium). Condyloid joint: Condyles of the occipital bone fit into elliptical depressions of the atlas, and the distal end of the radius fits into depressions of the carpal bones (scaphoid, lunate, and triquetrum). Ball and socket joint: Shoulder, hip, and knee. Gliding joint: Joints between the articular surfaces of successive vertebrae.

8. The knee joint is the largest, most complex, and most commonly injured joint in the body.

9. An intervertebral disk is composed of fibrous tissue and fibrocartilage.

10. Angular: Flexion, extension, abduction, and adduction. Circular: Rotation, circumduction, supination, and pronation. Gliding: Movement of an articular surface of one bone over the articular surface of another without any angular or circular movement. Special: Inversion, eversion, protraction, retraction, elevation, and depression.

11. Flexion decreases the angle between bones, whereas extension increases the angle between bones. If you bend your arm at the elbow, you are flexing the lower part of the arm. Extensions are straightening or stretching movements.

12. Special movements include inversion, eversion, protraction, retraction, elevation, and depression.

Answers to Case Study Questions (p. 309) 1. a: The anterior cruciate ligament runs between the tibia and femur and is one of many ligaments that hold the two bones together.

2. c: Although the proximal end of the fibula is close to the knee, the femur only articulates with the tibia.

3. b: The medial and lateral menisci are two pieces of cartilage in the knee joint that help stabilize the joint by filling in gaps between the tibia and femur.

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Chapter 14 | Articulations ___________________________________________________________________

Answers to Review Questions (p. 312) 1. The primary classification of joints is as follows: synarthroses, which structurally are fibrous joints and are immovable; amphiarthroses, which structurally are cartilaginous joints and are slightly movable; and diarthroses, which structurally are synovial joints and are freely movable.

2. Fibrous joints are joints in which the bones fit closely together. The connective tissue joining the bones permits little movement.

Cartilaginous joints are held together by hyaline or fibrocartilage. Limited movement occurs in cartilaginous joints.

Synovial joints are freely moving joints that are anatomically complex.

3. The three types of fibrous joints are syndesmoses, sutures, and gomphoses.

Syndesmoses are joints in which fibrous bands connect two bones. The example given in the textbook is the joint between the distal end of the ulna and radius.

Sutures are joints formed by teethlike projections that jut out from adjacent bones and interlock with one another with only a thin layer of fibrous tissue between them. The bones in the skull are examples.

Gomphoses are joints formed by the fibrous tissue between the root of the tooth and the periodontal membrane. The example is a tooth in the upper or lower jaw.

4. The two types of cartilaginous joints are synchondroses and symphyses.

Synchondroses are joints in which hyaline cartilage connects the articulating bones. The textbook uses the example of the attachment of the ribs to the sternum or the epiphyseal plate between the diaphysis and epiphysis of growing bones.

Symphyses are joints in which fibrocartilage connects the articulating bones. The textbook examples are the symphysis pubis and the joint between bodies of vertebrae.

5. Uniaxial joints permit movement around one axis and in only one plane. There are two types of these joints: hinge joints and pivot joints. Hinge joints permit back-and-forth movement, like that of a door hinge. The textbook examples are the elbow, knee, and interphalangeal joints. Pivot joints are those in which a projection in one bone articulates with a ring or notch in another bone. The textbook examples are the dens of the second vertebra with the ring in the first vertebra, or the head of the radius with the radial notch of the ulna.

Biaxial joints permit movement around two perpendicular axes or planes. There are two types of biaxial joints: saddle joints and condyloid joints. Saddle joints resemble reciprocally shaped saddles that fit into each other. The example is the metacarpal of the thumb articulating with the trapezium of the wrist. Condyloid joints are those in which a condyle fits into an elliptical socket. The textbook examples are the condyles of the occipital bone fitting into the elliptical depressions of the atlas, and the distal ends of the radius fitting into the depressions of the carpal bones.

Multiaxial joints permit movement in three or more axes or planes. There are two types of multiaxial joints: ball and socket and gliding joints. Ball and socket joints have a ball-shaped head of one bone fitting into a depression on another bone. The textbook examples are the shoulder and hip joints. Gliding joints are characterized by relatively flat articulating surfaces that allow limited movement along various axes. The textbook examples are joints between articular surfaces of vertebrae.

6. Flexion decreases the angle between bones. It bends or folds one part on another.

Extension increases the angle between bones. It returns a part of the body to its anatomical position. If the body part is stretched beyond its anatomical position, the action is called hyperextension.

Plantar flexion occurs when the foot is stretched down and back. This increases the angle between the top of the foot and leg. Dorsiflexion occurs when the foot is tilted upward, which decreases the angle between the top of the foot and leg.

Abduction moves a part of the body away from the medial plane of the body. Adduction moves a part of the body toward the medial plane of the body.

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7. Rotation consists of pivoting a bone on its own axis. The textbook example is moving the head from side to side as if indicating “no.”

Circumduction moves a body part so that its distal end moves in a circle. The textbook example is when a baseball pitcher winds up to throw a ball.

Pronation turns the palm of the hand down.

Supination turns the palm of the hand up.

8. A goniometer is a tool used to measure the range of motion of a joint.

9. The saddle joint makes possible much of the dexterity of the hand. It consists of two reciprocally shaped saddles. It allows the thumb to move to touch the tips of the fingers. This allows us to grip and manipulate small objects with our hands.

10. One vertebra connects to another by several joints. The joints between the bodies of the vertebrae permit slight movement and are classified as symphyses. The articulating surfaces of the vertebral processes are more movable and are classified as synovial gliding joints. The bodies of the adjacent vertebrae are also connected by intervertebral disks, which are composed of fibrous tissue and fibrocartilage in the outer rim and a pulpy elastic substance in the inner core.

11. The humeroscapular joint is formed by the head of the humerus and the glenoid cavity of the scapula. The glenoid cavity is shallow, allowing for great range of motion. The joint is stabilized by the glenoid labrum, which is a rim of fibrocartilage around the glenoid cavity, and a group of muscles and tendons that form a cufflike arrangement around the joint. This is called the rotator cuff.

The hip joint is formed between the head of the femur and the socket of the hip bone—the acetabulum. Its primary characteristic is stability. The deep cuplike shape of the acetabulum and the ball-like head of the femur give it much more stability than the humeroscapular joint. The hip joint is stabilized by some of the strongest ligaments of the body.

The knee joint is formed between the tibia and femur. The condyles of the femur articulate with the flat upper surface of the tibia. The medial and lateral menisci attach to the top of the tibia and form a shallow socket for the condyles of the femur.

There are many ligaments that help stabilize the knee. The anterior cruciate attaches the anterior part of the tibia to the posterior part of the lateral condyle of the femur. The posterior cruciate attaches posteriorly to the tibia and the front of the femur’s medial condyle. The ligament of Wrisberg attaches posteriorly to the lateral meniscus and the medial condyle behind the attachment of the posterior cruciate. The transverse ligament connects the anterior margins of menisci. Two collateral ligaments are present on the medial and lateral sides of the knee. The knee joint also has 13 bursae to serve as pads for the joint. The knee joint is much less protected than the hip and is therefore much more subject to injury.

12. The menisci are fibrocartilage pads that protect the ends of the bone. If these are damaged, small fragments may become detached and enter the joint cavity. The detached pieces are called joint mice.

13. The total hip replacement (THR) procedure involves the replacement of the femoral head with a metallic alloy prosthesis and the acetabular socket with a high-density polyethylene cup. Most new prostheses are porous coated to allow for the natural growth of bone to help hold them in place.

14. The two classifications of joint disorders are noninflammatory and inflammatory. Noninflammatory examples are osteoarthritis and traumatic injuries (dislocation, sprain). Inflammatory examples are juvenile rheumatoid arthritis and gouty arthritis.

Answers to Critical Thinking Questions (p. 312) 1. The elbow is a diarthrotic joint; its main characteristic is that it is a freely movable joint. The joints between the bodies of the vertebrae are amphiarthrotic joints and have limited movement. The joint that holds a tooth in the jaw is a synarthrotic joint; it allows no movement.

2. Joint capsule: Primarily for stability; may also add protection. Synovial membrane: Primarily for movement.

Articulating cartilage: Primarily for protection. Joint cavity: Primarily for movement. Menisci: Primarily for protection. Ligaments: Primarily for stability. Bursae: Primarily for protection.

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Chapter 14 | Articulations ___________________________________________________________________

3. Range of motion varies at different joints because of the shape of the articulating surfaces of the bones and the position of the joint ligaments and the nearby muscles. All of these factors together limit the range of motion of a specific joint.

4. The condyles of the femur articulate with the flat upper surface of the tibia. Two cartilages (the medial and lateral menisci) attach to the flat top of the tibia and form a shallow socket for the condyles of the femur. The anterior cruciate ligament attaches to the anterior part of the tibia between the condyles and attaches to the posterior part of the lateral condyle of the femur. The posterior cruciate ligament attaches posteriorly to the tibia and lateral meniscus and attaches to the front part of the femur’s medial condyle. The ligament of Wrisberg attaches posteriorly to the lateral meniscus and to the medial condyle behind the attachment of the posterior cruciate ligament. Transverse ligaments connect the anterior margins of the two menisci, and the fibular and tibial collateral ligaments are located at the sides of the knee. The knee joint is the main weightbearing joint in the body and is relatively unprotected by surrounding muscles. Consequently, it is susceptible to injury. When the knee twists while bearing weight, the cartilage on the tibia can become torn. This can result in damage to the ligaments that hold the tibia and femur together. This ligament damage can also occur when a weight-bearing knee is hit from the side.

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Instructor’s Resource Material for

15 Axial Muscles ANSWER KEYS

Answers to Quick Check Questions 1. (a) Endomysium, (b) perimysium, and (c) epimysium 2. The tendon attaches a muscle to bone.

3. Three types of fiber arrangements seen in a skeletal muscle are (1) parallel, (2) convergent, and (3) pennate.

4. (a) Origin and (b) insertion 5. Prime mover or agonist describes a muscle that directly performs a specific movement.

6. Fixator muscles help maintain posture or balance.

7. Fixator muscles generally function as joint stabilizers.

8. The components of any lever system are (1) a rigid rod or bar (bone); (2) a fixed pivot, or fulcrum around which the rod moves (joint); (3) a load or resistance that is moved; and (4) a force, or pull, that produces movement (muscle contraction).

9. The types of lever systems are (1) first class levers (tilting the head backward), (2) second class levers (raising the body up on the toes), and (3) third class levers (flexing the forearm at the elbow joint).

10. Third class levers are the most common in the body; they permit rapid and extensive movement.

11. A muscle name can be determined by (1) location (gluteus), (2) function (adductor muscles), (3) shape (deltoid), (4) direction of fibers (rectus abdominis), (5) number of heads or divisions (biceps), (6) points of attachment (sternocleidomastoid), and (7) size of muscle (gluteus maximus).

12. When deducing muscle action, start by making yourself familiar with names, shapes, and general locations of the larger muscles. Try to deduce which bones the two ends of a muscle attach. Next, determine which bone moves when the muscle shortens. Deduce a muscle’s action by applying the principle that is insertion moves toward its origin. Finally, to deduce which muscle produces a given action, start by inferring the insertion bone.

13. The occipitofrontalis has two parts: one lying over the forehead and the other covering the back of the skull.

14. Chewing is facilitated by the masseter, temporalis, and pterygoid muscles.

15. The sternocleidomastoid muscle flexes the head.

16. Internal and external intercostal muscles and the diaphragm produce respiratory movements.

17. The rectus abdominis muscle protects the abdominal viscera and flexes the spinal column.

18. The perineum is the area between the anus and genitals (pelvic floor).

Answers to Case Study Questions (p. 334) 1. c: Jeremy experienced pain along the side of the abdomen, so the external oblique is the correct choice. The external oblique muscles lie in the anterolateral wall of the abdomen. The pectoralis muscle is located on the anterior chest wall and not in the abdomen, and the external intercostal muscles are located in the thorax. The rectus abdominis muscle is an abdominal muscle, but it lies medially in the abdominal wall and not along the side.

2. d: The orbicularis oculi muscle encircles the eye. The orbicularis oris and buccinator both act on the mouth.

The buccinator also works with the masseter in mastication (chewing food).

3. c: The diaphragm is the primary muscle of respiration. In deep respiration, other muscles are recruited, including the internal and external intercostals.

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Chapter 15 | Axial Muscles _________________________________________________________________

4. a: The rectus abdominis is the only muscle listed that flexes the trunk.

Answers to Review Questions (p. 336) 1. Endomysium: A delicate connective tissue membrane that covers muscle cells or fibers.

Perimysium: A tougher connective tissue envelope that binds together groups of muscle fibers, called fascicles.

Epimysium: A very tough connective tissue that covers the muscle as a whole.

2. A third-class lever is the most common lever system found in the body. In a third-class lever, the pull is exerted between the fulcrum and resistance, or load to be moved.

3. Students should provide one example for each type: • Muscles named by location: brachialis; gluteales • Muscles named by function: abductors; adductors • Muscles named by shape: deltoid • Muscles named by fiber direction: rectus abdominis • Muscles named by number of heads: biceps brachii • Muscles named by points of attachment: sternocleidomastoid 4. The main muscles of the back include the trapezius, infraspinatus, teres major and minor, and latissimus dorsi. The main muscles of the chest include the pectoralis major and serratus anterior. The main muscles of the abdomen include the rectus abdominis and external oblique. The main muscles of the neck include the trapezius and sternocleidomastoid. The main muscles of the pelvic floor are the levator ani, ischiocavernosus, bulbospongiosus, deep transverse perinei, sphincter urethrae, and sphincter externus ani.

5. The main muscle that flexes the head is the sternocleidomastoid. The main muscles that extend the head are the semispinalis capitis, splenius capitis, and longissimus capitis. Any of these muscles can abduct if only the muscles on the same side contract, and they can adduct if only the muscles on the opposite side contract.

6. The main muscles that move the abdominal wall are the external oblique, internal oblique, transverse abdominis, and rectus abdominis. The main muscles that move the chest wall are the external intercostals and internal intercostals. Some students may include the diaphragm.

Answers to Critical Thinking Questions (p. 336) 1. The muscles of facial expression are occipitofrontalis, corrugator supercilii, orbicularis oculi, zygomaticus major, orbicularis oris, and buccinator. The muscles that facilitate smiling are zygomaticus major and buccinator. The muscles that facilitate frowning are corrugator supercilii.

2. The origin is the attachment point of a muscle that does not move when the muscle contracts. The insertion is the attachment point of the muscle that does move when the muscle contracts.

3. When the biceps brachii flexes the elbow, it is acting as the agonist, whereas the triceps brachii is the antagonist. When the triceps brachii extends the elbow, it is the agonist, whereas the biceps brachii is acting as the antagonist.

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Instructor’s Resource Material for

16 Appendicular Muscles ANSWER KEYS Answers to Quick Check Questions 1. The deltoid muscle flexes and extends the arm and abducts upper arm.

2. The biceps brachii muscle flexes the supinated forearm.

3. Extrinsic muscles, originating in the forearm, can pull on their insertions in the wrist, hand, and fingers to move them. Intrinsic muscles are actually within the part moved.

4. The gluteus maximus, medius, and minimus are the three gluteal muscles.

5. The gastrocnemius muscle extends the foot and flexes the lower leg.

6. Posture is maintaining optimal body position.

7. Muscle tone is the continuous, low-level tension of muscles that helps us resist gravity and, thus, maintain posture.

8. Poor posture puts abnormal strain on muscles, ligaments, and bones—possibly causing fatigue, deformities, and various dysfunctions.

Answers to Case Study Questions (p. 359) 1. c: Because the injury occurred at the posterior side of lower leg, the gastrocnemius is the correct response.

The gastrocnemius is the muscle on the posterior surface of the lower leg that forms the bulging “calf.” The biceps femoris is one of the hamstring muscles located on the posterior side of the thigh. The tibialis anterior is a lower leg muscle, but it is located anteriorly. The vastus medialis is a quadriceps muscle located on the anterior side of the thigh.

2. a. The extrinsic muscles located in the lower leg exert their actions by pulling on tendons that insert on bones in the ankle and foot. These include the tibialis anterior, gastrocnemius, soleus, fibularis longus, fibularis brevis, fibularis tertius, and extensor digitorum longus.

3. d: The common tendon of the gastrocnemius and soleus is called the calcaneal (Achilles) tendon. It inserts into the calcaneus, or heel bone.

4. d: The calcaneal tendon is the common tendon of the gastrocnemius and soleus. By acting together, these muscles serve as powerful flexors (plantar flexion) of the foot. The dorsiflexors of the foot include the tibialis anterior, fibularis tertius, and the extensor digitorum longus.

Answers to Review Questions (p. 360) 1. The main muscle of the shoulder is the deltoid. The main muscles of the upper arm are the biceps brachii, triceps brachii, and brachialis. The main muscles of the lower arm (forearm) are the brachioradialis, flexor carpi radialis, palmaris longus, flexor carpi ulnaris, pronator teres, flexor digitorum superficialis, flexor digitorum profundus, supinator, and pronator quadratus. The main muscles of the thigh are the quadriceps femoris group, sartorius, and hamstring group. The main muscles of the leg are the semitendinosus, biceps femoris, semimembranosus, adductor magnus, gracilis, vastus lateralis, vastus medialis, rectus femoris, sartorius, gastrocnemius, soleus, tibialis anterior, external digitorum longus, peroneus longus, and peroneus brevis.

2. The trapezius is the muscle that is used to “shrug” the shoulders.

3. The main muscles that flex the upper arm are the pectoralis major, deltoid, and coracobrachialis. The main muscles that extend the upper arm are the latissimus dorsi, deltoid, and teres major. The main muscles that abduct the upper arm are the deltoid and supraspinatus. The main muscles that adduct the upper arm are the pectoralis major, latissimus dorsi, coracobrachialis, and teres major. The main muscle that raises and lowers the shoulder is the trapezius.

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Chapter 16 | Appendicular Muscles ___________________________________________________________

4. The main muscles that flex the forearm are the biceps brachii, brachialis, and brachioradialis. The main muscle that extends the forearm is the triceps brachii. The main muscles that flex the wrist and hand are the flexor carpi radialis, palmaris longus, and flexor carpi ulnaris. The main muscles that extend the wrist and hand are the extensor carpi radialis longus, extensor carpi radialis brevis, and extensor carpi ulnaris.

5. The opponens pollicis is the muscle that allows the thumb to be drawn across the palm to touch the tip of any finger.

6. The main muscles that flex the thigh are the iliopsoas and rectus femoris. The main muscle that extends the thigh is the gluteus maximus. The main muscles that abduct the thigh are the gluteus medius, gluteus minimus, and tensor fasciae latae. The main muscles that adduct the thigh are the adductor brevis, adductor longus, adductor magnus, and gracilis. The main muscle that flexes the leg and thigh is the biceps femoris.

The main muscles that extend the leg and thigh are the rectus femoris, vastus lateralis, vastus medialis, semitendinosus, and semimembranosus. The main muscles that flex the foot are the tibialis anterior, peroneus brevis, and peroneus tertius. The main muscles that extend the foot are the gastrocnemius, soleus, and peroneus longus.

7. The gluteus medius muscle is often the site for intramuscular injections when the amount of medication is 2 to 3 ml.

Answers to Critical Thinking Questions (p. 360) 1. Posture is maintained by the tonicity, or muscle tone, of muscles that exert a continual pull in the opposite direction of gravity.

2. Because of the disparity in size between the large head of the humerus and the much smaller glenoid cavity, only about ¼ of the humeral head is in contact with the cavity. This makes the joint unstable and easy to dislocate. The rotator cuff plays an important role in stabilizing the shoulder joint.

3. The typist might experience carpal tunnel syndrome. This is caused by a swelling of the tendon sheath around the tendons of the wrist and median nerve. Pressure on the median nerve results in the pain this person is experiencing.

4. The muscles that make up the rotator cuff are the supraspinatus, infraspinatus, teres minor, and subscapularis muscles. These muscle tendons form the musculotendinous cuff (rotator cuff) that provides the necessary strength to prevent anterior, superior, and posterior displacement of the humeral head during most types of activities. However, those who are in activities that require a great deal of throwing (baseball) place a lot of stress and trauma on this articulation and the rotator cuff muscles and tendons. Hyperextension of this articulation may result in muscle strain or tear. The range of motion may be compromised through improper technique and overuse.

5. If the amount of medication to be injected is 2 to 3 ml, the gluteal area is often used. Injections are made into the gluteus medius muscle near the center of the upper outer quadrant.

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Instructor’s Resource Material for

17 Muscle Contraction ANSWER KEYS Answers to Quick Check Questions

1. Movement, heat production, and posture are the three major functions of skeletal muscles.

2. Excitability, contractibility, and extensibility are features unique to muscle fibers.

3. Muscle fiber striations are a result of the A bands of sarcomeres appearing as relatively wide, dark stripes under the microscope, which alternate with narrower, lighter-colored stripes formed by the I bands.

4. The triad allows an electrical impulse traveling along a T tubule to stimulate the membranes of adjacent sacs of the sarcoplasmic reticulum (SR).

5. Thin filament (actin, troponin, and tropomyosin): Molecules strung together like beads to form two fibrous strands that twist around each other. Thick filament (myosin): Shaped like golf clubs, with their long shafts bundled together to form a thick filament and their “heads” sticking out from the bundle.

6. A neuromuscular junction (NMJ) is a type of connection between a neuron and a muscle characterized by a narrow gap, or synaptic cleft, across which neurotransmitter molecules transmit signals. When impulses reach the end of a motor neuron fiber, small vesicles release a neurotransmitter into the synaptic cleft. These molecules contact the sarcolemma of the adjacent muscle fiber. There they stimulate receptors and thereby initiate an electrical impulse in the sarcolemma.

7. Calcium ions (Ca++) released from the sarcoplasmic reticulum (SR) bind to troponin in the thin filament and allow tropomyosin to shift from its position blocking the active sites of actin molecules, thus initiating the chemical reactions that produce contractions.

8. Catabolism of foods is the source of adenosine triphosphate (ATP) stored energy.

9. Aerobic pathway is a catabolic process that produces the maximum amount of energy available from each glucose molecule. Anaerobic pathway is a catabolic process that occurs when oxygen concentration is low.

Anaerobic pathway may allow the body to avoid the use of oxygen in the short term but not in the long term.

It results in the formation of lactic acid.

10. Myoglobin attracts oxygen molecules and holds them temporarily. When the oxygen concentration inside a muscle fiber decreases rapidly, it can be quickly resupplied from the myoglobin.

11. The three phases of a twitch contraction are latent period, contraction phase, and relaxation phase. During the latent period, an impulse initiated by stimulation travels through the sarcolemma and T tubules to the sarcoplasmic reticulum (SR) where it triggers the release of calcium ions into the sarcoplasm. During the contraction phase, calcium binds to troponin, sliding of myofilaments begins, and a contraction is observed.

During the relaxation phase, forceful sliding of myofilaments ceases and relaxation begins.

12. Twitch contraction: The muscle does not begin to contract at the instant of stimulation but rather a fraction of a second later. The muscle then increases tension until a peak is reached, after which it gradually returns to its resting state. Tetanic (tetanus) contraction: Smooth, sustained contraction resulting from a series of stimuli coming in a rapid enough succession that the muscle does not have the time to relax completely before the next contraction phase.

13. The treppe effect is a gradual, steplike increase in the strength of contraction. The muscle contracts more forcefully after it has contracted a few times than when it first contracts. This principle is used by athletes during their warm-up period.

14. Tetanus is a smooth, sustained contraction. Yes, tetanus is the kind of contraction exhibited by normal skeletal muscle organs most of the time.

15. Muscle tone (tonic contraction) is a continual, partial contraction in a muscular organ.

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Chapter 17 | Muscle Contraction _____________________________________________________________

16. The four factors that influence the strength of a skeletal muscle contraction are (1) metabolic condition of individual muscle fibers, (2) recruitment of motor units, (3) length-tension relationship, and (3) the amount of load imposed on the muscle.

17. “Recruitment of motor units” refers to the number of muscle fibers activated.

18. Isotonic: A contraction in which the tone or tension within a muscle remains the same as the length of the muscle changes. Isometric: A contraction in which the muscle length remains the same while the muscle tension increases. Concentric: A contraction in which movement results in shortening of the muscle.

Eccentric: A contraction in which movement results in lengthening of the muscle being contracted.

19. Cardiac muscle does not normally run low on adenosine triphosphate (ATP) and thus does not experience fatigue.

20. Each myofibril comprises sarcomeres that give the whole fiber a striated appearance.

21. Thin arrangements of myofilaments crisscross the cell and attach at their ends to the cell’s plasma membrane.

22. Single-unit: Most common type of smooth muscle—gap junctions join individual smooth muscle fibers into large, continuous sheets. Multiunit: Composed of many independent single-cell units. Each independent fiber does not usually generate its own impulse but rather responds only to nervous input.

Answers to Case Study Questions (pp. 386-387) 1. d: The creatine phosphate in muscle cells provides adenosine triphosphate (ATP) for about 20 seconds. After that the muscles use aerobic respiration until oxygen supplies are depleted. Contraction is still possible even then, using anaerobic respiration.

2. b: When the oxygen concentration inside a muscle fiber decreases rapidly, as it does during exercise, it can be quickly resupplied from myoglobin.

3. b: Although troponin and tropomyosin are involved in the contraction process (exposing binding sites), it is the interaction between actin and myosin that results in actual change in length of the sarcomere.

4. c: As is true of most chemical reactions, when glucose is converted to ATP and energy, some of that energy is in the form of heat.

5. a: Each muscle is composed of several motor units, which are in turn composed of individual muscle fibers.

To create more force, you have to “recruit” more muscle fibers, but you can only recruit them via their motor neuron. A motor unit is one motor neuron and all of the fibers with which it communicates.

Answers to Review Questions (p. 390) 1. Sarcolemma is the plasma membrane of a muscle fiber.

Sarcoplasm is the cytoplasm of a muscle fiber.

Sarcoplasmic reticulum (SR) is the structure that is analogous to the endoplasmic reticulum of other cells.

2. The function of the SR is the active transport and storage of calcium ions (Ca ++) in the canals and sacs that make up the SR. 3. Acetylcholine is the neurotransmitter that stimulates the sarcolemma and initiates the contraction. The result of that stimulus is the release of Ca++ from the SR. The calcium causes the troponin to pull the tropomyosin away from the binding sites on the actin. Adenosine triphosphate (ATP) supplies the energy to the cross bridges of the myosin so that the actin fiber can be pulled to the center of the sarcomere, causing the muscle to contract.

4. ATP consists of a molecule of adenine, a molecule of ribose sugar, and three molecules of phosphate. The last two phosphates are joined to the molecule by high-energy bonds. When the high-energy bonds are broken, the energy stored in the bonds is used for cell work.

5. ATP transfers the energy from the high-energy bonds to the myosin cross bridges. The energy is stored in the myosin until it is released when the myosin binds with the actin during muscle contraction.

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____________________________________________________________ Chapter 17 | Muscle Contraction

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6. A single motor neuron—plus all the muscle fibers it stimulates—is called a motor unit. Motor units can include many muscle fibers for less precise movement or few fibers for more delicate movement.

7. The different types of skeletal muscle contractions are incomplete tetanus, complete tetanus, isotonic contraction, and isometric contraction. The skeletal muscles can contract in a rapid series of contractions called incomplete tetanus. The muscle cannot fully relax before the next stimulus occurs. If the speed of the stimulus increases, the individual contractions fuse and become a single smooth contraction; this is called complete tetanus. In an isotonic contraction, the tension within the muscle remains the same. As the muscle contraction begins, the sarcomeres actually shorten and move the load on the muscle. In an isometric contraction the muscle length remains the same, but the tension on the muscle increases. The sarcomeres do not shorten, and the muscle is unable to move the load on the muscle.

8. Recruited refers to activation of motor units that lead to a muscle contraction. Recruitment of motor units depends on the intensity and frequency of stimulation. In general, the more intense and more frequent a stimulus, the more motor units are recruited and the stronger the contraction.

9. Rigor mortis is the stiffness that occurs in the muscles after death. The stiffness occurs because muscles that were contracting at the time of death need ATP to release the cross bridges. Because no more ATP is being made, the cross bridges do not release, and stiffness results.

10. Strength training can cause an increase in muscle size (hypertrophy). This increases the number of myofilaments in each muscle fiber. Endurance training does not usually result in muscle hypertrophy, but it does increase the muscle’s ability to sustain moderate contractions for a longer period. This increases the blood supply, which allows the muscle to obtain more glucose and oxygen during exercise. Also increased is the number of mitochondria in each muscle fiber, which allows for the more efficient production of ATP.

Answers to Critical Thinking Questions (p. 390) 1. The general functions of skeletal muscles are movement, heat production, and posture. Muscle contractions cause the joints to bend and the body to move. Heat is produced by the large number of contracting muscle cells. The continuous partial contraction of many skeletal muscles produces the relatively stable positions of the body when standing or sitting; this is known as posture.

2. Excitability is a characteristic shared with the nervous system.

Contractility refers to a muscle’s ability to get shorter.

Extensibility refers to a muscle’s ability to be pulled back to its original length. When a joint is bent, the agonist is exhibiting contractility and the antagonist is exhibiting extensibility.

3. Myofibrils are unique to muscle cells; they are primarily involved in contraction. T tubules and sarcoplasmic reticula are also unique to muscle cells; they are primarily involved in excitability.

4. The structure of the myofilament consists of thousands of smaller subunits called myofibrils. Each myofibril consists of thick and thin filaments lying parallel to one another. Four kinds of proteins make up the myofilament: actin, troponin, and tropomyosin make up the thin filaments; myosin makes up the thick filaments. The tropomyosin twists around the actin filament and is held in place by troponin. In this position the tropomyosin is blocking the binding sites between the actin and myosin. When the muscle is stimulated to contract, calcium ions (Ca++) are released from the sarcoplasmic reticulum (SR). When Ca ++ attach to the troponin, they cause the troponin to move the tropomyosin away from the binding sites, allowing the myosin to pull the actin so that the muscle fiber shortens.

5. The sliding filament theory explains how the excitation of the muscle fiber begins with the neurotransmitter acetylcholine, causing the stimulation of the sarcolemma, T tubule, and SR. When the SR is stimulated, it releases Ca++ into the sarcomere. The Ca++ attach to the troponin, which causes the troponin to move the tropomyosin away from the actin binding site. When this happens, the myosin forms cross bridges with the actin and pulls it toward the center of the sarcomere. The muscle shortens as a result of the filaments sliding past one another. Energy for the contraction is supplied by ATP. When the calcium is transported back to the SR, the tropomyosin returns to the blocking position, which prevents the joining of actin and myosin.

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Chapter 17 | Muscle Contraction _____________________________________________________________

6. The Ca++ is released into the sarcomere as a result of excitation of the SR. When the Ca ++ binds to the troponin, it moves the tropomyosin, allowing the cross bridges to form, which causes the muscle to contract.

When the calcium is transported back into the SR, the troponin returns the tropomyosin to its blocking position, causing relaxation.

7. The marathon runner would want muscles with a high proportion of slow fibers. These muscles can maintain contractions over a long period without fatigue. A sprinter would want a muscle with a high proportion of fast fibers. Fast fibers can respond much more rapidly; however, they use so much energy that they fatigue quickly.

8. The cardiac muscles do not taper at the ends like skeletal muscles but branch and form strong electrically coupled junctions with other fibers. This allows cardiac muscle fibers to form a continuous electrically coupled mass. This allows for the efficient conduction of electrical impulses necessary for coordinated pumping action.

9. Visceral smooth muscle is capable of auto rhythmicity, which means it is able to contract without external stimulus. Multiunit smooth muscle is unable to do this and must rely on an external stimulus to contract. The multiunit smooth muscle would be more affected by damage to the nerve that stimulates it.

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Instructor’s Resource Material for

18 Nervous System Cells ANSWER KEYS Answers to Quick Check Questions 1. Central and peripheral are the major subdivisions of the human nervous system.

2. The central nervous system (CNS) includes the brain and spinal cord.

3. Some pathways of the somatic nervous system carry information to the somatic effectors, which are the skeletal muscles. Pathways of the autonomic nervous system carry information to the visceral effectors, which are the smooth muscles, cardiac muscles, and glands.

4. The five main types of glia are (1) astrocytes, (2) microglia, (3) ependymal cells, (4) oligodendrocytes, and (5) Schwann cells.

5. The myelin sheath is formed by layers of Schwann cell membrane, containing the white, fatty substance called myelin. It is important in the proper conduction of impulses along the nerve fiber.

6. The neurilemma is a nerve sheath formed as each Schwann cell wraps around the nerve fiber, and its nucleus and cytoplasm are squeezed to the perimeter.

7. The three different forms or Schwann cells are (1) myelinated fibers (white fibers), which are nerve fibers with many Schwann cells forming a thick myelinated sheath; (2) unmyelinated fibers (gray fibers), which are nerve fibers held together by a single Schwann cell that does not wrap around them to form a thick myelin sheath; and (3) satellite cell, which is a special Schwann cell that surrounds the cell body of a neuron.

8. Both axons and dendrites are threadlike extensions from the neuron’s cell body. However, dendrites usually branch extensively from the body, and they receive stimuli and conduct electrical signals toward the cell body and/or axon. The distal ends may be called receptors, and some in the brain have small knoblike dendritic spines. Axons are a single process from the cell body that conducts impulses away from the cell body. The distal tips form branches called telodendria that terminate in synaptic knobs.

9. Multipolar, bipolar, and unipolar are the three structural categories of neurons.

10. Afferent, efferent, and interneurons are the three main functional categories of neurons.

11. A reflex arc is a signal conduction route to and from the central nervous system (CNS). Afferent (sensory) neurons conduct signals to the CNS from sensory receptors in the peripheral nervous system (PNS). Efferent (motor) neurons conduct signals from the CNS to effectors. Interneurons conduct signals from afferent neurons toward or to motor neurons. Simpler reflex arcs do not have interneurons.

12. Endoneurium, perineurium, and epineurium are the three layers of connective tissue that hold nerves together.

13. Nerves are bundles of peripheral nerve fibers held together by several layers of connective tissues. Within the CNS, bundles of nerve fibers are called tracts.

14. White matter is made up of myelinated fibers. Cell bodies and unmyelinated fibers make up the gray matter.

15. Nerve fibers can sometimes be repaired if damage is not extensive, when the cell body and neurilemma remain intact, and scarring has not occurred.

Answers to Case Study Questions (p. 408) 1. b: Oligodendrocytes are the glial cells that are associated with multiple sclerosis and other myelin disorders.

Multiple sclerosis (MS) is characterized by myelin loss and destruction accompanied by varying degrees of oligodendrocyte injury and death. Because the oligodendrocytes produce the myelin sheath around the nerve fibers in the central nervous system (CNS), demyelination throughout the CNS results. As the myelin surrounding the nerve fibers is lost, nerve conduction is impaired.

2. a: The cause of MS is thought to be related to autoimmunity and to viral infections in some individuals.

Susceptibility to MS is inherited in some individuals.

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Chapter 18 | Nervous System Cells ___________________________________________________________

3. d: MS is characterized by demyelination throughout the white matter of the CNS, the presence of hard plaque-like lesions replacing the destroyed myelin, and the impairment of nerve conduction leading to weakness, loss of coordination, visual impairment, and speech disturbances.

Answers to Review Questions (p. 411) 1. The general function of the nervous system is communication. Communication is what makes possible control, which in turn allows integration, which allows homeostasis, which allows survival.

2. The endocrine system also shares the function of communication.

3. The astrocytes form tight sheaths around the brain’s blood capillaries, forming the blood-brain barrier (BBB).

4. A reflex arc is called an ipsilateral reflex arc when the receptors and effectors are located on the same side of the body. A contralateral reflex arc is one whose receptors and effectors are located on opposite sides of the body.

5. Neuroma: General name for tumors in the nervous system structures.

Glioma: Brain tumor.

Astrocytoma: A type of glioma that originates from astrocytes.

Glioblastoma multiforme: A highly malignant form of astrocytic tumor.

Ependymoma: Glial tumor arising from ependymal cells.

Oligodendroglioma: A tumor that commonly occurs in anterior portion of the brain.

Acoustic neuroma: A lesion of the sheath of Schwann cells surrounding the eighth cranial nerve, which is responsible for hearing and balance.

Neurofibromatosis: An inherited disease characterized by numerous fibrous neuromas throughout the body.

Answers to Critical Thinking Questions (p. 411) 1. The central nervous system (CNS) consists of the brain and spinal cord. Its function is to integrate and evaluate incoming information and initiate an outgoing response. The peripheral nervous system (PNS) consists of the nerves outside the CNS, which originate from either spinal or cranial nerves. The function of the PNS is to carry information to and from the CNS. The terms afferent and efferent are directional terms.

Afferent fibers include nerves bringing information to the CNS. Efferent fibers include nerves bringing information away from the CNS. The somatic and autonomic nervous systems each have afferent and efferent fibers in them.

2. There are about 900 billion glial cells in the nervous system and only about 100 billion neurons. Only about 10% of the cells in the brain are nerve tissue; the other 90% are supportive glial cells.

3. In a multipolar neuron, there are many dendrites and one axon. Bipolar neurons have one dendrite and one axon. Unipolar neurons have only one process; the most distal part of the structure is the dendrite, and the rest of the process functions as an axon.

4. White matter consists of myelinated neurons. Gray matter consists of unmyelinated neurons. Multiple sclerosis is caused by the loss of myelination.

5. The inflammation that occurs after a spinal cord injury can cause damage to even more neurons. Treatment with very high doses of methylprednisolone can reduce the inflammation and therefore reduce the nerve damage.

