720
Glossary
beta-adrenergic receptor
(BAY-ta ad-ren-ER-
jik) a type of plasma membrane receptor for
epinephrine and norepinephrine;
compare
alpha-adrenergic receptor; also called
beta
adrenoceptor
beta cell
insulin-secreting cell in pancreatic islets
of Langerhans; also called
B cell
beta-endorphin
putative hormone released from
the anterior pituitary gland, believed to play a
role in adaptation to stress and pain relief; also
acts as a neurotransmitter
beta-lipoprotein
a protein formed from the
proopiomelanocortin precursor in the anterior
pituitary gland; further processing results in the
putative hormone beta-endorphin
beta oxidation
(ox-ih-DAY-shun) series of
reactions that generate hydrogen atoms (for
oxidative phosphorylation) from breakdown of
fatty acids to acetyl CoA
beta rhythm
low, fast EEG oscillations in alert,
awake adults who are paying attention to (or
thinking hard about) something
beta sheet
a form of secondary protein structure
determined by the relative hydrophobicity of
amino acid side chains
bicarbonate
(by-KAR-bah-nate) HCO
3
bicuspid valve
another term for the left
atrioventricular valve, also called the mitral
valve
bile
fl uid secreted by liver into bile canaliculi;
contains bicarbonate, bile salts, cholesterol,
lecithin, bile pigments, metabolic end
products, and certain trace metals
bile canaliculi
(kan-al-IK-you-lee) small ducts
adjacent to liver cells into which bile is secreted
bile pigment
colored substance, derived from
breakdown of heme group of hemoglobin,
secreted in bile
bile salt
one of a family of steroid molecules
produced from cholesterol and secreted in
bile by the liver; promotes solubilization and
digestion of fat in small intestine
bilirubin
(bil-eh-RUE-bin) yellow substance
resulting from heme breakdown; excreted in
bile as a bile pigment
binding site
region of protein to which a specifi c
ligand binds
biogenic amine
(by-oh-JEN-ik ah-MEEN)
one of family of neurotransmitters having
basic formula R-NH
2
; includes dopamine,
norepinephrine, epinephrine, serotonin, and
histamine
biological clock
neurons that drive body rhythms
bipolar cell
type of nerve cell that has one input
branch and one output branch
bivalent
paired homologous chromosomes, each
with two sister chromatids, that are produced
during meiosis
bladder
urinary bladder; thick-walled sac
composed of smooth muscle; stores urine prior
to urination
blastocyst
(BLAS-toh-cyst) particular early
embryonic stage consisting of ball of
developing cells surrounding central cavity
block to polyspermy
process that prevents more
than one sperm cell from fertilizing an ovum
blood
pressurized contents of the cardiovascular
system composed of a liquid phase (plasma)
and cellular phase (red and white blood cells,
platelets)
blood-brain barrier
group of anatomical barriers
and transport systems in brain capillary
endothelium that controls kinds of substances
entering brain extracellular space from blood
and their rates of entry
blood coagulation
(koh-ag-you-LAY-shun)
blood clotting
blood sugar
glucose
blood type
blood classifi cation according to
presence of A and/or B antigens or lack of
them (O)
blood vessel
tubular structures of various sizes
that transport blood throughout the body
body (of stomach)
middle portion of the
stomach; secretes mucus, pepsinogen, and
hydrochloric acid
body mass index (BMI)
method for assessing
degree of obesity; calculated as weight in
kilograms divided by square of height in meters
bone age
an x-ray determination of the degree
of bone development; often used in assessing
reasons for unusual stature in children
bone marrow
highly vascular, cellular substance
in central cavity of some bones; site of
erythrocyte, leukocyte, and platelet synthesis
Bowman’s capsule
blind sac at beginning of
tubular component of kidney nephron
Bowman’s space
fl uid-fi lled space within
Bowman’s capsule into which protein-free fl uid
fi lters from the glomerulus
Boyle’s law
pressure of a fi xed amount of gas
in a container is inversely proportional to
container’s volume
bradykinin
(braid-ee-KY-nin) protein formed by
