G-22
Glossary
Trombus
(throm
9
bus) A clot that develops and persists in an unbroken
blood vessel.
Tymine (t)
(thi
9
mēn) Single-ring base (a pyrimidine) in DNA.
Tymus
(thi
9
mus) Lymphoid organ and endocrine gland active in im-
mune response; site of maturation of T lymphocytes.
Tyroid gland
(thi
9
roid) One of the largest of the body’s endocrine
glands; straddles the anterior trachea.
Tyroid hormone (tH)
±e major hormone secreted by thyroid fol-
licles; stimulates enzymes concerned with glucose oxidation.
Tyroid-s±imula±ing hormone (tSH)
Anterior pituitary hormone that
regulates secretion of thyroid hormones.
Tyroxine (t
4
)
(thi-rok
9
sin) Iodine-containing hormone secreted by the
thyroid gland; accelerates cellular metabolic rate in most body tissues.
tigh± junc±ion
Area where plasma membranes of adjacent cells are
tightly bound together, forming an impermeable barrier.
tissue
A group of similar cells and their intercellular substance special-
ized to perform a specific function; primary tissue types of the body are
epithelial, connective, muscle, and nervous tissue.
tissue perfusion
Blood flow through body tissues or organs.
tonici±y
(to-nis
9
ĭ-te) A measure of the ability of a solution to cause a
change in cell shape or tone by promoting osmotic flows of water.
tonsils
A ring of lymphoid tissue around the entrance to the pharynx.
See also
Adenoids.
trabecula
(trah-bek
9
u-lah) (1) Any of the fibrous bands extending from
the capsule into the interior of an organ; (2) strut or thin plate of bone in
spongy bone.
trachea
(tra
9
ke-ah) Windpipe; cartilage-reinforced tube extending from
larynx to bronchi.
trac±
A collection of axons in the central nervous system having the
same origin, termination, and function.
transcrip±ion
One of the two major steps in the transfer of genetic code
information from a DNA base sequence to the complementary base se-
quence of an mRNA molecule.
transduc±ion
(trans-duk
9
shun) ±e conversion of the energy of a stim-
ulus into an electrical event.
transepi±helial ±ranspor±
(trans-ep
0
ĭ-the
9
le-al) Movement of sub-
stances through, rather than between, adjacent epithelial cells connected
by tight junctions, such as absorption of nutrients in the small intestine.
transfer RNA (±RNA)
Short-chain RNA molecules that transfer amino
acids to the ribosome.
transfusion reac±ion
Agglutination and destruction of red blood cells
following transfusion of incompatible blood.
transla±ion
One of the two major steps in the transfer of genetic code
information, in which the information carried by mRNA is decoded and
used to assemble polypeptides.
transverse (horizon±al) plane
A plane running from right to leF, divid-
ing the body or an organ into superior and inferior parts.
tricuspid valve
(tri-kus
9
pid) ±e right atrioventricular valve.
triglycerides
(tri-glis
9
er-īdz) ²ats and oils composed of fatty acids and
glycerol; are the body’s most concentrated source of energy fuel; also
known as neutral fats.
triiodo±hyronine (t
3
)
(tri
0
i-o
0
do-thi
9
ro-nēn) ±yroid hormone; secre-
tion and function similar to those of thyroxine (T
4
).
trophoblas±
(tro
9
fo-blast) Outer sphere of cells of the blastocyst.
tropic hormone (±ropin)
(trōp
9
ik) A hormone that regulates the secre-
tory action of another endocrine organ.
Sys±ole
(sis
9
to-le) Period when either the ventricles or the atria are
contracting.
Sys±olic pressure
(sis-tah
9
lik) Pressure exerted by blood on the blood
vessel walls during ventricular contractions.
t cells
Lymphocytes that mediate cellular immunity; include helper, cy-
totoxic, regulatory, and memory cells. Also called T lymphocytes.
t ±ubule (±ransverse ±ubule)
Extension of the muscle cell plasma mem-
brane (sarcolemma) that protrudes deeply into the muscle cell.
tachycardia
(tak
0
e-kar
9
de-ah) A heart rate over 100 beats per minute.
tas±e buds
Sensory receptor organs that house gustatory cells, which
respond to dissolved food chemicals.
telencephalon (endbrain)
(tel
0
en-seh
9
fuh-lon) Anterior subdivision of
the primary forebrain that develops into olfactory lobes, cerebral cortex,
and basal nuclei.
telophase
±e final phase of mitosis; begins when migration of chro-
mosomes to the poles of the cell has been completed and ends with the
formation of two daughter nuclei.
tendon
(ten
9
dun) Cord of dense fibrous tissue attaching muscle to bone.
tendon organ
Proprioceptor located in tendon; monitors muscle ten-
sion to prevent tearing and help smooth onset and termination of muscle
contraction.
tendoni±is
Inflammation of tendon sheaths, typically caused by overuse.
terminal branches
Branching ends of an axon that allow it to form
many axon terminals; terminal arborization.
tes±is
(tes
9
tis) Male primary reproductive organ that produces sperm;
male gonad.
tes±os±erone
(tes-tos
9
tĕ-rōn) Male sex hormone produced by the testes;
during puberty promotes virilization, and is necessary for normal sperm
production.
te±anus
(tet
9
ah-nus) (1) A smooth, sustained muscle contraction result-
ing from high-frequency stimulation; (2) an infectious disease caused by
an anaerobic bacterium.
Talamus
(thal
9
ah-mus) A mass of gray matter in the diencephalon of
the brain.
Termogenesis
(ther
0
mo-jen
9
ĕ-sis) Heat production.
Termorecep±or
(ther
0
mo-re-sep
9
ter) Receptor sensitive to temperature
changes.
Tird-degree burn
A burn that involves the entire thickness of the skin;
also called a full-thickness burn. Usually requires skin graFing.
Toracic cage (bony ±horax)
Bones and costal cartilages that form the
framework of the thorax; includes sternum, ribs, and thoracic vertebrae.
Toracic duc±
Large duct that receives lymph drained from the entire
lower body, the leF upper extremity, and the leF side of the head and
thorax.
Toracic ver±ebrae
±e 12 vertebrae that are in the middle part of the
vertebral column and articulate with the ribs.
Torax
(tho
9
raks) ±at portion of the body trunk above the diaphragm
and below the neck.
Treshold s±imulus
Weakest stimulus capable of producing a response
in an excitable tissue.
Trombin
(throm
9
bin) Enzyme that induces clotting by converting fi-
brinogen to fibrin.
Trombocy±e
(throm
9
bo-sīt) Platelet; cell fragment that participates in
blood coagulation.
Trombocy±openia
(throm
0
bo-si
0
to-pe
9
ne-ah) A reduction in the num-
ber of platelets circulating in the blood.
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