6. Peripheral nerve fibers can repair themselves if the neurilemma and endoneurium that surround the neuron are able to form a tunnel to the effector. Macrophages clear the debris, which allows this to occur. In the CNS, the neurons have no neurilemma, and astrocytes fill in the space between the neuron and the effector, blocking any tunnel formation. Because of these two different reactions, peripheral neurons are much more able to repair themselves than are central neurons.

7. The blood-brain barrier (BBB) helps maintain a stable environment in the brain. The tight junctions in the capillary walls and the astrocytes form a barrier that regulates most material. Many drugs are unable to cross this barrier.

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Instructor’s Resource Material for

19 Nerve Signaling ANSWER KEYS

Answers to Quick Check Questions 1. The mechanisms that produce and maintain the resting membrane potential (RMP) do so by promoting a slight ionic imbalance across the neuron’s plasma membrane. These mechanisms produce a slight excess of positive ions on its outer surface. Included among these mechanisms are gated channels and the sodiumpotassium pump.

2. Sodium is more abundant outside, whereas potassium is more abundant inside the plasma membrane.

3. During depolarization, the excess of positive ions outside the plasma membrane decreases and the magnitude of the membrane potential is reduced toward zero. Movement of the membrane potential away from zero (thus below the usual RMP) is called hyperpolarization.

4. The events that lead to initiation of an action potential are as follows: (1) A stimulus triggers stimulus-gated sodium ion (Na+) channels to open and allow inward Na+ diffusion. (2) As the threshold potential is reached, voltage-gated Na+ channels open. (3) As more Na+ enters the cell through voltage-gated sodium channels, the membrane depolarizes even further. (4) The magnitude of the action potential peaks (at +30 mV) when voltage-gated Na+ channels close. (5) Repolarization begins when voltage-gated potassium ion (K+) channels open, allowing outward diffusion of K+. (6) After a brief period of hyperpolarization, the resting potential is restored by the sodium-potassium pump and the return of ion channels to their resting state.

5. The threshold potential occurs when the magnitude of the local depolarization surpasses a limit (typically −59 mV).

6. Myelinated fibers conduct impulses faster than unmyelinated fibers.

7. The synaptic knob, synaptic cleft, and the plasma membrane of the postsynaptic neuron are the three structural components of a synapse.

8. Steps of synaptic transmission: (1) When an action potential reaches a synaptic knob, voltage-gated calcium channels in its membrane open and allow calcium ions to diffuse into the knob rapidly. (2) The increase in intracellular calcium ion (Ca++) concentration triggers the movement of neurotransmitter vesicles to the plasma membrane of the synaptic knob. (3) The released neurotransmitter molecules almost instantaneously diffuse across the narrow synaptic cleft and contact the postsynaptic neuron’s plasma membrane. Here they bind to receptor molecules that trigger the gated channels to open. (4) The opening of the ion channels in the postsynaptic membrane may produce a local potential called a postsynaptic potential. Excitatory neurotransmitters cause both Na+ and K+ channels to open, causing a temporary depolarization called an excitatory postsynaptic potential. Inhibitory neurotransmitters cause K+ channels and/or chloride ion (Cl−) channels to open. If K+ channels open, K+ rushes outward; if Cl−- channels open, Cl− rushes inward. Either event makes the inside of the membrane even more negative than at the resting potential (inhibitory postsynaptic potential). (5) Once a transmitter binds to its postsynaptic receptors, its action is quickly terminated.

9. Excitatory postsynaptic potential (EPSP) is a result of Na+ rushing inward faster than K+ rushes outward, thus causing a temporary depolarization. Inhibitory postsynaptic potential (IPSP) results when inhibitory transmitters cause K+ channels and/or Cl− channels to open. If K+ channels open, K+ rushes outward; if Cl− channels open, Cl− rushes inward. Either event makes the inside of the membrane even more negative than at the resting potential.

10. Spatial summation is when the sum of the local potential reaches the threshold potential, causing voltagegated channels in the axon membrane to open, thus producing an action potential. Temporal summation is when synaptic knobs stimulate a postsynaptic neuron in rapid succession, and their effects can add up over a brief period of time to produce an action potential.

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Chapter 19 | Nerve Signaling _______________________________________________________________

11. The most widely held idea on how memories are formed is that information is stored in the form of an increased flow of information at synapses in particular pathways. Thus, memories form when the flow of information is facilitated at synapses.

12. Excitatory neurotransmitters have an excitatory effect at synapses. Inhibitory neurotransmitters have an inhibitory effect at the synapses.

13. Acetylcholine, amines, amino acids, and other small molecules are the four chemical classes of neurotransmitters.

14. A neuromodulator is a “co-transmitter” that regulates or modulates the effects of the neurotransmitter(s) released along with it.

Answers to Case Study Questions (p. 432) 1. c: With declining acetylcholine receptors, Kelly is less and less able to connect messages sent from her brain to her skeletal muscles. The message starts, an action potential travels all the way down the first neuron, and acetylcholine is released from the axon terminal. But there are not enough receptors to bind to the acetylcholine to start an action potential in the postsynaptic cell.

2. a: Opening sodium channels allows a rush of the positively charged sodium into the cell. This positive move is depolarizing. Because the positive ions move the cell (the postsynaptic cell) closer to threshold, making it easier to start an action potential, it is called excitatory (postsynaptic potential).

3. b: Acetylcholinesterase is the enzyme that breaks down acetylcholine. If you can block that enzyme, then more acetylcholine stays in the synapse longer—potentially binding with more of the remaining receptors. If enough receptors respond and open ion channels, then depolarization may occur on the postsynaptic cell.

Answers to Review Questions (p. 435) 1.

Sodium ions have a high concentration outside the cell, and potassium ions have a high concentration inside the cell. When an action potential occurs, the sodium channels open, allowing sodium to rush into the cell. This causes the interior of the cell to become positive. The potassium channels also open, and, in response to the positive interior of the cell and the diffusion pressure, potassium ions leave the cell. The movement of sodium and potassium ions through the channels causes the voltage change in the cell, which is the action potential.

2.

The action potential is an all-or-none response because the cause of the action potential is the influx of sodium ions into the cell through the voltage-gated channels. These channels can be either open or closed.

When they open, they stay open for a specific time, making each action potential the same. If the channels do not open, there is no action potential.

3.

Myelinated fibers conduct impulses more rapidly than do unmyelinated fibers because the speed of saltatory conduction is faster than conduction in an unmyelinated fiber. The speed of conduction is also proportional to the diameter of the fiber. The larger the diameter, the faster the impulse is conducted.

4.

The synapse consists of a synaptic knob, which is a bulge at the end of the terminal branch of a presynaptic axon; a synaptic cleft, which is a space between the synaptic knob and the plasma membrane of the postsynaptic neuron; and the plasma membrane of the postsynaptic neuron, which contains protein receptors for the neurotransmitter released by the presynaptic axon.

5.

When an action potential reaches the synaptic knob, the calcium channels open, allowing calcium ions into the knob. This causes the release of neurotransmitters across the synaptic cleft. The neurotransmitters briefly bind to the receptor molecules in the plasma membrane of the postsynaptic neuron. This causes the ion channels to open. If they are sodium channels, it is an excitatory response. If they are potassium or chloride channels, it is an inhibitory response. The neurotransmitters leave the receptors by being reabsorbed by the axon, by being chemically broken down by enzymes, or by diffusing out of the synaptic cleft.

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6.

The four main chemical classes of neurotransmitters are (1) acetylcholine, which consists of two molecules—acetate and choline—that are joined together; (2) amines, which are synthesized from amino acids, such as tyrosine, tryptophan, or histidine (e.g., dopamine, epinephrine, and norepinephrine); (3) amino acids, which are themselves used as neurotransmitters (e.g., glutamate and glycine); and (4) neuropeptides, which are short chains of amino acids. Two subclasses of neuropeptides neurotransmitters are enkephalins and endorphins.

7.

Acetylcholine is found in various locations in the nervous system. When it is used as a neurotransmitter for skeletal muscles, it is excitatory. When it is used as a neurotransmitter for cardiac muscle, it is inhibitory.

Answers to Critical Thinking Questions (p. 435) 1. Potential is a difference in electrical charge across plasma membranes.

0 mV at 1 ms = Not action potential (absolute refractory period) −50 mV at 0.5 ms = Not action potential (absolute refractory period) +25 mV at 1.5 ms = Action potential (absolute refractory period) +25 mV at 3 ms = Action potential (relative refractory period) 2. Two mechanisms can allow subthreshold stimuli to generate an action potential: spatial summation, which occurs when two or more excitatory stimuli occur at different parts of the postsynaptic membrane; and temporal summation, which occurs when the same presynaptic axon sends a rapid succession of stimuli to a postsynaptic membrane. If the sum of these stimuli is above threshold at the axon hillock, an action potential is generated.

3. Many anesthetics produce their effect by inhibiting the opening of sodium channels and are able to block the initiation and conduction of a nerve impulse.

4. Convergence may explain referred pain. Convergence occurs when more than one presynaptic axon synapses with a postsynaptic neuron. This would take information from a wider area and funnel it into a single nerve.

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Instructor’s Resource Material for

20 Central Nervous System ANSWER KEYS Answers to Quick Check Questions 1. Dura mater, arachnoid membrane, and pia mater are the three membranous coverings of the central nervous system (from outermost layer inward).

2. From the choroid plexus (in the lateral ventricles), the cerebrospinal fluid (CSF) seeps through an opening, the interventricular foramen (of Monro), into the third ventricle, then through a narrow channel, the cerebral aqueduct, and into the fourth ventricle. Some of the fluid moves out of the fourth ventricle directly into the central canal of the cord. Some of it moves out of the fourth ventricle through openings in its roof, two lateral foramina (of Luschka), and one median foramen (of Magendie). These openings allow the CSF to move into the cisterna magna, a space behind the medulla that is continuous with the subarachnoid space around the brain and spinal cord. The fluid circulates in the subarachnoid space and then is absorbed into the venous blood through the arachnoid villi.

3. Spinal nerve roots are bundles of nerve fibers that project from each side of the spinal cord. The dorsal root carries sensory information, whereas the ventral root carries motor information.

4. White matter surrounding the gray matter is subdivided in each half of the cord into three columns: anterior, posterior, and lateral white columns. The gray matter looks like a flat letter H in transverse sections of the cord. The limbs of the H are called anterior, posterior, and lateral horns of gray matter, or gray columns.

5. Ascending tracts conduct sensory impulses up the cord to the brain. Descending tracts conduct motor impulses down the cord from the brain. Ascending tracts examples are lateral spinothalamic; anterior spinothalamic; fasciculi gracilis and cuneatus, anterior, and posterior spinocerebellar; and spinotectal.

Descending tracts examples are lateral corticospinal, anterior corticospinal, reticulospinal, rubrospinal, tectospinal, and vestibulospinal.

6. The three major divisions of the brainstem are medulla oblongata, pons, and midbrain. Medulla oblongata: Nuclei in the medulla that contain a number of reflex centers (cardiac, vasomotor, and respiratory centers).

Pons: Contains the pneumotaxic centers that help regulate respiration. Midbrain: Contains reflex centers for certain cranial reflexes (pupillary reflexes and eye movements).

7. Gyri (folia) are raised areas on the surface of both the cerebellum and the cerebrum. Sulci are grooves located on the surface of both the cerebellum and cerebrum.

8. The cerebellum works with the cerebrum to coordinate muscle or motor activity through a pair of cerebellar nuclei called the dentate nuclei. Tracts connect these nuclei with the thalamus and with motor areas of the cerebral cortex. By means of these tracts, cerebellar impulses influence the motor cortex. Impulses in other tracts enable the motor cortex to influence the cerebellum.

9. The main components of the diencephalon are the thalamus, each lateral mass of which forms one lateral wall of the third ventricle, and the hypothalamus, which lies beneath the thalamus and forms the floor of the third ventricle and the lower part of its lateral walls.

10. General functions of the thalamus include (1) plays a part in the mechanism responsible for sensation, (2) plays a part in the mechanism responsible for emotions, (3) plays a part in the arousal or alerting mechanism, and (4) plays a part in mechanisms that produce complex reflex movements. (Students are asked to name three general functions of the thalamus.)

11. The hypothalamus (1) functions as a higher autonomic center and as the major relay station between the cerebral cortex and lower autonomic centers, (2) synthesizes hormones released by the pituitary gland (some neurons of the hypothalamus have endocrine functions [growth hormone, sex hormones, thyroid, and adrenal cortex]), (3) plays an essential role in maintaining the waking state, (4) functions to regulate appetite, and (5) maintains normal body temperature. (Students are asked to name three general functions of the hypothalamus.)

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Chapter 20 | Central Nervous System _________________________________________________________

12. The pineal gland seems to be involved in the regulation of the body’s biological clock.

13. The lobes of each cerebral hemisphere are the (1) frontal, (2) parietal, (3) temporal, and (4) occipital lobes and are named for the bones that lie over them; the (5) insula lies hidden from view in the lateral fissure.

14. The basal nuclei are the caudate nucleus, lentiform nucleus, and amygdaloid nucleus. They are located as “islands” of gray matter deep inside the white matter of each hemisphere.

15. The precentral gyrus, that is, the most posterior gyrus of the frontal lobe, constitutes the primary somatic motor area of the cerebral cortex. The postcentral gyrus, the most anterior gyrus of the parietal lobe, is the primary somatic sensory area of the cerebral cortex.

16. The reticular activating system consists of centers in the brainstem’s reticular formation that receives impulses from the spinal cord and relays them to the thalamus and from the thalamus to all parts of the cerebral cortex.

17. The limbic system is involved in the subjective experience and objective expression of emotions.

18. Most impulses that reach the sensory areas of the cerebral cortex have traveled over at least three pools of sensory neurons.

19. Sensory pathways to the cerebral cortex are crossed pathways. This means that each side of the brain registers sensations from the opposite side of the body.

20. Only one final common path, namely, each single motor neuron from the anterior gray horn of the spinal cord, conducts impulses to a specific motor unit within a skeletal muscle.

21. Pyramidal pathways are those whose fibers come together in the medulla to form pyramids. Extrapyramidal tracts are much more complex than pyramidal tracts. They consist of all motor tracts from the brain to the spinal cord anterior horn motor neurons except the corticospinal tracts.

Answers to Case Study Questions (p. 472) 1. c: The dura mater is the most superficial layer of the meninges. Deep to that is the arachnoid mater. The pia mater lies closest to the spinal cord.

2. d: The cerebrospinal fluid (CSF) flows through the central canal and in the subarachnoid space (just deep to the arachnoid mater).

3. a: The fasciculi gracilis carries sensory information, in particular, discriminating touch.

4. b: The cerebellum coordinates motor function, including skilled movement, posture, and balance. However, the “higher” functions, including language control, are the cerebrum’s responsibility.

Answers to Review Questions (p. 478) 1. The membranous covering of the brain and spinal cord is called the meninges. It consists of the dura mater, the arachnoid membrane, and the pia mater.

2. The large fluid-filled spaces within the brain are called ventricles. There are four of them, and they are filled with cerebrospinal fluid (CSF).

3. The formation of CSF occurs in the choroid plexuses by removing fluid from the blood. The choroid plexuses are capillaries that project from the pia mater into the lateral ventricles and the third and fourth ventricles.

From each lateral ventricle, the fluid passes through the interventricular foramen into the third ventricle and then through the cerebral aqueduct into the fourth ventricle. Some of the fluid moves out of the fourth ventricle into the central canal of the spinal cord. Some of it moves out of the fourth ventricle through openings in its roof. These openings allow the fluid to move into the cisterna magna, which is a space behind the medulla continuous with the subarachnoid space around the brain and spinal cord. The fluid circulates in the subarachnoid space and is absorbed into the venous blood by the arachnoid villi.

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4. The spinal cord is an oval-shaped cylinder that tapers slightly from above downward and has two bulges, one in the cervical and one in the lumbar region. There are two deep grooves, the anterior median fissure and the posterior median sulcus. The anterior groove is deeper and wider. Two bundles of nerve fibers called nerve roots project from each side of the spinal cord. These two roots join to form spinal nerves. The gray matter of the spinal cord looks like the letter H in cross section. The limbs of the H are called the anterior, posterior, and lateral gray columns. The white matter surrounding the gray matter is subdivided in each half into three columns: anterior, posterior, and lateral white columns. The spinal cord performs two general functions: it provides conduction routes to and from the brain and serves as the integrator or reflex center for all spinal reflexes.

5. The three components of the brainstem are the medulla oblongata, the pons, and the midbrain. The medulla oblongata mediates a number of reflexes, such as the cardiac, vasomotor, and respiratory centers. Other centers in the medulla are the vomiting, coughing, sneezing, hiccupping, and swallowing centers. The pons contains centers for reflexes mediated by cranial nerves V, VI, VII, and VIII, as well as the pneumotaxic centers, which help regulate respiration. The midbrain contains centers for pupillary reflexes and eye movement mediated by cranial nerves III and IV. 6. The cerebellum has three general functions. It helps produce skilled movements by coordinating the activities of muscle groups. It helps control posture and makes muscle movement smooth, efficient, and coordinated.

And it controls skeletal muscles to help maintain balance.

7. The thalamus has a number of general functions. It produces conscious recognition of crude, less critical sensations of pain, temperature, and touch. It relays sensory impulses to the cerebrum. It plays a part in the mechanism responsible for emotions by associating sensory impulses with feelings of pleasantness or unpleasantness. It plays a part in the arousal or alerting mechanism, and it plays a part in complex reflex movements.

8. The hypothalamus has a number of general functions. It functions as the higher autonomic center, regulating and coordinating autonomic activity. It functions as the major relay center between the cerebral cortex and the lower autonomic center. This relay center can act as the route by which emotions express themselves in changes in bodily functions. It synthesizes hormones directly into the blood. It plays an essential role in maintaining the waking state. It regulates appetite and food intake, and it helps regulate body temperature.

9. The general functions of the cerebrum are the complex integrative functions of sensory perception, complex voluntary muscle movement, conscious thought, memory, language, and problem solving.

10. The cerebral cortex performs a variety of functions. It is involved in responding to and evaluating sensory information. It controls voluntary muscle movement, and it is responsible for consciousness, use of language, emotion, and memory.

11. Consciousness is a state of awareness of one’s self, one’s environment, and other beings. Normal states or levels of consciousness include times of high alertness or attentiveness, relaxed or nonattentive, slow wave sleep, and rapid eye movement sleep.

12. Some altered states of consciousness are anesthesia, coma, and meditation.

13. Alpha waves have a frequency of 8 to 13 Hz with a relatively high voltage. These occur during relaxation.

Beta waves have a frequency of more than 13 Hz with relatively low voltage. These occur when the brain is busy.

Delta waves have a frequency of less than 4 Hz but have high voltage. These are deep sleep waves.

Theta waves have a frequency of 4 to 7 Hz with low voltage and are called “drowsy” waves.

14. The axons, dendrites, and cell bodies of primary sensory neurons are located in the peripheral nervous system. The dendrites and cell bodies of secondary sensory neurons are located in the spinal cord or brainstem. Their axons ascend in the ascending tracts up the cord, through the brainstem, and terminate in the thalamus. The dendrites and cell bodies of tertiary sensory neurons are in the thalamus with their axons forming the thalamocortical tracts, which extend through the internal capsule to the cerebral cortex.

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Chapter 20 | Central Nervous System _________________________________________________________

Answers to Critical Thinking Questions (p. 478) 1. Reflex center means the center of a reflex arc or the place in the arc where incoming sensory impulses become outgoing motor impulses. Interneurons are not necessary in the reflex arc. There are also two-neuron arcs where interneurons are not used.

2. The arousal or alerting mechanism consists of stimuli generated throughout the brain by the reticular activating system, which arouses or alerts the cerebral cortex. Without this stimulus, consciousness could not be maintained.

3. The meditation state is a waking state but differs markedly in certain respects from the usual waking state. It is able to combine both a high degree of relaxation and a high degree of alertness. This leads some to believe it to be an expanded or “higher” state of consciousness.

4. If a reduction in neurotransmitter concentration causes difficulty in memory formation, it would imply that a specific concentration is necessary to form a memory. That would refute the theory of an increased number of presynaptic axons or postsynaptic receptors being necessary for memory formation.

5. The electrical activity of the brain is caused by the neurons in the brain conducting impulses. The number of neurons conducting impulses and the frequency of the impulses are reflected in the electroencephalogram brain waves.

6. A person having an absence of any reflex probably has a lower motor neuron injury. Other symptoms might be the inability to produce voluntary movement and a loss of muscle tone. This is called flaccid paralysis.

The person having exaggerated reflexes probably has an upper motor neuron injury. Other symptoms would be spasticity (rigidity) and a positive Babinski reflex.

7. The stimulation and precise control of individual muscle groups is the function of the pyramidal tracts. Willed movement cannot occur in the muscles without proper functioning of the pyramidal tracts. The extrapyramidal tracts cause a number of muscle groups to contract in sequence or simultaneously. The extrapyramidal tracts are necessary for the formation of motor programs used in walking or swimming.

8. Taking a sample at the level of the third or fourth vertebra would be unwise because any error in taking the sample could injure the spinal cord. A better place to take the sample would be just above or below the fourth lumbar vertebra. There is no risk of damage to the spinal cord because the cord does not extend down that far.

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Instructor’s Resource Material for

21 Peripheral Nervous System ANSWER KEYS Answers to Quick Check Questions 1. There are 31 pairs of spinal nerves: cervical (8 pairs), thoracic (12 pairs), lumbar (5 pairs), sacral (5 pairs), and coccygeal (1 pair).

2. A plexus is a complex network formed by converging and diverging nerves; the four major pairs of plexuses are the cervical plexus, brachial plexus, lumbar plexus, and sacral plexus.

3. Dermatomes are skin surface areas supplied by a single spinal nerve. A myotome is a skeletal muscle or group of muscles that receives motor axons from a given spinal nerve.

4. The cranial nerves are as follows: olfactory (CN I), optic (CN II), oculomotor (CN III), trochlear (CN IV), trigeminal (CN V), abducens (CN VI), facial (CN VII), vestibulocochlear (CN VIII), glossopharyngeal (CN IX), vagus (CN X), accessory (CN XI), and hypoglossal (CN XII).

5. Olfactory: Sense of smell. Optic: Vision. Oculomotor: Eye movements, regulation of pupil size, accommodation, and proprioception. Trochlear: Eye movements and proprioception. Trigeminal: Sensations of head and face, chewing movements, and proprioception. Abducens: Abduction of eye and proprioception.

Facial: Facial expressions, secretion of saliva and tears, and taste. Vestibulocochlear: Balance or equilibrium sense (cochlear branch—hearing). Glossopharyngeal: Sensation of tongue, swallowing movements, secretion of saliva, and aid in reflex control of blood pressure and respiration. Vagus: Sensations and movements of organs supplied (e.g., slows heart, increases peristalsis, and contracts muscles for voice production).

Accessory: Shoulder movements, turning movements of head, movements of viscera, voice production, and proprioception. Hypoglossal: Tongue movements and proprioception.

6. Motor cranial nerves consist mainly of motor axons. Sensory cranial nerves consist of sensory axons. Mixed cranial nerves contain axons of sensory and motor neurons.

7. Skeletal muscles are the somatic effectors.

8. The principle of final common path states that all of the somatic motor pathways involve a single motor neuron whose axon stretches from the cell body in the central nervous system all the way to the effector innervated by that neuron.

9. The knee-jerk reflex can be a spinal reflex because the center of the reflex arc lies in the spinal cord gray matter, or it can be a stretch reflex because of the kind of stimulation used to evoke it.

Answers to Case Study Questions (p. 499) 1. b: The hypoglossal cranial nerve (CN XII) controls tongue movement. Damage to this nerve would result in the tongue leaning or deviating to the damaged side. Glossopharyngeal includes the word part glosso (meaning tongue), but glosso refers to tongue sensation in this case.

2. c: The vestibulocochlear nerve (CN VIII) carries sensory information from the ear. The two branches of this nerve are associated with the sense of hearing and the sense of balance or equilibrium.

3. a: The optic nerve (CN II) is definitely associated with the eye, but it carries sensory information from the eye, not motor commands to the eye. The other three cranial nerves communicate with various muscles around the eye to allow movement.

4. d: The facial nerve (CN VII) innervates the front two-thirds of the tongue and the taste buds found there. In addition to this sensory function, CN VII functions in facial expression (hence the name). Although smell (olfaction) and taste are closely related, touching the tongue with the taste stimulus tests the facial nerve alone.

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Chapter 21 | Peripheral Nervous System ______________________________________________________

5. c: TBI stands for “traumatic brain injury” and would have explained the patient’s temporary loss of consciousness. Her form might instead state “MTBI” for “mild traumatic brain injury” or perhaps “concussion.”

Answers to Review Questions (p. 502) 1. The ventral root of a spinal nerve carries information away from the central nervous system (CNS) toward the effector.

2. Mixed nerves are nerves that contain both motor and sensory fibers.

3. Muscles and skin of the neck, upper shoulders, and parts of the head are innervated by nerves emerging from the cervical plexus. The phrenic nerve also exits at this plexus, and it innervates the diaphragm.

4. A dermatome is a section of the skin innervated by a single spinal nerve. Each spinal nerve innervates a different area of the skin. By testing for sensitivity of the skin in different dermatomes, one can determine which, if any, spinal nerves have been damaged.

5. Each myotome is a segment of the body muscles innervated by a specific spinal nerve. Therefore specific motions are possible or not possible, depending on the ability of specific spinal nerves to function.

6. The optic nerve transmits impulses that result in vision. The oculomotor nerve, the trochlear nerve, and the abducens nerve transmit impulses that result in eye movement.

7. The vestibulocochlear nerve transmits impulses that result in hearing. The facial nerve, the glossopharyngeal nerve, and the vagus nerve transmit impulses that result in taste.

8. The somatic motor nervous system includes all pathways outside the CNS. It involves the peripheral pathways to the skeletal muscles.

9. Compression of the fifth cranial nerve results in a condition called trigeminal neuralgia. This condition is characterized by recurring episodes of intense stabbing pains radiating from the angle of the jaw along the branch of the trigeminal nerve.

10. Shingles is a unique viral infection that almost always affects the skin of a single dermatome. It is caused by the varicella zoster virus. If the body’s immunological protective mechanism becomes weakened, the virus may reactivate. The virus travels down the sensory nerve to the skin of a single dermatome. It results in a painful eruption of red, swollen plaques or vesicles that eventually rupture and crust over in about 2 to 3 weeks. In severe cases, extensive inflammation, hemorrhagic blisters, and secondary bacterial infection can occur. In most cases of shingles, the eruption of vesicles is preceded by 4 or 5 days of pain, burning, and itching.

Answers to Critical Thinking Questions (p. 502) 1. The cardiac reflex is an autonomic reflex. It is mediated by impulses conducted over the autonomic reflex arcs. The skeletal reflex is a somatic reflex. The impulse is conducted over somatic reflex arcs, that is, anterior horn neurons.

2. This is a Babinski reflex, which should not occur in an adult. This usually means that there has been damage to pyramidal tract (corticospinal) fibers.

3. The knee reflex can be classified in a variety of ways. It can be classified as a spinal cord reflex, a segmental reflex, an ipsilateral reflex, a stretch (or myotatic) reflex, an extensor reflex, a tendon reflex, and a deep reflex.

4. Injury at this level of the spinal cord might injure the phrenic nerve. This nerve supplies the diaphragm, which permits inspiration and expiration. If this nerve is damaged, the impulses no longer reach the diaphragm and the diaphragm stops contracting. Unless artificial respiration is provided, the person dies of respiratory paralysis.

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Instructor’s Resource Material for

22 Autonomic Nervous System ANSWER KEYS Answers to Quick Check Questions 1. No, autonomic pathways do not follow the principle of final common path.

2. The sympathetic preganglionic neurons have their dendrites and cell bodies within the lateral gray horns of the thoracic and lumbar segments of the spinal cord.

3. The sympathetic pathway can branch along any of three paths: It can synapse with a sympathetic postganglionic neuron, it can send ascending or descending branches through the sympathetic trunk to synapse with postganglionic neurons in other ganglia, or it can pass through one or more ganglia without synapsing.

4. In a parasympathetic ganglion, preganglionic axons synapse with postganglionic neurons that send their short axons into the nearby autonomic effector. Therefore a parasympathetic preganglionic neuron usually synapses with postganglionic neurons to a single effector.

5. Axons that release acetylcholine are known as cholinergic fibers. Axons that release norepinephrine are known as adrenergic fibers. Acetylcholine released from cholinergic fibers similarly binds to cholinergic receptors to produce postsynaptic effects. Norepinephrine released from the adrenergic fibers binds to adrenergic receptors according to a lock-and-key model to produce regulatory effects in the postsynaptic cell.

6. The two major types of cholinergic receptors are nicotinic and muscarinic. The two major types of adrenergic receptors are alpha and beta.

7. The principle of autonomic antagonism involves the circumstance of both sympathetic and parasympathetic divisions continually conducting impulses to autonomic effectors, often exerting an opposite or antagonistic influence on them. For example, continual sympathetic impulses to the heart tend to accelerate the heart rate, whereas continual parasympathetic impulses tend to slow it. The actual heart rate is determined by whichever influence dominates.

8. The responses that occur in the fight-or-flight reaction are as follows: • Increased heart rate: Increased delivery of oxygen and glucose to skeletal muscles • Increased strength of cardiac muscle contraction: Increased delivery of oxygen and glucose to skeletal muscles • Dilation of coronary vessels: Increased delivery of oxygen and nutrients to cardiac muscle • Dilation of blood vessels in skeletal muscles: Increased delivery of oxygen and nutrients to skeletal muscles • Constriction of blood vessels in digestive and other organs: Shunting of blood to skeletal muscles • Contraction of spleen and other blood reservoirs: More blood discharged into general circulation, thus increasing delivery of oxygen and nutrients to skeletal muscles • Dilation of respiratory airways: Increased loading of oxygen into blood • Increased rate and depth of breathing: Increased loading of oxygen into blood • Increased sweating: Increased dissipation of heat • Increased conversion of glycogen into glucose: Increased amount of glucose available to skeletal muscles 9. The parasympathetic division is the dominant controller when the body is at rest.

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Chapter 22 | Autonomic Nervous System ______________________________________________________

Answers to Case Study Questions (p. 517) 1. c: Tim’s response to the presence of the mountain lion was a result of the sympathetic nervous system’s “fight-or-flight” innervation.

2. a: The increase in the heart rate was due to a sympathetic stimulation of the heart. Beta receptors in cardiac muscle have a stimulating effect that results in a stronger and faster heartbeat.

3. a, b, d: As a result of sympathetic innervation, breathing rate increases (bronchioles dilate) and sweating increases. Because of the secretion of adrenaline (sympathetic nervous system), muscles that innervate the ear may contract involuntarily. Pulse (heart rate) would increase, and digestive activity would be inhibited.

4. d: Norepinephrine binds to beta receptors in cardiac muscle resulting in a faster and stronger heartbeat.

5. b: During sympathetic stimulation, blood vessels are dilated increasing the delivery of oxygen and nutrients to skeletal muscles.

6. a: The response that Tim’s body had was a result of the sympathetic nervous system. The binding of norepinephrine to alpha receptors has a stimulating effect. Axons that release norepinephrine are known as adrenergic fibers.

Answers to Review Questions (p. 519) 1. An autonomic preganglionic neuron conducts impulses from the brainstem or spinal cord to an autonomic ganglion. Within the autonomic ganglion, the presynaptic neuron synapses with the postganglionic neuron.

2. After entering the sympathetic chain ganglion, the fiber may take one of three paths. It can synapse with a sympathetic postganglionic neuron. It can send ascending and/or descending branches through the sympathetic trunk to synapse with postganglionic neurons in other chain ganglia. Or it can pass through one or more ganglia without synapsing. Preganglionic neurons that pass through the chain ganglia without synapsing continue on through the splanchnic nerves to other sympathetic ganglia.

3. Sympathetic preganglionic neurons tend to be short, whereas sympathetic postganglionic neurons tend to be long.

4. Parasympathetic ganglia tend to be farther from the central nervous system (CNS) and near the effector. Most of the sympathetic ganglia are in the sympathetic chain ganglia, which are near the CNS. 5. Norepinephrine increases the rate and strength of the heartbeat and constricts blood vessels in the skin, as well as abdominal blood vessels and blood vessels of the external genitalia. It can constrict or dilate coronary blood vessels; it dilates bronchioles and decreases peristalsis of the digestive tract. Norepinephrine constricts sphincter muscles of the digestive tract; it relaxes the bladder while constricting the urinary sphincter. It causes contraction of the reproductive ducts. It also causes dilation of pupils, relaxes ciliary muscles, and causes piloerection. It increases sweat production, decreases the secretion of saliva, decreases secretion of the pancreas, raises blood glucose levels, and stimulates epinephrine from the adrenal medulla. The action of norepinephrine is terminated in two ways. Some of the norepinephrine is carried back to the axon and broken down by the enzyme monoamine oxidase. The rest is broken down by the enzyme catechol-O-methyl transferase (COMT).

6. Acetylcholine causes a decrease in the rate and strength of heartbeat. It also dilates the blood vessels of the external genitalia, constricts bronchioles, and causes increased digestive tract peristalsis and relaxation of digestive tract sphincters. It causes contraction of the bladder, relaxation of the urinary sphincter, and relaxation of the reproductive ducts. Acetylcholine causes constriction of the pupils and contraction of the ciliary muscles; it increases secretion of tears and saliva, as well as pancreatic secretions. The action of acetylcholine is terminated by hydroxylation by the enzyme acetylcholinesterase.

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Answers to Critical Thinking Questions (p. 519) 1. The cardiac reflex is an autonomic reflex. It is mediated by impulses conducted over the autonomic reflex arcs. The skeletal reflex is a somatic reflex. The impulse is conducted over somatic reflex arcs (that is, anterior horn neurons).

2. Dual innervation allows precise control over a body function because the two innervations are antagonistic to each other. This is analogous to the accelerator and brake on a car because they both control the speed of the car antagonistically—one increases the speed and one decreases the speed.

3. In a dually innervated autonomic effector, norepinephrine is released from a sympathetic fiber and binds to an alpha or beta receptor on the effector. Norepinephrine may also bind to alpha receptors in the presynaptic membrane of a nearby parasympathetic fiber, which inhibits the release of acetylcholine. Or acetylcholine from a parasympathetic fiber may bind to a muscarinic receptor in the presynaptic membrane of nearby sympathetic fibers, inhibiting the release of norepinephrine. Because of this complexity of function, the effector can be controlled with great precision by balancing the effects of sympathetic and parasympathetic stimulation in various ways.

4. The idea that the autonomic nervous system has little control from the higher brain centers is incorrect. Parts of the brain in the frontal lobe and the limbic system send impulses to the hypothalamus, and the neurons in the hypothalamus send either stimulating or inhibiting impulses to the sympathetic or parasympathetic preganglionic neurons located in the lower autonomic centers.

5. The body is under the influence of the sympathetic nervous system. This reaction to stress is called the fightor-flight reaction, and it allows for maximum expenditure of energy by skeletal muscles. The heartbeat becomes faster and stronger, blood vessels in the skeletal muscles are dilated, the bronchi are dilated, and blood glucose levels increase.

6. Propranolol (Inderal) is a beta blocker. It achieves its therapeutic effects by preventing the increased rate and strength of the heartbeat triggered by sympathetic stimulation of the beta receptors on the heart muscle. This can be used to treat irregular heartbeat and hypertension.

7. Some of these substances include gamma-aminobutyric acid (GABA), adenosine triphosphate (ATP), neuropeptides, vasoactive intestinal peptide (VIP), and luteinizing hormone–releasing hormone (LHRH). This group is called nonadrenergic-noncholinergic (NANC) transmitters. Their most likely role is a regulatory effect on postsynaptic or presynaptic receptors.

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Instructor’s Resource Material for

23 General Senses ANSWER KEYS

Answers to Quick Check Questions 1. Mechanoreceptors, chemoreceptors, thermoreceptors, nociceptors, photoreceptors, and osmoreceptors are classifications of receptors based on the type of activating stimuli.

2. The general (somatic) sense organs consist of microscopic receptors widely distributed throughout the body in the skin, mucosa, connective tissues, muscle tendons, joints, and viscera. The special senses are characterized by receptors grouped closely together or located in specialized organs.

3. Exteroceptors, visceroceptors (or interoceptors), and proprioceptors are three types of sense receptors classified according to location in the body.

4. Pain receptors: Nociceptors. Touch receptors: Merkel disks, Meissner corpuscle, Ruffini corpuscle, and Krause corpuscle. Pressure receptors: Pacinian corpuscle and Meissner corpuscle. Stretch receptors: Muscle spindles and Golgi tendon receptors.

Answers to Case Study Questions (p. 529) 1. c: Nociceptors are activated by intense stimuli (herniated disk causing pressure on Don’s spinal nerve). The sensation produced is one of pain.

2. c: Slow (B) pain fibers (chronic) carry impulses that result in dull or aching pain.

3. c: Visceral pain develops over time and travels over B fibers. This pain is often described as dull or aching. It originates in deeper body (visceral) structures and can cause severe conditions. Somatic pain travels over A fibers and is described as sharp, “take your breath away” type of pain.

4. a: When Don injured his disk, the compressed disk caused pressure on his sciatic nerve resulting in the sciatic irritation. The sciatic nerve travels down the leg toward the foot, thus causing radiating pain in that area.

Answers to Review Questions (p. 531) 1. General senses detect changes (such as, touch, temperature, and pain) throughout the body using many simple sensory receptors. Special senses detect complex stimuli (such as, vision, hearing, and equilibrium) using sensory receptors located in a complex sensory organ (such as, the eye or ear).

2. A receptor potential is a fluctuation in membrane voltage (local potential) of a sensory neuron that varies with the strength of the stimulus.

3. Adaptation occurs when the magnitude of the receptor potential decreases over time in response to a continuous stimulus.

