G-4 glossary
bronchiole A component of the finely branched bronchial
tree inside each lung.
bronchus (brong-cuss, brong-kee), plural: bronchi [Gk. bron-
chos, windpipe] Tubelike branchings of the trachea that lead
into the lungs.
brush border The collective array of microvilli on epithelial
cells lining the intestinal mucosa.
buffer A substance that can stabilize the pH of a solution by
donating or accepting hydrogen ions.
bulbourethral glands Two glands of the male reproductive
system that secrete mucus-rich fluid into the urethra when
the male is sexually aroused.
bulimia nervosa Eating disorder in which a person alter-
nately binges and purges.
bursa Fluid-filled sac between a tendon and a bone.
cancer A malignant tumor, the cells of which show pro-
found abnormalities in the plasma membrane and cytoplasm,
abnormal growth and division, and weakened capacity for
adhesion within the parent tissue (leading to metastasis).
Unless eradicated, cancer is lethal.
capillary [L. capillus, hair] A thin-walled blood vessel that
functions in the exchange of gases and other substances
between blood and interstitial fluid.
capillary bed Dense capillary networks containing true capil-
laries where exchanges occur between blood and tissues, and
also thoroughfare channels that link arterioles and venules.
carbaminohemoglobin A hemoglobin molecule that has car-
bon dioxide bound to it; HbCO 2.
carbohydrate [L. carbo, charcoal, and hydro, water] A bio-
logical molecule built of carbon, hydrogen, and oxygen
atoms, usually in a 1:2:1 ratio. All cells use carbohydrates as
structural materials, energy stores, and transportable forms of
energy. The three classes of carbohydrates include monosac-
charides, oligosaccharides, and polysaccharides.
carbon cycle A biogeochemical cycle in which carbon
moves from its reservoir in the atmosphere, through oceans
and organisms, then back to the atmosphere.
carcinogen (kar-sin-uh-jen) An environmental agent or sub-
stance, such as ultraviolet radiation, that can trigger cancer.
carcinogenesis The transformation of a normal cell into a
cancerous one.
cardiac conduction system (kar-dee-ak) Set of noncon-
tractile cells in heart muscle that spontaneously produce
and conduct the electrical events that stimulate heart muscle
contractions.
cardiac cycle The sequence of muscle contraction and relax-
ation constituting one heartbeat.
cardiac muscle Type of muscle found only in the heart wall;
cardiac muscle cells contract as a single unit.
cardiac output The amount of blood each ventricle of the
heart pumps in one minute.biome A broad, vegetational subdivision of a biogeographic
realm shaped by climate, topography, and composition of
regional soils.
biopsy Diagnostic procedure in which a small piece of tissue
is removed from the body through a hollow needle or explor-
atory surgery, and then examined for signs of a particular
disease (often cancer).
biosphere [Gk. bios, life, and sphaira, globe] All regions of
Earth’s waters, crust, and atmosphere in which organisms
live.
bipedalism A habitual standing and walking on two feet, as
by humans.
bladder See urinary bladder.
blastocyst (blass-tuh-sist) [Gk. blastos, sprout, and kystis,
pouch] In embryonic development, a blastula stage consist-
ing of a hollow ball of surface cells and an inner cell mass.
blastomere One of the small, nucleated cells that form
during cleavage of a zygote.
blood A fluid connective tissue composed of water, solutes,
and formed elements (blood cells and platelets); it carries
substances to and from cells and helps maintain an internal
environment that is favorable for cell activities.
blood–brain barrier Modified structure of brain capillaries
that helps control which blood-borne substances reach neu-
rons in the brain.
blood pressure Fluid pressure, generated by heart contrac-
tions, that keeps blood circulating.
BMI Body mass index, a measure of the ratio of weight to
height.
BMR See basal metabolic rate.
bolus Softened, lubricated ball of food, created by chewing
and mixing of food with saliva.
bone Connective tissue that functions in movement and
locomotion, protection of other organs, mineral storage, and
(in some bones) blood cell production.
bone marrow A connective tissue where blood cells are
formed.
bone remodeling Process of ongoing calcium deposits and
withdrawals from bone that adjusts bone strength and main-
tains levels of calcium and phosphorus in blood.
bone tissue Mineral-hardened connective tissue; the main
tissue in bone.
Bowman’s capsule Cup-shaped portion of a nephron that
receives water and solutes being filtered from blood.
brain Organ that receives, integrates, stores, and retrieves
information, and coordinates appropriate responses by stimu-
lating and inhibiting the activities of different body parts.
brain case The eight bones that together surround and
protect the brain.
brain stem The midbrain, pons, and medulla oblongata, the
core of which contains the reticular formation that helps gov-
ern activity of the nervous system as a whole.
Copyright 2016 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).