action of the enzyme kallikrein on precursor
brain self-stimulation
phenomenon in which
animals will press a bar to get electrical
stimulation of certain parts of their brains
brainstem
brain subdivision consisting of medulla
oblongata, pons, and midbrain and located
between spinal cord and forebrain
brainstem pathway
descending motor pathway
whose cells of origin are in the brainstem
Broca’s area
(BRO-kahz) region of left frontal
lobe associated with speech production
bronchiole
(BRON-key-ole) small airway distal
to bronchus
bronchus
(BRON-kus) large-diameter air passage
that enters lung; located between trachea and
bronchioles
brown adipose tissue
type of adipose (fat) tissue
found in newborns and in many mammals,
with a higher heat-producing capacity than
ordinary white fat; may be important in
regulating body temperature in extreme
conditions
brush border
small projections (microvilli) of
epithelial cells covering the villi of the small
intestine; major absorptive surface of the small
intestine
buffer
weak acid or base that can exist in
undissociated (H buffer) or dissociated
(H
+
+ buffer) form
buffering
reversible hydrogen-ion binding by
anions when H
+
concentration changes; tends
to minimize changes in acidity of a solution
when acid is added or removed
bulbourethral gland
(bul-bo-you-REETH-ral)
one of paired glands in male that secretes fl uid
components of semen into the urethra
bulk fl
ow
movement of fl uids or gases from
region of higher pressure to one of lower
pressure
bundle branch
pathway composed of cells that
rapidly conduct electrical signals down the
right and left sides of the interventricular
septum; these pathways connect the bundle of
His to the Purkinje network
bundle of His
(HISS) nervelike structure
composed of modifi ed heart cells that carries
electrical impulses from the atrioventricular
node down the interventricular septum
C
calcitonin
hormone from the thyroid gland that
inhibits bone resorption
calmodulin
(kal-MOD-you-lin) intracellular
calcium-binding protein that mediates many of
calcium’s second-messenger functions
calmodulin-dependent protein kinase
an
intracellular enzyme that, when activated
by calcium and the protein calmodulin,
phosphorylates many protein substrates within
cells; it is a component of many intracellular
signaling mechanisms
calorie (cal)
unit of heat-energy measurement;
amount of heat needed to raise temperature of
1 g of water 1°C;
compare
kilocalorie
calorigenic effect
(kah-lor-ih-JEN-ik) increase
in metabolic rate caused by epinephrine or
thyroid hormones
cAMP-dependent protein kinase
(KY-nase)
see
cyclic AMP-dependent protein kinase
capacitation
see
sperm capacitation
capillary
one of the smallest blood vessels
capillary fi
ltration coeffi
cient
a measure of
fl uid fl ow across a capillary wall at a given
hydrostatic pressure gradient; determined by
porosity of the barrier
capsaicin
(kap-SAY-sin) the molecule in chili
peppers that causes sensations of heat and pain
in the mouth and throat
carbamino hemoglobin
(kar-bah-MEEN-oh
HE-moe-glow-bin) compound resulting from
combination of carbon dioxide and amino
groups in hemoglobin
carbohydrate
substance composed of carbon,
hydrogen, and oxygen according to general
formula C
n
(H
2
O)
n
, where
n
is any whole number
carbonic acid
(kar-BAHN-ik) H
2
CO
3
; an acid
formed from H
2
O and CO
2
carbonic anhydrase
(an-HY-drase) enzyme that
catalyzes the reaction CO
2
+ H
2
O
34
H
2
CO
3
carbon monoxide
CO; gas that reacts with
hemoglobin; decreases blood oxygen-carrying
capacity and shifts oxygen-hemoglobin
dissociation curve to the left; also acts as an
intracellular messenger in neurons
carboxyl group
(kar-BOX-il) —COOH; ionizes
to carboxyl ion (—COO
)
carboxypeptidase
(kar-box-ee-PEP-tih-dase)
enzyme secreted into small intestine
by exocrine pancreas as precursor,
procarboxypeptidase; breaks peptide bond at
carboxyl end of protein
cardiac
(KAR-dee-ak) pertaining to the heart
cardiac cycle
one contraction-relaxation sequence
of heart
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