592 Introduction to Anatomy and Physiology
intrinsic factor glycoprotein secreted by cells in the
stomach that is essential for absorption of vitamin B12
inulin a nontoxic polysaccharide from plants; used to test
kidney function
inversion movement in which the sole of the foot is rolled
inward
in vitro fertilization (IVF) an assisted reproductive
technology in which the oocyte is fertilized outside the body
iris the anterior portion of the choroid, which gives the
eye its color
iron-defi cient anemia the most common anemia;
caused by an insuffi cient dietary intake of iron, loss of
iron from intestinal bleeding, or iron-level depletion during
pregnancy
irregular bones bones with shapes that do not allow
them to be classifi ed as long, short, or fl at, including the
bones of the pelvic girdle and spinal column
irregular dense connective tissue type of connective
tissue that is composed primarily of collagen fi bers that
are oriented in random directions
irritability the ability to respond to a stimulus
ischemia (is-KEE-mee-a) a lack of blood fl ow, usually
due to the narrowing of a blood vessel
ischemic stroke (is-KEE-mik) a stroke that occurs when
one of the arteries of the brain becomes blocked
ischium (IS-kee-um) bone forming the inferior (lowest)
portion of each coxal bone; supports the weight of the
upper body during sitting
islets of Langerhans (IGH-lets of LAHNG-er-hahnz)
cells of the pancreas that secrete insulin and glucagon
isometric (IGH-soh-MEHT-rik) a type of contraction that
causes no change in muscle length
isthmus (IS-mus) a center band of tissue that connects
the two lateral lobes of the thyroid gland
J
jaundice a blood disorder characterized by yellow-colored
skin and whites of the eyes
jejunum (jeh-JOO-num) middle segment of the
small intestine; between the duodenum and the ileum
juvenile onset diabetes see type I diabetes mellitus
juxtamedullary nephrons (JUKS-ta-MEHD-yoo-LAIR-ee)
nephrons located near the boundary between the
renal cortex and the renal medulla; have long nephron
loops that penetrate deeply into the renal medulla;
important regulators of urine concentration
K
keratin (KER-a-tin) a tough protein found in the skin, hair,
and nails
keratinocytes (keh-RAT-i-noh-sights) cells within the
epidermis that produce keratin
ketacidosis (keet-oh-as-i-DOH-sis) a condition caused
by the enhanced production of ketone bodies, which
causes the pH of the blood to decrease and become
dangerously acidic
kidney stone solid crystalline mass that can form in the
kidney and which may become stuck in the renal pelvis
or ureter; usually made of calcium, phosphate, uric acid,
and protein
killer T cell see cytotoxic T cell
kinetics the analysis of the actions of forces
L
labia majora two skin folds posterior to the mons pubis
that lie parallel on either side of the vaginal opening
labia minora a smaller set of skin folds inside the
labia majora
labyrinthitis (LAB-uh-rin-THIGH-tis) an infection of the
inner ear that produces infl ammation
lacrimal bones (LAK-ri-mal) tiny bones connecting to the
orbits and surrounding the tear ducts
lacrimal canaliculi (LAK-ri-mal kan-a-LIK-yoo-ligh) tiny
canals where tears are fl ushed from the eye
lacrimal glands (LAK-ri-mal) tear secretors; located
above the lateral end of each eye
lactation secretion of milk by the mammary glands
lactiferous duct (lak-TIF-er-us) a duct through which
milk is secreted and which opens at the nipple
lacunae (la-KOO-nee) tiny cavities laid out in concentric
circles around the Haversian canals
lamellae (la-MEHL-ee) concentric circles of lacunae
around the Haversian canals
lamina propria (LAM-in-a PROH-pree-a) loose, connective
tissue under the epithelium of a mucous membrane
large intestine the portion of the digestive tube between
the small intestine and the anus; its major segments are
the cecum, colon, rectum, and anal canal
laryngitis (LAIR-in-JIGH-tis) infl ammation of the larynx,
or voice box
laryngopharynx (la-RING-goh-FAIR-ingks) the lower
section of the pharynx
larynx (LAIR-ingks) a triangular-shaped space inferior to
the pharynx that is responsible for voice production; the
voice box
lateral extension term for the return from a position of
lateral fl exion to anatomical position
lateral fl exion trunk and neck motions away from
anatomical position in the frontal plane
lateral malleolus (mal-LEE-oh-lus) bony projection on
the end of each fi bula; the ankle bone
lateral rotation outward (lateral) movement of a body
segment in the transverse plane
left bronchomediastinal trunk (BRAHN-koh-MEE-dee-
as-tin-al) duct that drains lymph from the left side of the
chest and lower neck
left bundle branches the left limbs or branches through
which electrical impulses are transmitted from the bundle
of His through the left ventricle
left jugular trunk duct that drains lymph from the left side
of the head
left lumbar trunk duct carrying lymph from left lower
body toward the cisterna chyli
left subclavian trunk (sub-KLAY-vee-an) duct that drains
lymph from the left arm
lens a transparent, fl exible structure that is curved
outward on both sides
let-down refl ex contraction of smooth muscle cells in the
mammary glands that allows milk to be squeezed toward
and out of the nipple
leukemia a cancer caused by production of an extremely
high number of immature white blood cells in the
bone marrow
leukocytes (LOO-koh-sights) white blood cells
ligaments bands composed of collagen and elastic fi bers
that connect bones to other bones
limbic system a set of structures in the brain that
stimulate the sympathetic branch in the cardiac center
lingual tonsils (LING-gwal) two masses of lymphatic
tissue that lie on either side of the base of the tongue
lipids fatty molecules that dissolve poorly in water but
dissolve well in a nonpolar solvent; fats and oils