4. Exteroceptors are located superficially in the skin, whereas visceroceptors are located deep in the body within internal organs. Proprioceptors are found in skeletal muscles.

5. Mechanoreceptors are activated by mechanical stimuli that in some way deform or change the position of the receptor, resulting in the generation of a receptor potential.

Chemoreceptors are activated by either the amount or the changing concentration of certain chemicals.

Thermoreceptors are activated by changes in temperature.

Nociceptors are activated by intense stimuli of any type that results in tissue damage. The sensation produced is one of pain.

Photoreceptors, found in the eye, respond to light stimuli if the intensity is great enough to generate a receptor potential.

6. Pain stimulation in deep structures is frequently referred to surface areas. This is called referred pain. Pain originating in the viscera or other deep structures is generally interpreted as coming from the skin area whose sensory fibers enter the same segment of the spinal cord as the sensory fibers of the deep structure.

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Chapter 23 | General Senses ________________________________________________________________

7. The different types of touch are: skin movement (detects movement in or on the skin), itch (feeling the need to scratch), tickle (odd feeling usually caused by touching from outside the body), light touch (ability to precisely discriminate slight deformations of the skin), and deep touch (detects stronger touch stimuli, including vibrations).

8. Proprioception is the sense of position and movement of the skeleton by detecting varying tension in skeletal muscles.

Answers to Critical Thinking Questions (p. 531) 1. An above-threshold receptor potential occurs in the sense organ in the peripheral nervous system. The sensation of that stimulus occurs somewhere in the central nervous system.

2. Pain alerts us to disease and injury, and it also plays an important role pain in alerting us to threats in our environment.

3. Humans have different types of sensory receptors, each capable of detecting a different range of temperatures.

Some are most sensitive to changes in a colder range of temperature than others, which are more sensitive than those that detect changes only in a warmer range of temperatures. So one could say that we have a “sense of heat” that relies on different receptors that our “sense of cold.”

4. Light touch involves simple “free” nerve endings that are sensitive to very slight surface changes. On the other hand, the various forms of deep touch involve slightly more complex receptor structures that can detect a variety of stronger stimuli, such as pressure and vibration.

5. Although both types of receptor can detect changes in tension in a muscle organ (proprioception), the spindles are in the belly of the muscle and detect changes in the stretch of muscle, giving information about the normal range of changes in length and strength of muscle contraction. They trigger stretch reflexes that shorten a muscle back toward set point length if the muscle is stretched beyond its set point—thus maintaining posture.

Tendon organ, on the other hand are located at the tendon-muscle interface and are only triggered when the load on a muscle is extreme enough to start stretching the tendon, which is not very stretchy (elastic). The response triggered is sudden relaxation of the muscle—the opposite of the contraction triggered by stimulation of the spindles—in order to avoid tearing or other injury of the muscle organ.

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Instructor’s Resource Material for

24 Special Senses ANSWER KEYS

Answers to Quick Check Questions 1. The special senses are olfaction, taste, hearing, equilibrium, and vision.

2. If the level of the odor-producing chemicals dissolved in the mucus surrounding the olfactory cilia reaches a threshold, a receptor potential and then an action potential will be generated and passed to the olfactory nerves in the olfactory bulb.

3. Generation of a receptor potential begins when specialized areas called G-protein receptor sites on the cell membranes or pore-like ion channels in the covering gustatory hairs bind to taste-producing chemicals in the saliva. The nature and concentration of the chemicals that bind to either the G-protein receptor sites or ion channels determine how fast the receptor potential is generated.

4. (1) An action potential generated from the receptor potential travels to the olfactory nerves in the olfactory bulb. From there, the impulse passes through the olfactory tract and into the thalamic and olfactory centers of the brain for interpretation, integration, and memory storage. (2) The taste sensation begins with creation of a receptor potential in the gustatory cells of a taste bud. The generation and propagation of an action potential then transmit the sensory input to the brain.

5. Sour, sweet, bitter, umami (savory), and salty are the primary taste sensations.

6. No tongue or taste “map” accurately indicates areas of particular sensitivity to different tastes. All tastes can be detected in all areas of the tongue that contain taste buds.

7. The external ear, middle ear, and inner ear are the anatomical divisions of the ear.

8. The auditory ossicles are the malleus, incus, and stapes.

9. Membranous labyrinths: Utricle, saccule, cochlear duct, and membranous semicircular canals. Bony labyrinths: Vestibule, cochlea, and semicircular canals.

10. The ear is the sense organ responsible for hearing.

11. The sclera, choroids, and retina are the layers of the eyeball.

12. The photoreceptor neurons, bipolar neurons, and ganglion neurons are the layers of the retina.

13. The four processes that function to focus a clear image on the retina are (1) refraction of the light rays, (2) accommodation of the lens, (3) constriction of the pupil, and (4) convergence of the eyes.

14. Retinal is attached to opsin. Light causes retinal and opsin to change shape, causing change in rod cell membrane potential. Retinal separates from opsin (bleaching). Energy is required to bring opsin back to its original shape and to attach retinal to it.

Answers to Case Study Questions (p. 557) 1. b: As we age, the lens in our eye becomes less elastic and unable to constrict or thicken enough to bend light rays reflected off of objects close to us at an angle that will focus them onto the retina. This loss of flexibility is called presbyopia.

2. b The hair cells in the inner ear are bent by the moving fluid in the cochlea. The hair cells respond to this movement by sending an impulse to the brain; thus they are classified as mechanoreceptors (mechano = moving).

3. d: Your sense of smell (and taste too) is actually a sense of chemistry. The olfactory receptors in the nose respond to dissolved odorants (chemicals), which trigger a message to the brain.

4. c: A clouding of the lens is called a cataract. If the clouding is enough to limit vision, the lens may be removed and replaced by an artificial lens.

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Chapter 24 | Special Senses ________________________________________________________________

Answers to Review Questions (p. 561) 1. When the odor-producing chemical dissolved in the mucus of the olfactory cilia reaches threshold level, an action potential will be generated and passed to the nerves of the olfactory bulb. From here the impulses are passed through the olfactory tract, into the thalamus, and finally to the olfactory centers of the brain.

2. The G-protein–mediated receptor sites are located on cell membranes. Generation of a receptor potential begins when these sites bind to a taste-producing chemical (tastant) in the saliva. The nature and concentration of the chemicals that bind to these sites determine how fast the receptor potential is generated.

3. The middle ear is a tiny epithelium-lined cavity hollowed out of the temporal bone. It contains the auditory ossicles: the malleus, the incus, and the stapes. There is an opening from the external auditory meatus covered by the tympanic membrane, two openings to the internal ear (the oval window and the round window), and one opening into the eustachian tube. Posteriorly, the middle ear cavity is continuous with numerous air spaces in the temporal bone.

4. The bony labyrinth consists of three parts: the vestibule, the cochlea, and the semicircular canals. The membranous labyrinth consists of the utricle, the saccule, the cochlear duct, and the membranous semicircular canals. The membranous labyrinth structures are contained inside the bony labyrinth structures—the utricle and saccule inside the vestibule, the cochlear duct inside the cochlea, and the membranous semicircular canals inside the bony semicircular canals.

5. The hearing sense organ is located in the cochlear duct, which is inside the cochlea. The equilibrium sense organs are in the vestibule, semicircular canals, utricle, and saccule.

6. The hearing sense organ is the organ of Corti. The macula is the sense organ for static equilibrium, and the crista ampullaris is the sense organ for dynamic equilibrium.

7. Sound waves enter the external auditory canal with aid from the pinna. At the inner end of the canal, they strike the tympanic membrane, causing it to vibrate. These vibrations move the malleus, which moves the incus, which in turn moves the stapes against the oval window. When the stapes moves against the oval window, pressure is exerted on the perilymph in the scala vestibuli of the cochlea. This starts a ripple in the perilymph that is transmitted to the vestibular membrane, to the endolymph inside the duct, to the organ of Corti, and to the basilar membrane. From the basilar membrane, the ripple is transmitted to and through the perilymph in the scala tympani and finally expends itself against the round window.

8. Vertigo involves a sensation of one’s own body spinning in space or of the external world spinning around the individual. A new 5- to 10-minute treatment called the canalith repositioning procedure has been developed to move floating particles (canaliths) from the semicircular canal into the utricle. They then become attached to the membranous walls and are no longer able to move about.

9. The basilar (spiral) membrane vibration stimulates the hair cells of the organ of Corti, which is perceived as sound. The location that vibrates in the basilar membrane transmits the pitch, and the amplitude or amount of movement in the basilar membrane determines the loudness of the sound.

10. Static equilibrium is the sense of the position of the head relative to gravity and to the sense of acceleration or deceleration of the body. Dynamic equilibrium is needed to maintain balance when the body or head is rotated or moved suddenly. Static equilibrium is maintained by a structure called the macula, which is found in the utricle and saccule. The macula is covered by a gelatinous matrix containing otoliths, or “ear stones.”

Changing the position of the head produces a change in the amount of pressure on the otolith-weighted matrix, which stimulates the macula, which in turn stimulates the vestibular nerve. Dynamic equilibrium is maintained by the crista ampullaris in the semicircular canals. Each cone-shaped crista is composed of many hair cells embedded in a gelatinous cup called the cupula. As the cupula moves, it bends the hair cells embedded in it, producing an action potential that passes through the vestibular portion of the eighth cranial nerve.

11. The two involuntary muscles in the eye are the iris and the ciliary muscles. The iris regulates the size of the pupil, and the ciliary muscles control the shape of the lens.

12. Refraction means the deflection or bending of light rays. The refracting media of the eye are the cornea, aqueous humor, lens, and vitreous humor.

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13. The mechanism for accommodation for near vision necessitates three changes: increased curvature of the lens, contraction of the pupil, and convergence of the two eyes.

14. The photopigment in rods is rhodopsin, which is highly light sensitive. It allows us to see in dim light. The cones contain a photopigment different from the rhodopsin found in rod cells. Cones function to produce vision in bright light.

15. Retinal, which is a part of the visual pigment rhodopsin, is a vitamin A derivative. Rhodopsin is necessary to see in dim light. A vitamin A deficiency would cause a rhodopsin deficiency, which would make it difficult to see in dim light (night blindness).

Answers to Critical Thinking Questions (p. 561) 1. Taste information travels from taste buds in the mouth via CN VII and IX, through the thalamus, to the taste sensory cortex in the parietal lobe. Smell information is transmitted from receptors in the olfactory epithelium via CN I, through the thalamus, to the primary olfactory area of the temporal lobe. Olfaction has a powerful effect on memory, so it is likely that the smell of pie will trigger memories more easily than the taste of pie.

2. Muscles inside the ear reflexively contract when sounds are dangerously loud to reduce vibration of the auditory ossicles and tympanum and thus avoid overstimulation of the inner ear. Within the organ of Corti of the inner ear, the outer row of hair cells can respond to dangerously loud sounds by reducing their amplifying effect.

3. The three coats of the eye are (1) the sclera, which is the outer coat; (2) the choroid, which is the middle coat; and (3) the retina, which is the inner coat. The sclera is tough and protective and contains the cornea, which allows light to enter the eye. The cornea also begins the process of focusing the light on the retina. The choroid supplies blood vessels to the eye and contains the ciliary body, which causes the lens to change shape and focus light on the retina. It also contains the iris, which regulates the size of the pupil, which determines how much light enters the eye. The retina contains the receptors for light and converts light stimuli into an action potential.

4. The receptors for vision in dim light are the rods. They contain the photopigment rhodopsin. When even very dim light hits rhodopsin, it decomposes into opsin and retinal. When this happens, active sites are exposed and an action potential is created in the rod. Objects are seen in shades of gray—not in color. Cones are the receptors for vision in bright light. There are three types of cones, each containing a different photopigment: blue sensitive cones are sensitive in the blue range and are often called S cones (short wavelengths); green sensitive cones are often called M cones (medium wavelengths); and red sensitive cones are called L cones (long wavelengths). The breakdown of these pigments requires more energy than the breakdown of rhodopsin, so a brighter light is needed to stimulate cones. The axons of many rods converge on one neuron.

This allows the neuron to respond to very dim light, but the brain is unable to determine exactly which rod was stimulated. There is almost a one-to-one relationship between cones and the next neuron, so the brain is able to make a much sharper image when cones are stimulated.

5. The ability of sense organs to respond to stimuli will vary during one’s life. Age, disease, structural defects, or lack of structural maturation all affect our ability to identify and respond to sensory input. Regarding age, often structure and function response capabilities are related to developmental factors. Newborn children have limited sight, hearing, and tactile identification capabilities. As we mature, our senses become more acute.

However, by late adulthood, presbyopia, progressive hearing loss, and reduced sense of taste and smell are common.

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Instructor’s Resource Material for

25 Endocrine Regulation ANSWER KEYS Answers to Quick Check Questions 1. Cells with appropriate receptors that are influenced by a signaling chemical are target cells.

2. In the nervous system, neurotransmitters are sent over very short distances across a synapse, whereas hormones diffuse into the blood to be carried to nearly every point in the body. The nervous system can directly control only muscles and glands that are innervated with efferent fibers, whereas the endocrine system can regulate most cells in the body. The effects of neurotransmitters are rapid and short lived compared with the effects of hormones, which appear more slowly and last longer.

3. Steroids are lipid soluble; thus, they can easily pass through the phospholipid plasma membrane of target cells.

4. Protein hormones: Insulin, parathyroid hormones, growth hormone, prolactin, calcitonin, adrenocorticotropic hormone, and glucagon. Peptide hormones: Oxytocin, antidiuretic hormone, melanocyte-stimulating hormone (MSH), somatostatin, thyrotropin-releasing hormone, gonadotropin-releasing hormone (GnRH), and atrial natriuretic hormone (ANH). Glycoproteins: Follicle-stimulating hormone (FSH), luteinizing hormone (LH), thyroid-stimulating hormone (TSH), and human chorionic gonadotropin (hCG). Amino acid derivative hormones: Amine hormones (melatonin, epinephrine, and norepinephrine) and iodinated amino acid hormones (thyroxine and triiodothyronine).

5. Hormones can work together to regulate a tissue by synergism, permissiveness, and antagonism.

6. Steroid hormone receptors are not attached to the plasma membrane but seem to move freely in the nucleoplasm.

7. A nonsteroid hormone molecule acts as a “first messenger,” delivering its chemical message to fixed receptors in the target cell’s plasma membrane. The “message” is then passed into the cell, where a “second messenger” triggers the appropriate cellular changes.

8. Negative feedback and positive feedback loops can control endocrine cells. The simplest mechanism operates when an endocrine cell is sensitive to the physiological changes produced by its target cells. Another mechanism that may influence the secretion of hormones by a gland is input from the nervous system.

9. The term tissue hormone is appropriate because the secretion is produced in a tissue and diffuses only a short distance to other cells within the same tissue.

10. Prostaglandins are likely to play increasingly important roles in the treatment of such diverse conditions as hypertension, coronary thrombosis, asthma, and ulcers, because they are found in almost every body tissue and are capable of regulating hormone activity on the cellular level.

Answers to Review Questions (p. 578) 1. A hormone is a regulating substance secreted by an endocrine gland. A target cell is any cell with one or more receptors for a particular hormone.

2. All steroid hormones have a cholesterol molecule at their core. The molecule consists of three six-sided rings and one five-sided ring joined together.

3. The major categories of nonsteroid hormones are protein hormones, glycoprotein hormones, peptide hormones, and amino acid derivative hormones.

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Chapter 25 | Endocrine Regulation ___________________________________________________________

4. The following is the second messenger mechanism, which is most completely explained in the textbook. The hormone joins a receptor on the cell membrane. This hormone-receptor complex causes a membrane protein called the G protein to bind to a nucleotide called guanosine triphosphate. This activates a second membrane protein called adenyl cyclase. This is an enzyme that promotes the removal of two phosphate groups from an adenosine triphosphate (ATP) molecule in the cytosol. The product of this is cyclic adenosine monophosphate (cAMP), which acts as a second messenger within the cell. The cAMP activates protein kinases, which are a set of enzymes that activate other types of enzymes. It is this final set of specific, activated enzymes that catalyzes the reaction that is characteristic of the cell’s response to the hormone.

5. Calmodulin is an intercellular molecule that can bind to calcium ions. The calcium-calmodulin complex that forms can act as a second messenger, producing the target cell’s response.

6. There are nine structural classes of prostaglandins, classified as A through I. The textbook discusses the following three classes: • Prostaglandins A result in an immediate fall in blood pressure accompanied by an increase in regional blood flow to several areas, including the coronary and renal systems. These effects are apparently caused by the relaxation of smooth muscle fibers in the walls of certain arteries.

• Prostaglandins E (PGEs) have an important role in various vascular, metabolic, and gastrointestinal functions. Vascular effects include regulation of red blood cell deformability and platelet aggregation.

PGEs also have a role in systemic inflammations such as fever. PGEs also regulate hydrochloric acid secretions in the stomach, helping to prevent gastric ulcers.

• Prostaglandins F (PGFs) play an important role in the reproductive system. They cause uterine muscle contraction. PGFs also affect intestinal motility and are required for normal peristalsis.

Answers to Critical Thinking Questions (p. 578) 1. Driving a car would be a nervous system function because the nervous system directly controls muscles. The effects of the nervous system are rapid and short lived. Blood glucose regulation would be an endocrine function because hormones diffuse into the blood and are carried to almost every cell in the body. Hormones take longer to produce an effect; however, their effect lasts longer.

2. Hormones have three ways in which they can interact: (1) synergism, in which a combination of hormones have a greater effect on the target cell than the sum of the effects each would have if acting alone; (2) permissiveness, in which a small amount of one hormone allows a second hormone to have its full effect on a target cell; and (3) antagonism, in which one hormone produces the opposite effect of another hormone.

3. Steroid hormones are able to enter the cell. The hormone receptor is in the nucleus. When the hormone joins the receptor, it causes certain genes to begin transcription of messenger RNA (mRNA). The mRNA moves into the cytosol to associate with a ribosome and begins protein synthesis of the enzymes, which will change cell function. Because of the time needed for protein synthesis, cell responses to steroid hormones may not be seen for days. Nonsteroid hormones are unable to enter the cell. The hormone receptor is on the cell membrane. When the hormone and receptor join, it activates a membrane protein called a G protein. This activates a second membrane protein called adenyl cyclase, which is an enzyme that converts ATP into cAMP. The cAMP activates protein kinases, which activate other enzymes, which in turn cause the cell to respond to the hormone. Because the enzymes are already produced in the cell, the response to nonsteroid hormones occurs much more rapidly than the response to a steroid hormone.

4. Thyroxine and triiodothyronine are nonsteroid hormones that are able to enter the cell and have a direct effect on the interior of the cell. This mechanism is that of a steroid hormone in that the receptors are in the nucleus and they stimulate protein synthesis.

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5. The simplest negative feedback loop mechanism occurs when the endocrine cells are sensitive to physiological changes directly. For example, parathyroid hormone (PTH) produces responses in the target cells that increase calcium ion concentration in the blood. When the concentration exceeds the set point, the parathyroid cells sense it and reduce the output of PTH. The second type of negative feedback uses the change in a hormone rather than a physiological change. For example, the pituitary gland produces thyroidstimulating hormone (TSH), which stimulates the thyroid gland to release its hormones. The pituitary gland responds to changes in the controlled physiological variable, as well as to a change in the hormone concentration.

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Instructor’s Resource Material for

26 Endocrine Glands ANSWER KEYS Answers to Quick Check Questions

1. Adenohypophysis and neurohypophysis are the main divisions of the pituitary. The adenohypophysis is anterior, develops from any upward projection of the pharynx, and is composed of regular endocrine tissue.

The neurohypophysis is posterior, develops from a downward projection of the brain, and is composed of neurosecretory tissue.

2. Students are asked to name three hormones produced by adenohypophysis; all of the possible answers are given here. Somatotrophs secrete growth hormone. Corticotrophs secrete adrenocorticotropic hormone (ACTH). Thyrotrophs secrete thyroid-stimulating hormone (TSH). Lactotrophs secrete prolactin.

Gonadotrophs secrete luteinizing hormone (LH) and follicle-stimulating hormone (FSH).

3. Tropic hormones are hormones that have a stimulating effect on other glands. Releasing hormones are chemicals synthesized by parts of the hypothalamus that influence the secretion of hormones, which regulates the secretion of the adenohypophysis.

4. Neurons whose bodies are in either the supraoptic or the paraventricular nuclei of the hypothalamus synthesize the hormones of the neurohypophysis. These hormones are released from the adenohypophysis.

5. Antidiuretic hormone (ADH) and oxytocin are the hormones of the neurohypophysis.

6. Visual signals received by the pineal gland allow it to determine day length and lunar cycles and thereby adjust the body’s biological clock.

7. The thyroid is located in the neck, on the anterior and lateral surfaces of the trachea, just below the larynx.

The thyroid is butterfly shaped.

8. Thyroid hormone is a combination of tetraiodothyronine and triiodothyronine. Triiodothyronine is more physiologically active.

9. Calcitonin apparently controls calcium content of the blood by increasing bone formation by osteoblasts and inhibiting bone breakdown by osteoclasts. Calcitonin tends to decrease blood calcium levels and promote conservation of hard bone matrix. Parathyroid hormone (PTH) is an antagonist to calcitonin because it has the opposite effects.

10. The adrenal cortex is composed of regular endocrine tissue, but the adrenal medulla is made up of neurosecretory tissue.

11. Answers may include any of the following: Glucocorticoids (cortisol) accelerate the breakdown of proteins into amino acids, tend to accelerate mobilization of both lipids from adipose cells and lipid catabolism by nearly every cell in the body, and are essential for maintaining normal blood pressure. A high blood concentration of glucocorticoids causes a marked decrease in the number of white blood cells. Normal amounts of glucocorticoids act with epinephrine to bring about normal recovery from injury produced by inflammatory agents. Glucocorticoid secretion increases as part of the stress response, and except during the stress response, glucocorticoid secretion is controlled mainly by means of a negative feedback mechanism.

12. Medullary cells are modified versions of sympathetic postganglionic fibers of the autonomic nervous system.

They are innervated by sympathetic preganglionic fibers so that when the sympathetic nervous system is activated, the medullary cells secrete their hormones directly into the blood.

13. Glucagon, insulin, somatostatin, and pancreatic polypeptide are the principal hormones secreted by the pancreatic islets.

14. Glucagon tends to increase blood glucose levels by stimulating the conversion of glycogen to glucose in liver cells. Insulin tends to promote the movement of glucose out of the blood and into tissue cells.

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Chapter 26 | Endocrine Glands ______________________________________________________________

15. Testosterone, estrogen, progesterone, and human chorionic gonadotropin (hCG) are the major hormones secreted by reproductive tissues.

16. The thymus produces a hormone that regulates the development of cells important to the immune system.

17. The mucous lining of the gastrointestinal tract, similar to that of the pancreas, produces secretin.

18. Adipose tissue produces the hormone leptin.

Answers to Case Study Questions (p. 604) 1. a: Diabetes mellitus is the only condition listed that may have an effect on urination. Insufficient insulin (or lack of response to insulin) does not allow glucose to enter the body’s cells, resulting in an increased glucose concentration in the blood. In the kidneys, the excess glucose passes into the urine—“pulling” water with it.

With this increase in water leaving the body (polyuria), increased thirst (polydipsia) follows.

2. b: Insulin changes could cause the slowed healing, but you would have weight loss instead of weight gain.

Low levels of thyroid hormone may cause weight gain, but it would be more generalized, and there would be no effect on blood pressure. Testosterone could have an impact on blood pressure, but it would have no effect on healing. Only cortisol matches all the symptoms. Increasing cortisol levels inhibit the body’s use of glucose in muscle, so you get a wasting of muscle and weight gain in other parts of the body. Cortisol also works with epinephrine—increasing cortisol makes epinephrine work more, which increases blood pressure.

3. d: Increased cortisol levels would be an indication of Cushing syndrome. Addison disease is related to the adrenal cortex, but involves hypersecretion of aldosterone, not cortisol. Hashimoto disease and Graves disease both refer to thyroid conditions.

4. c: The body controls many hormone levels through a negative feedback system (similar to the thermostat in your house). Too much cortisol results in feedback to the hypothalamus, which decreases the amount of corticotropin-releasing hormone (CRH) produced. If the anterior pituitary is working properly, it should respond to this decreased CRH by reducing the amount of adrenocorticotropic hormone (ACTH) produced.

With a tumor, the anterior pituitary does not respond properly and so continues to produce excess ACTH, resulting in higher cortisol levels.

Answers to Review Questions (p. 608) 1. The two subdivisions of the adenohypophysis are the pars anterior and the pars intermedia.

2. There are three types of cells in the anterior pituitary gland that are identified by their staining tendency: (1) chromophobes, which literally means “afraid of color”; (2) acidophils, which have an attraction to acid stains; and (3) basophils, which have an attraction to basic stains (no percentages are given in the textbook).

3. Growth hormone (GH) promotes bodily growth indirectly by stimulating the liver to produce certain growth factors that accelerate amino acid transport into the cell. This allows protein anabolism at an increased rate, which allows an increased rate of growth. GH promotes growth in bone, muscle, and other tissue. GH also stimulates fat metabolism, accelerates mobilization of lipids from storage, and speeds up catabolism of those lipids. It also causes blood glucose levels to rise.

4. GH increases blood glucose levels, promotes fat mobilization and catabolism, and promotes protein anabolism.

5. The four tropic hormones secreted by the basophils of the anterior pituitary gland are (1) thyroid-stimulating hormone (TSH), (2) adrenocorticotropic hormone (ACTH), (3) follicle-stimulating hormone (FSH), and (4) luteinizing hormone (LH). FSH and LH are also called gonadotropins.

6. Antidiuretic hormone (ADH) acts to reduce the volume of urine. It does this by causing water to be reabsorbed from the tubules of the kidney and returned to the blood. This increases the water content of the blood and reduces the volume of urine.

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7. Oxytocin has two positive feedback mechanisms associated with it. The first is the release of milk. The mechanical and psychological stimulation of the baby’s suckling triggers the release of oxytocin. This provides more milk, which allows the baby to continue to suckle, which in turn stimulates the release of more oxytocin. The other feedback mechanism is the stimulation of uterine contractions. Once uterine contractions begin, they push down on receptors in the pelvis, which triggers the release of more oxytocin, which causes more uterine contractions.

8. Thyroxine and triiodothyronine synthesis occurs in tiny structural units called follicles. The colloid produced by the cuboidal cells of the follicle wall contains the protein-iodine complexes known as thyroglobulins, the precursors of thyroid hormones. The thyroid hormones are stored as thyroglobulins in the follicles until they are released into the blood. They are transported in the blood attached to plasma proteins, principally a globulin called thyroxine-binding globulin and albumin. They circulate in the blood as a hormone-globulin complex.

9. Parathyroid hormone (PTH) helps maintain calcium homeostasis. It acts on bone, kidney, and intestinal cells to increase the release of calcium into the blood.

10. There are three zones in the adrenal cortex, which are involved in hormone production: • The zona glomerulosa produces aldosterone, which stimulates the kidney tubules to conserve sodium, which triggers the release of ADH, which in turn results in the conservation of water.

• The zona fasciculata produces cortisol, which influences the metabolism of food molecules and has an antiinflammatory effect in large amounts.

• The zona reticularis produces androgens and estrogens, which may have a role in supporting sexual function.

11. The adrenal medulla secretes two important hormones, epinephrine and norepinephrine. Both of these hormones can bind to the receptors of sympathetic effectors to prolong and enhance the effects of the sympathetic nervous system.

12. Alpha cells in the pancreatic islets produce glucagon, beta cells produce insulin, delta cells produce somatostatin, and pancreatic polypeptide cells produce pancreatic polypeptide.

13. The “pregnancy-promoting” hormone is progesterone.

14. Human chorionic gonadotropin (hCG) is produced by the placenta. It serves as a signal to the mother’s gonads to maintain the uterine lining rather than allow it to degenerate and fall away in menstruation.

15. Atrial natriuretic hormone (ANH) is secreted by cells in the atrium in response to increased stretch due to abnormally high blood volume or blood pressure. The principal effect of this hormone is to promote the loss of sodium in the urine. The increased concentration of sodium in the urine draws water from the body into the urine, which acts to decrease blood volume.

16. The condition resulting from hypersecretion of GH during the growth years is gigantism. The condition resulting from hyposecretion of GH during the growth years is pituitary dwarfism.

17. Cushing syndrome causes a fatty “moon face” with thin, reddened skin.

18. Exercise along with other lifestyle changes can control type 2 maturity-onset diabetes mellitus, often without the need for insulin.

Answers to Critical Thinking Questions (p. 608) 1. The simplest negative feedback loop mechanism occurs when the endocrine cells are sensitive to physiological changes directly. For example, parathyroid hormone (PTH) produces responses in the target cells that increase calcium ion concentration in the blood. When the concentration exceeds the set point, the parathyroid cells sense it and reduce the output of PTH. The second type of negative feedback uses the change in a hormone rather than a physiological change. For example, the pituitary gland produces thyroidstimulating hormone (TSH), which stimulates the thyroid gland to release its hormones. The pituitary gland responds to changes in the controlled physiological variable, as well as to a change in the hormone concentration.

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Chapter 26 | Endocrine Glands ______________________________________________________________

2. This question has two acceptable answers: (1) Prolactin generates or initiates milk secretion; milk production cannot be initiated or maintained without prolactin; or (2) oxytocin causes the milk-producing cells to release milk into the breast. This is important because milk cannot be removed by suckling unless it has first moved into the ducts.

3. The hypothalamus has an important function in the body’s response to stressful situations. Under stress the cerebral cortex—especially the limbic system—sends impulses to the hypothalamus, thus stimulating the hypothalamus to secrete releasing hormone. This stimulates the release of hormones from the pituitary gland, which in turn stimulates a response in the pituitary hormone target cells. This is the “mind-body link” between the nervous system and endocrine system, which shows how thoughts and emotions can influence the hypothalamus—which, in turn, can influence almost every cell in the body.

4. The interaction of glucagon and insulin functions to maintain the set point value for blood glucose. If the level drops below set point, glucagon secretions increase and insulin secretions decrease. This causes less glucose to be taken up by cells and more glucose to be released from the liver. If the glucose level drops below set point, insulin secretions increase and glucagon secretions decrease. This causes a decrease in glucose released from the liver and an increase in the uptake of glucose by the cells.

5. A cell can become more or less sensitive to a specific hormone by increasing or decreasing the number of hormone receptors it has for that hormone. It can become more sensitive by increasing the number of receptors—a process called up-regulation. It can become less sensitive by decreasing the number of receptors—a process called down-regulation.

6. After menopause, the ovaries no longer produce estrogen. The pituitary gland responds to the drop in estrogen by the release of follicle-stimulating hormone (FSH) in an attempt to raise the level of estrogen. The levels of estrogen do not increase, because the ovaries no longer produce it; therefore more FSH is released. Women have high levels of FSH after menopause.

7. Iodine is required to produce the thyroid hormones. When the diet lacks iodine, the blood levels of the thyroid hormones drop. The hypothalamus stimulates the pituitary to release TSH. Because there is no iodine, the only response to the TSH is an increase in the size of the thyroid gland. Because this does not increase the thyroid hormone level, more TSH is released and the thyroid gland continues to enlarge.

8. Tell your friend that prolonged use of steroids may lead to atrophy of the testes and possibly to permanent sterility. Behavioral changes may also occur.

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Instructor’s Resource Material for

27 Blood ANSWER KEYS

Answers to Quick Check Questions 1. Plasma is the fluid portion of whole blood.

2. Red blood cells (RBCs), white blood cells (WBCs), and platelets are the formed elements of blood.

3. Blood volume is influenced by a person’s gender, age, body composition, and by the method of measurement.

4. Component percentages of normal hematocrit are plasma, 55%, and packed cell volume (hematocrit), 45%.

5. The red pigment found in RBCs is hemoglobin. The normal range in men is 5,500,000/mm 3, and it is 4,800,000/mm3 in women.

6. Erythrocytes begin their maturation sequence in the red bone marrow from nucleated cells known as hematopoietic stem cells. In RBCs, differentiation begins with the appearance of proerythroblasts. Mitotic divisions then produce basophilic erythroblasts. The next maturation division produces polychromatic erythroblasts, which produce hemoglobin. These cells subsequently lose their nuclei and become reticulocytes. After being released in the circulating blood, reticulocytes become mature erythrocytes in about 24 to 36 hours.

7. The rate of RBC production soon speeds up if blood oxygen levels reaching the tissues decrease. Oxygen deficiency increases RBC numbers by increasing the secretion of a glycoprotein hormone called erythropoietin. If oxygen levels decrease, the kidneys release increasing amounts of erythropoietin, which in turn stimulates bone marrow to accelerate its production of RBCs. With increasing numbers of RBCs, oxygen delivery to tissue increases and less erythropoietin is produced and is available to stimulate RBC production in the red bone marrow.

8. As RBCs age and fragment, the macrophages in the liver and spleen ingest and destroy the old cells. The process results in the breakdown of hemoglobin with the release of amino acids, iron, and the pigment bilirubin. Iron is returned to the bone marrow, bilirubin is transported to the liver, and amino acids are released from the globin and used by the body for energy or for synthesis of new proteins.

9. Granulocytic leukocytes: Neutrophils, eosinophils, and basophils. Agranulocytic leukocytes: Lymphocytes and monocytes.

10. The normal percentages of the different WBCs in a differential count are: neutrophils, 65% to 75%; eosinophils, 2% to 5%; basophils, 0.5% to 1%; lymphocytes, 20% to 25%; and monocytes, 3% to 8%. Refer to Table 27-3 in the textbook.

11. Type A: A antigen, anti-B antibody. Type B: B antigen, anti-A antibody. Type AB: A and B antigens, no antibodies. Type O: No antigens, anti-A and anti-B antibodies.

12. Extrinsic pathway and intrinsic pathway are the basic coagulation steps.

Answers to Case Study Questions (p. 633) 1. c: Plasma is the liquid portion of blood. By itself, plasma is a clear, straw-colored liquid. This liquid constitutes about 55% of blood.

2. b: As soon as tissue damage occurs, the platelets in the bloodstream become sticky. They stick both to the torn vessel lining and to themselves, quickly forming a plug to limit the blood loss.

3. a: The clotting cascade is a series of chemical reactions that require different chemicals (factors) at specific points in the process. The final step in the process is the conversion of soluble fibrinogen to insoluble fibrin, which acts as a meshwork for trapping blood cells and seals off the gap to allow healing to begin.

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Chapter 27 | Blood ________________________________________________________________________

4. d: Hemophilia A is a condition in which factor VIII is missing from the body. Without this factor, the coagulation process cannot be completed. Thrombocytopenia is a decrease in platelet count. This also affects the body’s ability to form a clot at the first step of the process (forming the platelet plug).

Answers to Review Questions (p. 636) 1. The formed elements of blood are red blood cells (RBCs), white blood cells (WBCs), and platelets.

2. Carbonic anhydrase is the enzyme that catalyzes the joining of carbon dioxide and water to form carbonic acid.

3. Each hemoglobin molecule is composed of four protein chains called globins. Each globin is joined to a molecule of heme, and each heme molecule contains one atom of iron.

4. Oxygen is able to combine with the heme portion of hemoglobin. Therefore one molecule of hemoglobin can combine with four molecules of oxygen.

5. Erythropoiesis begins with the differentiation of stem cells into proerythroblasts, which divide to form basophilic erythroblasts. These become polychromic erythroblasts, which form hemoglobin. These cells then lose their nuclei and become reticulocytes. Reticulocytes are released into the blood and mature into erythrocytes in about 24 to 36 hours.

6. The average life span of a RBC in the bloodstream is about 105 to 120 days.

7. Granulocytes contain granules in their cytoplasm, whereas agranulocytes do not. All WBCs have nuclei and are usually larger than RBCs. 8. Bacterial infections, which produce inflammation, cause damaged cells to release a chemical that attracts neutrophils and other phagocytes. This process, positive chemotaxis, helps the body concentrate phagocytes at the point of infection.

9. Platelets have three important physical properties: agglutination, adhesiveness, and aggregation.

10. Type AB blood has both A and B antigens on the RBCs and neither A nor B antibodies in the plasma. Rhnegative blood has no Rh antigens on the RBCs. 11. The liver is responsible for the synthesis of most plasma proteins.

12. In 100 ml of plasma, there are 6 to 8 grams of plasma protein. Of this, 55% is albumin, 38% is globulins, and 7% is fibrinogen.

13. Fibrinogen is important in blood clot formation. Globulins are important in immunity. All plasma proteins contribute to normal blood viscosity, blood osmotic pressure, and blood volume.

14. In hemostasis, a few seconds after injury to a capillary, platelets adhere to the damaged lining and to one another, forming a platelet plug that helps stop the flow of blood to the tissue. In blood clot formation, platelets participate in the intrinsic pathway by releasing platelet factor VIII. This substance activates factor X, which then produces prothrombinase, a prothrombin activator.

15. There are two triggers to blood clotting. In the extrinsic clotting pathway, chemicals released from damaged tissue outside the blood system trigger blood clotting. In the intrinsic clotting pathway, damage to the endothelial lining of the blood vessels, which exposes collagen fibers, triggers blood clotting.

16. Factors that oppose blood clotting include the perfectly smooth surface of normal endothelial lining of the blood vessels; antithrombins in the blood; and coumarin compounds, which impair the liver’s utilization of vitamin K. Factors that hasten blood clotting include rough spots on the epithelial linings of blood vessels and body immobility.

17. Normal blood contains an inactive plasma protein called plasminogen that can be activated by several substances released from damaged cells. Plasmin, the active form, hydrolyzes fibrin strands and dissolves clots.

