G-3
Glossary
and respiratory effort; a score of 10 indicates thebest possible condition.
apical ectodermal ridge
Layer of surface ectoder-mal cells at the lateral margin of the embryoniclimb bud; stimulates growth of the limb.
apical foramen
[L., aperture] Opening at the apexof the root of a tooth, gives passage to the nerveand blood vessels.
apocrine sweat gland
(ap ′ ō -krin) [Gr.,
apo,
awayfrom +
krino,
to separate] Gland whose cells con-tribute cytoplasm to its secretion (e.g., mammaryglands). Sweat glands that produce organic secre-tions traditionally are called apocrine. These sweatglands, however, are actually merocrine glands.
appendicular skeleton
(ap ′ en-dik ′ ū -l ă r) The por-tion of the skeleton consisting of the upper limbsand the lower limbs and their girdles.
appositional growth
(ap- ō -zish ′ ŭ n-al) [L.,
ap
+
pono,
to put or place] To place one layer of bone,cartilage, or other connective tissue against anexisting layer.
aqueous humor
(ak ′ w ē - ŭ s, ā ′ kw ē - ŭ s) Watery,clear solution that fills the anterior and posteriorchambers of the eye.
arachnoid
( ă -rak ′ noyd) [Gr.,
arachne,
spider, cob-web] Thin, cobweb-appearing meningeal layer sur-rounding the brain; the middle of the three layers.
arcuate artery
(ar ′ k ū - ā t) Artery that originates fromthe interlobar arteries of the kidney and formsan arch between the cortex and medulla of thekidney.
areola
( ă -r ē ′ ō -l ă , -l ē ) [L., area] Circular, pig-mented area surrounding the nipple; its sur-face is dotted with little projections causedby the presence of the areolar glands beneath.
areolar gland
( ă -r ē ′ ō -l ă r) Gland forming small,rounded projections from the surface of the areolaof the mamma.
arrectores pilorum;
pl.
arrector pili
( ă -rek-t ō ′ rezp ī -l ō r ′ um, ă -rek ′ t ō r p ī ′ l ī ) [L., that which raises;hair] Smooth muscle attached to the hair follicleand dermis that raises the hair when it contracts.
arterial capillary
(ar-t ē ′ r ē - ă l) Capillary openingfrom an arteriole or a metarteriole.
arteriole
(ar-t ē r ′ ē - ō l) Minute artery with all threetunics that transports blood to a capillary.
arteriosclerosis
(ar-t ē r ′ ē - ō -skler- ō ′ sis) [L.,
arterio
+ Gr.,
sklerosis,
hardness] Hardening of thearteries.
arteriovenous anastomosis
(ar-t ē r ′ ē - ō -v ē ′ n ŭ să -nas ′ t ō -m ō ′ sis) Vessel through which bloodis shunted from an arteriole to a venule withoutpassing through the capillaries.
artery
(ar ′ ter- ē ) Blood vessel that carries bloodaway from the heart.
articular cartilage
(ar-tik ′ ū -l ă r kar ′ ti-lij) Hyalinecartilage covering the ends of bones within asynovial joint.
articulation
(ar-tik- ū -l ā ′ sh ŭ n) Place where two bonescome together; also called joint.
arytenoid cartilages
(ar-i-t ē ′ noyd) Small, pyramidallaryngeal cartilages that articulate with the cri-coid cartilage.
ascending aorta
Part of the aorta from which thecoronary arteries arise.
ascending colon
(k ō ′ lon) Portion of the colonbetween the small intestine and the right colicflexure.
asthma
(az ′ m ă ) Condition of the lungs in whichwidespread narrowing of airways occurs, causedby contraction of smooth muscle, edema of the
mucosa, and mucus in the lumen of the bronchiand bronchioles.
astrocyte
(as ′ tr ō -s ī t) [Gr.,
astron,
star +
kytos,
a hollow, a cell] Star-shaped neuroglia cell in-volved with forming the blood-brain barrier.
atherosclerosis
(ath ′ er- ō -skler- ō ′ sis) Arterioscle-rosis characterized by irregularly distributed lipiddeposits in the intima of large and medium-sizedarteries.
atomic number
( ă -tom ′ ik) Number of protons ineach type of atom.
atrial diastole
( ā ′ tr ē - ă l d ī -as ′ t ō -l ē ) Dilation of theheart’s atria.
atrial natriuretic hormone (ANH)
( ā ′ tr ē - ă ln ā ′ tr ē - ū -ret ′ ik) Peptide released from the atriawhen atrial blood pressure is increased; lowersblood pressure by increasing the rate of urinaryproduction, thus reducing blood volume.
atrial systole
( ā ′ tr ē - ă l sis ′ t ō -l ē ) Contraction of theatria.
atrioventricular (AV) bundle
( ā ′ tr ē - ō -ven-trik ′ ū -lar)Bundle of modified cardiac muscle fibers thatprojects from the AV node through the interven-tricular septum.
atrioventricular (AV) node
Small node of spe-cialized cardiac muscle fibers that gives rise tothe atrioventricular bundle of the conductionsystem of the heart.
atrioventricular valve
One of two valves closingthe openings between the atria and ventricles.
atrium;
pl.
