radiation (ra"de-a'shun) A form of energy that includes visible light, ultraviolet light, and X rays; the means by which body heat is lost in the form of infrared rays. p. 182 radioactive (ra"de-o-ak'tiv) An atom that releases energy at a constant rate. p. 42 rate-limiting enzyme (rät lim'i-ting en'zlm) An enzyme, usually present in limited amount, that controls the rate of a metabolic pathway by regulating one of its steps. p. 121 reabsorption (re"ab-sorp'shun) Selective reuptake of substances into or across tissues. p. 835 reactant (re-ak'tant) Substance entering a chemical reaction. p. 45 receptor (re"sep'tor) A structure, usually protein, at the distal end of a sensory dendrite that can be stimulated. p. 402 receptor-mediated endocytosis (re"sep'tor-me'de-a-tid en"do-si-to'sis) A selective uptake of molecules into a cell by binding to a specific receptor. p. 91 recessive allele (re-ses'iv ah-lel) The form of a gene that is not expressed if the dominant form is present. p. 983 recruitment (re-kroot'ment) Increase in number of motor units activated as intensity of stimulation increases. p. 312 rectum (rek'tum) The terminal end of the digestive tube between the sigmoid colon and the anus. p. 724 red blood cell (red blud sel) A disc-shaped cell, lacking a nucleus, that is packed with the oxygen-carrying molecule hemoglobin. p. 548

red marrow (red mar'o) Blood cell-forming tissue in spaces within bones. p. 208 red muscle (red mus'el) Slow-contracting postural muscles that contain abundant myoglobin. p. 315 reduction (re-duk'shun) A chemical reaction in which electrons are gained; to properly realign a fractured bone. p. 1035 referred pain (re-ferd' pan) Pain that feels as if it is originating from a part other than the site being stimulated. p. 458 reflex (re'fleks) A rapid, automatic response to a stimulus. p. 402 reflex arc (re'fleks ark) A nerve pathway, consisting of a sensory neuron, interneuron, and motor neuron, that forms the structural and functional bases for a reflex. p. 402

refraction (re-frak'shun) A bending of light as it passes from one medium into another medium with a different density. p. 489 refractory period (re-frak'to-re pe're-od) Time period following stimulation during which a neuron or muscle fiber will not respond to a stimulus. p. 311 relaxin (re-lak'sin) Hormone from the corpus luteum that inhibits uterine contractions during pregnancy. p. 917 releasing hormone (re-le'sing hor'mon) A substance secreted by the hypothalamus whose target cells are in the anterior pituitary gland. p. 514 renal (re'nal) Pertaining to the kidney. p. 820 renal corpuscle (re'nal kor'pusl) Part of a nephron that consists of a glomerulus and a glomerular capsule; Malpighian corpuscle. p. 825 renal cortex (re'nal kor'teks) The outer portion of a kidney. p. 821 renal medulla (re'nal me-dul'ah) The inner portion of a kidney. p. 821 renal pelvis (re'nal pel'vis) The cavity in a kidney. p. 820 renal tubule (re'nal tu'bul) Portion of a nephron that extends from the renal corpuscle to the collecting duct. p. 825 renin (re'nin) Enzyme released from the kidneys that triggers a rise in blood pressure. p. 834 repair enzyme (re-par' en'zlm) Protein that removes mismatched nucleotides from a section of DNA and replaces them with complementary nucleotides. p. 131 replication (rep"li-ka'shun) Production of an exact copy of a DNA sequence. p. 128 repolarization (re-po"lar-i-za'shun)

Returning the cell membrane potential to resting potential. p. 376 reproduction (re"pro-duk'shun) Offspring formation. p. 5 residual volume (re-zid'u-al vol'um) The amount of air remaining in the lungs after the most forceful expiration. p. 797 resorption (re-sorp'shun) Decomposition of a structure as a result of physiological activity. p. 203 respiration (res"pi-ra'shun) Cellular process that releases energy from nutrients; breathing. p. 779 respiratory capacity (re-spi'rah-to"re kah-pas'i-te) Combination of any two or more respiratory volumes. p. 797 respiratory center (re-spi'rah-to"re sen'ter) Portion of the brain stem that controls the depth and rate of breathing. p. 423 respiratory cycle (re-spi'rah-to"re si'kl) An inspiration followed by an expiration. p. 797 respiratory membrane (re-spi'rah-to"re mem'bran) Membrane composed of a capillary wall and an alveolar wall through which gases are exchanged between the blood and the air. p. 805 respiratory volume (re-spi'rah-to"re vol'um) Any one of four distinct quantities of air within the lungs. p. 797

Shier-Butler-Lewis: I Back Matter I Glossary I I © The McGraw-Hill

Human Anatomy and Companies, 2001

Physiology, Ninth Edition response (re-spons') The action resulting from a stimulus. p. 403 resting membrane potential (res'ting mem'brain po-ten'shal) The difference in electrical charge between the inside and outside of an undisturbed nerve cell membrane. p. 376 reticular fiber (rei-tik'u-lar fi'ber) Threadlike structure within a network of like structures in connective tissue. p. 153 reticular formation (rei-tik'u-lar foir-ma'shun) A complex network of nerve fibers within the brain stem that arouses the cerebrum. p. 423

reticulocyte (rei-tik'u-lo-siit) An immature red blood cell that has a network of fibrils in its cytoplasm. p. 552 reticuloendothelial system (rei-tik"u-lo-en"do-the'le-al sis'tem) Tissue composed of widely scattered phagocytic cells. p. 661

retina (ret'ii-nah) Inner layer of the eye wall that contains the visual receptors. p. 487 retinal (ret'ii-nal) A form of vitamin A;

retinene. p. 750 retinene (ret'ii-nein) Chemical precursor of rhodopsin. p. 493 retraction (rei-trak'shun) Movement of a part toward the back. p. 278 retroperitoneal (ret"ro-per"ii-to-ne'al)

Located behind the peritoneum. p. 820 reversible reaction (re-ver'sii-b'l re-ak'shun) Chemical reaction that occurs in either direction. p. 47 rhodopsin (ro-dop'sin) Light-sensitive biochemical in the rods of the retina; visual purple. p. 493 rhythmicity area (rith-mis'ii-te a're-ah) A portion of the respiratory control center in the medulla. p. 800 riboflavin (ri"bo-fla'vin) A vitamin of the

B-complex group; vitamin B2. p. 754 ribonucleic acid (ri"bo-nu-kle'ik as'id) A single strand polymer of nucleotides, each containing a phosphate group, a nitrogen base (adenine, uracil, cytosine, or guanine) and the sugar ribose; RNA. p. 56 ribose (ri'bos) A 5-carbon sugar in RNA. p. 56

ribosomal RNA (ri-bo-som'al) A type of RNA that forms part of the ribosome. p. 127

ribosome (ri'bo-soim) An organelle composed of RNA and protein that is a structural support for protein synthesis. p. 74 RNA Ribonucleic acid. p. 56 rod (rod) A type of light receptor that provides colorless vision. p. 491 rotation (ro-ta'shun) Movement turning a body part on its longitudinal axis. p. 276 round window (rownd win'do) A

membrane-covered opening between the inner ear and the middle ear. p. 471 rugae (roo'je) Thick folds in the inner wall of the stomach that disappear when the stomach is distended. p. 700

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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