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_______________________________________________________________________ Chapter 27 | Blood

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18. In sickle cell trait, the RBCs contain a small proportion of a type of hemoglobin that is less soluble than normal. This hemoglobin forms solid crystals when the blood oxygen level is low, causing distortion and fragility of the RBCs. 19. Students should list and describe three of the following blood disorders: • Anemia: An inability of the blood to carry sufficient oxygen to the body • Polycythemia: Bone marrow produces an excess of RBCs • Aplastic anemia: Abnormally low number of RBCs • Pernicious anemia: Another disorder characterized by low RBCs • Folate deficiency: Similar to pernicious anemia in that RBC numbers are low; brought on by a vitamin deficiency • Hemolytic anemia (sickle-cell anemia, thalassemia): Inherited blood disorders characterized by abnormal types of hemoglobin • Leukocytosis: Abnormally high WBC count • Hemophilia: X-linked inherited blood disorder that affects blood clotting • Thrombocytopenia: Clotting disorder

Answers to Critical Thinking Questions (p. 636) 1. The machine should be set for 8 m or larger. Lymphocytes might be missed. Neutrophils, basophils, eosinophils, and monocytes would be counted. Neutrophils have a life span of hours to 3 days, and they are phagocytes for small pathogenic microorganisms. Basophils also have a life span of hours to 3 days; they secrete heparin and histamine. Eosinophils have a life span of 10 to 12 days, and they are the phagocytes for larger pathogenic organisms. They also release antiinflammatory substances in allergic reactions. Monocytes have a life span of months. They are able to migrate into tissue spaces as macrophages, an aggressive phagocyte capable of ingesting bacteria, cellular debris, and cancerous cells.

2. Hematocrit (Hct) is the volume percentage of RBCs in whole blood. One of the ways hematocrit can be determined is to allow whole blood to separate. This can be done rapidly by putting the blood into a centrifuge. The normal hematocrit value is 45%; the normal range is between 38% and 52%. If your friend’s hematocrit was below 38%, it would be below normal.

3. The most likely cause would be a blood transfusion with an incompatible blood type. The antibodies in the transfused blood reacted with the antigens in the receiver’s blood to cause the agglutination.

4. The hormone calcitonin causes a reduction in the blood calcium level. The calcium ion is necessary in the blood for the final two steps in the formation of fibrin for blood clot formation. A serious drop in the blood calcium levels would hinder these reactions and slow the blood clotting time.

5. The following steps could be taken to speed up clot formation: applying a rough surface, applying heat, squeezing the tissue around the cut to stimulate platelets to release platelet factor, applying purified thrombin to speed up the conversion of fibrinogen to fibrin, and applying fibrin directly to the cut.

6. Blood doping is a practice in which athletes have blood drawn and stored a few weeks before competition.

The RBCs are separated and frozen. Just before competition, the RBCs are thawed and injected back into the athlete. Theoretically, the increased number of RBCs and hemoglobin would increase the oxygen consumption and muscle performance during exercise. The positive effects are minimal, and the risk of affecting viscosity of blood may have harmful effects on the athlete.

7. Erythroblastosis fetalis occurs when an Rh-negative mother forms anti-Rh antibodies resulting from one or more previous Rh-positive pregnancies. These antibodies enter the baby’s blood and cause agglutination of the RBCs.

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Patton

Instructor’s Resource Material for

28 Heart ANSWER KEYS

Answers to Quick Check Questions 1. The heart lies in the mediastinum just below the body of the sternum between points of attachment of the second through sixth ribs. Approximately two-thirds of the heart’s mass is to the left of the midline of the body, and one-third is to the right.

2. The heart tends to resemble the configuration of the chest. In tall, thin people, the heart is described as elongated. In short, stocky people, the heart has a greater width and is described as transverse.

3. The heart attains its adult shape and weight between puberty and 25 years of age.

4. The tissue layers that make up the pericardium are the fibrous pericardium and serous pericardium (parietal and visceral layers).

5. The pericardium provides protection against friction by producing a lubricating serous fluid.

6. The three layers of tissue that make up the wall of the heart are epicardium, myocardium, and endocardium.

Epicardium: Protection. Myocardium: Contraction. Endocardium: Lining of the interior of the myocardial wall; covers the trabeculae.

7. The four chambers of the heart are right atrium, right ventricle, left atrium, and left ventricle. Right atrium: Tricuspid valve. Right ventricle: Tricuspid and pulmonary semilunar valves. Left atrium: Bicuspid valve. Left ventricle: Bicuspid valve and aortic semilunar valve.

8. Atrioventricular (AV) valves consist of two or three flaps (cusps) of endocardium. Semilunar valves consist of half-moon flaps growing out from the lining of the pulmonary artery and aorta.

9. Myocardial cells receive blood by way of the right and left coronary arteries. They branch off of the aorta at its very beginning and are its first branches. After blood has passed through capillary beds in the myocardium, it enters a series of cardiac veins before draining into the right atrium through a common venous channel called the coronary sinus.

10. More than one-half million Americans die every year from coronary disease, and another 3.5 million or more are estimated to have some degree of incapacitation. Therefore, knowledge about the distribution of coronary artery branches has great practical importance.

11. The conduction system of the heart refers to the structures that initiate and maintain a rhythmic heartbeat.

12. Myocardial infarction is the death of ischemic heart muscle cells.

13. The principle structures of the heart’s conduction system are the sinoatrial node, AV node, AV bundle, and Purkinje system.

14. P wave, QRS complex, and T wave are the types of deflection waves seen in a typical ECG. 15. P wave: Represents depolarization of the atria. QRS complex: Represents depolarization of the ventricles. T wave: Reflects repolarization of the ventricles.

16. (1) Atrial systole: Emptying of blood out of the atria into the ventricles. (2) Isovolumetric ventricular contraction: Between the start of ventricular systole and the opening of the semilunar valves. (3) Ejection: The semilunar valves open and blood is ejected from the heart. (4) Isovolumetric ventricular relaxation: Period between closure of the semilunar valves and opening of the AV valves. (5) Passive ventricular filling: Return of venous blood increases intraatrial pressure until the AV valves are forced open and blood rushes into the relaxing ventricles.

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Chapter 28 | Heart ________________________________________________________________________

17. The abrupt inflow of blood that occurred immediately after opening of the AV valves is followed by a slow but continuous flow of venous blood into the atria and then through the open AV valves into the ventricles.

This (diastasis) lasts about 0.2 second and is characterized by a gradual increase in ventricular pressure and volume.

Answers to Case Study Questions (p. 661) 1. c: V-fib is ventricular fibrillation—a condition in which the cells in the ventricles of the heart are not responding to the message from the sinoatrial (SA) node (or any other pacemaker). When not contracting in unison, the ventricles cannot pump blood effectively. This is a life-threatening condition that has to be corrected (defibrillated) within minutes.

2. b: The sinoatrial (SA) node is a group of autorhythmic cells (meaning they contract on their own, with no external impulse). There are other groups of autorhythmic cells in the heart, but the SA node fires the fastest and sets the pace for all the cells.

3. a: EKG (or ECG) stands for electrocardiogram—a measurement of electrical activity in the cardiac muscle cells.

4. d: The QRS complex reflects the electrical activity during ventricular depolarization. The P wave reflects atrial depolarization, and the T wave shows the activity during ventricular repolarization.

Answers to Review Questions (p. 664) 1. The heart is roughly the size of a person’s fist with a length of 12 cm, a width of 9 cm, and a depth of 6 cm.

The position and location of the heart are in the mediastinum behind the body of the sternum between the attachments of the second through sixth rib. About two-thirds of the heart’s mass is to the left of the midline.

Posteriorly, the heart rests against the bodies of the fifth to eighth thoracic vertebrae. The lower border of the heart lies on the diaphragm, pointing toward the left. The upper border of the heart lies just below the second rib.

2. The pericardium is a loose-fitting sac that covers the heart. The fibrous pericardium is a tough, loose-fitting, and inelastic sac around the heart. The serous pericardium consists of two layers: the parietal layer, which lines the inside of the fibrous layers, and the visceral layer, which adheres to the outside of the heart.

3. Pericardial fluid is found between the parietal and visceral layers of the serous pericardium. Its function is to act as a lubricant between the heart and the pericardium.

4. Intercalated disks are the joining points of heart cells.

Syncytium refers to a group of joined cells. In the heart, this occurs because the intercalated disks include many gap junctions, which join large areas of the heart into an electrical unit.

Autorhythmic refers to the ability of heart muscle cells to contract on their own without an external stimulus.

5. The chambers of the heart are the right and left atria, which are the upper chambers, and the right and left ventricles, which are the lower chambers. The valves of the heart are the atrioventricular (AV) valves, which are between the atria and ventricles, and the semilunar valves, which are between the right ventricle and the pulmonary artery, and between the left ventricle and the aorta.

6. Blood begins in the right atrium, passes through the right AV valve; into the right ventricle; out through the pulmonary semilunar valve; and into the pulmonary artery, which carries blood to the lung. The blood returns by way of the pulmonary veins into the left atrium, through the left AV valve, into the left ventricle, through the aortic semilunar valve, and out the aorta.

7. The sinoatrial (SA) node consists of cells located in the right atrial wall near the opening of the superior vena cava. The SA node initiates the contraction and spreads it through the rest of the atrial myocardium.

The AV node is a small mass of cardiac muscle that lies in the right atrium along the lower part of the interatrial septum. The AV node is stimulated by the SA node. It then initiates a signal that is conducted to the ventricles.

The AV bundles are bundles of special cardiac muscle fibers that originate in the AV node and carry the stimulus down the two sides of the AV septum. They form the Purkinje fibers, which extend out to the lateral walls of the ventricles, causing the ventricles to contract.

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8. The normal cardiac impulse that initiates the contraction of the heart arises from the SA node located just below the atrial epicardium at its junction with the superior vena cava. Each impulse generated at the SA node travels throughout the muscle fibers of both atria, causing atrial contraction. This stimulates the AV node at the base of the right atrium. The AV node sends an impulse down the AV bundles, which are located in the interventricular septum. They branch laterally to form the Purkinje fibers, which actually stimulate the ventricles to contract.

9. The ECG measures the electrical activities of the heart and its conduction of impulses. The ECG records a graphic representation of the electrical activity and conduction. The P wave represents the depolarization of the atria. The QRS complex represents the entire process of ventricular depolarization. During this time, atrial repolarization occurs, but the ventricular depolarization hides this electrical event. The T wave represents the repolarization of the ventricles. An additional U wave may be seen, which represents the repolarization of Purkinje fibers in the papillary muscles. The intervals are between the P waves, the QRS waves, and the T waves. Measurement of the intervals can provide valuable information about the rate of conduction of an action potential through the heart.

10. Cardiac cycle means a complete heartbeat or pumping cycle consisting of contraction and relaxation of both atria and both ventricles.

11. The phases of the cardiac cycle are as follows: • Atrial systole is the contraction of the atria emptying the blood into the ventricles.

• Isovolumetric ventricular contraction is the brief period between the start of ventricular contraction and the opening of the semilunar valves (ventricular volume remains constant during this phase).

• Ejection occurs when the semilunar valves open and the blood is ejected from the ventricles into the arteries.

• Isovolumetric ventricular relaxation occurs during ventricular relaxation between the closure of the semilunar valves and the opening of the AV valves.

• Passive ventricular filling is caused by the return of venous blood, which increases intraatrial pressure until the AV valves are forced open and blood rushes into the relaxing ventricles.

12. Residual volume refers to the amount of blood that normally remains in the ventricles at the end of the ejection period.

13. The typical “lubb-dupp” sounds are caused by the following: the first sound is caused primarily by the contraction of the ventricles and the vibration of the closing AV valves; the second sound is caused by the closing of the semilunar valves.

14. Echocardiography is a noninvasive technique for evaluating the internal structures and motions of the heart and the great vessels. It is used to diagnose valvular heart disease, congenital heart disease, cardiomyopathy, congestive heart failure, pericardial disease, cardiac tumors, and intracardiac thrombi. It is also used to evaluate the functions of the left ventricle after a myocardial infarction, and it can detect the presence of pericardial fluid.

15. When the heart muscle is damaged, enzymes within the muscle cells are released into the blood. Studies of cardiac enzymes are useful in confirming a myocardial infarction. The rate of release and distribution of specific enzymes vary over time after an infarction. It is the pattern of the enzyme elevation that is of diagnostic importance.

16. Coronary artery disease can be caused by coronary thrombosis, coronary embolism, and atherosclerosis.

17. Congestive heart failure, or left-sided heart failure, is the inability of the left ventricle to pump blood effectively.

18. A heart block occurs when impulses cannot get through damaged areas of the myocardium, thus disruption of cardiac conduction occurs. Bradycardia is an abnormally slow rhythm and tachycardia is an abnormally rapid rhythm. Sinus dysrhythmia is a change in rate during the phases of breathing. Premature contractions occur outside the regular heart rhythm, and fibrillation occurs when various cardiac fibers are out of step with each other.

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Chapter 28 | Heart ________________________________________________________________________

Answers to Critical Thinking Questions (p. 664) 1. The heart is located between the sternum and bodies of the thoracic vertebrae. This allows the heart to be compressed by application of pressure to the lower portion of the body of the sternum using the heel of the hand. Rhythmic compression of the heart in this way can maintain blood flow in cases of cardiac arrest. If compression is combined with effective artificial respiration, the resulting procedure is called cardiopulmonary resuscitation (CPR).

2. Anastomoses are connections between larger arterial branches. An anastomosis provides a detour for arterial blood if the usual route becomes obstructed. The blood supply to the heart has few anastomoses. Because of this, if a main route of blood is blocked in the heart, there is no other route for the blood to take and the cells will not receive the food and oxygen they need to survive.

3. An ectopic pacemaker is a pacemaker other than the SA node. Ectopic pacemakers usually cause rates to be slower than normal, 40 to 60 beats/min.

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Anatomy and Physiology, 9th ed.

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Instructor’s Resource Material for

29 Blood Vessels ANSWER KEYS

Answers to Quick Check Questions 1. The three major types of blood vessels are the artery, vein, and capillary.

2. The walls of the arteries and veins have three layers. The middle layer is thicker in arteries. The inner layer of the veins contains valves. The capillaries have only one layer (endothelium).

3. The thinness of the capillary wall permits ease of transport across the vessel wall.

4. Pulmonary circulation moves blood from the heart to the lungs and back to the heart. Systemic circulation blood flows from the heart through blood vessels to all parts of the body and back to the heart.

5. Arterial anastomoses provide detour routes for blood to travel in the event of obstruction of a main artery.

The incidence of arterial anastomoses increases as distance from the heart increases, and smaller branches tend to anastomose more often than larger vessels. Veins anastomose with each other in the same way as arteries. Venous anastomoses provide for collateral return blood flow in cases of venous obstruction.

6. Systemic arteries and veins are generally named according to their anatomical position, relation to regions, and adjacent organs.

7. Excess glucose is removed from the blood and stored in liver cells as glycogen to be used later. Also, toxic molecules, such as alcohol, can be partially removed or detoxified before the blood is distributed to the rest of the body.

8. Umbilical arteries, placenta, umbilical vein, ductus venosus, foramen ovale, and ductus arteriosus are part of the fetal circulation but not part of the adult circulation.

9. Function of placenta: Structure attached to uterine wall that facilitates the exchange of oxygen and other substances between maternal and fetal blood. Function of umbilical vessels: Veins return oxygenated blood from the placenta to the fetus; arteries carry fetal blood to the placenta.

10. The placenta is shed from the body with part of the umbilical vessels attached. The sections of these vessels become fibrous cords. The ductus venosus becomes the ligamentum venosum. The foramen ovale normally becomes functionally closed soon after a newborn takes the first breath. It will become the fossa ovalis. The ductus arteriosus contracts as soon as respiration is established. It becomes the ligamentum arteriosum.

Answers to Case Study Questions (p. 696) 1. d: The coronary arteries are the major blood supply vessels for the muscle cells in the heart. Kyle’s symptoms are typically related to the heart. The angiogram is a tool for viewing the coronary arteries.

2. c: Many arteries, veins, and nerves are named according to the body region in which they are located. The upper leg is the femoral region, and the artery in that area is the femoral artery.

3. a: You may have learned the names of the arteries from the heart outward. Now, trace your path backward.

The femoral artery is a continuation of the external iliac artery, which branches off from the abdominal aorta, which is a continuation of the descending aorta, a continuation of the aortic arch, and then a continuation of the ascending aorta.

4. b: The left ventricle contains the most muscle tissue of all the chambers because it has to generate the most force on contraction. More muscle tissue means more oxygen and nutrients are required, which must be supplied by the coronary arteries.

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Chapter 29 | Blood Vessels _________________________________________________________________

Answers to Review Questions (p. 698) 1. The vessels that join to form the hepatic portal vein are the cystic, gastric, splenic, inferior mesenteric, pancreatic, superior mesenteric, and gastroepiploic veins.

2. The six unique structures necessary for fetal circulation are (1) the two umbilical arteries, which carry blood to the placenta; (2) the placenta, which is the structure attached to the uterine wall, where substances are exchanged between the blood of the mother and the baby; (3) the umbilical vein, which returns blood from the placenta to the baby; (4) the ductus venosus, which returns blood from the placenta directly to the inferior vena cava, bypassing the liver; (5) the foramen ovale, which is an opening in the septum between the right and left atria that allows most of the blood to bypass the fetal lungs; and (6) the ductus arteriosus, which is a small vessel connecting the pulmonary artery with the descending aorta, which allows more blood to bypass the fetal lungs.

3. After birth, the foramen ovale normally becomes functionally closed once the baby takes the first breath and full circulation becomes established. Full closure usually requires 9 months. The ductus arteriosus contracts as soon as respiration is established and eventually becomes a fibrous cord. This separates oxygenated and deoxygenated blood.

4. The branches of the external jugular vein may allow a route for infection to spread into the cranial cavity.

5. Aneurysm is a section of an artery that has become abnormally widened because of a weakening of the arterial wall.

Atherosclerosis (hardening of the arteries) is a thickening of arterial walls that progresses to hardening as calcium deposits form, reducing blood flow to the tissues.

Phlebitis is an inflammation of a vein.

6. Hemorrhoids are varicose veins in the anal canal. Excessive straining during defecation can create pressure that can cause hemorrhoids. The usual pressure of carrying a child during pregnancy predisposes expectant mothers to hemorrhoids.

Answers to Critical Thinking Questions (p. 698) 1. Because the main function of the transport system is the exchange of material from the tissue and blood in one part of the body with another part of the body, the most important structures are the blood vessels that actually accomplish this exchange, the capillaries.

2. All arterial blood in systemic circulation contains oxygen. Arterial blood in pulmonary circulation has low oxygen, because pulmonary arterial blood is on its way to the lungs to become oxygenated.

3. Arteries leaving the heart continue to branch into smaller and smaller branches until one of these small branches enters a capillary bed. These arteries are called end-arteries. If they become occluded, the capillary bed they serve will stop receiving blood. Arteries other than end-arteries frequently have other routes through which blood may be detoured.

4. The longitudinal sinus, basilic, internal jugular, and azygos veins eventually drain into the superior vena cava.

The great saphenous, popliteal, and hepatic portal veins eventually drain into the inferior vena cava.

5. A portal system has several advantages. In the hepatic portal system, the liver is able to remove excess glucose after a meal and add glucose between meals; therefore the glucose concentration in the rest of the system does not vary so widely. Also, toxic substances (such as, alcohol) can be partially removed or detoxified before they enter the rest of the system.

6. The blood cell begins in the right atrium; passes through the right atrioventricular valve, the right ventricle, the pulmonary semilunar valve, the pulmonary artery, the lung, and the pulmonary vein; then moves into the left atrium to the left atrioventricular valve to the left ventricle, through the aortic semilunar valve, and into the aorta. From the aorta it continues to the common iliac, external iliac, femoral, popliteal, and anterior or posterior tibial arteries; the plantar arch; and digital arteries. It returns to the heart by way of the digital vein; the dorsal veins of the foot; and the anterior tibial, popliteal, femoral, external iliac, and common iliac veins.

The common iliac vein empties into the inferior vena cava, which returns blood to the right atrium.

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7. The cardiovascular system undergoes profound anatomical changes during early development in the womb.

At birth, the switch from a placenta-dependent system causes other anatomical changes. Throughout one’s life, from childhood through adulthood, the cardiovascular system normally maintains its basic structure and function with the apparent normal changes resulting from regular exercise. Regular exercise can thicken the myocardium and increase the supply of blood vessels in response to increased oxygen and glucose use during prolonged exercise. As we reach later adulthood, various degenerative changes can occur in the cardiovascular system. For example, atherosclerosis can block or weaken arteries, and heart valves and myocardial tissue may also degenerate, becoming fibrotic and less able to perform their functions properly.

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Instructor’s Resource Material for

30 Circulation of Blood ANSWER KEYS Answers to Quick Check Questions

1. Fluid always travels from an area of high pressure to an area of low pressure. Blood tends to move from an area of high average pressure at the beginning of the aorta toward the area of lowest pressure at the end of the venae cavae. Blood flow between any two points in the circulatory system can always be predicted by the pressure gradient.

2. Stroke volume  Heart rate = Cardiac output (CO).

3. An increase in the amount of blood to the heart tends to increase stroke volume. Starling’s law of the heart is the principle that explains this.

4. These pressoreflexes contain receptors (baroreceptors) sensitive to changes in pressure. Baroreceptors operate with integrators in the cardiac control centers in negative feedback loops that oppose changes in pressure by adjusting heart rate.

5. Peripheral resistance is also affected by the diameters of arterioles and capillaries.

6. A decrease in the diameter of the arteries results in an increase in peripheral resistance.

7. Vasomotor reflexes detect changes in blood pressure and send the information back to the cardiac control center and the vasomotor center in the medulla. In response, these control centers alter the ratio between the sympathetic and parasympathetic output. If the pressure is too high, a dominance of parasympathetic impulses reduces it by slowing the heart rate, reducing stroke volume, and dilating blood “reservoir” vessels. If the pressure is too low, a dominance of sympathetic impulses increases it by increasing heart rate and stroke volume and constricting reservoir vessels.

8. Chemoreflexes detect changes in carbon dioxide, decreases in oxygen, and decreases in pH. When changes are detected, this information is fed back to the cardiac control center and the vasomotor control center of the medulla, which, in turn, alter the ratio of parasympathetic and sympathetic output. When oxygen drops, carbon dioxide increases, or pH drops, a dominance of sympathetic impulses increases heart rate and stroke volume and constricts reservoir vessels in response.

9. Venous return refers to the amount of blood that is returned to the heart by way of the veins.

10. The respiratory pump operates by alternately decreasing thoracic pressure during inspiration and increasing pressure in the thorax during expiration. The skeletal muscle pump operates by the alternate increase and decrease in peripheral venous pressure that normally occur when the skeletal muscles are used for the activities of daily living.

11. At the arterial end of a capillary, the outward driving force of blood pressure is larger than the inwardly directed force of osmosis; thus, fluid moves out of the vessel. At the venous end of the capillary, the inward driving force of osmosis is greater than the outwardly directed force of hydrostatic pressure; thus, fluid enters the vessel.

12. Antidiuretic hormone (ADH), renin-angiotensin and aldosterone mechanisms, and atrial natriuretic hormone all work together to regulate blood volume.

13. Minute volume is the volume of blood circulating through the body per minute.

14. The volume of blood circulated per minute is directly related to mean arterial pressure minus central venous pressure and inversely related to resistance.

15. A sphygmomanometer is used in the clinical setting to measure arterial blood pressure.

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Chapter 30 | Circulation of Blood _____________________________________________________________

16. Diastolic pressure is more important for assessing health.

17. Blood is most likely to flow at a very slow rate in the capillaries.

18. The pulse can be felt wherever an artery lies near the surface and over a bone or other firm backgrounds.

Some specific locations where the pulse point is most easily felt are: radial artery, temporal artery, common carotid artery, facial artery, brachial artery, popliteal artery, posterior tibial artery, and dorsalis pedis artery.

Answers to Case Study Questions (p. 723) 1. c: The sounds of turbulence generated by blood pressure measurements are called Korotkoff sounds. These sounds are named after Nicolai Korotkoff, the Russian surgeon who in 1905 developed the method for using these sounds to measure arterial blood pressure indirectly.

2. c: The difference between systolic pressure and diastolic pressure is called pulse pressure (PP). Luke’s reading was 150/85, which means his pulse pressure is 65 (150 − 85 = 65).

3. a: Mean arterial pressure (MAP) is calculated by this equation: MAP = (2  diastolic BP) + systolic BP/3.

Using Luke’s blood pressure reading of 150/85, his MAP would be 106 mm Hg.

Answers to Review Questions (p. 726) 1. The arterioles present the greatest resistance to blood flow.

2. The primary determinant of arterial blood pressure is the volume of blood in the arteries.

3. The two most important factors that indirectly determine arterial pressure by their influence on arterial volume are cardiac output (CO) and peripheral resistance.

4. CO is determined by the volume of blood pumped out of the ventricles by each beat, stroke volume, and heart rate.

5. Anxiety, fear, and anger often make the heart beat faster. Grief tends to slow the heartbeat. The ability of emotions to change heart rate occurs through the influence of higher centers in the cerebrum via the hypothalamus.

6. Friction caused by blood viscosity and the small diameter of the arterioles account for peripheral resistance.

The arterioles can constrict, which increases peripheral resistance, or dilate, which decreases peripheral resistance. Also, the viscosity is determined by the concentration of red blood cells and blood proteins. Any increase or decrease in these concentrations will increase or decrease resistance, respectively.

7. The components of the vasomotor control mechanism are the vasomotor pressoreflexes, the vasomotor chemoreflexes, the medullary ischemic reflex, and the vasomotor control by higher brain centers.

8. Antidiuretic hormone (ADH) increases the amount of water reabsorbed from the urine. This decreases the volume of the urine and increases the volume of the blood.

9. Low blood pressure stimulates the release of both ADH and aldosterone. Both of these hormones increase the amount of water reabsorbed from the urine, which causes an increase in blood volume and therefore blood pressure.

10. Blood pressure is measured by a sphygmomanometer and is given in millimeters of mercury. An inflatable cuff is placed around the upper arm. Air is pumped into the cuff until the pressure of the cuff compresses the artery. At this point, no pulse can be heard by a stethoscope placed on the brachial artery below the cuff. As air is released from the cuff, there comes a point where the pressure in the cuff equals the pressure in the artery and a small spurt of blood comes through. This produces a sharp, taplike sound. This is the upper pressure, or systolic pressure. Air continues to be released until the sound of the blood moving through the artery can no longer be heard. The point just before the sound disappears is the lower pressure, or diastolic pressure.

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11. The eight locations where the pulse point is most easily felt are as follows: (1) the radial artery at the wrist; (2) the temporal artery in front of the ear; (3) the common carotid artery along the anterior edge of the sternocleidomastoid at the level of the thyroid cartilage; (4) the facial artery in the groove in the mandible about a third of the way forward from the angle; (5) the brachial artery at the bend of the elbow; (6) the popliteal artery behind the knee; (7) the posterior tibial artery behind the medial malleolus; and (8) the dorsal pedis artery in the dorsum of the foot. The six pressure points are (1) the temporal artery in front of the ear; (2) the facial artery at the same place the pulse is taken; (3) the common carotid artery, where the pulse is taken; (4) the subclavian artery behind the medial third of the clavicle; (5) the brachial artery, a few inches above the elbow on the inside of the arm; and (6) the femoral artery in the middle of the groin, where the artery passes over the pelvic bone.

Answers to Critical Thinking Questions (p. 727) 1. The primary principle of circulation says that a fluid—in this case, blood—will move from an area of higher pressure to an area of lower pressure. Because the blood must flow from the left ventricle, a pressure gradient must be maintained to move the blood in the proper direction.

2. Starling’s law of the heart says that the longer or more stretched the heart fibers at the beginning of the contraction, the stronger the contraction will be. Because of the fact that more blood entering the heart means that the muscle fibers are more stretched, venous return (which is the amount of blood being returned to the heart by the vein) is a major determinant of contraction strength.

3. Heart rate is influenced by both the parasympathetic nervous system, which decreases heart rate, and the sympathetic nervous system, which increases heart rate. This dual innervation provides precise control over heart rate. The parasympathetic fibers of the vagus nerve release acetylcholine, and the sympathetic fibers of the cardiac nerve release norepinephrine.

4. The cardiac sinus is a small dilation at the beginning of the internal carotid artery. It contains pressure sensors that send information to the cardiac control center of the medulla. If the pressure in the cardiac sinus rises above set point, an impulse is sent to slow down the heart rate and reduce the pressure.

5. Arterial runoff is the amount of blood that runs out of the arteries and into the arterioles. The less the arterial runoff, the higher the peripheral resistance. The greater the runoff, the less the peripheral resistance.

6. If the blood flow to the medulla drops below a certain point, carbon dioxide begins to build up in the tissues.

This stimulates the medulla to stimulate the vasomotor centers to constrict both arteries and veins. This tends to raise blood pressure and supply more blood to the brain.

7. The process of respiration and skeletal muscle contraction assist the body in returning blood to the heart. In inspiration, the pressure in the chest is lowered, which tends to pull more blood toward the heart. When skeletal muscles contract, veins that run through them are squeezed and the blood is pushed toward the heart.

Veins are lined with one-way valves, which ensure the blood will move in the proper direction and that it will not fall away from the heart during expiration or skeletal muscle relaxation.

8. The forces that act on capillary exchange are hydrostatic forces and osmotic forces. At the arterial end of the capillary, hydrostatic force generates more pressure than osmotic force so there is a net movement of material out of the capillary. At the venous end of the capillary, the osmotic force generates more pressure than the hydrostatic force, so there is a net movement of material into the capillary. The recovery of material at the venous end of the capillary is only about 90% effective.

9. Poiseuille’s law says that the minute volume of blood is equal to the difference between mean arterial pressure and central venous pressure divided by resistance. It can be expressed by the following equation: Mean arterial pressure − Central venous pressure Resistance If resistance increased, it would seem that the minute volume would go down. But an increased resistance would also increase mean arterial pressure. If the mean arterial pressure were high enough, the minute volume would not go down.

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Chapter 30 | Circulation of Blood _____________________________________________________________

10. The two factors that determine blood viscosity are the number of red blood cells and the concentration of protein in the plasma. Viscosity refers to the stickiness of the blood. Conditions that reduce protein concentration or number of red blood cells in the blood would lower viscosity. If viscosity drops, it reduces resistance and reduces arterial pressure. If the arterial pressure drops too low, it can lead to circulatory failure.

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Instructor’s Resource Material for

31 Lymphatic System ANSWER KEYS Answers to Quick Check Questions

1. Maintenance of fluid balance in the internal environment and immunity is the overall function of the lymphatic system.

2. Lymph originates in the blood and tissue fluid.

3. Lymphatic vessels resemble veins in structure with these exceptions: lymphatics have thinner walls, contain more valves, and contain lymph nodes located at certain intervals along their course. The lymphatic capillary walls contain openings that are larger than those found in blood capillaries. Boundaries between layers are less distinct in the thinner lymphatic vessel walls than in arteries or veins.

4. Lymph nodes are oval-shaped structures. Each lymph node is enclosed by a fibrous capsule. The lymph node acts as a “biological” filter with internal sinuses and one-way valves in both the afferent and efferent vessels.

Fibrous septa, or trabeculae, extend from the covering capsule toward the center of the node. Cortical nodules within the sinuses are separated from each other by connective tissue (trabeculae). Each cortical nodule is composed of packed lymphocytes that surround a less dense area called a germinal center.

5. Most of the lymph nodes occur in groups, or clusters, in certain areas: just in front of the ear, in the floor of the mouth, in the neck along the sternocleidomastoid muscle, just above the bend of the elbow, deep within the underarm and upper chest, and in the groin.

6. Lymph nodes provide defense and hematopoiesis.

7. Cancerous cells often spread to other areas because of the lymphatic drainage of the breast. Lymphatics originate in and drain the skin over the breast. Cancer cells can spread easily through the extensive network of lymphatic vessels associated with the breasts. Also, anastomoses (connections) occur between superficial lymphatics from both breasts across the middle line. This type of communication can result in the spread of cancerous cells from one breast to the other.

8. The major tonsils are located in a protective ring under the mucous membranes in the mouth and back of the throat. Palatine tonsils are located each side of the throat; pharyngeal tonsils are located near the posterior opening of the nasal cavity; lingual tonsils are located near the base of the tongue; and tubal tonsils are located near the opening of the auditory tube. The tonsils help protect against bacteria that may invade tissues in the area around the openings between the nasal and oral cavities.

9. The thymus plays a critical part in the body’s defense against infections in that it is a vital immunity mechanism. It serves as the final site of lymphocyte development before birth, and it secretes hormones and other regulators that enable lymphocytes to develop into mature T cells.

10. The major functions of the spleen are defense, hematopoiesis, red blood cell destruction and platelet destruction, and blood reservoir. Defense: The spleen removes and destroys microorganisms from the blood.

Hematopoiesis: Nongranular leukocytes complete their development before becoming activated in the spleen.

Red blood cell destruction and platelet destruction: Macrophages lining the spleen’s sinusoids remove and destroy worn-out red blood cells and imperfect platelets from the blood and destroy them by phagocytosis.

Blood reservoir: At any given point in time, the spleen contains a considerable amount of blood that can rapidly be added back into the circulatory system from this functional reservoir if needed.

Answers to Case Study Questions (pp. 745-746) 1. d: Lymphedema is caused by a blockage of lymphatic vessels. The interstitial fluid that should be drained by the lymph vessels instead builds up in the surrounding tissues. A similar process occurs when you stand on your feet all day and end up with slightly swollen ankles. Your lymphatic system must work against gravity when you are standing. With lymphedema, the swelling is much more extensive and occurs without regard to body position.

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Chapter 31 | Lymphatic System _____________________________________________________________

2. a: The lymphatic system drains excess fluid from the interstitial area back into the bloodstream, but it has no effect on the movement of fluid out of the bloodstream.

3. b: Back to those swollen ankles at the end of the day: If you are able to walk around or shift your weight from foot to foot, the skeletal muscle contractions can help move the lymph along, reducing the amount of fluid trapped in the interstitial area.

4. c: The lymph vessels drain in a one-way pattern, toward the heart. Moving from the lower leg upward, the lymph from Juba’s leg will pass through the inguinal lymph nodes. The axillary nodes are in the armpit; cervical nodes are in the neck; and the mediastinal nodes are in the thoracic region, just behind the sternum.

Answers to Review Questions (p. 748) 1. The anatomical components of the lymphatic system are the lymph vessels, lymph nodes, tonsils, thymus gland, and spleen.

2. The main way lymph and interstitial fluid differ from blood plasma is that blood has a higher percentage of protein.

3. Lymph vessels originate as microscopic blind-end vessels called lymphatic capillaries.

4. The wall of the lymphatic capillaries consists of a single layer of flattened endothelial cells.

5. Lymph from the entire body except the upper right quadrant drains into the thoracic duct. Lymph from the upper right quadrant drains into the right lymphatic duct.

6. The cisterna chyli is a dilated structure in the lumbar region of the abdominal cavity, which is the origin of the thoracic duct.

7. Lymph from the thoracic duct drains into the left subclavian vein. Lymph from the right lymphatic duct drains into the right subclavian vein.

8. Lymphatics resemble veins in structure except that lymphatics (1) have thinner walls, (2) have more valves, and (3) contain lymph nodes at intervals along their course.

9. The specialized lymphatics that originate in the villi of the small intestines are called lacteals.

10. Chyle is lymph that contains 1% to 2% fat. It is formed in the small intestines, where lacteals absorb the digested fat.

11. There are two main mechanisms for moving lymph back to the blood. The first is breathing. During inspiration, the thoracic cavity experiences a drop in pressure, and the abdominal cavity has an increase in pressure. This causes a drop in the pressure of the lymph vessels in the thorax and an increase in the pressure of lymph vessels in the abdomen. This pressure gradient moves lymph toward the subclavian veins. Lymph is also moved by the contraction of skeletal muscles pushing against lymph vessels. Because the lymph vessels contain one-way valves, the lymph moves only in the proper direction.

12. The important groups or clusters of lymph nodes are as follows: the preauricular lymph node, the submental and submaxillary groups, the superficial cervical lymph nodes, the superficial cubital lymph nodes, the axillary lymph nodes, and the inguinal lymph nodes.

13. Because of the netlike structure of the lymph nodes, they can act as filters for the lymph. The harmful material that is filtered out can be phagocytosed by cells in the lymph node. Also, lymph nodes are areas where various white blood cells, lymphocytes, and monocytes go through their final stage of maturation.

14. Because breast tissue has an extensive lymphatic network, cancer cells from the breast can easily be carried to other parts of the body by the lymphatic system. Thus surgical treatment of breast cancer often includes the removal of lymph nodes, which might contain cancer cells or possibly spread them.

15. The thymus is located in the mediastinum, extending up into the neck as far as the lower edge of the thyroid gland and inferiorly as far as the fourth costal cartilage. It is an unpaired organ consisting of two pyramidshaped lobes with delicate and finely lobed surfaces. Its size relative to the rest of the body is largest in a child about 2 years old. Its absolute size is largest during puberty, when its weight ranges between 35 and 40 grams. From then on, it gradually atrophies until in advanced old age it may be largely replaced by fat and

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_____________________________________________________________ Chapter 31 | Lymphatic System

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weigh less than 10 grams. The thymus is pinkish gray in color early in childhood but with advanced age becomes yellowish as lymphatic tissue is replaced by fat.

16. The thymus performs two important functions. First, it serves as the final site of lymphocyte development before birth. Second, soon after birth, the thymus begins secreting a group of hormones collectively called thymosin that enable lymphocytes to develop into mature T cells.

