Circumduction (ser'-kum-DUK-shun) A movement at a synovial joint
in which the distal end of a bone moves in a circle while the proxi-
mal end remains relatively stable.
Cirrhosis (si-RO-sis) A liver disorder in which the parenchymal cells
are destroyed and replaced by connective tissue.
Cisterna chyli (sis-TER-na KF-le) The origin of the thoracic duct.
Cleavage The rapid mitotic divisions following the fertilization of a
secondary oocyte, resulting in an increased number of progres-
sively smaller cells, called blastomeres.
Climacteric (klT-mak-TER-
i
k) Cessation of the reproductive function in
the female or decreased testicular activity in the male.
Climax The peak period or moments of greatest intensity during
sexual excitement.
Clitoris (KLI-to-ris) An erectile organ of the female, located at the
anterior junction of the labia minora, that is homologous to the
male penis.
Clone (KLON) A population of identical cells.
Clot The end result of a series of biochemical reactions that changes
liquid plasma into a gelatinous mass; specifically, the conversion
of fibrinogen into a tangle of polymerized fibrin molecules.
Clot retraction (re-TRAK-shun) The consolidation of a fibrin clot to
pull a damaged tissue together.
Clotting Process by which a blood clot is formed. Also known as
coagulation (co-ag-u-LA-shun).
Coccyx (KOK-six) The fused bones at the inferior end of the vertebral
column.
Cochlea (KOK-le-a) A winding, cone-shaped tube forming a portion of
the inner ear and containing the spiral organ (organ of Corti).
Cochlear duct The membranous cochlea consisting of a spirally
arranged tube enclosed in the bony cochlea and lying along its
outer wall. Also called the scala media (SCA-la ME-de-a).
Coenzyme A nonprotein organic molecule that is associated with
and activates an enzyme; many are derived from vitamins. An
example is nico tinamide adenine dinucleotide (NAD), derived
from the B vitamin niacin.
Coitus (KO-i-tus) Sexual intercourse.
Collagen (KOL-a-jen) A protein that is the main organic constituent of
connective tissue.
Collateral circulation The alternate route taken by blood through an
anastomosis.
Colliculus (ko-LIK-u-lus) A small elevation.
Colloid (KOL-loyd) The material that accumulates in the center of
thyroid follicles, consisting of thyroglobulin and stored thyroid
hormones.
Colon The portion of the large intestine consisting of ascending,
transverse, descending, and sigmoid portions.
Colostrum (ko-LOS-trum) A thin, cloudy fluid secreted by the mam-
mary glands a few days prior to or after delivery before true milk
is produced.
Column (KOL-um) Group of white matter tracts in the spinal cord.
Common bile duct A tube formed by the union of the common
hepatic duct and the cystic duct that empties bile into the duode-
num at the hepatopancreatic ampulla (ampulla of Vater).
Compact (dense) bone tissue Bone tissue that contains few spaces
between osteons (haversian systems); forms the external portion
of all bones and the bulk of the diaphysis (shaft) of long bones;
is found immediately deep to the periosteum and external to
spongy bone.
Complement (KOM-ple-ment) A group of at least 20 normally inactive
proteins found in plasma that forms a component of innate and
adaptive nonspecific resistance and immunity by bringing about
cytolysis, inflammation, and opsonization.
Compound A substance that can be broken down into two or more
other substances by chemical means.
Concha (KONG-ka) A scroll-like bone found in the nose.
P lu r a l is
conchae (KONG-ke).
Concussion (kon-KUSH-un) Traumatic injury to the brain that pro-
duces no visible bruising but may result in abrupt, temporary loss
of consciousness.
Conduction system A group of autorhythmic cardiac muscle fibers
that generates and distributes electrical impulses to stimulate
coordinated contraction of the heart chambers; includes the
sinoatrial (SA) node, the atrioventricular (AV) node, the atrioven-
tricular (AV) bundle, the right and left bundle branches, and the
Purkinje fibers.
Conductivity (kon'-duk-TIV-i-te) The ability of a cell to propagate
(conduct) action potentials along its plasma membrane; charac-
teristic of neurons and muscle fibers (cells).
Condyloid joint (KON-di-loyd) A synovial joint structured so that
an oval-shaped condyle of one bone fits into an elliptical cav-
ity of another bone, permitting side-to-side and back-and-forth
movements, such as the joint at the wrist between the radius and
carpals.
Cone (KON) The type of photoreceptor in the retina that is special-
ized for highly acute color vision in bright light.
Congenital (kon-JEN-i-tal) Present at the time of birth.
Conjunctiva (kon'-junk-TF-va) The delicate membrane covering the
eyeball and lining the eyes.
Connective tissue One of the most abundant of the four basic tissue
types in the body, performing the functions of binding and sup-
porting; consists of relatively few cells in a generous extracellular
matrix (the ground substance and fibers between the cells).
Consciousness (KON-shus-nes) A state of wakefulness in which an
individual is fully alert, aware, and oriented, partly as a result of
feedback between the cerebral cortex and reticular activating
system.
Continuous conduction (kon-DUK-shun) Propagation of an action
potential (nerve impulse) in a step-by-step depolarization of each
adjacent area of an axon membrane.
Contraception (kon'-tra-SEP-shun) The prevention of fertilization or
impregnation without destroying fertility.
Contractility (kon'-trak-TIL-i-te) The ability of cells or parts of cells to
actively generate force to undergo shortening for movements.
Muscle fibers (cells) exhibit a high degree of contractility.
Contralateral (kon'-tra-LAT-er-al) On the opposite side; affecting the
opposite side of the body.
Glossary 523
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