atria
( ā ′ tr ē - ŭ m, ā ′ tr ē - ă ) [L., entrancehall] One of two chambers of the heart intowhich veins carry blood.
auditory cortex
(aw ′ di-t ō r- ē k ō r ′ teks) Portion ofthe cerebral cortex that is responsible for the con-scious sensation of sound; in the dorsal portionof the temporal lobe within the lateral fissure andon the superolateral surface of the temporal lobe.
auditory ossicle
(os ′ i-kl) Bone of the middle ear;includes the malleus, incus, and stapes.
auditory tube
Auditory canal; extends from themiddle ear to the nasopharynx.
auricle
(aw ′ ri-kl) [L.,
auris,
ear] Part of the exter-nal ear that protrudes from the side of the head;also called pinna. Small pouch projecting fromthe superior, anterior portion of each atrium ofthe heart.
auscultatory
(aws-k ŭ lt ă -t ō -r ē ) Relating to auscul-tation, listening to the sounds made by the variousbody structures as a diagnostic method.
autoimmune disease
(aw-t ō -i-m ū n ′ di-z ē z ′ )Disease resulting from a specific immune sys-tem reaction against self-antigens.
autonomic ganglia
(aw-t ō -nom ′ ik gang ′ gl ē - ă )Ganglia containing the nerve cell bodies of theautoimmune division of the nervous system.
autonomic nervous system (ANS)
Nervous systemcomposed of nerve fibers that send impulses fromthe central nervous system to smooth muscle,cardiac muscle, and glands.
autophagia
(aw-t ō -f ā ′ j ē - ă ) [Gr.,
auto,
self +
phage-in,
to eat] Segregation and disposal of organelleswithin a cell.
autoregulation
(aw ′ t ō -reg- ŭ -l ā ′ sh ŭ n) Mainten-ance of a relatively constant blood flow througha tissue despite relatively large changes in bloodpressure; maintenance of a relatively constantglomerular filtration rate despite relatively largechanges in blood pressure.
autorhythmic
Spontaneous and periodic—for ex-ample, in smooth muscle, spontaneous (without
nervous or hormonal stimulation) and periodiccontractions.
autosome
(aw ′ t ō -s ō m) [Gr.,
auto,
self +
soma,
body] Any chromosome other than a sex chro-mosome; normally exist in pairs in somatic cellsand singly in gametes.
axial skeleton
(ak ′ s ē - ă l) Skull, vertebral column,and rib cage.
axillary
(ak ′ sil- ā r- ē ) Relating to the axilla; thespace below the shoulder joint, bounded by thepectoralis major anteriorly, the latissimus dorsiposteriorly, the serratus anterior medially, andthe humerus laterally.
axolemma
(ak ′ s ō -lem ′ ă ) [Gr.,
axo
+
lemma,
husk]Plasma membrane of the axon.
axon
(ak ′ son) [Gr., axis] Main central process of aneuron that normally conducts action potentialsaway from the neuron cell body.
axon hillock
Area of origin of the axon from thenerve cell body.
axoplasm
(ak ′ s ō -plazm) Neuroplasm or cytoplasmof the axon.
baroreceptor
(bar ′ ō -r ē -sep ′ ter, bar ′ ō -r ē -sep ′ t ō r)Sensory nerve ending in the walls of the atriaof the heart, venae cavae, aortic arch, and caro-tid sinuses; sensitive to stretching of the wallcaused by increased blood pressure; also calledpressoreceptor.
baroreceptor reflex
Detects changes in bloodpressure and produces changes in heart rate,heart force of contraction, and blood vessel di-ameter that return blood pressure to homeostaticlevels.
basal ganglia
(b ā ′ s ă l gang ′ gl ē - ă ) Nuclei at thebase of the cerebrum involved in controllingmotor functions.
base
(b ā s) Molecule that is a proton acceptor; anysubstance that binds to hydrogen ions. Lower partor bottom of a structure; the base of the heart isthe flat portion directed posteriorly and superi-orly; veins and arteries project into and out ofthe base, respectively.
basement membrane
(b ā s ′ ment mem ′ br ā n)Specialized extracellular material located at thebase of epithelial cells and separating them fromthe underlying connective tissues.
basilar membrane
(bas ′ i-l ă r mem ′ br ā n) Wall ofthe membranous labyrinth bordering the scalatympani; supports the organ of Corti.
basophil
(b ā ′ s ō -fil) [Gr.,
basis,
baso +
phileo,
tolove] White blood cell with granules that stainspecifically with basic dyes; promotes inflammation.
B cell
Type of lymphocyte responsible for antibody-mediated immunity.
belly
(bel ′ ē ) Largest portion of muscle between theorigin and insertion.
beta-oxidation
(b ā ′ t ă ok-si-d ā ′ sh ŭ n) Metabolismof fatty acids by removing a series of two-carbonunits to form acetyl-CoA.
bicarbonate ion
(b ī -kar ′ bon- ā t) Anion (HCO
3−
)remaining after the dissociation of carbonic acid.
bicuspid valve
(b ī -k ŭ s ′ pid) Valve closing the ori-fice between left atrium and left ventricle of theheart; also called mitral valve.
bile
(b ī l) Fluid secreted from the liver into theduodenum; consists of bile salts, bile pigments,bicarbonate ions, cholesterol, fats, fat-solublehormones, and lecithin.
B