17. The spleen is located in the left hypochondrium directly below the diaphragm, above the left kidney and descending colon, and behind the fundus of the stomach. The spleen has four major functions. First, the macrophages in the spleen remove microorganisms from the blood and destroy them by phagocytosis.

Second, monocytes and lymphocytes complete their development to become activated in the spleen. Third, macrophages remove worn-out blood cells and imperfect platelets from the blood and destroy them by phagocytosis. They also break apart the hemoglobin and salvage the iron and hemoglobin content by returning them to the bloodstream for storage in the bone marrow and liver. Fourth, the spleen acts as a reservoir for blood. The pulp and the venous sinuses of the spleen contain a considerable amount of blood.

This blood can be returned to circulation by sympathetic stimulation, resulting in constriction of the smooth muscle, which makes up the capsule of the spleen.

18. It is impossible to maintain adequate serum protein levels by dietary means if significant loss of lymph continues over time. As lymph is lost, rapid emaciation occurs, with progressive and eventually fatal decrease in total blood fat and protein levels.

19. Because cancer cells can spread easily through the extensive lymphatic vessels associated with the breast, these vessels are sometimes removed. Occasionally, such procedures interfere with the normal flow of lymph fluid from the arm. When this happens, tissue fluid may accumulate in the arm, resulting in swelling, or lymphedema.

Answers to Critical Thinking Questions (p. 748) 1. Because lymph is not contained in continuous vessels all the time, the term circulation is not appropriate to describe lymph flow.

2. Lymph is formed by the fluid leaving the capillaries, which is not reabsorbed by the capillaries at the venous end. If the venous end of the capillary were more successful in recovering fluid, the amount of lymph formed would be proportionally reduced. The more fluid recovered, the less lymph there would be.

3. Because the lymphatic system has no pump to generate a pressure gradient, lymph must be moved by skeletal muscle contraction pushing on a vessel or the reduced pressure in the thoracic cavity pulling lymph through a vessel. When the skeletal muscle relaxes or expiration increases thoracic pressure, the lymph would fall back to its lower position if the one-way valves did not stop it from doing so.

4. The most likely regions that might begin new growth of cancer would be the axillary region or the region at the lateral stage of the sternum. About 85% of the lymph from the breast drains into these areas.

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Anatomy and Physiology, 9th ed.

Patton

Instructor’s Resource Material for

32 Innate Immunity ANSWER KEYS

Answers to Quick Check Questions 1. Self refers to our own cells, which have unique cell markers embedded in our plasma membranes that identify each cell as belonging to us as individuals. Nonself molecules are those that are found on foreign cells or particles. These serve as recognition markers for our immune system.

2. Innate immunity is in place before a person is exposed to a particular harmful particle or condition (already present naturally at birth). Adaptive immunity involves mechanisms that recognize specific threatening agents and adapt or respond by targeting their activity against these agents—and these agents only.

3. Cytokines are chemicals released from cells to trigger or regulate innate and adaptive immune responses.

Examples include interleukins, leukotrienes, and interferons.

4. The skin and mucous membranes serve as a mechanical barrier that protects the internal environment of the human body. These membranes provide several layers of densely packed cells and other materials, forming a “castle wall” that protects the internal environment from invasion by foreign cells.

5. When bacteria enter and damage the tissue, mediators are released. These inflammation mediators include histamine, kinins, prostaglandins, and leukotrienes. Many of these mediators are chemotactic factors. Others increase blood flow or increase vascular permeability. All of these increase the number of leukocytes at the site of tissue damage. The leukocytes contain, destroy, and phagocytize bacteria.

6. Macrophages are phagocytes, which ingest and destroy microorganisms or other small particles.

7. Interferons interfere with the ability of viruses to cause disease. They do this by preventing viruses from multiplying in cells. Complement molecules are activated in a cascade of chemical reactions triggered by either specific or nonspecific mechanisms. The complement cascade causes lysis of the foreign cell that triggers it.

Answers to Review Questions (p. 761) 1. Innate immunity is a group of mechanisms that resist various threatening agents or conditions. These immune mechanisms do not simply act on one or two specific invaders but rather provide a more general defense by acting against anything recognized as nonself.

2. The mechanisms for innate defense are as follows: species resistance, which involves genetic characteristics of the human species that protect the body from certain pathogens; mechanical and chemical barriers, which act as physical impediments to the entry of foreign cells or substances and include the skin, the mucosa, and various secretions; inflammation, which isolates the pathogens and stimulates the speedy arrival of a large number of immune cells; phagocytosis, which is the ingestion and destruction of pathogens by phagocytic cells, such as neutrophils and macrophages; natural killer cells, which are a group of lymphocytes that kill many types of cancer cells and virus-infected cells; interferon, which is a protein produced by cells after they have been infected by a virus to inhibit the spread or further development of the viral infection; and complement, which is a group of plasma proteins that produce a cascade of chemical reactions ultimately resulting in lysis of foreign cells.

3. The body’s first line of defense is the mechanical and chemical barriers, which include the skin, the mucosa, and various secretions.

4. Chemotaxis brings blood cells to local area, and the activation of complements produce changes that result in heat and redness from increased local blood flow, swelling, and pain from increased tissue fluid volume—all of which help white blood cells reduce and repair damage.

5. Such factors attract the migration of white blood cells to a site of injury.

6. Natural killer (NK) cells recognize foreign cells and destroy them.

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Chapter 32 | Innate Immunity _______________________________________________________________

7. Interferon proteins interfere with the ability of viruses to cause disease. They do this by preventing viruses from multiplying in the cells.

8. Complements are functional proteins (enzymes) that can be activated by innate immunity to help identify and destroy foreign particles that threaten the body.

Answers to Critical Thinking Questions (p. 761) 1. The body’s second line of defense against microorganisms is phagocytosis by neutrophils and macrophages.

After the microorganism has been ingested by the phagocyte, digestive enzymes and hydrogen peroxide are used to kill and digest the microorganism. Bacteria that are resistant to these substances are much more difficult for the body to fight off.

2. If a person were unable to form complement proteins, the process of lysis of foreign cells (called cytolysis) would be lessened. The vasodilation in the area of infection would be lessened, and the chemotactic attraction of neutrophils to the infected area would be lessened.

3. An increase in body temperature can make the body less hospitable to dangerous foreign cells and can also increase the activity rate of our own immune cells. Both effects temporarily increase the efficiency of the immune system’s ability to recover from injury or infection.

4. Phagocytosis of foreign particles and infected cells can remove these threats from our internal environment.

5. Toll-like receptors (TLRs) are pattern-recognition receptors that trigger a variety of nonspecific responses of innate immunity. If TLR genes are abnormal, then the TLRs themselves would probably not function properly—disabling the innate immune mechanisms to some degree.

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Anatomy and Physiology, 9th ed.

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Instructor’s Resource Material for

33 Adaptive Immunity ANSWER KEYS Answers to Quick Check Questions

1. An antigen is a macromolecule that induces the immune system to make certain responses. Self-antigens are the membrane molecules that identify all the normal cells. Nonself-antigens are those molecules that identify foreign and tumor cells.

2. A clone is one of a “family” of cells, all of which have descended from one cell.

3. As discovered in chickens, the first stage of B-cell development occurs in the bursa of Fabricius, hence the name B cell.

4. An inactive B cell develops into an activated B cell, which divides rapidly and repeatedly to form a clone of plasma cells and a clone of memory cells. Plasma cells secrete antibodies capable of combining with specific antigens that cause inactive B cells to develop into active B cells. Thus, the ultimate function of B cells is to serve as ancestors of antibody-secreting plasma cells.

5. The structure of antibodies permits them to distinguish nonself-antigens from self-antigens. This recognition occurs when an antigen’s epitopes (small regions on its surface) fit into and bind to an antibody molecule’s antigen-binding site. The binding of the antigen to antibody forms an antibody-antigen complex that may render toxins harmless.

6. Complement molecules activated by antibodies form doughnut-shaped complexes in a bacterium’s plasma membrane. Holes in the complement complex allow sodium and then water to diffuse into the bacterium.

After enough water has entered, the swollen bacterium bursts.

7. During their residence in the thymus, pre–T cells develop into thymocytes. Thymocytes divide and increase enormously in a relatively short time. They stream out of the thymus into the blood and find their way to areas of the lymph nodes and spleen called T-development zones. From this time on, they are known as T cells.

8. A T cell becomes activated or sensitized when an antigen encounters a T cell whose surface receptors fit the antigen’s epitopes and the antigen binds to the T cell’s receptors.

9. Cytotoxic T cells release lymphotoxins that kill cells by lysing them.

10. Inherited immunity occurs when specific or nonspecific immune mechanisms are put in place by genetic mechanisms during the early stages of human development in the womb. Acquired immunity is resistance that develops after we are born.

11. Natural immunity results from exposure, is not deliberate, and occurs in the course of everyday living.

Artificial immunity results from deliberate exposure to harmful antigens (immunizations).

12. Active immunity occurs when an individual’s own immune system responds to a harmful agent, regardless of whether that agent was naturally or artificially encountered. Passive immunity results when immunity to a disease that has developed in another individual or animal is transferred to an individual who was not previously immune.

Answers to Case Study Questions (p. 782) 1. c: Kostas’ white blood cells, specifically the lymphocytes (B cells and T cells), will respond to the introduced molecules and proteins that will be identified by his immune system as not belonging to him (nonself).

2. d: Both B cells and T cells respond to invasion from nonself materials. T cells tend to attack the pathogens more directly. B cells produce antibodies that either attack the invader or “call in the troops” (other cells) for an attack.

3. a: Although IgG constitutes most of the antibodies in your bloodstream, it is produced only after a second exposure to an antigen. In this case, a first exposure to the flu antigens will produce primarily IgM antibodies.

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Chapter 33 | Adaptive Immunity ______________________________________________________________

4. c: Pyrogens (as in pyrotechnics or pyromaniac) are the molecules that can trigger an increased temperature “set point” in the body.

5. b: Because the antigens were intentionally introduced into his body, this immunity would have to be artificial. Because they were antigens and not already developed antibodies, his body will have to work to create the antibodies; that makes this artificial active immunity.

Answers to Review Questions (p. 784) 1. Antigens are macromolecules that induce the immune system to make certain responses.

Antibodies are plasma proteins of the immunoglobulin class that destroy or inactivate specific antigens.

Antigenic determinants are variously-shaped small regions on the surface of an antigen molecule that allow the lymphocyte to recognize the antigen.

Combining sites are two small concave regions on the surface of an antibody molecule. The combining sites are shaped so that an antigen’s antigenic determinant, or epitope (which has a complementary shape), can fit into the combining site and thereby bind the antigen to the antibody.

Clones are a family of cells that have descended from one cell.

2. Two terms that are synonyms for combining sites are antigen receptors and antigen-binding sites.

3. The epitope, or antigenic determinant, of the antigen fits into the combining site of the antibody.

4. B cells produce clones of two types: plasma cells and memory B cells.

5. Plasma cells synthesize and secrete copious amounts of antibodies.

6. Memory B cells do not themselves secrete antibodies, but if they are later exposed to the antigen that triggered their formation, memory B cells become plasma cells, which secrete antibodies that can combine with the initiating antigen.

7. Antibodies belong to a class of compounds called immunoglobulins. Each immunoglobulin molecule consists of four polypeptide chains—two light chains and two heavy chains. Each polypeptide chain is folded to form globular regions that, as a whole, are Y shaped. Each light chain consists of one variable region and one constant region. Each heavy chain consists of one variable region and three constant regions. Disulfide bonds join the two heavy chains to each other and also bind the heavy chain to its adjacent light chain. An antibody has two antigen-binding sites, one at the top of each pair of variable regions. It also has two complement binding sites. Students’ diagrams should be based on Figure 33-7.

8. The two tenets of Burnet’s clonal selection theory are as follows: First, the body contains an enormous number of diverse clones of cells, each committed by certain of its genes to synthesize a different antibody.

Second, when an antigen enters the body, it selects the clone whose cells are committed to synthesizing its specific antibody and stimulates these cells to proliferate and produce antibodies.

9. Cytokines are chemical factors released by T cells. They include chemotactic factors, migration-inhibiting factors, and macrophage activating factor. Lymphotoxins are powerful poisons that act by quickly killing any cell they attack.

10. In natural immunity, the exposure to the causative agent is not deliberate. In artificial immunity the exposure to the causative agent is deliberate.

11. Modern vaccines work by exposing the body to substances that trigger the formation of antibodies against specific pathogens; the vaccines are introduced orally or by injection. These vaccines can be killed pathogens, live attenuated pathogens, or parts of the pathogen that contain the antigen. This triggers the formation of the proper antibodies.

12. Monoclonal antibodies are specific antibodies produced by or derived from a population or culture of identical cells. B lymphocytes that have been activated by the injection of a specific antigen are harvested and fused with other cells that have been transformed to grow and divide indefinitely in culture media. The cells, called hybridomas, continue to produce the same antibody produced by the original lymphocyte. The result is a rapidly growing population of identical cells that produce large quantities of a specific antibody.

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Answers to Critical Thinking Questions (p. 784) 1. There are two types of T cells that can fine-tune a response by the immune system. Helper T cells help B cells differentiate into antibody-secreting plasma cells. Suppressor T cells act to suppress B cell differentiation and help end the immune response.

2. Cancer cells frequently form in the body. Lymphocytes should discover and destroy them while there are only a few cells. If the lymphocytes are fooled and the cancer becomes too large, the lymphocytes will be unable to destroy it. In this regard, the development of cancer can be seen as a failure of the immune system.

3. Inherited immunity occurs when a specific or nonspecific immune mechanism is put in place by genetic mechanisms during the early stages of human development in the womb. Acquired immunity is resistance to disease that develops after we are born.

4. HIV attaches to specific receptors on the surface of a T cell. Viral RNA, which is used to synthesize a DNA molecule, is then released into the cytoplasm. This new “viral” DNA is then spliced into the cell’s chromosomal DNA. After a latency period (usually several years), the viral DNA initiates transcription of RNA molecules. The new RNA molecules direct synthesis of HIV, RNA, and HIV proteins. The cell assembles whole HIV particles. Finally, new HIV viruses are released from the cell by lysis. They are now free to infect more cells.

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Instructor’s Resource Material for

34 Stress ANSWER KEYS

Answers to Quick Check Questions 1. Stress syndrome is a set of signs and symptoms that occur together but seem to be characteristic of one particular disease. Stress is a state, or condition, of the body produced by “diverse nocuous agents” and manifested by a syndrome of changes.

2. Hans Selye identified enlarged adrenal glands, shrunken lymphatic organs, and bleeding gastrointestinal ulcers as being the three “stress triad” changes.

3. Four characteristic of stressors are: (1) Stressors are extreme stimuli. (2) They are very often injurious, unpleasant, or painful stimuli. (3) Anything that an individual perceives as a threat (emotions) acts as a stressor, and (4) stressors differ in different individuals and in one individual at different times.

4. The syndrome or group of changes that makes the presence of stress in the body known is called the general adaptation syndrome.

5. The three stages of the general adaptation syndrome are: (1) the alarm reaction, (2) the stage of resistance, and (3) the stage of exhaustion. Among the responses of the alarm reaction are hypertrophied adrenal cortex, atrophied lymphatic organs, and bleeding gastric and duodenal ulcers. The responses that characterize the stage of resistance are the adrenal cortex and medulla return to their normal rates of hormone secretion. If stress continues until the body reaches the stage of exhaustion, corticoid secretion and adaptation eventually decrease markedly.

6. Stress activates the organs that produce responses that make up the general adaptation syndrome. “Alarm signals,” presumably through the hypothalamus, stimulate the sympathetic nervous system and the pituitary gland. These actions lead to the secretion of epinephrine and adrenocorticotropic hormone (ACTH), hypertrophy of the adrenal cortex, and increased secretion of glucocorticoids.

7. “Diseases of adaptation” occur when the body’s adaptive mechanisms fail to meet the challenge issued by stressors. When they fail, disease results.

8. The fight-or-flight reaction is a stimulation of sympathetic centers by impulses from the stress-stimulated hypothalamus. This leads to many stress responses, such as increase in rate and strength of heartbeat, a rise in blood pressure, hyperglycemia, pallor and coolness of skin, sweaty palms, and dry mouth.

9. Answers may include an increase in the rate and force of the heartbeat, a rise in systolic blood pressure, an increase in blood and urine concentration of epinephrine and norepinephrine, sweating of the palms and hands, dilation of pupils, an increased amount of urinary adrenocorticoids, and an increased level of adrenocorticoids in the blood plasma.

10. Physiological stress refers to the condition or state of the body. Psychological stress refers to the state of the mind.

Answers to Case Study Questions (p. 796) 1. d: The general adaptation syndrome (or stress response) follows a particular pattern. The first stage, the alarm reaction, involves a stimulation of the sympathetic nervous system. Jiang-Mei’s increased heart rate; dry mouth, sweaty palms, and likely increased blood pressure are all fight-or-flight responses. These are meant to allow your body to survive. Imagine a bear chasing you; you would need these responses to get away from the bear. Strangely, though, your body does not differentiate between a bear chasing you and a physiology test you have not studied for. They are both perceived as a threat.

2. b: The hypothalamus responds to the perceived threat and releases corticotropin-releasing hormone (CRH).

This hormone stimulates the anterior pituitary gland to release adrenocorticotropic hormone (ACTH). ACTH targets the adrenal cortex, which increases secretion of cortisol.

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Chapter 34 | Stress _______________________________________________________________________

3. d: The “stress triad” identified by Selye includes enlarged lymphatic organs, enlarged adrenal glands (from the increased CRH and ACTH), and bleeding gastrointestinal ulcers. A decrease in lymphatic organs is associated with a decline in immune function.

4. a: Your body can respond to a variety of stressors. If your body considers something to be a threat, the same physiological reaction occurs whether the perceived threat is real or imagined. However, what you perceive as a threat may seem totally harmless to someone else (like Jiang-Mei’s friend). Although it may seem a little counterintuitive, stressors may be intensely negative or intensely positive. A similar reaction occurs in response to winning a race (elation, increased heart rate) as to running from a bear. This stress response is intact in a developing fetus, too—for example, the prenatal stress experienced with fetal alcohol syndrome.

Physical and emotional stress experienced by the mother may have an impact on the fetus as well.

Answers to Review Questions (p. 798) 1. Stress is a state or condition of the body produced by diverse noxious agents and manifested by a syndrome of changes. A stressor is any agent or stimulus that produces stress. The general adaptation syndrome is a syndrome or group of changes that makes the presence of stress known to the body.

2. Stressors can be any extreme stimuli; they are often injurious, unpleasant, or painful. Anything that an individual perceives as a threat, whether real or imagined, can be a stressor. Stressors differ from individual to individual and in the same individual from one point in time to another.

3. The three stages that make up the general adaptation syndrome are (1) the alarm stage, in which there is an increase in glucocorticoid secretions, an increase in the activity of the sympathetic nervous system, increased norepinephrine secreted by the adrenal medulla, the initiation of the fight-or-flight response, and a lowered resistance to stressors; (2) the resistance stage, in which glucocorticoid secretions return to normal, sympathetic nervous system activity returns to normal, norepinephrine secretions return to normal, the fightor-flight response disappears, and there is a higher resistance to stressors; and (3) the exhaustion stage, in which glucocorticoid secretion initially increases but eventually decreases, the stress triad appears, and there is a loss of resistance to stressors. This final stage may lead to death.

4. The “stress triad” consists of hypertrophied adrenal glands, atrophied thymus gland and lymph nodes, and bleeding ulcers in the stomach or duodenum.

5. An increase in glucocorticoids, epinephrine, and norepinephrine secretions brings about the changes in the general adaptation syndrome.

6. Selye thought the general adaptation syndrome seemed to protect the animals from serious damage by extreme stimuli and to promote their healthy survival. He looked on the syndrome as a crucial part of the body’s defense mechanism.

7. According to the current operational definition, stress is any stimulus that directly or indirectly stimulates neurons of the hypothalamus to release corticotropin-releasing hormone (CRH). This acts as a trigger, which initiates many diverse changes in the body.

8. The part of the brain that plays the key role in initiating the stress syndrome response is the hypothalamus.

9. The limbic lobe and part of the cerebral cortex are also involved in inducing the stress syndrome.

10. ACTH stimulates the adrenal cortex to secrete greatly increased amounts of cortisol and aldosterone. ADH causes an increase in water absorbed from the urine and decreases urine volume. Aldosterone increases sodium and water reabsorption. Cortisol causes increased catabolism of tissue protein; glyconeogenesis, producing hyperglycemia; decreased lymphocyte and immune responses; and decreased eosinophils and allergic responses. CRH stimulates the anterior pituitary gland to secrete increased amounts of ACTH. Epinephrine and norepinephrine initiate the fight-or-flight response, which includes increased heart rate, blood pressure, and blood glucose concentration.

11. Some clinical evidence seems to indicate that corticoids do increase a human’s coping ability.

12. No one has proven by an unequivocal experiment that a higher-than-normal blood level of corticoids increases an animal’s ability to cope with stress.

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13. The text states that a psychological stressor is “anything that an individual perceives as a threat to survival or self-image, either real or imagined.” Any examples that fit these criteria are acceptable.

14. Psychological stressors are not the same for all individuals. The feelings of anxiety, anger, hate, depression, fear, and guilt may vary from one individual to another.

15. Some subjective indicators of psychological stress are anxiety, anger, hate, depression, fear, and guilt.

16. Examples of objective responses that are part of the syndrome of psychological stress are restlessness, fidgeting, criticizing, quarreling, lying, crying, and an increase in lactic acid levels in the blood.

Answers to Critical Thinking Questions (p. 798) 1. In Selye’s experiments, rats were injected with various extracts of ovaries, placenta, pituitary gland, kidney, spleen, and even poisons; the reaction of the rats was the same to each of the stressors. The cortexes of the adrenal glands were enlarged, their lymphatic organs were atrophied, and they developed bleeding ulcers. He determined that it was not a reaction to a specific substance but to any and all kinds of harmful stimuli.

2. Selye proposed that sometimes the body’s adaptive mechanisms fail to meet the challenge issued by stressors, and disease results. He called these the diseases of adaptation. It has been postulated that stress and stressrelated syndrome tend to augment age-related changes in the body. This would make older adults more susceptible to stress-related diseases. Also, the high-stress, hard-driving type A individuals have been found to be at greater risk of elevated blood pressure and coronary disease than the more relaxed, less impatient type B personality.

3. Increase in rate and force of heartbeat; a rise in systolic blood pressure; an increase in blood and urine concentrations of epinephrine, norepinephrine, and adrenocorticoid hormone; sweating in the palms of the hand; and dilated pupils would be observations or clinical test results that would indicate an individual was under stress.

4. When the Chinese suspected a person of lying, they made him chew rice powder and spit it out. If the powder came out dry, they judged the person guilty. The person who was lying was under stress. This caused the release of epinephrine and norepinephrine, which suppressed the secretion of saliva, which kept the rice powder dry. There is some psychophysiological support for the rice powder test.

5. Stress as defined by Selye is physiological stress; that is, a state of the body. Psychological stress is defined as state of the mind. Physiological stress almost always is accompanied by psychological stress. In most people, psychological stress leads to some physiological stress responses. Identical psychological stressors do not always induce identical physiological responses in different individuals. In any one individual, certain autonomic responses are better indicators of psychological stress than others.

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Instructor’s Resource Material for

35 Respiratory Tract ANSWER KEYS Answers to Quick Check Questions

1. The respiratory system functions as an air distributor and a gas exchanger. It filters, warms, and humidifies the air we breathe; influences sound production; and makes the sense of smell possible with specialized epithelium in the respiratory tract. The respiratory system also plays an important role in the regulation, or homeostasis, of pH in the body.

2. The principal organs of the upper respiratory tract are the nose, nasopharynx, oropharynx, laryngopharynx, and larynx. The principal organs of the lower respiratory tract include the trachea, all segments of the bronchial tree, and the lungs.

3. The paranasal sinuses are air-containing spaces that open, or drain, into the nasal cavity. The paranasal sinuses are located in the skull bones (frontal, maxillary, ethmoid, and sphenoid).

4. The three main divisions of the pharynx are the nasopharynx, oropharynx, and laryngopharynx.

5. The pharyngeal tonsils are located in the nasopharynx on its posterior wall opposite the posterior nares. The palatine tonsils are located behind and below the pillars of the fauces. The lingual tonsils are located at the base of the tongue.

6. When air is expired through the glottis, it causes the true vocal cords to vibrate, thus producing sound. The false vocal cords are the upper pair of folds that jut into the cavity of the larynx. They play no part in vocalization.

7. C-shaped rings of cartilage give firmness to the walls of the trachea and bronchi, tending to prevent them from collapsing and shutting off vital airways.

8. The trachea and the two primary bronchi and their many branches resemble an inverted tree trunk, which is why it is called the bronchial tree.

9. Each alveolus is extremely thin walled and lies in contact with the blood capillaries, thereby facilitating gas exchange.

10. Each lung is divided into lobes by fissures. The left lung is partially divided into two lobes and the right lung into three lobes. The lobes of the lungs are further divided into functional units called bronchopulmonary segments, which consist of the almost innumerable tubes that serve as air distributors.

11. When the diaphragm contracts, it flattens out and thus pulls the floor of the thoracic cavity downward, enlarging the volume of the thorax. When the diaphragm relaxes, it returns to its resting, domelike shape, thus reducing the volume of the thoracic cavity.

Answers to Case Study Questions (p. 821) 1. b: The oropharynx is located just behind the mouth. The next part of the pharynx (heading toward the lungs) is the laryngopharynx. Air then passes through the larynx and into the trachea.

2. c: The trachea branches into two large tubes called primary bronchi (singular, bronchus).

3. d: The trachea and bronchi are lined with pseudostratified ciliated columnar epithelium. The cilia assist in trapping and moving small dust particles.

4. a: The epiglottis is a flap of cartilage that normally moves during swallowing to cover the larynx so that food (and liquids) will go down the esophagus.

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Chapter 35 | Respiratory Tract ______________________________________________________________

Answers to Review Questions (p. 823) 1. The anatomical structures of the nose are the ala, palatine bones, cribriform plate, septum, turbinates, anterior nares, and vestibule.

2. Each nasal cavity is divided into three passages by the projections of the turbinates from the lateral walls of the internal portion of the nose. The superior and middle turbinates are processes of the ethmoid bone, whereas the inferior turbinates are separate bones.

3. The frontal, maxillary anterior, and middle ethmoid sinuses drain into the middle meatus. The posterior ethmoid sinuses drain into the superior meatus, and the sphenoid sinuses drain into the space above the superior turbinates.

4. The pharyngeal tonsils are located in the nasopharynx.

5. The right and left auditory or eustachian tubes and the two posterior nares open into the nasopharynx.

6. The pharynx is common to both the respiratory and digestive systems.

7. The two named divisions of the larynx given in the text are (1) the laryngeal cavity above the false vocal cords, called the vestibule, and (2) the very short middle portion of the cavity between the false and true vocal cords, called the ventricle.

8. The voice box is another name for the larynx. The larynx consists largely of cartilages attached to one another and to the surrounding structures by muscle or fibrous and elastic tissue components. It is lined by a ciliated mucous membrane. The Adam’s apple is another name for the thyroid cartilage.

9. The epiglottis is a small leaf-shaped cartilage that projects upward behind the tongue and hyoid bone. It is attached below to the thyroid cartilage, but its free superior border can move up and down. The function of the epiglottis is to prevent food from entering the trachea during swallowing.

10. The mucous membrane lining the larynx forms two pairs of folds that jut inward into its cavity. The lower pair of folds serves as the true vocal cords. The opening between the vocal cords is called the rima glottidis.

11. The trachea is a tube about 11 cm long that extends from the larynx in the neck to the primary bronchi in the thoracic cavity. It has a diameter of about 2 to 5 cm. The wall of the trachea is made up of smooth muscle in which are embedded C-shaped rings of cartilage. The rings are incomplete on the posterior surface. The trachea is lined with the type of pseudostratified ciliated columnar epithelium typical of the respiratory tract.

The trachea is part of the open passageway through which air can reach the lung from the outside.

12. The trachea divides at its lower end into two primary bronchi. These divide into secondary and tertiary bronchi and into small bronchioles. The bronchioles divide into smaller and smaller tubes, eventually terminating in microscopic branches that divide into alveolar ducts, which terminate in several alveolar sacs.

13. The student’s diagrams should look something like Figure 35-13 in the textbook.

14. The right lung is divided into three lobes; the left lung is divided into two lobes. Bronchopulmonary segments are subdivisions of a lobe of the lung that act as functional units. Each segment is served by a tertiary bronchus. There are ten segments in the right lung and eight segments in the left lung.

15. When the chest is raised and the diaphragm contracts, the thorax becomes larger and air comes into the lung; this is inspiration. When the chest is lowered and the diaphragm relaxes, the thorax becomes smaller and the air is forced out of the lung; this is expiration.

16. The upper respiratory tract is composed of the nose, nasopharynx, oropharynx, laryngopharynx, and larynx.

The lower respiratory tract consists of the trachea, all of the segments of the bronchial tree, and the lungs.

17. Current research suggests that the vomeronasal organ may play a role in detection of complex body chemicals called pheromones.

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Answers to Critical Thinking Questions (p. 823) 1. The respiratory mucosa in the nasal passages consists of pseudostratified ciliated columnar epithelium that is rich in goblet cells. The respiratory tract is lined with ciliated mucous membrane. The function of the mucosa is to humidify the air and help clean it.

2. The olfactory epithelial area of the mucosa contains many nerve cells. The production of mucus is especially important in this area because, for the sense of smell to be stimulated, the material must be dissolved in the mucus.

3. The right and left auditory tubes and the two posterior nares open into the nasopharynx. The mouth opens into the oropharynx, and the larynx and esophagus open into the laryngopharynx. The pharyngeal tonsils are located in the nasopharynx; the palatine and lingual tonsils are located in the oropharynx. Changes in the shape of the pharynx allow for the formation of different vowel sounds.

4. The arytenoid cartilages are the most important of the paired cartilages, because they serve as points of attachment for the vocal cords.

5. The epiglottis is associated with epiglottitis, a potentially life-threatening condition in children. The symptoms include a high fever and anxiety. Also, the child appears ill, is sitting straight up, is unable to swallow, and is drooling from an open mouth.

6. Because of the polarity of water, the molecules have a strong attraction to one another. Because the alveoli are lined with fluid that is primarily water, they would tend to collapse during expiration. This problem is solved by the respiratory system through the production of surfactant, which tends to disrupt the attractive force between the water molecules.

7. Air distribution refers to air being carried to the interior of the lung. Gas exchange refers to the exchange of oxygen and carbon dioxide between the respiratory system and the transport system. The nasal passages, pharynx, larynx, trachea, and most of the bronchial tree are involved in air distribution. The alveoli and the tiny tubes that open into them serve as gas exchangers.

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Instructor’s Resource Material for

36 Ventilation ANSWER KEYS

Answers to Quick Check Questions 1. Pulmonary ventilation is a technical term for what most of us call breathing.

2. Enlargement of the thoracic cavity reduces air pressure inside the lungs.

3. Inspiration requires more energy expenditure.

4. Pulmonary capacity is the sum of two or more pulmonary volumes. Pulmonary volumes include tidal volume, inspiratory reserve volume, and expiratory reserve volume.

5. Tidal volume is the amount of air expired after a normal inspiration.

6. Vital capacity represents the largest volume of air an individual can move in and out of the lungs.

7. Total minute volume is the volume of air moved per minute. Tidal volume (milliliters per cycle) multiplied by respiration rate (cycles per minute) yields the total minute volume (milliliters per minute).

8. The chief regulatory centers of respiratory function are located in the brainstem.

9. Changes in the carbon dioxide pressure (PCO2), oxygen pressure (PO2), and pH of systemic arterial blood all influence the medullary rhythmicity area. PCO2 increases stimulate chemoreceptors, which results in faster breathing. Decreases produce an opposite effect. Decreases in arterial blood pH have a stimulating effect on chemoreceptors, resulting in an increase in the breathing rate. The role of arterial blood P CO2 is not entirely clear. Other factors include arterial blood pressure, which controls breathing through the respiratory pressor reflex mechanism. A rise in blood pressure results in a slowing of respirations. A drop in blood pressure would result in an increase of the rate and depth of respirations. Hering-Breuer reflexes help control respirations by stimulating stretch receptors within the lungs. When lungs are expanded, the stretch receptors are stimulated and send inhibitory messages to the inspiratory center, relaxing the inspiratory muscles.

Finally, the cerebral cortex can influence breathing by voluntarily increasing or decreasing the respiration rate.

Answers to Case Study Questions (p. 845) 1. c: For inspiration to occur, the thoracic cavity must be enlarged. The rectus abdominis muscle may assist with forced expiration but not inspiration.

2. b: When the thoracic cavity enlarges, the alveolar pressure drops (Boyle’s law). This causes air to move from the outside (higher atmospheric pressure) to inside (lower alveolar pressure).

3. b: Vital capacity is the sum of: Inspiratory reserve volume + tidal volume + expiratory reserve volume. Using Derrick’s pulmonary capacity numbers (IRV: 2900 ml + TV: 490 ml + ERV: 1000 ml), his vital capacity is 4390 ml.

4. d: Air in the pleural space may accumulate when the visceral pleura ruptures and air from the lung rushes out or when atmospheric air rushes in through a wound in the chest wall and parietal pleura. In either case, the lung collapses and normal respiration is impaired. Air in the thoracic cavity is a condition known as pneumothorax.

Answers to Review Questions (p. 847) 1. Respiratory physiology is a complex series of interacting and coordinated processes that play a critical role in maintaining the stability, or constancy, of our internal environment—specifically, the supply of adequate oxygen and the prompt removal of carbon dioxide.

2. The diaphragm is the main inspiratory muscle.

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Chapter 36 | Ventilation ____________________________________________________________________

3. Tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume make up the total lung capacity.

4. About 30% of the tidal volume normally fills the anatomical dead air space.

5. About 70% of the tidal volume normally ventilates the alveoli.

6. The major factors that influence breathing are blood oxygen tension, blood carbon dioxide tension, and blood pH. 7. Orthopnea is common in patients with heart disease.

8. Dyspnea, which is labored breathing, is often associated with hypoventilation.

9. The diving reflex is responsible for the recovery of drowning victims who have been submerged for more than 40 minutes. Survivors are most often preadolescent children who have been immersed in water below 20° C. The colder the water, the better the chance of survival. Studies have shown that when the head and face are immersed in ice-cold water, there is an immediate shunting of blood to the core of the body area with peripheral vasoconstriction and slowing of the heart. Metabolism is slowed, and the tissue requirements for oxygen and nutrients decrease. The diving reflex is a protective response to cold water immersion and is a function of water temperature, age, lung volume, and posture.

10. The four reflexes that indirectly affect breathing are the cough reflex, sneeze, hiccup, and yawn. The cough reflex occurs when foreign matter enters the trachea or bronchi. The epiglottis and glottis reflexively close, and a contraction of expiratory muscles cause air pressure in the lung to increase. The epiglottis and glottis then open suddenly, resulting in an upward burst of air that removes the contaminants. The sneeze reflex is stimulated by contaminants in the nasal cavity. A burst of air is directed through the nose and mouth, forcing the contaminants out of the respiratory tract. The hiccup is an involuntary spasmodic contraction of the diaphragm. When this occurs, generally at the beginning of inspiration, the glottis suddenly closes, producing the characteristic sound. The yawn is a slow, deep inspiration through an unusually widened mouth.

11. Respiration increases abruptly at the beginning of exercise and decreases even more markedly as it ends. The mechanism that explains why this occurs is still unknown.

Answers to Critical Thinking Questions (p. 847) 1. The proper functioning of the respiratory system ensures the tissues of an adequate oxygen supply and the prompt removal of carbon dioxide. This complex function would not be possible without integration between other control systems, such as acid-base, water and electrolyte balance, circulation, and metabolism.

2. The respiratory system accomplishes its main function with a variety of processes, including pulmonary ventilation, gas exchange in the lungs and tissues, transport of gases by the blood, and the overall regulation of respiration.

3. Pulmonary ventilation is the technical term for breathing. It includes inspiration and expiration. The lungs are passive during this process. It is the expansion and contraction of the thoracic cavity that moves air in and out of the lungs, and the changes in the size of the thoracic cavity depend on the activity of the diaphragm and the other respiratory muscles, not on the lungs.

4. In inspiration, the diaphragm contracts, moving downward toward the abdomen. This increases the volume of the thoracic cavity, which causes a decrease in pressure in the thoracic cavity, causing air to rush into the lungs. During expiration, the diaphragm relaxes, moving up toward the thorax. This decreases the size of the thoracic cavity, which increases the pressure, which in turn forces air out of the lungs. Elastic recoil refers to the tendency of the thorax and lung to return to their preinspiration volume. If disease reduces this, expiration must be forced, even at rest. Compliance refers to the ability of the lungs and the thorax to stretch. If this is reduced by injury or disease, inspiration becomes difficult or impossible.

5. Infant respiratory distress syndrome usually occurs in premature or newborn babies. It is usually caused by a lack of surfactant in the lung. Without this surfactant, many air sacs collapse during expiration because of the increased surface tension of water. The effort required to reinflate the collapsed alveoli is much greater than that needed when there is adequate surfactant. The baby soon develops labored breathing, and the symptoms of respiratory distress appear shortly after birth. Adult respiratory distress syndrome is caused by impairment

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___________________________________________________________________ Chapter 36 | Ventilation

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or removal of surfactant in the alveoli by the accidental inhalation of foreign substances. Edema in the alveolar tissue can impair surfactant and reduce the alveoli’s ability to stretch, causing respiratory distress.

6. During inspiration, the diaphragm contracts, increasing the volume of the thoracic cavity. If an athlete, after strenuous exercise, bends over or sits down, he or she decreases the volume of the thoracic cavity, thus reducing the amount of oxygen and increasing the time it would take to return to normal breathing. The athlete should “cool down” by remaining upright with hands on head to maximize thoracic volume.

