Our Marvelous Bodies: An Introduction to the Physiology of Human Health

GLOSSARY

185 absorptive state. the period during which a meal is being ingested, digested, and absorbed. acrosome. the head of a mature sperm cell actin. a muscle protein of relatively low molecular weight; a main constituent of the myofibrillar thin filament activators. cells, tissues, and organs that are innervated by efferent motor neurons adenylyl cylase. an enzyme that converts adenosine triphosphate (ATP) to cyclic adenosine monophosphate (cAMP) adrenocorticoids. steroid hormones produced by the adrenal glands afferent arterioles. small renal arteries that give rise to glomerular capillaries agglutination. changes in the surface properties of antigens that cause them to adhere to one another airborne pathogens. disease-causing agents transported in the air by any means including on pollen, spores, and molds akinesia. difficulty initiating movement aldosterone. an important salt-regulating hormone produced by the adrenal cortex alveolar ventilation. abbreviated VA, difference between minute ventilation and dead space ventilation androgens. male gonadal steroid hormones anemia. reduced number of red blood cells in the circulation angiogenesis. the process of forming new blood vessels angiotensin I. AI; a decapeptide clipped off of angiotensinogen by renin that is physiologically inert GLOSSARY angiotensin II. AII; an octapeptide created when pulmonary angiotensinconverting enzyme (ACE) removes two amino acids from AI angiotensinogen. also called renin substrate; a circulating macromolecule produced by the liver that serves as substrate for renin anterior. in the upright individual, the front of the body antidiuretic hormone. ADH, a hypothalamic/pituitary hormone that minimizes renal excretion of water aortic bodies. peripheral chemoreceptors located on or near the aorta aquaporins. proteins that make water channels in cell membranes arginine vasopressin. AVP, vasopressin; an acronym for ADH atresia. loss of female oogonia during embryogenesis autocrine. a hormone released by cell A that acts on cell A autoregulation. also called pressure-flow autoregulation; the ability of an organ to maintain a relative constant flow despite changes in pressure baroreceptor reflex. a cardiovascular reflex that begins at the carotid sinus mechanoreceptors biconcave disk. the shape of the red blood cell with concavity on both sides of the cell bilateral. on both sides, such as the kidneys are bilateral organs bipotential gonads. early in embryogenesis, gonads that have the potential to become either male or female blastocyst. a spherical mass of cells with fluid-filled cavity that continues to develop inside the uterus Bowman’s capsule. a renal capsular structure containing glomerular capillaries Bowman’s space. the site of formation of ultrafiltrate; space between glomerular capillaries and the interior of Bowman’s capsule bradycardia. slow heart rate, fifty beats per minute or less calorie. a basic unit of heat (the amount of heat needed to raise the temperature of water one degree centigrade) capacitation. influence of the ovum (egg) on the sperm cell that enables it (the sperm) to fertilize the egg cardioaccelerator. an agent or action that increases heart rate GLOSSARY 186 cardioaccelerator center. neurons in the brain stem that cause heart rate to increase cardioinhibitor center. neurons in the brain stem that cause heart rate to decrease cardioinhibitory. an agent or action that inhibits cardiac function carotid baroreceptor. a neuronal structure that detects changes in blood pressure (mechanoreceptor, pressoreceptor, or pressure receptor) carotid bifurcation. division of the main carotid artery, left or right, into internal and external branches carotid bodies. peripheral chemoreceptors located on or near the bifurcation of both common carotid arteries central pattern generator. neurons in the respiratory control centers whose cyclic discharge drives the inspiratory and expiratory cycles chemoattractants. chemicals released by injured cells or tissues that act as signals for other chemical/cellular/metabolic processes chemoreceptors. in respiratory physiology, sensory receptors—both central and peripheral—that detect changes in PO, PCO, and H
content of body fluids chemotaxis. process by which one chemical or molecule signals another to draw near chronotropic response. a change in heart rate caused by an action or agent; can be either positive or negative chylomicron. reconstituted triglycerides and other fat products inside mucosal epithelial cells CICR. calcium-induced calcium release; interaction of dihydropyridine and ryanodine receptors that leads to calcium release colloid oncotic pressure. the ability of a protein-containing aqueous fluid to attract water and cause pressure comparator. the component of a physiological control system that compares two sets of values such as actual blood pressure and physiological values for blood pressure conducting zone. trachea, bronchi, and nonrespiratory bronchioles conduction. movement of an action potential down an axon (neuron) GLOSSARY 187 controllers. neurons, usually found in...