Readers learn the basics of feedback control systems, homeostasis, and physiological gradients. These principles apply to an understanding of the body’s functioning under optimal, healthy conditions, and they provide insight into states of acute and chronic illness. Separate chapters are devoted to each of the body’s systems in detail: nervous, endocrine, cardiovascular, respiratory, renal, gastrointestinal, musculoskeletal, reproductive, and immune. Through a series of real-life examples, the book also shows the importance of maintaining careful medical records for health care professionals, scientists, and patients alike.