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Instructor’s Resource Material for

37 Gas Exchange and Transport ANSWER KEYS Answers to Quick Check Questions 1. According to the law of partial pressures, the partial pressure of a gas in a mixture of gases is directly related to the concentration of that gas in the mixture and to the total pressure of the mixture.

2. Oxygen continues diffusing across the respiratory membrane as long as there is a pressure gradient.

3. The four major factors that influence how much oxygen diffuses into pulmonary blood per minute are (1) the oxygen pressure gradient between alveolar air and incoming pulmonary blood, (2) the total functional surface area of the respiratory membrane, (3) the respiratory minute volume, and (4) alveolar ventilation are factors that influence oxygen diffusion. The student is asked to list two.

4. Most oxygen in the blood is transported in the form of oxyhemoglobin.

5. Most carbon dioxide in the blood is transported in the form of bicarbonate ions.

6. Oxyhemoglobin is the result of oxygen combining with hemoglobin. Carbaminohemoglobin is the result of carbon dioxide combining with hemoglobin.

7. Carbon dioxide lowers the pH by increasing the H+ ions in the blood.

8. The increased carbon dioxide pressure (PCO2) in systemic tissues decreases the affinity between hemoglobin and oxygen.

9. Increasing PCO2 and decreasing oxygen pressure (PO2) favor carbon dioxide association with hemoglobin to form carbaminohemoglobin.

Answers to Case Study Questions (p. 858) 1. a: As carbon dioxide increases, there is also an increase in hydrogen ions. This would make the blood more acidic.

2. d: Most carbon dioxide (~70%) is carried in the form of bicarbonate. It can also be carried bound to hemoglobin (~20% to 25%) and dissolved in the plasma (~10%).

3. a: Oxygen travels in two forms: as dissolved O2 in the plasma and as O2 associated with hemoglobin (oxyhemoglobin).

Answers to Review Questions (p. 859) 1. One gram of hemoglobin can combine with 1.34 ml of oxygen.

2. Factors that influence the amount of oxygen that diffuses into the blood from the alveoli include the amount of hemoglobin in the blood and the blood oxygen tension.

3. Increasing PCO2 and decreasing PO2 together produces two effects: they favor oxygen dissociation from oxyhemoglobin and carbon dioxide association with hemoglobin to form carbaminohemoglobin.

4. Carbon dioxide is carried in the blood through dissolved CO 2 in plasma, unites with NH2 (amine) groups to form carbamino compounds, and in the form of bicarbonate ions.

5. Oxygen is transported in the blood as dissolved O2 in the plasma and as O2 associated with hemoglobin (oxyhemoglobin).

6. Of the two forms of transport, oxyhemoglobin carries the vast majority of the total oxygen transported by the blood.

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Chapter 37 | Gas Exchange and Transport _____________________________________________________

Answers to Critical Thinking Questions (p. 859) 1. There is a reciprocal relationship between oxygen and carbon dioxide transport mechanisms. Increases in the carbon dioxide tension decrease the affinity between oxygen and hemoglobin. This allows more oxygen to be released to the tissues. This mechanism is called a right shift or the Bohr effect. A drop in plasma pH, which normally accompanies an increase in blood carbon dioxide tension, also causes a right shift. There is also an increase in carbon dioxide loading into the blood caused by a drop in the oxygen tension in the blood. As the blood gives up more oxygen, carbon dioxide loading is facilitated. This mechanism is referred to as the Haldane effect.

2. One gram of hemoglobin, fully saturated, can carry 1.34 ml of oxygen. If 15 grams of hemoglobin were 97% saturated, this would carry 19.497 ml of oxygen (15  1.34  0.97 = 19.497).

3. As the rate of oxygen used by the cells increases, intracellular and interstitial P O2 decreases. This tends to increase the oxygen pressure gradient between blood and tissues, which accelerates oxygen diffusion out of the tissue capillaries. In this way, the rate of oxygen used by the cells automatically tends to regulate the rate of oxygen delivery to cells.

4. Air in the alveolus is always a mix of incoming air (high P O2) and outgoing “used” air (low PO2). Because some of the alveolar air had already had some of its oxygen transported into the blood, it will always have a lower PO2 than “fresh” air that has not entered the respiratory tract.

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Instructor’s Resource Material for

38 Upper Digestive Tract ANSWER KEYS Answers to Quick Check Questions 1. The digestive tract is also called the gastrointestinal (GI) tract or alimentary canal.

2. Mucosa, submucosa, muscularis, and serosa are the layers of the digestive tract.

3. The lips surrounding the orifice of the mouth, the cheeks, the tongue and its muscles, and the hard and soft palates are the boundaries of the oral cavity.

4. Taste buds are located in a moatlike depression on the lateral surfaces of the papillae and on the sides of the fungiform papillae, which are chiefly on the sides and tip of the tongue.

5. Parotid, sublingual, and submandibular are the salivary glands.

6. Parotids (para-, beside; -ous, ear) are the largest of the salivary glands. They are located between the skin and underlying masseter muscle in front of and below the external ear. Submandibular glands are located just below the mandibular angle. Sublingual glands lie in front of the submandibular glands under the mucous membrane covering the floor of the mouth.

7. The three main parts of a typical tooth are the crown, neck, and root.

8. Only the terminal portions of the pharynx serve the digestive system. After a bolus has passed through the pharynx, it enters the digestive tube proper—the portion of the digestive tract that serves only the digestive system.

9. The esophagus is the first segment of the digestive tube proper. It extends from the pharynx to the stomach, piercing the diaphragm in its descent from the thoracic cavity to the abdominal cavity. It lies posterior to the trachea.

10. The main divisions of the stomach are the fundus, body, and pylorus.

11. Gastric pits are depressions within the epithelial lining of the stomach.

Answers to Case Study Questions (pp. 878-879) 1. d: The mucosa is the inner lining of the alimentary tract—from the esophagus all the way through to the anus.

2. a: The upper esophageal sphincter is located in the cervical part of the esophagus. The lower esophageal sphincter (cardiac sphincter) is located at the junction of the stomach. The pyloric sphincter controls the opening from the pyloric portion of the stomach into the first part of the small intestine (duodenum).

3. c: Gastric glands within the stomach secrete most of the gastric juice, a mucous fluid containing digestive enzymes and hydrochloric acid (HCl). Amylase is secreted by the salivary glands and the pancreas.

Answers to Review Questions (p. 881) 1. The component parts or segments of the gastrointestinal (GI) tract include the mouth; oropharynx; esophagus; stomach; duodenum, jejunum, and ileum of the small intestine; cecum; ascending colon, transverse colon, descending colon, sigmoid colon of the large intestine; rectum; and anal canal. The accessory organs of the digestive system include the parotid, submandibular, and sublingual salivary glands; tongue; teeth; liver; gallbladder; pancreas; and vermiform appendix.

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Chapter 38 | Upper Digestive Tract ___________________________________________________________

2. The four tissue layers that form the wall of GI tract organs are the mucosa, submucosa, muscularis, and serosa.

The mucosa is the innermost layer of the GI wall. It is made up of three layers: an inner layer called the mucous epithelium, a middle layer of loose connective tissue called the lamina propria, and an outer thin layer of smooth muscle called the muscularis mucosae.

The next layer in the GI wall is the submucosa. It is composed of connective tissue and contains numerous small glands, blood vessels, and parasympathetic nerves that form the submucosal plexus.

The next GI layer is the muscularis. It is a thick layer of muscle tissue that wraps around the submucosa. This portion of the wall is characterized by an inner layer of circular muscle and an outer layer of longitudinal smooth muscle.

The outermost layer of the GI wall is the serosa. It is made up of connective tissue and peritoneum.

3. The structures that form the mouth include the lips, the cheeks, the tongue and its muscles, and the hard and soft palates.

4. The philtrum is a shallow vertical groove near the midline of the upper lip.

The oral fissure refers to the line of contact between the upper and lower lips when the mouth is closed.

The hard palate is the roof of the mouth. It is made up of four bones: two maxillae and two palatines.

The soft palate is made of muscle arranged in the form of an arch. It forms a partition between the mouth and nasopharynx.

The fauces is the name given to the opening in the arch formed by the soft palate, which leads from the mouth to the oropharynx.

The uvula is a small cone-shaped process that is suspended from the midpoint of the posterior border of the arch formed by the soft palate.

The foramen cecum is a median pit in the tongue.

The lingual frenulum is a fold of mucous membrane in the midline of the undersurface of the tongue to the floor of the mouth.

5. Ankyloglossia is a congenital condition in which the lingual frenulum is too short for free tongue movements.

The individual is said to be “tongue-tied,” and speech is faulty.

6. There are three types of papillae: the vallate, the fungiform, and the filiform. Dissolved substances to be tasted enter a moatlike depression surrounding the vallate papillae to contact the taste buds located on their lateral surface. Taste buds are also located on the sides of the fungiform papillae, which are found chiefly on the sides and tip of the tongue.

7. The parotids are located between the skin and the underlying masseter muscle in front of and below the external ear. The parotid, or Stensen, ducts drain the parotid glands. The submandibular glands are located just below the mandibular angle. They are irregular in form and about the size of a walnut. The Wharton ducts drain the submandibular glands. The sublingual glands lie in front of the submandibular glands under the mucous membrane covering the floor of the mouth. The sublingual glands are drained by the ducts of Rivinus.

8. The parotid glands produce a watery, or serous, type of saliva containing enzymes but no mucus. The term mixed, or compound, salivary gland refers to salivary glands that produce both serous or enzyme saliva and mucus saliva.

9. A typical tooth can be divided into three parts: the crown, the neck, and the root. The crown is the exposed part of the tooth. It is covered by enamel. The neck is the narrow portion that is surrounded by gingivae. The neck joins the crown of the tooth to the root. The root fits into the socket of the alveolar process of either the upper or lower jaw. The root may have a single peglike structure, or it may have two or three conical projections. Teeth can be of four types: incisors, canines, premolars, and molars.

10. Early in life 20 deciduous, or baby, teeth appear, to be replaced later by 32 permanent teeth. The first deciduous tooth usually erupts at about 6 months, with the rest following at the rate of one or more a month until all 20 have appeared. Deciduous teeth are generally shed between ages 6 and 13 years and then replaced by permanent teeth, ending with the third molars, or wisdom teeth, which usually appear after 17 years of age.

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11. Deglutition is the act of swallowing.

12. The stomach has three divisions: fundus, body, and pylorus.

13. The three major types of cells in the gastric glands are the chief cells, parietal cells, and the endocrine cells.

Parietal cells produce hydrochloric acid, endocrine cells secrete ghrelin and gastrin, and chief cells produce gastric enzymes.

14. The seven functions of the stomach are (1) it serves as a reservoir, storing food until it can be partially digested and moved farther along the GI tract; (2) it secretes gastric juices containing acids and enzymes to aid in the digestion of food; (3) through contractions of its muscular coat, it churns food, breaking it into small particles, mixing it with gastric juice, and moving gastric contents into the duodenum; (4) it secretes intrinsic factor; (5) it carries on a limited amount of absorption (certain drugs, some water, alcohol, and short-chain fatty acids); (6) it produces gastrin, which helps regulate digestive functions; and (7) it helps protect the body by destroying pathogenic bacteria swallowed with food or with mucus from the respiratory tract.

15. Mumps can cause an inflammation of the testes called orchitis.

16. Dental caries, or tooth decay, is a disease of the enamel, dentin, and cementum of teeth that results in the formation of a permanent defect called a cavity. Periodontitis is the inflammation of the periodontal membrane that anchors the tooth to the bone in the jaw.

17. Pyloric stenosis is an obstructive narrowing of the pyloric sphincter.

Answers to Critical Thinking Questions (p. 881) 1. Intrinsic muscles give the tongue extreme maneuverability. Changes in the size and shape of the tongue caused by intrinsic muscle contraction assist in the placement of food between the teeth during chewing.

Extrinsic muscles allow for the protrusion and depression of the tongue; contraction of the extrinsic muscles is important during swallowing and speech.

2. By adulthood, enamel no longer contains any living cells.

3. The wall of the esophagus is unique because it contains both striated and smooth muscle. Like some other digestive organs, the muscular layer of the esophageal wall has thickened rings called sphincters that act as valves to control the passage of materials. Unlike other digestive organs, the muscle layer of the esophagus is striated muscle in the upper third, a mix of striated and smooth muscle in the central third, and smooth muscle only in the lower third. The presence of voluntary striated muscle in the upper third allows some level conscious control during swallowing when needed, although in most circumstances swallowing involves involuntary reflexes. Peristalsis of smooth muscle in the lower esophagus permits involuntary movement of material (usually downward, but upward during a vomiting or gag reflex).

4. Gastric pits are marked depressions in the epithelial lining of the stomach. Gastric glands are numerous coiled, tubular-type glands below the level of the pits, particularly in the fundus and the body of the stomach.

5. The “pointy” end, or apex, of the stomach is the pylorus.

6. An upper gastrointestinal (UGI) x-ray study is used to diagnose a hiatal hernia. In the test, the patient is asked to drink a flavored drink containing barium sulfate. As the contrast medium travels through the system, the lower esophagus, gastric wall, pyloric channel, and duodenum are each evaluated for defects. The barium enema study is used to diagnose intestinal diverticula.

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Instructor’s Resource Material for

39 Lower Digestive Tract ANSWER KEYS Answers to Quick Check Questions 1. The three main divisions of the small intestine are the duodenum, jejunum, and ileum.

2. Intestinal villi are modifications (projections) of the mucosal layer of the small intestine. Intestinal digestive enzymes are produced in the brush border cells toward the top of the villi. The presence of villi and microvilli increases the surface area of the small intestine.

3. The four main divisions of the colon are the ascending colon, transverse colon, descending colon, and sigmoid colon.

4. Haustra are pouchlike rings in the large intestine formed by the taeniae coli and circular muscles.

5. The vermiform appendix is most often found just behind the cecum or over the pelvic rim. It is attached to the cecum of the large intestine near the ileocecal valve.

6. Spotty deposits of fat accumulate in the omentum and give it the appearance of a lace apron.

7. The liver lies immediately under the diaphragm and occupies most of the right hypochondrium and part of the epigastrium.

8. Answers may include any of the following: detoxify various substances; secrete bile; carry on important steps in the metabolism of proteins, carbohydrates, and fats; store iron and vitamins A, B 12, and D; produce plasma proteins; and serve as the site of hematopoiesis during fetal development. Students are asked to name three.

9. Bile travels from the cystic duct in the gallbladder, to the common bile duct, and then is injected into the duodenum at the greater duodenal papilla.

10. The acinar units of the pancreas secrete the digestive enzymes found in pancreatic juice.

Answers to Case Study Questions (p. 898) 1. a: The button will pass from esophagus to stomach (through the lower esophageal sphincter), from stomach to small intestine (through the pyloric sphincter), from small intestine to large intestine (through the ileocecal valve), and from the rectum through the anus (through the internal and external anal sphincters).

2. c: The projections are called villi. The plicae are folds of the mucosal lining. Rugae are the ridges found in the stomach. Crowns are part of the teeth.

3. c: The longitudinal muscles grouped into tapelike strips are called taeniae coli, and the circular muscles are grouped into rings that produce pouchlike haustra between them. Rugae are folds of epithelial lining in the stomach. Although cells lining the large intestine have microvilli, the cells do not form villi like those that appear in the lining of the small intestine.

4. a: The colon is divided into the following portions: ascending colon, transverse colon, descending colon, and sigmoid colon (see Figure 39-5).

Answers to Review Questions (p. 900) 1. The three divisions of the small intestine, from proximal to distal, are the duodenum, the jejunum, and the ileum.

2. The villi are found in the small intestine. The haustra and teniae coli are found in the large intestine.

3. The large intestine has three divisions: cecum, colon, and rectum.

4. The function of the vermiform appendix is not certain. It may serve as a breeding ground for intestinal bacteria, often called intestinal flora. The predominance of nonpathogenic bacteria is thought to help prevent disease. Some of these bacteria are thought to aid in the digestion or absorption of essential nutrients.

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Chapter 39 | Lower Digestive Tract ___________________________________________________________

5. The peritoneum is a large continuous sheet of serous membrane that lines the walls of the abdominal cavity and also forms the serous outer coat of the organs. In several places it forms reflections that bind abdominal organs together.

The mesentery is a fan-shaped projection of the parietal peritoneum from the lumbar region of the posterior abdominal wall. The mesentery allows for the free movement of each coil of the small intestine, which helps prevent strangulation of the long tube.

The transverse mesocolon attaches the transverse colon to the posterior abdominal wall.

The greater omentum is a continuation of the serosa of the greater curvature of the stomach and the first part of the duodenum to the transverse colon.

The lesser omentum attaches from the liver to the lesser curvature of the stomach and the first part of the duodenum 6. Liver lobules are tiny hexagonal or pentagonal cylinders about 2 mm high and 1 mm in diameter. A small branch of the hepatic vein extends through the center of each lobule. Hepatic cells are arranged in plates radiating outward from the central vein. On the outer corners of each lobule are arranged several sets of tiny tubes, branches of the hepatic artery, the portal vein, and the hepatic duct. From these tubes, irregular branches of the interlobular veins extend between the radiating plates of hepatic cells to join the central vein.

Minute bile canaliculi are formed by spaces around each cell that collect bile secreted by the hepatic cells.

Sinusoids in the lobule have many reticuloendothelial cells along their lining, which can remove bacteria, worn-out red blood cells, and other particles from the bloodstream.

7. The liver has two ducts—the right and left hepatic ducts—which join to form a single hepatic duct. The gallbladder drains into a cystic duct, which joins the hepatic duct to form the common bile duct, which drains into the small intestine.

8. The functions of the gallbladder are to concentrate and store bile. During digestion, the gallbladder contracts, ejecting the concentrated bile into the duodenum.

9. The exocrine function of the pancreas is the production and release of digestive enzymes. The endocrine function is the production and release of the hormones insulin and glucagon.

10. Cholelithiasis is a condition in which stones develop in the gallbladder.

Answers to Critical Thinking Questions (p. 900) 1. Villi and microvilli increase the surface area of the small intestine hundreds of times.

2. A barium enema study is used to diagnose intestinal diverticula. In the test, the patient is asked to drink a flavored drink containing barium sulfate. As the contrast medium travels through the system, the lower esophagus, gastric wall, pyloric channel, and duodenum are each evaluated for defects, using an x-ray. 3. The opening between the lumen of the appendix and the cecum is large in children and young adults. Food or fecal material can be trapped in the appendix and cause it to become irritated or inflamed, causing appendicitis. This opening is often completely obliterated in older adults, which explains the low incidence of appendicitis in this population.

3. Some liver functions (such as, red blood cell destruction, storage of nutrients, and detoxification) can be wholly or partly compensated by the action of other organs. It is the metabolism of proteins, fats, and carbohydrates by the liver that is particularly vital to survival and unique to the liver. Liver function occurs in microscopic lobules. As long as a person has the minimum number of functioning lobules after donating a lobe of their liver, they can survive.

4. Although very useful, one can survive without a gall bladder. It stores and concentrates bile from the liver; and without the gall bladder, the liver continues to secrete bile. Sometimes, removal of the gall bladder may require a patient to adjust their food intake (especially meals high in fat) to accommodate the change in the amount of bile available during digestion.

5. The mesenteries (connecting folds) of the peritoneum help hold the coils of intestinal tubing in place and thus prevent tangling or kinking.

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Instructor’s Resource Material for

40 Digestion and Absorption ANSWER KEYS Answers to Quick Check Questions 1. Motility is movement of small food particles along the gastrointestinal (GI) tract.

2. The first step of deglutition, which involves the formation of a food bolus to be swallowed on a depression or groove in the middle of the tongue, is voluntary (under control of the cerebral cortex). The pharyngeal and esophageal stages are under involuntary control.

3. Peristalsis propels material from point to point along the GI tract.

4. The enterogastric reflex that inhibits gastric emptying is triggered by the sensory and motor fibers in the vagus nerve.

5. Digestive enzymes catalyze the hydrolysis of food molecules.

6. The shape of an enzyme can be altered by pH and temperature.

7. The final digestive products of proteins: amino acid; of carbohydrates: glucose; of triglycerides: fatty acids and glycerol.

8. Water, mucus, amylase, lipase, and sodium bicarbonate are the primary components of saliva.

9. Gastric juice contains water, mucus, pepsin (produced by chief cells), pepsinogen (produced by chief cells), and hydrochloric acid (produced by parietal cells).

10. Pancreatic enzymes include trypsin, trypsinogen, enterokinase, chymotrypsin, nuclease, and amylase.

11. Excretion is waste material destined for removal from the body. Excreted substances in bile include cholesterol, products of detoxification, and bile pigments.

12. The three phases of gastric secretion are the cephalic phase, gastric phase, and intestinal phase.

13. Gastric inhibitory peptide adjusts gastric juice secretion as chyme passes to and through the intestinal tract.

14. Secondary active transport refers to the absorption of glucose, sodium, and amino acids involving two carriers, one of which is active. The active carrier on the basal side of the epithelial cell maintains a sodium gradient, which facilitates passive transport of sodium, and perhaps another molecule, out of the GI lumen via a passive carrier on the luminal side of the cell.

15. Fatty acids are transported with the aid of lecithin and bile salts from the watery intestinal lumen to absorbing cells on the villi.

16. Defecation is brought about by stimulation of receptors in the rectal muscles.

Answers to Case Study Questions (pp. 925-926) 1. c: Although Clarence’s initial thought was skeletal (back), magnetic resonance imaging (MRI) showed nothing wrong. No change in the pain with movement would seem to indicate any muscular injury. The urinalysis was normal as well, eliminating the urinary system as a cause. So we are left with the digestive system. Having the pain return immediately after eating is the final clue.

2. a: See Table 40-5 for a summary of digestive hormones. Gastrin is secreted in the stomach when food enters the stomach. Gastric inhibitory peptide (GIP), cholecystokinin (CCK), and secretin all are released in response to chyme entering the duodenum. GIP acts on the stomach, whereas CCK and secretin act on both the pancreas and the gallbladder.

3. d: The liver produces bile, but bile is stored in the gallbladder. Eating fatty foods (such as, gravy) increases the amount of CCK released, which causes constriction of the gallbladder. Clarence’s pain is likely caused by inflammation or irritation of the gallbladder.

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Chapter 40 | Digestion and Absorption ________________________________________________________

Answers to Review Questions (p. 929) 1. The four mechanical processes that occur during digestion are mastication, deglutition, peristalsis, and segmentation.

2. The three steps, or stages, of deglutition are the oral stage, pharyngeal stage, and esophageal stage.

3. The deglutition center of the medulla coordinates the muscles needed to close the larynx and contracts the pharynx and esophagus so that food can be moved through the esophageal tube.

4. Fats and other nutrients in the duodenum stimulate the intestinal mucosa to release gastric inhibitory peptide (GIP). When GIP reaches the stomach wall, it has an inhibitory effect on gastric muscle, decreasing peristalsis and slowing the passage of food to the duodenum. The enterogastric reflex is a nervous mechanism that is sensitive to the presence of acid and distention. Sensory and motor fibers in the vagus nerve cause a reflex inhibition of gastric peristalsis.

5. Gastric juices are mixed with ingested food in the stomach to form chyme.

6. Chyme is a thick, milky material formed when gastric juices are mixed with ingested food.

7. Digestive enzymes are classified as extracellular, because they operate in the lumen of the digestive tract, outside any cells of the body. All digestive enzymes are also classified chemically as hydrolases, because they catalyze the hydrolysis of food molecules.

8. Enzymes are specific in their action; they act on only one specific substrate. Enzymes function optimally at a specific pH. The change in hydrogen ion concentration can change the shape of the enzyme and make it less efficient. Most enzymes catalyze a chemical reaction in both directions. The direction and rate of reaction are governed by rate laws. An accumulation of products slows the reaction and tends to reverse it.

9. Proteins are digested by the enzymes pepsin, trypsin, chymotrypsin, and peptidases. Carbohydrates are digested by the enzymes amylase, sucrase, maltase, and lactase. Fats are digested by the enzyme lipase.

10. The cephalic phase of gastric secretion occurs when the sight, smell, taste, or thought of food stimulates the release of gastrin, which stimulates the release of gastric secretions. In the gastric phase, end products of protein digestion in the pyloric portion of the stomach cause the release of gastrin, which stimulates gastric secretions. In the intestinal phase, chyme-containing fats, carbohydrates, and acid cause cells in the duodenum to release GIP, secretin, and CCK, which inhibit gastric secretions.

11. The pancreas produces a number of digestive enzymes. Proteases (trypsin, chymotrypsin, collagenase, and elastase) assist in the digestion of protein; lipases assist in the digestion of fats; nucleases assist in the digestion of nucleic acids; and amylase assists in the digestion of carbohydrates.

12. Glucose is absorbed from the lumen of the small intestine by the process of sodium cotransport. This occurs when glucose is passively transported into the cell by the same mechanism that brings sodium into the cell.

This process works only if sodium is being actively transported out of the basal side of the cell, maintaining a low sodium concentration in the cell. This process is referred to as secondary active transport.

13. The fat-soluble vitamins—vitamins A, D, E, and K—depend on bile salts for absorption.

14. Hormones that control the ejection of bile are secretin and CCK. Gastrin stimulates the secretion of gastric enzymes. GIP inhibits gastric emptying. Secretin stimulates the secretion of alkaline fluid from the pancreas.

CCK stimulates the secretion of pancreatic enzymes.

15. Defecation is a reflex brought about by stimulation of receptors in the rectal mucosa. Normally, the rectum is empty until mass peristalsis moves fecal matter out of the colon into the rectum. This distends the rectum. It also stimulates colonic peristalsis and initiates reflex relaxation of the internal sphincters of the anus.

Voluntary straining efforts and relaxation of the external anal sphincter may then follow as a result of the desire to defecate.

16. Oral rehydration therapy is used to treat dehydration brought about by diarrhea. It involves liberal doses of an easily prepared solution containing sugar and salt. This sugar-salt solution uses undamaged transport mechanisms and thus replaces water, nutrients, and electrolytes lost in the diarrheal fluid.

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Answers to Critical Thinking Questions (p. 929) 1. The primary function of the digestive system is to bring essential nutrients into the internal environment so that they are available to each cell in the body.

2. The two types of processes are mechanical digestion and chemical digestion.

Mechanical digestion consists of all the motility of the digestive tract, which causes a change in size from relatively large to small particles; the churning of the contents of the gastrointestinal (GI) lumen so that they become mixed with digestive enzymes and come in contact with the wall of the small intestine; and the movement of food forward along the digestive tract.

Chemical digestion consists of all the chemical composition changes that food undergoes in the movement through the digestive tract. These changes result in the hydrolysis of food.

3. The two forms of intestinal motility are peristalsis and segmentation. The main function of peristalsis is to move the food forward along the GI tract. Segmentation helps break down food particles; mixes food and digestive juices; and brings food into contact with intestinal mucosa, which facilitates absorption.

4. Trypsin is the active form of a protein digestive enzyme that is made in the pancreas and works in the small intestine. Pepsin is also an active form of a protein digestive enzyme, but it is made and works in the stomach. Peptides are the result of the partial digestion of protein. A polysaccharide is a complex starch, whereas a monosaccharide is the digestive end product of a polysaccharide. Trypsin and pepsin are enzymes; the others are pairs of foods.

5. To make hydrochloric acid, stomach cells break down carbonic acid, keep the hydrogen ion, and release the bicarbonate ion into the blood. The cells in the pancreas also break down carbonic acid, but they keep the bicarbonate ion and release the hydrogen ion into the blood. When the stomach releases the bicarbonate ion, it causes the pH of the blood to rise above the set point. When the pancreas releases the hydrogen ion into the blood, it decreases the blood pH back to set point. Both processes are necessary to maintain the proper pH of the blood.

6. Lecithin and bile salts, both found in bile, are used to emulsify fats to make them more water soluble. Both of these substances have a lipid-soluble part of the molecule and a water-soluble part of the molecule. The lipidsoluble part is attracted to the fats, and the water-soluble part is attracted to the surrounding water. This process provides a shell for fats with a water-soluble layer on the exterior. This structure is called a micelle.

7. Emulsification is an example of mechanical rather than chemical digestion because there is no chemical change in the fat after emulsification, only a change in size.

8. Glucose and amino acids are absorbed into the cells lining the small intestine by a process of sodium cotransport. This process uses the passive transport of the sodium ions to assist in the absorption of glucose and amino acids. The diffusion gradient for sodium is maintained in the cells by a process called secondary active transport in which sodium is actively transported out of the cell on the basal side. Because fats are not water soluble, they must be surrounded by bile salts or lecithin to form micelles. Micelles are absorbed into the cells of the intestinal wall. In the cell, the products of fat digestion are reformed into triglycerides, packaged by the Golgi apparatus into chylomicrons, moved out of the cell, and absorbed by the lacteals in the villi of the small intestine.

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Instructor’s Resource Material for

41 Nutrition and Metabolism ANSWER KEYS Answers to Quick Check Questions 1. The two types of metabolism are catabolism and anabolism. Catabolism: Breaks down food molecules into smaller molecular compounds and, in so doing, releases energy from them. Anabolism: Synthesizes various compounds and expends energy.

2. Phosphates from the nutrients are added to adenosine diphosphate (ADP) to form adenosine triphosphate (ATP), which is used for anabolism and other cell work.

3. Glycolysis is the first process of carbohydrate catabolism. It breaks apart one glucose molecule to form two pyruvic acid molecules. For every molecule of glucose undergoing glycolysis, a net of two molecules of ATP is formed.

4. Essentially, the citric acid cycle converts the two acetyl molecules to four carbon dioxide and six water molecules.

5. The electron transport system accepts the high-energy electrons from the citric acid cycle. These electrons move quickly down the chain, from cytochrome to cytochrome, to their final acceptor, oxygen. As these electrons move down the carrier chain, they release small bursts of energy.

6. A cell switches to anaerobic respiration when oxygen supply is inadequate.

7. The oxygen debt is the oxygen required for ATP synthesis to remove excess lactic acid after anaerobic exercise.

8. Glycogenesis: Process of glycogen formation. Glycogenolysis: The splitting of glycogen. Glycogenesis occurs when the blood glucose level increases above the midpoint of its normal range. As a result of glycogenesis, the blood glucose level decreases to its normal level. Glycogenolysis is the reversal of glycogenesis. When blood glucose levels decrease, glycogenolysis accelerates to maintain homeostasis of blood glucose concentration.

9. Insulin, glucagons, epinephrine, adrenocorticotropic hormone, glucocorticoids, and growth hormone all affect glucose metabolism.

10. Lipids are transported to cells in the form of chylomicrons, lipoproteins, and free fatty acids.

11. Glycerol is converted to glyceraldehyde-3-phosphate. Fatty acids are broken down by a process called betaoxidation into two carbon pieces, the familiar acetyl coenzyme A (acetyl CoA). These are then catabolized via the citric acid cycle.

12. Essential fatty acids cannot be produced by the body.

13. Essential amino acids are those that must be in the diet.

14. An amino acid is deaminated when an amino group splits off from the amino acid molecule to form a molecule of ammonia and one of keto acid.

15. During deamination, most of the ammonia formed is converted by liver cells to urea and later excreted in the urine. The keto acid formed from deamination may be oxidized via the citric acid cycle or may be converted to glucose via gluconeogenesis or to fat (lipogenesis).

16. When the body is in protein balance (rate of protein anabolism equals rate of protein catabolism), it is also in a state of nitrogen balance.

17. Vitamins are organic molecules needed in small quantities for normal metabolism throughout the body.

18. General functions of minerals in the body may include nerve conduction, muscle contraction, and building strong structural components of the skeleton.

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Chapter 41 | Nutrition and Metabolism ________________________________________________________

19. Metabolic rates can be expressed (1) in terms of the number of kilocalories of heat energy expended per hour or per day or (2) as normal or as a definite percentage above or below normal.

20. Basal metabolic rate (BMR) can be influenced by body size, sex, body temperature, drugs, emotions, pregnancy, and lactation.

21. Basal metabolic rate is the body’s rate of energy expenditure under “basal” conditions. Total metabolic rate is the amount of energy used or expended by the body in a given time.

22. The control centers for regulating food intake are in the hypothalamus.

Answers to Case Study Questions (p. 961) 1. c: Vitamin C is a micronutrient, not a macronutrient.

2. b: Sodium, chloride, potassium, calcium, magnesium, and phosphorus are the macrominerals in the human body. Although we are composed of many carbon atoms, carbon itself is not considered a macronutrient (or micronutrient).

3. a: The first step in lipid catabolism (at least in triglyceride lipids) is to break apart the glycerol molecule from the three fatty acids. The glycerol is then either converted to glucose or shunted into the glycolysis pathway.

Fatty acids are broken down into acetyl coenzyme A (acetyl CoA). Glycolysis, although potentially part of lipid catabolism, is not the first step. Lipogenesis is the formation of lipids. Deamination is part of protein catabolism.

4. d: Gluconeogenesis is a process that produces new glucose molecules from other materials (e.g., proteins and fats). This would result in increased glucose levels in the blood. Glycolysis breaks apart a glucose molecule into two pyruvic acid molecules. Glycogenesis is the formation of glycogen from glucose molecules.

Oxidative phosphorylation is part of carbohydrate catabolism.

Answers to Review Questions (p. 965) 1. Metabolism refers to the complex interactive set of chemical processes that make life possible. More simply, it refers to the ways in which your body uses food. Nutrition is the science of food; the nutrients and substances therein; their action, interaction, and balance in relation to health and disease; and the process by which the organism ingests, digests, absorbs, transports, uses, and excretes food substances.

2. Metabolism is made up of the two processes of anabolism and catabolism.

3. The body does not digest dietary fiber because the body does not produce the enzymes capable of their digestion.

4. Glycolysis breaks apart a glucose molecule to form two molecules of pyruvic acid. Glycolysis consists of a series of chemical reactions; each reaction is catalyzed by a specific enzyme. Glycolysis does not require oxygen to provide the cell with energy. It forms adenosine triphosphate (ATP) for cell use and prepares glucose for entry into the citric acid cycle.

5. Glycolysis occurs in the cytoplasm of the cell.

6. The process of splitting glycogen is called glycogenolysis. This process can be used by almost all cells to break down glycogen to glucose-6-phosphate. The liver, kidneys, and intestinal mucosa cells can convert glycogen back to glucose.

7. Dietary fats are classified as either saturated or unsaturated fats.

8. Lipids are transported in blood in three forms: chylomicrons, lipoproteins, and free fatty acids. Chylomicrons are the result of fat digestion and are moved to the blood by lymph and usually stored in adipose tissue. When the chylomicrons have been removed from the blood, the liver can add lipoproteins to the blood. There are three types of lipoproteins: very low–density lipoproteins (VLDLs), low-density lipoproteins (LDLs), and high-density lipoproteins (HDLs). Free fatty acids enter the blood from adipose tissue and are carried in the blood combined with albumin.

9. Lipid metabolism is controlled mainly by the following hormones: insulin, adrenocorticotropic hormone (ACTH), growth hormones, and glucocorticoids.

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10. The essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

11. The term metabolic rate means the amount of energy released in the body in a given period of time by catabolism.

12. The factors that influence basal metabolic rate (BMR) are size measured in body surface area, sex, lean body mass, age, amount of thyroid hormone produced, body temperature, drugs, emotional state, pregnancy, and lactation.

13. The amount of food a person eats is regulated by the hypothalamus. Factors that can influence food intake include body temperature (high body temperature suppresses appetite; lower body temperature stimulates appetite) and the amount of glucose in the blood (high glucose levels suppress appetite; low glucose levels stimulate appetite).

14. A calorie is defined as the amount of energy needed to raise the temperature of 1 gram of water 1° C.

Answers to Critical Thinking Questions (p. 965) 1. Acetyl CoA carries an acetyl group to the citric acid cycle. It combines with a four-carbon substance to form citric acid, a six-carbon substance. This six-carbon substance is converted to a five-carbon substance with a carbon dioxide molecule given off along with the formation of a high-energy electron carried by NADH (reduced nicotinamide adenine dinucleotide [NAD]). The five-carbon substance is converted to a four-carbon substance with another carbon dioxide molecule being lost and the formation of another high-energy electron carried by NADH. The four-carbon substance is chemically rearranged and, in the process, gives off an ATP molecule; another high-energy electron carried by NADH; and an FADH2, another electron carrier. Finally, the four-carbon substance is formed that is able to join with another acetyl group to form citric acid. The question asks the student to draw a picture; see Figure 41-5.

2. Although glycolysis occurs in the cytoplasm of the cell, only a small amount of energy needed by the cell is produced by this process. Most of the energy needed by the cell is released by the citric acid cycle, the electron transport system, and oxidative phosphorylation. These processes take place in the mitochondria. The citric acid cycle occurs in the mitochondrial matrix. The electron transport system and oxidative phosphorylation occur on the inner membrane of the mitochondria.

3. The obvious difference between anaerobic and aerobic pathways is the use of oxygen. Anaerobic pathway does not use oxygen, whereas aerobic pathway does. Another difference is the amount of ATP produced by each process. All the steps in aerobic pathway produce a total of 36 molecules of ATP. Anaerobic pathway produces only four molecules of ATP; the cell could not survive on only anaerobic pathway. The important role played by lactic acid in anaerobic pathway is that it is the substance that converts the NADH produced by glycolysis back to NAD. 4. The maintenance of the homeostatic level of glucose in the blood has a wide variety of mechanisms. Insulin, produced by the islet cells of the pancreas, causes the cells of the body to absorb glucose, which lowers blood glucose levels. The pancreas also produces glucagon, which stimulates the liver to release glucose into the blood, thereby raising blood glucose levels. The adrenal glands produce epinephrine, which increases the rate of glycogenolysis, which in turn causes an increase in blood glucose levels. ACTH stimulates the release of glucocorticoids, which cause the liver to produce and release glucose into the blood. Growth hormone causes a shift in the body from carbohydrate catabolism to fat catabolism. The “carbohydrate-sparing” effect causes an increase in blood glucose levels. Thyroid-stimulating hormone causes the release of thyroid hormone, which stimulates metabolism. Because glucose is the body’s preferred fuel, it causes a drop in the blood glucose level. All of these mechanisms together are used to regulate glucose homeostasis.

