Preface

This course is based on the premise that you are a healthcare professional and that you already understand physiology but want a crash course in pathophysiology or the study of disease states. The study of pathophysiology recognizes that there are normal homeostatic mechanisms in place in the healthy person that drive health and defend against disease. For a variety of reasons—from genetic disorders, to stress or wear-andtear on the system, to patient behaviors—there are things that throw off these homeostatic mechanisms, creating an environment where the normal compensatory activities in place that defend against aberrations in the human body are driven off course. The end result is the creation of diseases you will learn about as part of this course.

The first chapter in the course introduces pathophysiology by identifying some of the many genetic diseases involving humans. As you know, there are 23 pairs of human chromosomes with an estimated 19,000-20,000 human protein-coding genes. The estimate of the number of human genes has been repeatedly revised down from initial predictions of 100,000 or more. Genetic disease can be chromosomal, autosomal dominant, autosomal recessive, or x-linked recessive. The basis of these and the types of genetic disorders seen in the different categories is covered in this chapter.

The focus of chapter two in the course is the immune system and the pathophysiology of immune disorders. This chapter talks about inflammation and infection, which are two different but interrelated dysfunctions of the immune system. In addition, there are individuals who have immunodeficiency states, which can be primary or acquired, as is the case with human immunodeficiency virus or HIV disease and when individuals receive immunosuppressants after a transplant. Finally, there can be overactivity of the immune system with autoimmune disorders that involve action of the immune system against the individual’s own cells or cell components.

Chapter three in the course focuses on the pathophysiology of the diseases of the nervous system. This includes diseases of the brain, including delirium, dementia,

seizures, brain infections, and traumatic brain injury. Other degenerative diseases, such as Parkinson disease, are covered as part of the discussion as well. Diseases of the peripheral nerves, including peripheral neuropathy and Guillain-Barre disease, are important to the discussion of the nervous system and are covered as part of this chapter.

Chapter four discusses the different endocrine disorders in the body. The discussion starts with an overview of the coordination between the hypothalamus and the pituitary gland—both of which can be called a “master gland” because of the far-reaching implications of their activities. The other glands have more specific functions and include the thyroid gland, the adrenal gland, the parathyroid gland, and endocrine pancreatic gland. Each of these glands produces hormones and will have various dysfunctions based on overactivity or underactivity of the gland.

The topic of chapter five in the course is hematological disorders. There are three main cellular components in human blood: the red blood cells or erythrocytes, the white blood cells or leukocytes, and the platelets. These cells are all made in the bone marrow and many of them will mature there. Each type of cell serves a different function within the body. Red blood cells carry oxygen, white blood cells fight infection, and platelets aid in blood clotting. Disorders of these cells and cell fragments are covered as part of this chapter.

The focus of chapter six in the course is heart disease. This involves a wide-reaching discussion of true heart diseases, such as heart muscle disorders, heart failure, endocarditis, and pericarditis, as well as blood vessel-related diseases. It talks about atherosclerosis, which is a disease that can involve the heart, the brain, and the peripheral vascular system. Other disorders involving clotting, including deep venous thromboses and dyslipidemia (which leads to heart disease), are covered as part of this chapter.

Chapter seven involves a discussion of the pulmonary system and lung disorders. Chronic diseases of the lungs involve chronic obstructive pulmonary disease, which encompasses chronic bronchitis and emphysema, and asthma. Interstitial lung diseases are usually relatively chronic as well. Acute pulmonary diseases can be as simple as an

acute respiratory infection or as severe as pneumonia. Tuberculosis can be acute or chronic and may not always involve the lungs. The discussion concludes with coverage of the causes and pathophysiology of pleural effusion, which also may or may not always involve the lungs.

Chapter eight in the course talks about the various digestive system diseases—from the esophagus to the large bowel. Esophageal diseases involve the various motility disorders of the esophagus. Stomach disease usually means some type of peptic ulcer disease. Malabsorption syndromes are many and include celiac disease and other disorders of the small bowel. The GI tract as a whole can be affected by Crohn disease, while the large bowel is affected by ulcerative colitis. Other disorders of the digestive system include acute and chronic pancreatitis, non-alcoholic steatohepatitis, cirrhosis, and acute and chronic cholecystitis.

The topic of chapter nine is kidney disease and other urologic diseases. There are many possible insults that can involve the kidneys, including acute processes leading to acute kidney injury and chronic processes leading to chronic kidney disease. These can lead to nephrotic syndrome as well as what can be described as nephritic syndromes. There are also several different types of urinary tract infections—the vast majority of which are bacterial and involve the bladder and/or kidneys.

Chapter ten in the course encompasses the various electrolyte and acid-base disorders. These represent the various causes of hyponatremia, hypernatremia, hypokalemia, hyperkalemia, hypocalcemia, and hypercalcemia. There are many checks and balances which yield a normal electrolyte level; several disorders can lead to an imbalance of one or more organ functions, with the patient developing an electrolyte abnormality. Acid-base disorders can be secondary to a problem with the kidneys, a problem with the lungs, or a dysfunction of both of these organs.

The focus of chapter eleven is reproductive system disease. It involves the various disorders that can affect the male reproductive system, such as prostatitis, orchitis, epididymitis, testicular torsion, and erectile dysfunction. Females also have a wide range of reproductive system diseases, including those affecting the menstrual cycle, endometriosis, pelvic inflammatory disease, and polycystic ovary syndrome. The

problem of infertility affects both males and females; it can also be a combined problem, with problems involving both the male and female fertility leading to the couple’s infertility.

Chapter twelve in the course focuses on the various musculoskeletal system disorders, including bone diseases, muscle diseases, and disorders of the joints. These can include osteoporosis and osteomyelitis, as well as Paget disease of the bone. Autoimmune myositis, which includes dermatomyositis, is also covered in this chapter. There are many different joint diseases, some of which are immune-related. Osteoarthritis, gout, and pseudogout are not immune-related, although rheumatoid arthritis and the different types of spondyloarthropathies have more of an immune etiology.

The purpose of chapter thirteen is to cover some of the more common and important skin diseases. There are several types of skin infections that vary in the common pathogens and in presentation. Acne is another skin disease affecting young people, while rosacea has the appearance of acne, seen in older individuals. Psoriasis is an immune disease of the skin, as is bullous pemphigoid. Another common skin disease is atopic dermatitis, which can affect individuals as early as in infancy.

Chapter fourteen in the course is a brief look at the pathophysiology of different types of cancer. Cancer can affect any part of the body with varying degrees of virulence. Some cancers, such as lung cancer, certain brain cancers, and ovarian cancer have a high mortality rate, while others are not particularly lethal. In all cases, there is the uncontrolled growth of cells in the body that is accompanied by a relative lack of apoptosis or programmed cell death.