Glossary 555Chemoreceptors (KEE-moh-re-SEP-ters) 1. A sensory
receptor that detects a chemical change. 2. Olfactory
receptors, taste receptors, and the carotid and aortic
chemoreceptors that detect changes in blood gases and
blood pH (Chapter 9).
Chemotherapy(KEE-moh-THER-uh-pee) The use of
chemicals (medications) to treat disease (Chapter 3).
Chief cells(CHEEF SELLS) The cells of the gastric pits of
the stomach that secrete pepsinogen, the inactive form of
the digestive enzyme pepsin (Chapter 16).
Chlamydia(kluh-MID-ee-ah) A group of simple bacteria;
Chlamydia trachomatisis a sexually transmitted pathogen
that may cause conjunctivitis or pneumonia in infants
born to infected women (Chapter 20).
Cholecystokinin (KOH-lee-SIS-toh-KYE-nin) A hor-
mone secreted by the duodenum when food enters; stim-
ulates contraction of the gallbladder and secretion of
enzyme pancreatic juice (Chapter 16).
Cholesterol(koh-LESS-ter-ohl) A steroid that is synthe-
sized by the liver and is part of cell membranes (Chap-
ter 2).
Cholinesterase (KOH-lin-ESS-ter-ays) The chemical
inactivator of acetylcholine (Chapter 7).
Chondrocyte(KON-droh-sight) A cartilage cell (Chapter
4).
Chordae tendineae(KOR-day ten-DIN-ee-ay) Strands of
connective tissue that connect the flaps of an AV valve to
the papillary muscles (Chapter 12).
Chorion(KOR-ee-on) An embryonic membrane that is
formed from the trophoblast of the blastocyst and will
develop chorionic villi and become the fetal portion of
the placenta (Chapter 21).
Chorionic villi(KOR-ee-ON-ik VILL-eye) Projections of
the chorion that will develop the fetal blood vessels that
will become part of the placenta (Chapter 21).
Chorionic villus sampling(KOR-ee-ON-ik VILL-us) A
diagnostic procedure in which a biopsy of the chorionic
villi is performed; used to detect genetic diseases or other
abnormalities in the fetus (Chapter 21).
Choroid layer(KOR-oyd) The middle layer of the eyeball,
contains a dark pigment derived from melanin that
absorbs light and prevents glare within the eye (Chap-
ter 9).
Choroid plexus(KOR-oyd PLEK-sus) A capillary network
in a ventricle of the brain; forms cerebrospinal fluid
(Chapter 8).
Chromatid (KROH-mah-tid) A potential chromosome
formed by the replication of the DNA of a chromosome
during interphase; two identical chromatids are formed
and are attached at the centromere; they separate during
cell division (Chapter 3).
Chromatin(KROH-mah-tin) The thread-like structure of
the genetic material when a cell is not dividing; is not vis-
ible as individual chromosomes (Chapter 3).
Chromosomes(KROH-muh-sohms) Structures made ofDNA and protein within the nucleus of a cell. A human
cell has 46 chromosomes (Chapter 3).
Chronic(KRAH-nik) Characterized by long duration or
slow progression (Chapter 22).
Chylomicron(KYE-loh-MYE-kron) A small fat globule
formed by the small intestine from absorbed fatty acids
and glycerol (Chapter 16).
Cilia (SILLY-ah) Thread-like structures that project
through a cell membrane and sweep materials across the
cell surface (Chapter 3).
Ciliary body(SILLY-air-ee BAH-dee) A circular muscle
that surrounds the edge of the lens of the eye and
changes the shape of the lens (Chapter 9).
Ciliated epithelium(SILLY-ay-ted) The tissue that has
cilia on the free surface of the cells (Chapter 4).
Circle of Willis (SIR-kuhl of WILL-iss) An arterial
anastomosis that encircles the pituitary gland and sup-
plies the brain with blood; formed by the two internal
carotid arteries and the basilar (two vertebral) artery
(Chapter 13).
Circulatory shock(SIR-kew-lah-TOR-ee SHAHK) The
condition in which decreased cardiac output deprives all
tissues of oxygen and permits the accumulation of waste
products (Chapter 5).
Cisterna chyli(sis-TER-nah KYE-lee) A large lymph ves-
sel formed by the union of lymph vessels from the lower
body; continues superiorly as the thoracic duct (Chapter
14).
Clavicle(KLAV-i-kuhl) The flat bone that articulates with
the scapula and sternum (from the Latin “little key”)
(Syn.—collarbone) (Chapter 6).
Cleavage(KLEE-vije) The series of mitotic cell divisions
that take place in a fertilized egg; forms the early multi-
cellular embryonic stages (Chapter 21).
Cleft palate(KLEFT PAL-uht) A congenital disorder in
which the bones of the hard palate do not fuse, leaving an
opening between the oral and nasal cavities (Chapter 6).
Clinical infection(KLIN-i-kuhl) An infection in which the
patient exhibits the symptoms of the disease (Chapter 22).
Clitoris(KLIT-uh-ris) An organ that is part of the vulva; a
small mass of erectile tissue at the anterior junction of the
labia minora; enlarges in response to sexual stimulation
(Chapter 20).
Clot retraction(KLAHT ree-TRAK-shun) The shrinking
of a blood clot shortly after it forms due to the folding of
the fibrin strands; pulls the edges of the ruptured vessel
closer together (Chapter 11).
Coccus (KOK-us) (Pl.—cocci) A spherical bacterium
(Chapter 22).
Coccyx(KOK-siks) The last four to five very small verte-
brae; attachment site for some muscles of the pelvic floor
(Chapter 6).
Cochlea(KOK-lee-ah) The snail-shell–shaped portion of
the inner ear that contains the receptors for hearing in
the organ of Corti (Chapter 9).30Scanlon(p3) Glossary 8/17/06 11:08 AM Page 555