5. Fats are broken down to fatty acids and glycerol. The glycerol is converted to glyceraldehyde-3-phosphate, which is one of the steps in glycolysis. The fatty acids are broken down into two-carbon units, which can enter the citric acid cycle as acetyl CoA. The catabolism of fat enters the same catabolic system as carbohydrates at various steps in the process. When fat catabolism takes place at an accelerated rate, excessive numbers of acetyl CoA units are formed. The liver then condenses acetyl CoA units to form acetoacetic acid, which is classified as a ketone body.

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Chapter 41 | Nutrition and Metabolism ________________________________________________________

6. Protein catabolism begins with the removal of the amino group from the amino acid. This part of the molecule is converted to urea and is passed out of the body in the urine. The rest of the molecule becomes a keto acid. This keto acid can enter various steps in energy-releasing pathways. If protein catabolism is more rapid than protein ingestion, the body loses more nitrogen than it takes in. This puts the body in a negative nitrogen balance.

7. Fats and carbohydrates are used primarily as sources of energy; protein is used primarily for structure.

8. Most vitamins are used as coenzymes, which allow the enzymes they join with to function properly. Vitamins A, D, and E, however, have other functions. Vitamin A is important as a visual pigment for the eye. Vitamin D can be converted to calcitriol, which helps in the regulation of calcium. Vitamin E functions as an antioxidant, which protects cells from damage by free radicals.

9. The basal metabolic rate (BMR) is the body’s rate of energy expenditure under “basal conditions.” These conditions include being awake but resting, lying down, not moving a muscle (as much as possible), being in the postabsorptive state, and being in a comfortably warm environment. The total metabolic rate is the amount of energy used or expended by the body in a given time. The main determinants are the BMR, the energy used by skeletal muscles, and the thermic effect of foods.

10. To find the BMR, convert 6 feet (72 inches) into centimeters by multiplying inches by 2.5 (72  2.5 = 180 cm). Convert pounds to kilograms by dividing by 2.2. (176/2.2 = 80 kg). By looking on the chart (p. 953), this converts to a body surface area of 2.0 square meters. Table 41-5 gives kilocalories per hour per square meter of body surface based on age and sex. A man between 20 and 30 years of age burns 39.5 kcal per hour per square meter. To determine the BMR, use the following equation: 2.0  39.5  24 = 1896. The man would burn 1896 kilocalories per day.

11. The difference between 17,500 kcal burned and 26,250 kcal taken in is 8750 kcal. An excess of 3500 kcal is equal to 1 pound of adipose tissue. This would mean the man gained about 2.5 pounds (8750/3500 = 2.5).

12. High blood concentrations of low-density lipoprotein (LDL) can lead to atherosclerosis, a type of hardening of the arteries. LDL delivers cholesterol to the cells. Some cells have too few LDL receptors on their membrane, which causes too much cholesterol to accumulate in the blood. Some mechanism in endothelial cells moves the excess LDL into the walls of the blood vessel, which causes the lipid accumulation that is characteristic of atherosclerosis.

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Instructor’s Resource Material for

42 Urinary System ANSWER KEYS

Answers to Quick Check Questions 1. The accessory organs of the urinary system are the ureters, urinary bladder, and urethra.

2. The urinary system processes blood and forms urine as a waste to be excreted.

3. The renal cortex is the outer region of the kidney. The medulla is the inner region of the kidney.

4. Approximately one-fifth of all the blood pumped by the heart per minute goes to the kidneys.

5. The ureter attaches to the bottom of the bladder and then runs at an angle for about 2 cm through the bladder wall and opens at the lateral angles of the trigone (floor) of the bladder. The ureter’s oblique angle through the bladder wall causes the ends of the tube to close and act as valves when the bladder is full, thus preventing backflow of urine.

6. Mucous transitional epithelium that forms folds called rugae lines most of the urinary tract. Because of the folds and the extensibility of transitional epithelium, the bladder can distend considerably.

7. The bladder serves as a reservoir for urine before it leaves the body; and, aided by the urethra, it expels urine from the body.

8. The order of the nephron segments is renal corpuscle, Bowman capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct.

9. Many pores, or fenestrations, are present in the glomerular endothelium.

10. The blood supply surrounding the nephron is the peritubular blood supply; the “straight arterioles” are called the vasa recta.

11. Filtration, tubular reabsorption, and tubular secretion are the basic processes of the nephron.

12. The glomerular filtration rate (GFR) is directly proportional to the effective filtration rate. When the GFR is low, filtration decreases.

13. A decrease in blood pressure tends to produce a decrease in both the glomerular pressure and the GFR. 14. Sodium ions (Na+) are pumped from tubule cell to interstitial fluid, increasing Na + concentration to a level that drives diffusion of Na+ into blood. As Na+ is pumped out of the cell, more Na+ passively diffuses in from filtrate to maintain equilibrium of the concentration. Enough Na + moves out of the tubule and into blood that an electrical gradient is established. (Blood is positive relative to filtrate.) Electrical attraction between oppositely charged particles drives diffusion of negative ions in filtrate, such as chloride (Cl −), into blood. As ion concentration in blood increases, osmosis of water from the tubule occurs. Thus active transport of sodium creates a situation that promotes passive transport of negative ions and water.

15. Sodium cotransport is a type of active transport in which the proximal tubules absorb nutrients from the tubule fluid, notably glucose and amino acids, into peritubular blood.

16. The transport maximum of a substance is the maximal capacity for moving any substance limited by availability of carriers.

17. A countercurrent mechanism is one that is made up of parallel passages where the contents flow in opposite directions. The countercurrent mechanism of the kidneys functions to keep the solute concentration of the medulla extremely high.

18. The thin-walled descending limb allows water and urea to diffuse freely into or out of the tubule, depending on their concentration gradients. The thick-walled ascending limb limits the diffusion of most molecules while actively transporting selected molecules out of the tubule and into the interstitial fluid.

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Chapter 42 | Urinary System ________________________________________________________________

19. The countercurrent multiplier in the loop of Henle allows for Na + and Cl− to be pumped from the ascending limb and moved into interstitial fluid to maintain a high osmolality there.

20. Antidiuretic hormone (ADH) targets cells of the distal and collecting tubules and causes them to become more permeable to water. The more ADH present, the more water is allowed out of the tubule and the closer the tubule fluid’s solute concentration matches that of the surrounding tissue fluid. If no water is reabsorbed by the distal and collecting tubules, urine volume is relatively high, and water loss from the body is high. As water is reabsorbed under the influence of ADH, the total volume of urine is reduced by the amount of water removed from the tubules. Thus ADH reduces water loss by the body.

21. Aldosterone targets distal and collecting tubule cells and causes them to increase activity of the sodiumpotassium pumps that move sodium out of the tubule and potassium into the tubule. Potassium secretion increases when blood aldosterone concentration increases.

22. Aldosterone increases distal and collecting tubule absorption of sodium, which in turn causes an osmotic imbalance that drives the reabsorption of water from the tubule.

23. Urochrome gives urine its yellowish color.

Answers to Case Study Questions (p. 994) 1. b: The blood in the urine suggests the urinary system is involved. The stabbing pain could be coming from a stone stuck in the ureter. The rhythmic contractions of the ureter are trying to push the stone through, and the expansion of the ureter causes extreme pain.

2. d: The ureter carries urine from the kidney to the bladder. The urethra carries urine from the bladder to outside the body (through the urethral orifice).

3. b: Fluid that passes into the kidney goes through three processes: (1) filtration (in the glomerulus), (2) reabsorption (in the tubules), and (3) secretion (in the tubules). Filtration is the movement of fluid and dissolved substances from blood to filtrate. Reabsorption is the movement from filtrate back to blood, and secretion is from blood to filtrate. Absorption is a process that occurs in the digestive system. Reabsorption is a urinary function, not a kidney function, because the material is moving “back” into the blood.

4. c: The kidneys freely filter glucose, but unless you have a massive intake of sugar or you are developing diabetes mellitus, all the glucose is reabsorbed.

Answers to Review Questions (p. 998) 1. The principal and accessory organs of the urinary system are the kidneys, ureters, urinary bladder, and urethra.

2. The kidneys are in a retroperitoneal position against the posterior wall of the abdomen. They are located on either side of the last thoracic vertebra to the third lumbar vertebra. The main functions of the kidneys are to process blood plasma and excrete urine.

The ureter is a tube about 28 cm long. It is composed of three layers: a mucous lining, a muscular middle layer, and a fibrous outer layer. The ureter of each kidney conducts urine inferiorly from the kidney to the urinary bladder.

The urinary bladder is a collapsible bag located directly behind the symphysis pubis. It performs two major functions: it serves as a reservoir for the urine; and, aided by the urethra, it expels urine from the body.

The urethra is a small tube lined with mucous membrane leading from the floor of the bladder to the exterior of the body. Its function is to carry urine out of the body.

3. The calyces are considered the beginning of the “plumbing system” of the urinary system.

4. The mechanism for voiding urine starts with the voluntary relaxation of the external sphincter muscle of the bladder.

5. The male urethra is part of the urinary system and the reproductive system.

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6. Bowman capsule is the cup-shaped mouth of the nephron. It is formed by two layers of epithelial cells with a space between them. The outer wall is composed of simple squamous epithelium. The inner layer is composed of special epithelial cells called podocytes. The primary branches of these cells extend from the cell bodies and divide into a network of branches that terminate in little “feet” called pedicels. The pedicels are packed so closely that only narrow slits lie between them. These spaces are called filtration slits. There is a mesh of fine connective tissue fibers called the slit-diaphragm that prevents the slits from enlarging under pressure, while still maintaining the permeability of the slit. The glomerulus is a network of fine capillaries.

The glomerulus fits into Bowman capsule. It has thin walls that are composed of a single layer of endothelial tissue. Many pores or fenestrations are present in the glomerular endothelium. These pores are larger than most other capillaries; this is necessary for filtration to occur for normal kidney function. Between the glomerulus and Bowman capsule lays a basement membrane. It consists of a thin layer of fine fibrils embedded in a matrix of glycoprotein. The proximal tubule is the tubule segment nearest to Bowman capsule.

It follows a winding, convoluted course (so it is also called the proximal convoluted tubule). Its walls consist of one layer of epithelial cells. These cells have brush borders facing the lumen of the tubule. Thousands of microvilli form the brush borders, which greatly increase the luminal surface area. The Henle loop is the segment just beyond the proximal tubule. It consists of a descending limb, a sharp turn, and an ascending limb. The distal tubule, or distal convoluted tubule, is the tubule distal to the Henle loop. It has thick walls.

The juxtaglomerular (JG) apparatus is found at the point where the afferent arteriole brushes past the distal tubule. The specialized cells of the JG apparatus represent a modification of cells in the walls of both distal tubules and afferent arterioles at the point where they touch. Large smooth muscle cells in the wall of the afferent arterioles, called the JG cells, contain granules of renin. These are sensitive to increased pressure in the arteriole and are considered functional mechanoreceptors. Modified distal tubule cells in the JG apparatus form a dense, tightly packed structure called the macula densa. Cells in the macula densa are chemoreceptors that can sense the concentration of solute materials in the fluid passing through the tubule. The collecting duct is a straight tubule joined by the distal tubules of several nephrons. Collecting ducts join larger ducts, and the larger collecting ducts of one renal pyramid converge to form one tube that opens at a renal papilla into one of the small calyces.

7. The flow of blood through the kidney tissue is as follows: interlobular artery → afferent arteriole → glomerular capillaries (glomerulus) → efferent arteriole → peritubular capillaries (including vasa recta) → venules → interlobular vein.

8. Filtration is the movement of water and protein-free solutes from the plasma in the glomerulus-capsular membrane and into the capsular space of Bowman capsule.

Tubular reabsorption is the movement of molecules out of various segments of the tubule and into the peritubular blood.

Tubular secretion is the movement of molecules out of the peritubular blood and into the tubules of the nephron to be excreted.

9. The effective filtration pressure can be calculated by taking the glomerular hydrostatic pressure, adding the capsular osmotic pressure, and subtracting the sum of the glomerular osmotic pressure and the capsular hydrostatic pressure. This value is the effective filtration pressure.

10. The concentration of solute in the interstitial fluid of the medulla is extremely high, as high as 1200 mOsm. 11. Sodium and chloride ions are actively transported out of the ascending limb of the Henle loop into the interstitial fluid.

12. Potassium secretion increases when the blood aldosterone concentration increases.

13. The two drugs mentioned in the text that are secreted by tubular cells are penicillin and para-aminohippurate (PAH).

14. The normal pH range of freshly voided urine is between 4.6 and 8.0.

15. Three body systems, in addition to the urinary system, that also excrete unneeded substances are the integumentary system, the respiratory system, and the digestive system.

16. Retention is the inability to void urine even though the bladder contains an excessive amount of urine.

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Chapter 42 | Urinary System ________________________________________________________________

17. The most common cause of glycosuria is diabetes mellitus.

18. Elevated blood urea nitrogen (BUN) levels indicate the failure of the kidney to clear urea from the blood.

19. Osmolarity is the osmotic pressure of a solution expressed as the number of osmols of pressure per kilogram of water. One osmol is equivalent to the osmotic pressure produced when 1 gram of nonionizing substance is dissolved in 1 kg of water.

Answers to Critical Thinking Questions (p. 998) 1. Disruption of the nerve input to the bladder results in the loss of normal control of voiding. Such paralysis is termed neurogenic bladder. This is characterized by involuntary retention of urine, subsequent distention of the bladder, and perhaps a burning sensation or fever with chills.

2. The filtration of water and small solute particles occurs in the renal corpuscle. Reabsorption of sodium ions, glucose, and amino acids by active transport and chloride ions, phosphate ions, urea, other solutes, and water by passive transport occurs in the proximal tubules. Reabsorption of water and secretions of urea occur passively in the descending Henle loop. Active reabsorption of sodium ions and passive reabsorption of chloride ions occur in the ascending Henle loop. Active reabsorption of sodium ions, passive reabsorption of chloride and other anions, and the possible reabsorption of water (if ADH is present) occur in the distal tubule. The distal tubule also actively secretes potassium ions, hydrogen ions, and certain drugs and passively secretes ammonia. The collecting duct actively reabsorbs sodium ions and passively reabsorbs urea (and water, if ADH is present). It also actively secretes potassium ions, hydrogen ions, and certain drugs and passively secretes ammonia. Finally, the urine leaves the collecting duct.

3. If the proximal tubules were unable to transport sodium ions into the blood, there would be chloride ions in the urine also, because the chloride ions passively follow the sodium ions. This is due to the electrostatic attraction between the positive charge of the sodium ion and the negative charge of the chloride ion.

4. Given no other circumstances, the kidney produces and excretes only very hypotonic urine. This causes the body to dehydrate rapidly. ADH, which is secreted by the posterior pituitary gland, targets cells in the distal and collecting tubules and causes them to become more permeable to water. When this happens, water is permitted to flow osmotically to equilibrium. The more ADH present, the more water is allowed out of the tubule—and the more the tubule concentration matches that of the surrounding tissue fluid. Because the tissue fluid in the medulla can be as high as 1200 mOsm, the fluid in the distal and collecting tubule could also be that high. The solute concentration of the urine depends largely on the amount of ADH present.

5. Atrial natriuretic hormone (ANH) promotes the loss of sodium ions in the urine, thus reducing the plasma and interstitial fluid sodium ion concentration. This reduces the amount of water that is reabsorbed by osmosis, leaves more water in the urine, and thereby increases urine volume.

6. Kidney function in the newborn is less efficient than in the older child and adult. Incontinence, or the inability to control urination, is normal in young children. Many older adults have problems with incontinence because of loss of sphincter tone or control. Renal clearance decreases with age, indicating deterioration of kidney function. Changes in the porosity of the filtration membrane and loss of functional nephrons also occur in older adults.

7. Renal clearance is an expression of how efficiently the kidney is “clearing” or removing a substance from the blood. When blood creatinine concentration is abnormally high, the kidney’s clearance of creatinine out of the blood is below normal. Renal clearance of creatinine often falters when the glomerular filtration rate (GFR) is below normal, and the kidney is unable to process blood at its normal high rate. This is why renal clearance of creatinine is often used as an indirect way to assess a patient’s GFR.

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Instructor’s Resource Material for

43 Fluid and Electrolyte Balance ANSWER KEYS Answers to Quick Check Questions 1. Three important cations are sodium, calcium, potassium, and magnesium. Three important anions are chloride, bicarbonate, phosphate, and many proteins.

2. The most abundant chemical constituent in blood plasma is sodium and chloride; in interstitial fluid is sodium and chloride; in intracellular fluid (ICF) is potassium and phosphate.

3. Milligrams, valence, electrovalent or ionic bonding, and milliequivalent are the units used to describe electrolyte concentration and electrolyte reactivity.

4. Electrolytes break up (or dissociate) in solution to form ions.

5. Plasma and interstitial fluid are subdivisions of the extracellular fluid (ECF) compartment.

6. Plasma: 4%. Interstitial fluid: 11%. ICF: 35%. Total: 50%.

7. Water enters from the digestive tract in liquids and food. But, in addition, water enters the body—that is, is added to its total fluid volume from its billions of cells. Water normally leaves the body by four exits: kidneys, lungs, skin, and intestines.

8. When ECF decreases, arterial blood pressure decreases. This decrease in blood pressure stimulates baroreceptors in the thorax and hypothalamus to stimulate the adrenal cortex to secrete aldosterone.

Aldosterone increases kidney tubule reabsorption of Na +. This then leads to the reabsorption of water in the kidney tubule. The reabsorption of water results in an increase of ECF volume.

9. ADH and aldosterone are the substances most important to regulating the amount of water reabsorbed by the kidney tubules.

10. The rate of respiration and the volume of sweat secreted are the most important factors that alter fluid loss under abnormal conditions.

11. Blood hydrostatic pressure and colloid osmotic pressure on one side of the capillary membrane, and interstitial fluid hydrostatic pressure and colloid osmotic pressure on the other side, control water exchange between plasma and interstitial fluid.

12. Edema is the swelling of a tissue caused by accumulation of excess fluids in the tissue spaces. Inflammation or burns can cause edema by promoting loss of plasma proteins from the blood, thus decreasing the blood colloid osmotic pressure to a point that permits effective filtration pressure (EFP) out of the blood and into the fluid spaces.

13. Interstitial fluid and ICF hydrostatic and colloid osmotic pressures regulate movement of solutes and water between ECF and ICF spaces.

14. Sodium is the chief electrolyte in interstitial fluid. The ICF’s main electrolyte is potassium. Therefore a change in the sodium or the potassium concentration of these fluids causes the exchange of fluid between them to become unbalanced.

Answers to Case Study Questions (p. 1016) 1. c: Whitney has lost a lot of water through sweat. One term for her condition is dehydration. Another term (referring to the body’s fluid volume) is hypovolemia—low blood volume.

2. d: Despite television advertising, the best fluid to drink after exercising to replenish your body’s water and electrolyte balance is not a cold beer or soda. Beer (or any alcoholic beverage) actually inhibits antidiuretic hormone (ADH) (see question 3), which would exacerbate the dehydration. Any oral rehydration drink (commonly marketed as sports drinks), or simply a quart of water with the addition of a handful of sugar and a pinch each of salt and baking soda, will help get your body back in balance.

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Chapter 43 | Fluid and Electrolyte Balance _____________________________________________________

3. a: ADH and aldosterone both act on the kidney (in different places) to enable it to retain water and increase blood volume.

Answers to Review Questions (p. 1018) 1. An infant has very high body water content—about 75% of body weight. This drops rapidly during the first 10 years of life until it reaches between 50% and 60% as a young adult.

2. In men, the total body water is about 57% of body weight. In women, the total body water is about 47% of body weight.

3. The compartments of ECF are interstitial fluid, plasma, transcellular fluid, and lymph.

4. The four exits by which water normally leaves the body are the lungs, skin, kidneys, and intestines.

5. The cardinal principle about fluid balance is this: Fluid balance can be maintained only if intake equals output.

6. The two factors that regulate urine volume are glomerular filtration rate and water reabsorption from renal tubules. Glomerular filtration is usually fairly constant, so the regulation of urine volume comes about by changes in the reabsorption of water. The amount of ADH and aldosterone secreted regulates the amount of water reabsorbed by the kidney tubules. The amount of atrial natriuretic hormone (ANH) also has an impact on urine volume.

7. Cations are ions with a positive charge. Anions are ions with a negative charge.

8. Chemically, plasma and interstitial fluid are almost identical. There are some differences, however. Plasma contains a slightly larger total of electrolytes than does interstitial fluid. Also, plasma contains an appreciable amount of protein anions, whereas interstitial fluid contains almost no protein anions.

9. The electrolyte composition of blood plasma is as follows: about 142 mEq of sodium ions, 4 mEq of potassium ions, 5 mEq of calcium ions, 2 mEq of magnesium ions, 102 mEq of chloride ions, 26 mEq of bicarbonate ions, 2 mEq of monohydrogen phosphate ions, 17 mEq of protein anions, and 6 mEq of other anions.

10. Milliequivalent measures the number of ionic charges or electrovalent bonds in a solution. This is an accurate measure of the physiological combining power, or reactivity, of a particular electrolyte solution.

11. The four pressures involved in Starling’s law of the capillaries are blood hydrostatic pressure, blood colloid osmotic pressure, interstitial fluid hydrostatic pressure, and interstitial fluid colloid osmotic pressure.

12. When the effective filtration pressure equals zero, there is no net transfer of water between blood and interstitial fluid.

13. A net transfer of water, or “fluid shift,” occurs when the effective filtration pressure does not equal zero.

14. Various mechanisms that may lead to edema include the retention of electrolytes—especially sodium ions— in the ECF, an increase in capillary blood pressure, and a decrease in the concentration of plasma proteins normally retained in the blood.

15. It is the plasma membrane that separates the ICF from the extracellular compartments. The fluid balance between these two compartments depends on the electrolyte balance. By electrolytes being actively transported across the plasma membrane into or out of the cell, the proper fluid composition can be maintained.

16. ADH regulates ECF electrolyte concentration and colloid osmotic pressure by regulating the amount of water reabsorbed into the blood from the renal tubules.

17. Dehydration is the condition that results from the excessive loss of body water and also causes a disruption of the electrolyte balance in the body.

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Answers to Critical Thinking Questions (p. 1018) 1. The fluid and electrolyte balance implies homeostasis, or constancy, of the body fluid and electrolyte levels.

It means that both the amount and distribution of body fluids and electrolytes are normal and constant. A glucose deficiency would have no effect on the electrolyte balance of the body because glucose does not dissociate into electrolytes.

2. The aldosterone mechanism is used to decrease fluid output to compensate for decreased intake. Cells in the outer zone of the adrenal cortex that secrete aldosterone are influenced by the juxtaglomerular cells in the kidney. If the blood pressure decreases or potassium level increases, additional aldosterone is secreted. When stimulated, the juxtaglomerular cells in the kidney secrete renin, which acts on angiotensinogen in the bloodstream to form angiotensin I, which is converted to angiotensin II in the lungs. This increases aldosterone secretions and acts on the brain to stimulate the sensation of thirst.

3. The biggest difference in the anions between blood plasma and interstitial fluid is protein. This exists because the normal capillary is almost completely impermeable to protein and, hence, almost no protein can leave the blood.

4. Starling’s law of the capillaries explains the nature of the mechanisms that control water movement between the plasma and the interstitial fluid. Starling identified four pressures that control water movement: blood hydrostatic pressure and interstitial fluid colloid osmotic pressure, which tend to pull fluid out of the blood and into the interstitial fluid, and interstitial fluid hydrostatic pressure and blood colloid osmotic pressure, which tend to move fluid out of the interstitium and into the blood. Fluid balance exists when the pressures moving fluid out of and into the blood and interstitial fluid are equal.

5. Hyponatremia is a condition of decreased serum sodium ion concentration, less than 136 mEq/L. Any disturbance in the electrolyte balance can lead to fluid imbalance. Possible causes include skin losses via perspiration, overuse of salt-wasting diuretics, adrenal insufficiency, renal or liver failure, low salt intake, or excessive water intake.

6. Osmoreceptors are specialized cells in the thirst center of the hypothalamus. They detect an increase in solute concentration in the ECF caused by water loss. Osmoreceptors send signals to the cerebrum, which are interpreted as thirst.

7. Atypical circumstances, such as fluid deprivation or specific electrolyte losses, cause the body to initiate “compensatory activities” that help maintain homeostasis. These activities involve neuroendocrine responses that affect multiple body organ systems, including the muscular, digestive, cardiovascular, respiratory, and urinary systems.

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Instructor’s Resource Material for

44 Acid-Base Balance ANSWER KEYS Answers to Quick Check Questions

1. pH is a numerical symbol (on a scale from 0 to 14) used to represent the negative logarithm of the number of hydrogen ions present in 1 L of solution.

2. A solution with a pH above 7 is alkaline.

3. Acid-forming elements are carbonic, lactic, sulfuric, phosphoric acids, and ketone bodies. Base-forming elements are potassium, calcium, sodium, and magnesium. Students are asked to identify three of each.

4. CO2 entering venous blood decreases pH. 5. A buffer is a substance that prevents marked changes in the pH of a solution when an acid or a base is added to it.

6. The chemical buffer system and the physiological buffer system are the major buffer systems in the body. The chemical buffer system acts more rapidly.

7. HCl + NaHCO3 = H2CO3 + NaCl; NaOH + H2CO3 = NaHCO3 + HOH 8. Chloride shift is the process of exchanging a bicarbonate ion formed in the red blood cell with a chloride ion from the plasma.

9. Carbonic anhydrase is an enzyme that is required when forming carbonic acid from carbon dioxide and water.

Carbonic acid is then buffered primarily by the potassium salt in hemoglobin inside the red blood cell.

10. An increase in arterial blood CO2 content or a decrease in its pH stimulates respiratory center neurons.

Hyperventilation results. Less CO2 and therefore less carbonic acid and fewer hydrogen ions remain in the blood so that blood pH increases, often reaching the normal level.

11. The test that shows the key characteristics of blood as it is related to respiratory function is the analysis of the arterial blood gases (ABGs).

12. Distal and collecting tubules secrete hydrogen ions into the urine in exchange for basic ions, which they reabsorb. Renal tubules can excrete hydrogen or potassium in exchange for the sodium they reabsorb. Distal and collecting tubules excrete ammonia into the tubular urine.

Answers to Case Study Questions (p. 1033) 1. a: With decreased respirations, less carbon dioxide is expelled from the body. This accumulating carbon dioxide is carried in the bloodstream in the form of carbonic acid. Increased carbon dioxide would cause increasing acidity—respiratory acidosis. It is respiratory, not metabolic, because the respiratory system is causing the problem.

2. c: Because the respiratory system is causing the problem, it cannot also be the solution. The urinary system is the other primary pH balancing system.

3. b: The urinary system has several options for getting rid of hydrogen ions. One commonly used option is dumping (excreting) hydrogen ions (H+) into the urine. To maintain the balance between positively and negatively charged ions in the body, if hydrogen ions are being dumped, the body needs to conserve an alternative positive ion. Sodium (Na+) is commonly used for this purpose.

4. d: Blood must be maintained within a narrow pH range for all the metabolic processes to occur.

Compensatory mechanisms are in place to help maintain this limited range. Deviating by as little as 0.5 would result in death.

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Chapter 44 | Acid-Base Balance _____________________________________________________________

Answers to Review Questions (p. 1036) 1. Carbonic acid and lactic acid are produced by aerobic and anaerobic metabolism, respectively.

2. Fruits and vegetables are base-forming foods.

3. Chlorine, sulfur, and phosphorus are acid-forming elements.

4. A physiological buffer is a mechanism by which the functioning of a system (either respiratory or renal) is used to maintain proper blood pH. 5. The normal pH range of the blood is between 7.36 and 7.41.

6. If a strong acid (such as, hydrochloric acid) is added to the sodium bicarbonate–carbonic acid buffer system, the following reaction will occur: HCl + NaHCO3 ⇌ H2CO3 + NaCl This forms a weak acid, carbonic acid, which replaces the strong acid, hydrochloric acid. The hydrogen ion concentration in the blood increases much less than if the hydrochloric acid were not buffered. If a strong base (such as, sodium hydroxide), is added to this buffer system, the following reaction will occur: NaOH + H2CO3 ⇌ NaHCO3 + H2O The hydrogen ion from the weak acid joins with the hydroxide ion from the sodium hydroxide to form water.

This decreases the number of hydroxide ions and prevents a drastic rise in pH. 7. The main buffer pairs in body fluids are as follows: (1) bicarbonate pairs: NaHCO3 and H2CO3, KHCO3 and H2CO3, and so on; (2) plasma protein pair: Na+  proteinate and proteins (weak acids); (3) hemoglobin pairs: K  Hb and Hb, K  HbO2 and HbO2 (Hb and HbO2 are weak acids); and (4) phosphate pair: Na2HPO4 (basic phosphate) and NaH2PO4 (acid phosphate).

8. The key characteristics revealed in an arterial blood gas (ABG) test are: oxygen partial pressure, oxygen saturation of hemoglobin, pH, concentration of bicarbonate ions, and carbon dioxide partial pressure.

9. There are several mechanisms by which the distal renal tubule is involved in the acidification of urine and the conservation of base. The distal tubules secrete hydrogen ions into the urine in the exchange for basic ions, which are then reabsorbed. Carbon dioxide diffuses from the capillaries into the distal tubules and is converted to carbonic acid by reacting with water. The carbonic acid dissociates into the hydrogen ion and the bicarbonate ion. The hydrogen ions diffuse into the urine where they displace basic ions from the basic salts of weak acids, converting them to weak acids, which are eliminated in the urine. The displaced basic ions, usually sodium, combine with the bicarbonate ions to form sodium bicarbonate, which is reabsorbed into the blood. The renal tubules can also excrete hydrogen or potassium ions in exchange for sodium ions. In acidosis, the tubule excretion of hydrogen ions increases markedly. The distal tubules excrete ammonia into the urine. The ammonia can combine with the hydrogen ion to form the ammonium ion. The ammonium ion displaces sodium or some other basic ion from a salt of a fixed acid to form an ammonium salt. The basic ion joins with the bicarbonate ion and is reabsorbed into the blood.

10. Cases of metabolic and respiratory acidosis are both treated by intravenous infusions of solutions containing sodium lactate. The lactate ions are metabolized by liver cells and are converted to bicarbonate ions. This therapy helps replace depleted bicarbonate reserves to restore the acid-base balance in metabolic acidosis. In respiratory acidosis, the additional bicarbonate ions function to offset elevated carbonic acid levels.

11. Hyperventilation can result in the excessive loss of carbonic acid and lead to respiratory acidosis with a bicarbonate buffer pair ratio of 20/0.5. Compensatory mechanisms may adjust the ratio to 10/0.5 and return the blood pH to normal.

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Answers to Critical Thinking Questions (p. 1036) 1. The pH scale indicates the acidity or alkalinity of a solution. A pH less than 7 indicates an acid solution, which contains more hydrogen ions than hydroxide ions. A pH more than 7 indicates a basic solution, which contains more hydroxide ions than hydrogen ions. A solution with a pH of exactly 7 indicates a neutral solution, which contains equal numbers of hydrogen and hydroxide ions. A solution with a pH of 4 would have a hydrogen ion concentration of 1  10−4; a solution with a pH of 6 would have a hydrogen ion concentration of 1  10−6.

2. The chloride shift is the process by which bicarbonate ions formed on the red blood cells are exchanged for chloride ions in the blood plasma. This maintains the electrical balance on both sides of the red blood cell membrane. This process makes it possible for carbon dioxide to be buffered in the red blood cell and then carried as bicarbonate ions in the plasma.

3. If the NaHCO3 concentration were lowered to 23.8 mEq and the H 2CO3 concentration were unchanged at 1.3 mEq, the ratio of base to acid would be 18.3/1. This decrease would cause a decrease in pH. 4. If blood pH decreases, that means the hydrogen ion concentration has increased. Respiration increases to eliminate carbon dioxide from the body and leave less carbonic acid and fewer hydrogen ions. This occurs when neurons in the respiratory center that are sensitive to changes in arterial blood carbon dioxide detect an increase in carbon dioxide, which would cause a drop in pH to below 7.38. This causes an increase in the rate and depth of breathing. This eliminates more carbon dioxide, reduces the amount of carbonic acid and hydrogen ions, and raises pH. 5. The pH is below 7.35 (the bottom of the normal range), so there is acidosis. The PCO2 is normal, so we move to the [HCO3−], which at 20 mEq/L is below the normal 22 to 26 mEq/L—thus indicating metabolic acidosis.

Because the pH is low and PCO2 is normal, it appears that this is uncompensated metabolic acidosis.

6. One of the most frequent and serious complications of severe vomiting is metabolic alkalosis. The bicarbonate ion excess results from the massive loss of chloride from the stomach in the form of hydrochloric acid. The loss of chloride causes a compensatory increase of bicarbonate in the extracellular fluid. The result is metabolic alkalosis. The therapy includes intravenous administration of chloride-containing solutions such as normal saline. The chloride ions in the solution replace the bicarbonate ions and help relieve the bicarbonate excess responsible for the imbalance.

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Instructor’s Resource Material for

45 Male Reproductive System ANSWER KEYS Answers to Quick Check Questions 1. The proper functioning of the reproductive system and its complex control mechanisms ensures survival not of the individual but of the species.

2. Essential organs (male): Gonads (testes). Accessory organs (male): Epididymides, vasa deferentia, ejaculatory ducts, and the urethra.

3. The perineum in males is a roughly diamond-shaped area between the thighs. It extends from the symphysis pubis anteriorly to the coccyx posteriorly. Its most lateral boundary on either side is the ischial tuberosity.

The two subdivisions of the perineum are the urogenital triangle and the anal triangle.

4. The testes are small ovoid glands located in the scrotum that are somewhat flattened from side to side, measure about 4 or 5 cm in length, and weigh 10 to 15 g each.

5. The two primary functions of the testes are spermatogenesis and secretion of hormones. Spermatogenesis: Production of sperm. The seminiferous tubules produce sperm. Secretion of hormones: Interstitial cells.

6. Testosterone promotes development and maintenance of male secondary sex characteristics, helps regulates metabolism (protein anabolism), plays a part in fluid and electrolyte metabolism, and inhibits anterior pituitary secretion of gonadotropins (follicle-stimulating hormone and luteinizing hormone).

7. Head: Highly compact package of genetic material covered by a specialized acrosome and acrosomal cap, which contain enzymes that are released during capacitation. Cylindrical middle piece: Characterized by a helical arrangement of mitochondria arranged end-to-end around a central core, which provides energy for sperm locomotion. Tail: Divided into a principal piece and short-end piece, both typical in appearance of all flagella capable of motility.

8. Sperm pass through the epididymis, vas deferens, ejaculatory duct, and urethra.

9. The urethra passes through the small hole in the center of the prostate.

10. Seminal vesicles: Secrete an alkaline, viscous liquid that constitutes about 60% of the semen. Semen contains fructose, which serves as an energy source. Other components include prostaglandins and a non–blood type coagulating enzyme called vesiculase. Prostate: Secretes a watery, milky-looking, and slightly acidic fluid that constitutes about 30% of the semen. Components of secretion include citrate and enzymes (hyaluronidase and prostate-specific antigen). Bulbourethral glands: Secrete an alkaline fluid containing mucus.

11. The scrotum and penis constitute the external genitals of males.

12. Contraction of the dartos muscle fibers causes slight elevation of the testes and wrinkling of the scrotal pouch.

Contraction of the cremaster muscle causes significant elevation of the testes. By elevating the scrotum closer to the warmth of the perineal wall, the temperature of the testicles can be maintained at a more constant level, which ensures optimal temperature for sperm formation.

13. The corpus cavernosa (2) and corpus spongiosum are the cylindrical masses of erectile tissue in the penis.

14. The number of sperm ejaculated, size of sperm, shape of sperm, and sperm motility all influence male fertility.

Answers to Case Study Questions (p. 1053) 1. c: Sperm are produced best at 3° C below body temperature. This is why the testes are held in a sac outside the male body cavity. Higher temperatures decrease sperm production. The physician asked Carlos about his underwear because briefs hold the scrotal sacs closer to the body (producing a higher temperature) than boxer-style undershorts.

2. b: A sperm count less than 25 million/ml is considered a problem.

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Chapter 45 | Male Reproductive System _______________________________________________________

3. a: The seminiferous tubules are in the testes. They flow into the rete testis, then into the efferent ductules and on into the epididymis. From there, sperm flow through the vas deferens, the ejaculatory duct, and finally out through the urethra.

4. d: Testosterone targets the spermatogenic cells in the seminiferous tubules and stimulates them to make more sperm. Luteinizing hormone (LH) does have an effect on sperm production but in a secondary manner. LH targets interstitial cells and stimulates them to make more testosterone.

Answers to Review Questions (p. 1056) 1. The accessory glands of the male reproductive system are a pair of seminal vesicles; one prostate gland; and a pair of bulbourethral, or Cowper, glands.

2. The genital ducts in the male are a pair of epididymides, a pair of vas deferentia, a pair of ejaculatory ducts, and the urethra.

3. The supporting structures of the male reproductive system are the scrotum, the penis, and a pair of spermatic cords.

4. The tunica albuginea is a dense, fibrous capsule that encases each testis. It then enters the gland, sending out partitions that radiate through the interior, dividing it into 200 or more cone-shaped lobules.

