Introduction Calcium plays a fundamental role in the physiology of all living organisms. At the macroscopic level, calcium is essential to maintaining the structural integrity of the skeleton. At the molecular level, calcium is central to several physiologic processes, including…
Introduction The adrenal gland plays a pivotal role in human endocrine physiology. It is subdivided into two sections, which function separately and originate from different embryonic tissues. The outermost shell of the adrenal gland, the adrenal cortex, is divided into…
Introduction The thyroid—named from the Greek thureoeides , meaning “shield-shaped”—bears two essential responsibilities in the endocrine system: Maintains metabolic rate necessary for heat generation in warm-blooded species. Promotes normal growth and development from fetal life into childhood. Roughly 5% of…
Introduction The hypothalamus and pituitary gland constitute an elegant center of hormonal control known as the hypothalamic-pituitary axis (HPA). Each hormone controlled by the pituitary is regulated separately along its own pathway, or “axis.” The HPA integrates information from the…
Introduction In the 1920s, Frederick Banting and Charles Best isolated insulin and made possible the treatment and survival of millions of diabetics. This helped initiate the era of modern medicine, in which the empiricism of the 18th century and its…
D.L. is a 9-year-old female who is being seen by her pediatrician for the fifth time this summer. She has been seen for multiple gastrointestinal (GI) complaints including abdominal pain, bloating, and frequent nausea. Her mother is worried because she…
Introduction As described in Chapter 8 , the immune system is a complex cellular network that defends the body against danger. To do so, the immune system must distinguish between safe and dangerous substances. Safe or nonthreatening substances can be…
Introduction The kidney modifies the contents of the plasma by filtering its components into the urine, whereas the liver modifies the blood contents by metabolically transforming them. The liver is where drugs, hormones, and toxic waste products, such as ammonia,…
Introduction In Chapter 24 , we saw that the acquisition of energy and building blocks requires digestion and absorption. We now focus on two other critical gastrointestinal (GI) capabilities, without which digestion and absorption could not occur: Motility is the…
Introduction The gastrointestinal (GI) system supplies the fuel and the building blocks for the functioning of the body through the digestion and absorption of nutrients. Its machinery for doing so is the alimentary canal, also called the gastrointestinal tract, a…