722
Glossary
circular muscle
smooth-muscle layer in stomach
and intestinal walls that has muscle fi bers
circumferentially oriented around these organs
circulatory system
(SIRK-you-la-tor-ee) the heart
and system of vessels that deliver blood to all
parts of the body
citric acid cycle
see
Krebs cycle
classical complement pathway
antibody-
dependent system for activating complement;
begins with complement molecule Cl
clathrin
(clathrin-coated pits) a cytosolic
protein that binds to regions of the plasma
membrane and helps initiate receptor-mediated
endocytosis; clathrin forms localized regions
known as clathrin-coated pits that invaginate to
become endocytotic vesicles
clearance
volume of plasma from which a
particular substance has been completely
removed in a given time
cleavage
mitotic cell division
clitoris
(KLIT-or-iss) small body of erectile
tissue in female external genitalia; homologous
to penis
clonal deletion
destruction by apoptosis in the
thymus of those T cells that have receptors
capable of binding to self proteins
clonal expansion
lymphocyte cell divisions
initiated by binding of an antigen to a
lymphocyte cell membrane receptor
clonal inactivation
process occurring in the
periphery (that is, not in the thymus) that
causes potentially self-reacting T cells to
become nonresponsive
clone
one of a set of genetically identical
molecules, cells, or organisms
clot
solid phase of blood, formed from platelets,
trapped blood cells, and a polymer of the
protein fi brin
clotting
phase transition of blood from a liquid
cell suspension into a solid, gel-like mass
coactivation
pattern of nerve fi ring to a muscle,
in which alpha and gamma motor neurons
simultaneously activate contractile (extrinsic)
fi bers while increasing tension in the ends of
the muscle spindle (instrinsic) fi bers
coagulation
(koh-ag-you-LAY-shun) blood clotting
cochlea
(KOK-lee-ah) inner ear; fl uid-fi lled spiral-
shaped compartment that contains cochlear duct
cochlear duct
(KOK-lee-er) fl uid-fi lled
membranous tube that extends length of inner
ear, dividing it into compartments; contains
organ of Corti
coding
process by which neural signals from
sensory receptors are converted into action
potentials in the CNS
codon
(KOH-don) three-base sequence in mRNA
that determines the position of a specifi c amino
acid during protein synthesis or that designates
the end of the coded sequence of a protein
coenzyme
(koh-EN-zime) organic cofactor;
generally serves as a carrier that transfers atoms
or small molecular fragments from one reaction
to another; is not consumed in the reaction
and can be reused
coenzyme A
see
acetyl coenzyme A
cofactor
(KOH-fact-or) organic or inorganic
substance that binds to a specifi c region of an
enzyme and is necessary for the enzyme’s activity
colipase
protein secreted by pancreas that binds
lipase, bringing it in contact with lipid droplets
in the small intestine
collagen fi
ber
(KOL-ah-jen) strong, fi brous
protein that functions as extracellular structural
element in connective tissue
collateral
branch of a nerve axon
collecting duct system
portion of renal tubules
between distal convoluted tubules and renal
pelvis; comprises
cortical collecting duct
and
medullary collecting duct
colloid
(KOL-oid) large molecule, mainly protein,
to which capillaries are relatively impermeable;
also, part of the inner structure of the thyroid
gland
colon
(KOH-lun) a portion of the large intestine,
specifi cally the part extending from cecum to
rectum
colony-stimulating factor (CSF)
collective
term for several hematopoietic growth factors
that stimulate production of neutrophils and
monocytes
colostrum
watery, protein-rich liquid secreted by
mother’s breasts for fi rst 24 to 48 hours after
delivery of baby
commissure
(KOM-ih-shur) bundle of nerve
fi bers linking right and left halves of the brain
common bile duct
carries bile from gallbladder to
small intestine
competition
ability of similar molecules to
combine with the same binding site or receptor
complement
(KOM-plih-ment) one of a group
of plasma proteins that, upon activation,
kills microbes directly and facilitates the
infl ammatory process, including phagocytosis
compliance
stretchability;
see also
lung compliance
concentration
amount of material per unit
volume of solution
concentration gradient
gradation in
concentration that occurs between two regions
having different concentrations
concentric contraction
muscle activity that
involves shortening of muscle length
conceptus
collective term for the fertilized egg
and everything derived from it
conducting system
network of cardiac muscle
fi bers specialized to conduct electrical activity
between different areas of heart
conducting zone
air passages that extend from
top of trachea to beginning of respiratory
bronchioles and have walls too thick for gas
exchange between air and blood
conduction
(heat) transfer of thermal energy
during collisions of adjacent molecules
cone
one of two retinal receptor types for photic
energy; gives rise to color vision
conformation
three-dimensional shape of a
molecule
congenital
existing at birth; usually referring to a
birth defect
connective tissue
one of the four major categories
of tissues in the body; major component of
extracellular matrices, cartilage, and bone
connective tissue cell
cell specialized to form
extracellular elements that connect, anchor,
and support body structures
conscious experience
things of which a person
is aware; thoughts, feelings, perceptions,
ideas, and reasoning during any state of
consciousness
consciousness
see
conscious experience, state of
consciousness
consolidation
process by which short-term
memories are converted into long-term
memories
contractility
(kon-trak-TIL-ity) force of heart
contraction that is independent of sarcomere
length
contraction
operation of the force-generating
process in a muscle
contraction time
time between beginning of
force development and peak twitch tension by
the muscle
contralateral
on the opposite side of the body
control system
see
homeostatic control system
convection
(kon-VEK-shun) process by which
a fl uid or gas next to a warm body is heated
by conduction, moves away, and is replaced
by colder fl uid or gas that in turn follows the
same cycle
convergence
(neuronal) many presynaptic
neurons synapsing upon one postsynaptic
neuron; (of eyes) turning of eyes inward (that
is, toward nose) to view near objects
cooperativity
interaction between functional
binding sites in a multimeric protein
core body temperature
temperature of inner body
cornea
(KOR-nee-ah) transparent structure
covering front of eye; forms part of eye’s
optical system and helps focus an object’s
image on retina
coronary
pertaining to blood vessels of heart
coronary artery
vessel delivering oxygenated
blood to the muscular walls of the heart
coronary blood fl
ow
blood fl ow to heart muscle
corpus callosum
(KOR-pus kal-LOH-sum)
wide band of nerve fi bers connecting the two
cerebral hemispheres; a brain commissure
corpus luteum
(LOO-tee-um) ovarian structure
formed from the follicle after ovulation;
secretes estrogen and progesterone
cortex
(KOR-tex) outer layer of organ;
see also
adrenal cortex, cerebral cortex;
compare
medulla
cortical association area
region of cerebral
cortex that receives input from various sensory
types, memory stores, and so on, and performs
further perceptual processing
cortical collecting duct
primary site of sodium
reabsorption at the end of the nephron
cortical nephron
functional unit of the kidney
contained in the renal cortex and with a small
(or no) loop of Henle
cortical reaction
release of factors by the ovum
that hardens the zona pellucida
corticobulbar pathway
(kor-tih-koh-BUL-bar)
descending pathway having its neuron cell
bodies in cerebral cortex; its axons pass without
synapsing to region of brainstem motor
neurons
corticospinal pathway
descending pathway
having its neuron cell bodies in cerebral
cortex; its axons pass without synapsing to
region of spinal motor neurons; also called the
pyramidal tract;
compare
brainstem pathway,
corticobulbar pathway
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