5. The two primary functions of the testes are the production of sperm cells and the secretion of hormones, chiefly testosterone.

6. The general functions of testosterone are as follows: (1) it ensures the development and maintenance of male secondary sex characteristics, accessory organs (such as, the prostate and seminal vesicles), and adult male sexual behavior; (2) it helps regulate metabolism and is sometimes referred to as the anabolic hormone because of its marked stimulating effect on protein metabolism; (3) it plays a part in fluid and electrolyte metabolism; (4) it has a mild stimulating effect on kidney tubule reabsorption of sodium and water; and (5) it inhibits the anterior pituitary secretions of gonadotropins, namely follicle-stimulating hormone (FSH) and LH. 7. The spermatozoon has three parts: the head, middle piece, and tail. The head is a highly compact package of genetic chromatin material covered by a specialized acrosome and acrosomal cap. These structures assist the sperm in moving through the female reproductive system. The cylindrical middle piece is characterized by a helical arrangement of mitochondria arranged end-to-end around a central core. It is this mitochondrial sheath that provides energy for the sperm’s locomotion. The tail is divided into a principal piece and a short endpiece—both are typical in appearance of all flagella capable of motility.

8. Capacitation is the release of hydrolytic enzymes, which allow the sperm to move through the cervical mucosa into the uterus and uterine tubes. These enzymes are also necessary to digest and penetrate the outer covering of the egg and initiate fertilization.

9. The three functions of the epididymis are as follows: (1) it serves as one of the ducts through which sperm pass in their journey from the testes to the exterior; (2) it contributes to the maturation of the sperm, which spend from 1 to 3 weeks in this segment of the duct system; and (3) it secretes a small amount of seminal fluid.

10. The anatomical divisions of the epididymis are the head, body, and tail.

11. The two ejaculatory ducts are short tubes that pass through the prostate gland and terminate in the urethra.

They are formed by the union of the vas deferens with the ducts from the seminal vesicles.

12. The prostate secretes a watery, milky-looking, and slightly acidic fluid that constitutes about 30% of the seminal fluid volume. The seminal vesicles secrete an alkaline, viscous liquid component of seminal fluid that is rich in fructose. The seminal fluid must be alkaline because acid can depress or kill sperm.

13. The bulbourethral glands surround the urethra just in front of the prostate gland. They are about the size of a pea. They secrete an alkaline fluid like the seminal vesicle. They also produce mucus, which serves to lubricate the urethra.

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______________________________________________________ Chapter 45 | Male Reproductive System

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14. The scrotum is a skin-covered pouch suspended from the perineal region. Internally it is divided into two sacs by a septum, each sac containing a testis, epididymis, and the lower part of the spermatic cord. The function of the scrotum is to permit the placement of the testes in a location that allows their temperature to be about 3° C below normal body temperature.

15. The three cylindrical masses of erectile, or cavernous, tissue in the penis are the corpora cavernosa (which are the two larger, uppermost cylinders) and the corpus spongiosum (which is the smaller, lower cylinder).

16. The distal part of the corpus spongiosum overlaps the terminal ends of the two corpora cavernosa to form a slightly bulging structure called the glans penis. The skin over the glans penis is folded doubly to form a more or less loose-fitting, retractable casing known as the prepuce or foreskin.

17. The spermatic cord is a cylindrical casing of white fibrous tissue located in the inguinal canals between the scrotum and the abdominal cavity. It encloses the vas deferens, blood vessels, lymphatics, and nerves.

18. The anatomical structures and functional control mechanisms that result in the production, transfer, and introduction of viable sperm into the female reproductive tract are the primary reproductive functions of the male.

Answers to Critical Thinking Questions (p. 1056) 1. The proper functioning of the reproductive system ensures the survival of the species rather than the individual.

2. The functions of the male reproductive system consist of the production, transfer, and introduction of sperm into the female reproductive tract, where fertilization can occur.

3. The seminiferous tubules are coiled tubules found in the lobules of the testes. There can be one to three tubules in each lobule. The tubules from each lobule come together to form a plexus called the rete testis. The efferent ductules are a series of sperm ducts, which drain the rete testis and pierce the tunica albuginea to enter the head of epididymis.

4. The urethra passes through the small hole in the center of the prostate gland. If the gland enlarges, it squeezes the urethra, frequently closing it so completely that urination becomes impossible.

5. The structures that contribute to the formation of seminal fluid are the testes, epididymis, seminal vesicles, prostate gland, and bulbourethral glands.

6. The course from the formation of seminal fluid to its ejaculation to the exterior begins in the testes; passing through the epididymis, the vas deferens, and the ejaculatory duct; and exiting the body by way of the urethra.

7. The substance hyaluronidase is important in the functioning of the semen. It is a digestive enzyme that assists in liquefying the intercellular substances between the cells that encase the ovum, making fertilization possible.

8. The spermatozoa function to fertilize the ovum. Various parts are specialized for this purpose: the head is capped by acrosome, an enzyme that allows the sperm to penetrate the ovum; the head contains the genetic material (23 chromosomes); the middle piece contains mitochondria, which provide energy; and the flagellum (tail) allows the sperm to swim.

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Anatomy and Physiology, 9th ed.

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Instructor’s Resource Material for

46 Female Reproductive System ANSWER KEYS Answers to Quick Check Questions 1. The ovaries are the essential organs of the female reproductive system.

2. The major accessory organs are the uterine tubes, uterus, vagina, vulva, and mammary glands.

3. The two ovaries, one on each side of the uterus, are located below and behind the uterine tubes.

4. The ovarian follicles are epithelial cells located in the ovaries and embedded in a connective tissue matrix.

5. The ovaries produce female gametes, or ova. The ovaries also secrete the female sex hormones estrogen and progesterone.

6. The body, cervix, and fundus are the principal layers of the uterine wall.

7. Normally, the uterus is flexed between the body and cervix, with the body lying over the superior surface of the bladder, pointing forward and slightly upward. The cervix points downward and backward from the point of flexion, joining the vagina at approximately a right angle. Eight uterine ligaments (three pairs, two single ones) hold the uterus in its normal position by anchoring it in the pelvic cavity.

8. The uterus permits sperm to ascend toward the uterine tubes. If fusion of gametes occurs, the developing offspring implants in the endometrial lining of the uterus and continues its development. Tiny endometrial glands of the uterus produce nutrient secretions to sustain the developing offspring until the placenta can be produced. Finally, the rhythmic contractions of the myometrium occur during delivery, which help push the offspring out of the mother’s body.

9. The uterine tubes collect the ovum when it is released from the ovary and transport it to the uterus. The tubes are also the site of fertilization.

10. The vagina lubricates and stimulates the glans penis during intercourse, serves as a receptacle for semen, serves as the lower part of the birth canal, and transports blood and tissue shed from the lining of the uterus during menstruation.

11. The external genitals of females are referred to as the vulva.

12. The clitoris is composed of erectile tissue homologous to the corpora cavernosa and glans of the penis. Also, the prepuce, or foreskin, covers the clitoris, as it does the glans penis.

13. The corpus luteum secretes progesterone.

14. The corpus luteum is formed from the cells of the ruptured follicle. These cells enlarge and become transformed into the golden corpus luteum.

15. The ovarian cycle refers to the events that aid and lead to the development of the egg in the ovary and the release of that egg (ovulation). The menstrual cycle refers to the events that prepare the endometrium for the fertilized egg.

16. Proliferative phase is another name for the postmenstrual cycle because proliferation of the endometrial cells occurs at this time.

17. Ovulation is associated with a surge in follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

18. An increase in blood estrogens produces the following changes in the uterus: proliferation of endometrial cells, a thickening of the endometrium, growth of endometrial glands and of the spiral arteries of the endometrium, increase in water content of the endometrium, and increased myometrial contractions.

19. Menopause is the termination of menstrual cycles. Menopause occurs when ovarian follicles cease to respond to gonadotropins.

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Chapter 46 | Female Reproductive System _____________________________________________________

20. Each breast consists of several lobes separated by septa of connective tissue. Each lobe consists of several lobules, which, in turn, are composed of connective tissues in which are embedded the secreting cells of the gland, arranged in grapelike clusters around the minute ducts. The ducts from the various lobules unite, forming a single lactiferous duct for each lobe. These main ducts converge toward the nipple, like the spokes of a wheel. Each of these ducts terminates in a tiny opening on the surface of the nipple.

21. Estrogen and progesterone prepare the breast for lactation.

22. Oxytocin causes milk to be ejected into the lactiferous ducts.

Answers to Case Study Questions (p. 1085) 1. d: The cervix is a passageway into the uterus. The uterine tubes lead from the uterus toward the ovaries.

However, the uterine tubes do not actually connect to the ovaries. Fingerlike projections (fimbriae) are in close proximity to the ovaries, but still a small gap exists between the two. This allows the dye to exit into the peritoneal cavity.

2. a: Follicle-stimulating hormone (FSH) is produced by the anterior pituitary in response to low estrogen levels as part of the monthly female reproductive cycle. As FSH increases, there is a corresponding increase in follicles, which produces estrogen. The estrogen level increases dramatically on about day 12, followed by a surge of luteinizing hormone (LH), which stimulates ovulation.

3. b: The corpus luteum (literally “yellow thing body”) forms from follicular cells immediately after ovulation.

If fertilization does not occur, the corpus luteum degenerates into the corpus albicans, which is reabsorbed by the ovary.

4. c: The oocyte can survive only a short time after ovulation. So the sperm must swim up through the uterus and into the uterine tube to meet the recently released oocyte, rather than wait for its descent into the uterus.

Answers to Review Questions (p. 1089) 1. The essential organs of the female reproductive system are the ovaries. The accessory organs are the uterine tubes, the uterus, the vagina, the vulva, and the mammary glands.

2. The inner layer of the uterine wall is made up of a mucous membrane called the endometrium. It is composed of three layers of tissue: (1) a compact surface layer of partially ciliated simple columnar epithelium called the stratum compactum; (2) a spongy middle layer of loose connective tissue called the stratum spongiosum; and (3) a dense inner layer that attaches the endometrium to the underlying myometrium, called the stratum basale.

The middle layer of the uterine wall is made up of three layers of smooth muscle fibers that extend in all directions—longitudinally, transversely, and obliquely—called the myometrium.

The external layer, which is incomplete (because it does not cover the cervix and covers only part of the body of the uterus), is called the parietal peritoneum.

3. The uterus receives blood from the uterine, vaginal, and ovarian arteries.

4. The eight ligaments that hold the uterus in a normal position are: two broad ligaments, two uterosacral ligaments, a posterior ligament, an anterior ligament, and two round ligaments.

5. The uterus permits sperm to ascend toward the uterine tubes. It provides the place for gestation of the fertilized egg, and the endometrium is shed during menstruation.

6. The uterine tubes lie in the upper free margin of the broad ligament and extend upward and outward toward the sides of the pelvis and then curve downward and backward. The uterine tubes are about 10 cm long. The uterine tubes are lined with a mucous layer. The lining is continuous with the peritoneum on the distal ends and with the uterus and vagina at the proximal ends. Because the lining of the uterine tubes is continuous from the vagina to the peritoneum, any infection in the vagina can spread through the uterine tubes directly to the peritoneum.

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7. The development of a female sex cell from its most primitive state through ovulation is as follows: the primary follicle made up of an oocyte and a single layer of follicular cells; the double-layered follicle stage; the follicle-beginning of the antrum formation; the maturing follicle with the follicular or granulosa cells; the mature follicle with the oocyte surrounded by the zona pellucida; and the release of the ovum during ovulation.

8. The hormones secreted by the cells in the ovarian tissue are estrogen and progesterone.

9. The vagina has several functions. During sexual intercourse, the lining of the vagina lubricates and stimulates the glans penis, which triggers the ejaculation of semen. The vagina serves as a receptacle for semen and as the lower portion of the birth canal. Also, the vagina serves to transport the shed endometrial tissue out of the body during menstruation.

10. The structures that make up the female external genitals are the mons pubis, labia majora, labia minora, clitoris, urinary meatus, vaginal orifice, and Bartholin glands.

11. An episiotomy is a surgical incision of the perineum to prevent tearing of the perineum during childbirth.

12. Some of the advantages that breast-feeding provide are: (1) milk is a rich source of protein, fat, calcium, and other nutrients in proportions needed by a young, developing body; (2) nursing provides passive immunity to the offspring in the form of maternal antibodies in the milk; and (3) nursing appears to enhance the emotional bond between the mother and child.

13. The development of a method called radioimmunoassay makes it possible to measure blood levels of gonadotropins.

14. After menopause, there is a dramatic decrease in estrogen. This causes a negative feedback increase in gonadotropin levels.

15. Pain within a few hours after ovulation is referred to as mittelschmerz. It has been ascribed to irritation of the perineum by the hemorrhage from the rupture of the egg follicle.

Answers to Critical Thinking Questions (p. 1089) 1. Estrogen and progesterone made in the ovary act on the breasts to make them structurally ready to secrete milk. The anterior pituitary gland produces prolactin, which stimulates the alveoli of the mammary glands to secrete milk. The posterior pituitary gland produces oxytocin, which stimulates the alveoli of the breast to eject milk into the ducts. Suckling by the baby and various favorable mental and physical conditions can also stimulate lactation.

2. The phases of the menstrual cycle include menses, or menstrual period; postmenstrual phase, which can also be called the preovulatory, estrogenic, follicular, or proliferative phase; ovulation; and premenstrual phase, which can also be called the postovulatory, luteal, secretory, or progesterone phase.

The phase showing the most variation in time is the postmenstrual phase. Each phase contributes to reproductive system. The menstrual phase removes the lining of the uterus and prepares it for a new cycle.

The postmenstrual phase begins the ovarian development of an egg cell and begins the early preparation of the uterus. Ovulation releases the mature egg for possible fertilization. The premenstrual phase prepares the uterus for the possibility of the implantation of the fertilized egg.

3. Follicle-stimulating hormone (FSH) stimulates the secretion of estrogen from the follicular cells. The concentration of estrogen increases gradually for a few days during the postmenstrual phase; then suddenly, on about the twelfth day of the cycle, it leaps upward to its maximum peak. About 12 hours after this, a luteinizing hormone (LH) surge occurs and presumably triggers ovulation a day or two later. Because ovulation causes the formation of the corpus luteum, a process called luteinization, the hormone that stimulates ovulation is called luteinizing hormone.

4. FSH stimulates the growth of primary follicles and stimulates the ovarian follicles to secrete estrogen. LH and FSH work synergistically to complete the development of the follicle and oocyte. The LH surge midway through the cycle stimulates ovulation. LH and FSH assist in the formation of the corpus luteum. Low levels of FSH and LH are responsible for the regression of the corpus luteum into the corpus albicans.

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Chapter 46 | Female Reproductive System _____________________________________________________

5. The uterus is affected by variations in blood estrogen and progesterone levels. Increasing blood estrogen levels cause proliferation of the endometrial cells, resulting in the thickening of the endometrium. This leads to growth of the endometrial glands and arteries, an increased water content of the endometrium, and increased myometrial contractions. Increasing blood progesterone levels stimulate secretions of the endometrium glands, which prepare the uterus for implantation of the fertilized egg. Progesterone increases the water content of the endometrium and decreases the myometrial contractions. A drop in estrogen and progesterone levels triggers endometrial sloughing, which characterizes the menstrual phase.

6. Contraceptive pills contain either progesterone-like substances or estrogen and progesterone-like substances.

If the levels of progesterone and estrogen remain high, the secretion of FSH and LH are suppressed. Without FSH or LH, no ovum is formed, so no pregnancy could take place. The postmenstrual phase is inhibited.

7. The release of FSH and LH stimulates the development of an egg follicle and the release of estrogen and progesterone. The estrogen stimulates the growth of the lining of the uterus in terms of size, blood supply, and endometrial glands. Estrogen and the LH surge cause ovulation and the formation of the corpus luteum.

The corpus luteum begins the production of progesterone, which greatly increases the blood level of progesterone. This further stimulates the growth of the endometrium and suppresses the secretions of FSH and LH. If fertilization does not occur, the corpus luteum regresses to the corpus albicans and the blood level of progesterone and estrogen drops. This causes the sloughing of the endometrium, the menstrual phase. The estrogen drop also causes the increased secretion of FSH and LH, beginning the cycle again.

8. Amenorrhea can be caused by having a body fat composition that is too low to sustain normal reproductive function. A person with severe anorexia would probably have amenorrhea.

9. Failure to have a menstrual period is called amenorrhea. Amenorrhea may occur in some female athletes as a result of low body fat composition. Besides infertility, amenorrhea may cause low blood levels of estrogen, which may cause osteoporosis.

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Instructor’s Resource Material for

47 Growth and Development ANSWER KEYS Answers to Quick Check Questions 1. Meiotic division reduces the number of chromosomes in each daughter cell to half the number present in the parent cell.

2. Mitosis is one cell division resulting in two daughter cells with exactly the same number of chromosomes as the parent cell. Meiotic division consists of two cell divisions that take place one after the other. The result of these divisions is four daughter cells, each with half the number of chromosomes as the parent.

3. Fertilization occurs in the uterine (fallopian) tubes.

4. A fertilized ovum is called a zygote.

5. A morula is a solid mass of cells formed by the division of a fertilized egg. A blastocyst is a hollow ball of cells with an inner cell mass.

6. The chorion, chorionic villi, and placenta are derived from the outer wall of the blastocyst.

7. Human chorionic gonadotropin (hCG) maintains the corpus luteum during the early weeks of pregnancy.

8. A trimester is a 3-month segment of the gestation period.

9. The term embryo is used to describe the developing individual during the first trimester. The term fetus is used to describe the developing individual from weeks 8 to 39.

10. The primary germ layers are the endoderm, ectoderm, and mesoderm.

11. Histogenesis is the process by which the primary germ layers develop into many different kinds of tissues.

12. Stage one: Period from onset of uterine contractions until dilation of the cervix is complete. Stage two: Period from the time of maximal cervical dilation until the baby exits through the vagina. Stage three: Process of expulsion of the placenta through the vagina.

13. Identical twins result from the splitting of embryonic tissue from the same zygote early in development.

Fraternal twins result from the fertilization of two different ova by two different spermatozoa. Fraternal twinning requires the production of more than one mature ovum during a single menstrual cycle.

14. The four major phases of the postnatal period are (1) infancy, (2) childhood, (3) adolescence and adulthood, and (4) older adulthood.

15. Neonatal development occurs during the first 4 weeks of infancy.

16. Adolescence is marked by rapid and intense physical growth, breast development, and menstruation among girls; enlargement of the testicles among boys; and a spurt of growth in height in both sexes.

17. Research shows that many types of human cells cannot reproduce more than 50 times, thus limiting the maximal life span. Other answers may include nutrition, injury, disease, and other environmental factors that affect the aging process. Some gerontologists have proposed that aging is caused by “aging” genes that regulate apoptosis or other cell functions. Another proposal is that the cause of aging is autoimmunity. This theory suggests that as a person ages, mitochondria become less able to shuttle adenosine triphosphate (ATP) out to the cytosol. This decrease in ATP renders cells less able to perform their functions.

18. During the aging process, bones undergo changes in texture, degree of calcification, and shape. Instead of clean-cut margins, older bones develop indistinct and shaggy-appearing margins with spurs (lipping). With age, bones become more porous and subject to fracture. Degenerative joint diseases are common in elderly adults.

19. Atherosclerosis, arteriosclerosis, and hypertension are age-related changes in the cardiovascular system.

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Chapter 47 | Growth and Development ________________________________________________________

20. Hardening of the lens (presbyopia) is a result of the “old eye” losing elasticity in the lens. This condition results in the lenses being unable to change shape to accommodate for near vision. Also, loss of transparency of the lens is common among elderly adults. If the lens becomes cloudy and significantly impairs vision (cataract), surgery is needed. Glaucoma is the most serious age-related eye disorder. It causes an increase in the pressure within the eyeball and may result in blindness.

21. Cancer, heart disease, and stroke are leading causes of death in the United States.

Answers to Case Study Questions (p. 1121) 1. a: The first stage in development is the single cell created by fertilization (zygote), which will immediately start to divide. In about 3 days, it will be a solid ball of cells called a morula. The next stage is the blastocyst (a hollow ball of cells). Although the term embryo encompasses the time from fertilization until the end of the eighth week, the more accurate term for the newly fertilized ovum would be a zygote. From week 9 until birth, the term fetus is used to describe the developing baby.

2. d: One of the reasons for unequal cytoplasmic division in oogenesis is to provide the developing zygote with enough resources to ensure survival until implantation. It takes about 1 week for the zygote to travel down the uterine tube and find a place to burrow into the uterine wall. About 2 to 3 more days are required for the blastocyst to embed fully into the uterine wall and start receiving nourishment from the maternal blood vessels.

3. b: Identical twins are formed from the same zygote and have the exact same DNA, so they would have to be the same sex. Fraternal twins are formed from two separate zygotes (another term for them is dizygotic). They are really no more alike than any other siblings; they just happen to share the uterus at the same time.

4. c: The placenta is the main “container” around the fetus, but the inner liner is the amnion. This layer holds the fluid cushioning the fetus. The rupture of the amniotic sac usually occurs near the beginning of labor. The fluid may come out as a gush or as a trickle or anywhere in between.

Answers to Review Questions (p. 1125) 1. Developmental biology is the study of the changes that occur during the cycle of life from conception to death. Growth is an increase in body mass. Development refers to the complex series of changes that occur at various times of life. Early stages of development (prenatal stage) are characterized by rapid growth. Later stages are characterized by little, if any, growth.

2. In the process of spermatogenesis, each primary spermatocyte undergoes meiotic division I to form two secondary spermatocytes, each with 23 chromosomes. Each secondary spermatocyte undergoes meiotic division to form four spermatids, each with 23 chromosomes. In the process of oogenesis, primitive female sex cells called oogonia undergo mitotic division to form primary oocytes. Meiosis I produces a secondary oocyte and the first polar body. If the egg is fertilized, meiotic division of the secondary oocyte and the production of a second polar body leave the egg with 23 chromosomes.

3. The two processes necessary to bring the sperm and ovum into proximity with each other are ovulation and insemination of the seminal fluid from the male urethra into the female vagina.

4. The ovum and its surrounding layers of granulosa cells and a thick film called the zona pellucida attract sperm with special peptides.

5. At the blastocyst stage, the zygote implants into the uterus.

6. A morula is a solid mass of cells. The cells of the morula begin to form a cavity in the center. When this becomes a hollow ball, the structure is called a blastocyst.

7. The blastocyst consists of an outer layer of cells and an inner cell mass. The outer layer is called the trophoblast. The trophoblast forms the support structures of the chorion and the placenta. The chorion develops from the trophoblast to become an important fetal membrane in the placenta. The chorionic villi are extensions of the blood vessels of the chorion that bring the embryonic circulation to the placenta.

8. The functions of the placenta are to structurally anchor the developing embryo to the wall of the uterus; to provide nutrition, respiration, and excretion; and to provide endocrine functions.

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9. Placental tissue secretes large amounts of human chorionic gonadotropin (hCG) in early pregnancy, which peaks about 8 or 9 weeks after fertilization, then drops to a continuous low level by about week 16. This keeps the corpus luteum functioning in its production of estrogen and progesterone. As the level of these hormones produced by the placenta increases, the level of hCG decreases. This reduces the levels of estrogen and progesterone produced by the corpus luteum, and after about 3 months, the corpus luteum degenerates.

The placenta is then able to produce enough estrogen and progesterone to sustain the pregnancy.

10. During the period from fertilization to the end of 8 weeks of gestation, the term embryo is used. From week 9 to week 39, the term fetus is used.

11. The endoderm forms the linings of the respiratory tract, gastrointestinal tract, tonsils, pancreatic ducts, hepatic ducts, and urinary tract, as well as the glandular epithelium of the thymus, thyroid, and parathyroid glands.

The mesoderm forms the dermis of the skin, skeletal muscles, bones, many glands of the body, the kidneys, gonads, and parts of the circulatory system. The ectoderm forms the epidermis of the skin, enamel of the teeth, cornea and lens of the eye, brain, and spinal cord.

12. Stage one is the period from the onset of uterine contractions until dilation of the cervix is complete. Stage two is the period from maximal cervical dilation until the baby exits through the vagina. Stage three is the process of expulsion of the placenta through the vagina.

13. Identical twins result from the splitting of embryonic tissue from the same zygote early in development.

Identical twins usually share a placenta. Identical twins have the same genetic code. Fraternal twins result from the fertilization of two different ova by two different sperm. Fraternal twins have two different placentas and are no more genetically related than any other two siblings.

14. The head of an infant is approximately one-fourth of the total height of the body. The adult head is only about one-eighth of the total height of the body.

15. The period of infancy begins at birth and lasts about 18 months. Childhood extends from the end of infancy to sexual maturity, usually at 12 to 14 years of age for girls and 14 to 16 years of age for boys. Adolescence generally spans the teenage years, from 13 to 19.

16. The secondary sex characteristics develop during adolescence. These characteristics are initiated by the secretion of sex hormones.

17. The structural changes that can occur as a result of bone calcification due to aging include the development of indistinct and shaggy-appearing bone margins with spurs, a process called lipping. The changes in calcification may also result in the reduction of bone size and in bones that are porous and more subject to fracture.

18. Atherosclerosis consists of fatty deposits that build up in blood vessel walls and thus narrow the passageway for the movement of blood. Arteriosclerosis is the calcification of the fatty deposits or other substances in the blood vessels. This is sometimes called hardening of the arteries. Hypertension is high blood pressure.

19. The most serious age-related eye disorder is glaucoma. Glaucoma causes an increase in the pressure within the eyeball and, unless treated, can result in blindness.

Answers to Critical Thinking Questions (p. 1125) 1. The process of meiosis is different from the process of mitosis in that the outcome of meiosis produces cells with half the number of chromosomes present in the parent cell.

2. In the process of spermatogenesis, each primary spermatocyte undergoes meiotic division I to form two secondary spermatocytes, each with 23 chromosomes (haploid). Each secondary spermatocyte undergoes meiotic division to form four spermatids, each with 23 chromosomes (haploid). In the process of oogenesis, primitive female sex cells called oogonia undergo mitotic division to form primary oocytes. Meiosis I produces a secondary oocyte and the first polar body. If the egg is fertilized, meiotic division of the secondary oocyte and the production of a second polar body leave the egg with 23 chromosomes (haploid). If a diploid cell (46 chromosomes) rather than the haploid cell were used for human reproduction, the exact genetic material would not be restored to the offspring.

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Chapter 47 | Growth and Development ________________________________________________________

3. Histogenesis is the process by which the primary germ layers develop into many different kinds of tissues.

Organogenesis is the arrangement of these tissues into organs. Histogenesis comes first.

4. If abnormal conditions of the mother or fetus make normal vaginal delivery hazardous or impossible, a cesarean section can be used. This is a surgical procedure in which the newborn is delivered through an incision in the abdominal and uterine walls.

5. The symptoms of the drop in estrogen levels during menopause are the cessation of menstrual cycles, hot flashes, and thinning of the vaginal wall. The drop in estrogen levels is associated with a loss of bone mass called osteoporosis.

6. In vitro fertilization refers to a procedure in which the ovum is fertilized outside of the mother’s body. The ovum is obtained from the mother by the insertion of a laparoscope through a small incision in the woman’s abdomen. Once in the abdomen, the device allows the physician to see the ovary and to puncture a mature follicle. The mature ovum is released, then sucked up and transferred to—and maintained in—a specialized medium until it is capable of being fertilized. It is then fertilized by the father’s sperm; after development to the 8- or 16-cell stage, it is placed into the mother’s uterus, where implantation may occur. Under the best conditions, only about 50% of the fertilized ova successfully implant. In most clinics in the United States, about 20% to 30% of in vitro fertilization cases result in implantation and a pregnancy that progress to term.

7. A sound exercise program throughout life can reduce some of the common effects of aging. Improved cardiovascular condition associated with aerobic training can prevent or reduce the effects of several agerelated circulatory problems. The loss of bone mass that occurs in older adulthood is less of a problem if one enters this period of life with a higher bone density developed by exercise. The relatively high ratio of body fat to muscle often seen in older adults can be avoided entirely by a lifelong fitness program.

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Instructor’s Resource Material for

48 Genetics and Heredity ANSWER KEYS Answers to Quick Check Questions 1. Each gene contains a genetic code that the cell transcribes to a messenger RNA (mRNA) molecule. Each mRNA molecule associates with a ribosome in which the code is translated to form a specific polypeptide molecule. Many of the protein molecules formed from these polypeptides are enzymes. These enzymes and other functional proteins regulate the entire structure and function of the body. Thus, genes determine the structure and function of the body by producing a set of enzymes and other proteins.

2. Gregor Mendel may be considered the founder of the scientific study of genetics.

3. An autosome is one of 44 (22 pairs) chromosomes in the human genome. Each member of a pair of autosomes matches the other in size and other structural features. Sex chromosomes are a pair of chromosomes in the human genome that determine gender; normal males have one X chromosome and one Y chromosome, and normal females have two X chromosomes.

4. Independent assortment and crossing over increase genetic variation.

5. A dominant genetic trait is one whose effects are both seen and capable of masking the effects of a recessive gene for the same trait. Recessive traits are “hidden,” or not expressed, when matched with a dominant gene for the same trait. Recessive traits are only expressed when not matched with a dominant gene for the same trait.

6. Codominance occurs when two different dominant genes occur together and have equal effects.

7. A mutant gene can benefit a human population if it can provide some biological advantage for a human population.

8. X-linked inheritance refers to those traits that are carried on the X chromosome.

9. Single-gene diseases occur when individual mutant genes in the nuclear DNA are passed from one generation to the next.

10. Nondisjunction occurs when a pair of chromosomes fails to separate. This produces a gamete with two autosomes that are “stuck together” instead of the usual one.

11. Inheritance of mitochondrial DNA occurs only through one’s mother because the few mitochondria that a sperm may contribute to the ovum during fertilization do not survive. Because mDNA contains the only genetic code for several important enzymes, it has the potential to carry mutations that produce disease.

12. Phenylketonuria (PKU) is caused by a recessive gene that fails to produce the enzyme phenylalanine hydroxylase. This enzyme is needed to convert the amino acid phenylalanine into another amino acid, tyrosine. A high concentration of phenylalanine destroys brain tissue. Avoiding phenylalanine in the diet maintains lower levels for those who do not have the enzyme phenylalanine hydroxylase.

13. Tay-Sachs disease is a recessive condition involving failure to make a subunit of an essential lipid-processing enzyme, hexosaminidase. Abnormal lipids accumulate in brain tissue of those with Tay-Sachs disease, causing severe retardation and death by age 4 years.

14. Trisomy 21 (Down syndrome) is characterized by mental retardation and multiple structural defects.

15. Abnormal genes (oncogenes) are thought to cause cancer by transforming a cell into a cancer cell only when certain environmental conditions occur. Another hypothesis involves tumor suppressor genes. When these genes are nonfunctional because of mutation, cells are allowed to divide abnormally, possibly producing cancer. Yet another possible genetic basis for cancer relates to the genes that govern the cell’s ability to repair damaged DNA.

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Chapter 48 | Genetics and Heredity __________________________________________________________

16. Genetic counseling refers to professional consultations with families regarding genetic diseases. Genetic counselors may help a family determine the risk of producing children with genetic diseases. They may also help evaluate whether any offspring already with a genetic disorder and offer advice on treatment or care.

17. Pedigrees are charts that illustrate genetic relationships in a family over several generations. Pedigrees are useful in determining the possibility of producing offspring with certain genetic disorders.

18. The Punnett square provides data that determine the ratio of different gene combinations in the offspring, which allows one to predict their probability of occurrence in the next generation.

19. The first step in producing a karyotype is getting a sample of cells from the individual to be tested. Collected cells are grown in a special culture medium and allowed to reproduce. Cells in metaphase are stained and photographed using a microscope. The chromosomes are then cut out of the photo and pasted on a chart in pairs according to size. Genetic counselors can then examine the karyotype and determine the presence of any chromosomal abnormalities.

20. Patients with most genetic disorders are treated with gene therapy.

21. In gene replacement therapy, genes that specify production of abnormal, disease-causing proteins are replaced by normal or “therapeutic” genes. Genetically altered viruses are used as carriers.

Answers to Case Study Questions (p. 1145) 1. a: For their daughter to have phenylketonuria (PKU; a homozygous recessive condition), both Carlos and Maria would have to be carriers. Draw a Punnett square using P for the dominant trait and p for the recessive.

Both Carlos and Maria would be Pp. The chance for each child (each fusion of sperm and egg) to inherit PKU (pp) is 25%.

2. b: The gene for color blindness is sex-linked, meaning it is carried on the X chromosome. Carlos and Maria’s son inherited his Y chromosome from Carlos. His X chromosome comes from Maria. Because Maria’s father was color-blind, his X chromosome carried the recessive allele for color-blindness. That means that the X Maria received from her father was recessive. Her mother was not color-blind, and neither is Maria, so she must have one dominant and one recessive allele. So, Maria’s son has a 50% chance of receiving the recessive allele.

3. c: The same principles that determined the percentage in question 2 apply here as well. Draw a Punnett square crossing a female (XX) with a male (XY). Every single time, the chance of an offspring being male is 50%. It is the same as flipping a coin. Every time you flip, you have a 50% chance of getting tails.

Answers to Review Questions (p. 1149) 1. The first person to discover the basic mechanism by which traits are transmitted from parent to offspring was Gregor Mendel.

2. Albinism is a recessive trait, which means the formation of normal melanin pigment is dominant. The only genotype that would cause albinism would be the presence of two recessive genes.

3. A genotype is the internal condition of what genes an organism possesses for a particular trait. The phenotype is the manner in which the genotype is expressed.

4. Codominance occurs when there are two dominant genes for the same trait. In this form of dominance, both genes have an equal effect. The textbook gives sickle cell anemia as an example of codominance.

5. If a certain trait is X-linked recessive, the only genotype that would cause a female to express the trait is having two X chromosomes that both have the recessive trait.

6. Mutagens include chemicals, some forms of radiation, and some viruses.

7. Mutations can be beneficial to a species if they produce a phenotype that is able to resist specific diseases. For example, people who are heterozygous for sickle cell anemia are more resistant to malaria. People who are heterozygous for Tay-Sachs disease are more resistant to tuberculosis.

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8. Some genetic diseases result from the combined effects of inheritance and environmental factors. Because they are not solely caused by genetic mechanisms, they are not genetic diseases in the usual sense of the term.

They are instead said to involve a genetic predisposition.

9. When a pair of chromosomes fails to separate during meiosis, a gamete with two autosomes stuck together is produced, rather than a gamete with the usual single autosome. The result is a zygote with three chromosomes in a pair. This is called trisomy, and the mistake that caused it is called nondisjunction.

10. Cystic fibrosis, PKU, and Tay-Sachs disease are all autosomal recessive, single-gene diseases. The gene for cystic fibrosis is found on chromosome 7, the gene for PKU is found on chromosome 12, and the gene for Tay-Sachs disease is found on chromosome 15.

11. The chromosomal disorder that involves trisomy 21 is Down syndrome.

12. Oncogenes are abnormal genes thought to cause cancer. One hypothesis states that most normal cells contain such cancer-causing genes, but it is uncertain how these genes become activated. Tumor suppressor genes are a class of genes that all normal cells contain. These genes regulate cell division so that it proceeds normally.

13. In gene replacement therapy, genes that specify production of abnormal or disease-causing proteins are replaced by normal or therapeutic genes. In gene augmentation therapy, normal genes are introduced with the hope that they will augment or add to the production of the needed protein. In both cases, viruses are used to deliver the therapeutic genes to the cells.

14. Genome refers to the entire collection of genetic material in each typical cell of the human body.

15. A congenital disorder is any pathological condition present at birth.

Answers to Critical Thinking Questions (p. 1149) 1. Proteins have two major functions in the body: structure and enzymes. The proper structural proteins are necessary so that body structures function properly. Enzymes are necessary to catalyze almost all chemical reactions in the body.

2. Chromatin refers to a thin, threadlike form that DNA assumes when it is actively transcribing mRNA. Chromosomes are the compact mass of DNA that forms during cell division when each strand of chromatin coils in on itself. Genes are distinct codes within the DNA molecule.

3. According to one of Mendel’s principles, each chromosome assorts itself independently during meiosis. This principle of independent assortment states that as sperm are formed, the chromosome pairs separate and the chromosomes get mixed up and redistribute themselves. Thus each sperm is likely to have a different set of 23 chromosomes. Because the ovum forms in the same way, each ovum would be genetically different from every other ovum. This ensures that each offspring from a single set of parents is likely to be genetically unique. Also, during one phase of meiosis, when pairs of matching chromosomes line up along the equator of the cell, they exchange genes with one another. This process is called crossing over. Sometimes entire groups of genes stay together and cross over as a unit. Crossing over introduces additional opportunities for genetic variation among offspring of a single set of parents. The genetic variation produced by independent assortment and crossing over accounts for the tremendous variation that is seen in the human population.

4. The X chromosome is much larger than the Y chromosome. The X chromosome carries other traits besides sex determination. The Y chromosome carries only those traits necessary for male sexual characteristics. For a female to express a recessive sex-linked disorder, she must have two recessive genes, one on each X chromosome. Because there is no corresponding gene on the Y chromosome to stop their expression, a single recessive gene on the X chromosome will be expressed in the male.

5. A pedigree is a chart that illustrates genetic relationships in a family over several generations. A karyotype is an ordered arrangement of photographs of chromosomes taken from a single cell. A karyotype would be most helpful in the diagnosis of Down syndrome. A pedigree would be most helpful in the diagnosis of Huntington disease.

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Anatomy and Physiology, 9th ed.

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