582 Introduction to Anatomy and Physiology
basal nuclei small regions of gray matter interspersed
within the brain’s white matter
base (1) the nitrogen-containing part of a nucleotide;
(2) the broad end of the heart, which is positioned closer
to the neck, at the second rib; (3) the broad end of the
lung, which rests on the diaphragm
base pairs pairs of complementary nucleic acid bases;
that is, A and T or C and G
bedsores see decubitus ulcers
bending a loading pattern created by a combination of
off-center forces
benign (bi-NIGHN) term for conditions that involve
non-metastasized tumors
beta cells cells in the islets of Langerhans that secrete
insulin
beta interferons (IN-ter-FAIR-ahns) interferons produced
by virus-infected fi broblasts
bicarbonate an alkaline molecule that neutralizes acidic
chyme
bicuspid valve (bigh-KUS-pid) the mitral valve, which
has two cusps and is located on the right side of the
heart
bile an alkaline fl uid made in the liver and secreted into
the duodenum; aids especially in the emulsifi cation and
absorption of fats
bile canaliculi (kan-a-LIK-yoo-ligh) small ducts in the
liver that collect bile
bile salts substances found in bile that aid fat absorption;
derived from cholesterol
biochemistry the detailed study of the molecules of life,
how they are made, and how they are broken down
bipolar neurons nerve cells that have one axon and one
dendrite
birth canal see vagina
bitter one of the fi ve basic tastes
bladder a muscular sac in the pelvic cavity where urine
from the kidneys is stored before it is excreted
bladder neck location at which the urethra connects to
the bladder
blastocyst (BLAS-toh-sist) a fl uid-fi lled cavity
blind spot a tiny area where the optic nerve joins the
retina and where there are no rods and cones
blood-brain barrier protective mechanism in the tiny
blood vessels supplying the brain that prevents invasion
of the brain by many potentially harmful substances
blood glucose test a test for the presence of glucose in
the body; a result of 126 mg/dL or higher after an eight-
hour fast is considered positive for diabetes
blood pressure cuff device used to measure blood
pressure; sphygmomanometer
blood vessel capillaries the tiniest blood vessels in the
body; they connect the smallest arteries to the smallest
veins
bone marrow material with a rich blood supply found
within the marrow cavity of long bones; yellow marrow
stores fat, and red marrow is active in producing blood
cells
bony labyrinth winding tunnels located in the inner ear
brachial artery (BRAY-kee-al) the artery located at the
fold of the elbow where the brachial pulse is detected
bradycardia (BRAD-ee-KAHR-dee-a) a normal heart
rhythm but with a rate below 60 bpm; a condition
common among athletes
breech presentation a position of the fetus in which
the buttocks or legs exit the mother’s body fi rst, making
delivery more diffi cult
Broca’s area a portion of the left frontal lobe that controls
the tongue and lip movements required for speech
bronchioles (BRAHNG-kee-ohls) the thin-walled
branches of the bronchi; the smallest air-conducting
passageways of the bronchi. The terminal bronchioles
conduct a small amount of gas exchange in the
respiratory zone
bronchospasms (BRAHNG-koh-spazmz) spasmodic
contractions of the bronchial muscles that constrict the
airways in the lungs during an asthma attack
brush border collective term for the microvilli on the
epithelial cells of the small intestine
buffy coat a thin layer of white blood cells and platelets
that lies between the red blood cells and plasma in a
blood sample that has gone through a centrifuge
bulbourethral glands (BUL-boh-yoo-REE-thral) two
small glands at the base of the penis that secrete mucus
into the urethra
bulimia nervosa disordered eating that involves a
minimum of two eating binges a week for at least three
months; an associated feeling of lack of control; use of
self-induced vomiting, laxatives, diuretics, strict dieting,
or exercise to prevent weight gain; and an obsession with
body image
bundle of His a slender bundle of modifi ed cardiac
muscle that conducts electrical impulses from the
AV node to the left and right bundle branches to Purkinje
fi bers in the ventricle
burning mouth syndrome a condition that involves a
sensation of moderate to severe burning in the mouth
that may continue for months or even years
bursae (BER-see) small capsules lined with synovial
membranes and fi lled with synovial fl uid; they cushion
the structures they separate
bursitis (ber-SIGHT-is) infl ammation of one or more bursae
C
calcaneus (kal-KAY-nee-us) the heel bone
calcitonin (kal-si-TOH-nin) hormone secreted by the
thyroid gland that works with parathyroid hormone to
maintain calcium homeostasis
Calorie the unit that food scientists use to measure the
potential energy in foods; the amount of heat required
to raise the temperature of 1 kilogram of water by 1°C;
kilocalorie
canaliculi (kan-a-LIK-yoo-ligh) tiny canals that connect
central Haversian canals with cavities called lacunae
cancer the uncontrolled division and growth of abnormal
cells
capacitation (ka-pas-i-TAY-shun) the process by which
sperm becomes able to fertilize an oocyte
capillaries small, thin-walled vessels where oxygen
and carbon dioxide gas exchange occurs between the
capillaries and the tissues
capillary beds network of intertwined vessels formed by
multiple capillaries
carbaminohemoglobin (kar-BAM-i-noh-HEE-moh-GLOH-
bin) molecule that is created when CO2 attaches to a
globin part of the hemoglobin molecule
carbohydrate sugar and starch molecules; saccharides
cardiac muscle the major tissue of the heart
cardiac output the amount of blood pumped from the
heart per minute
cardiomyopathy (KAHR-dee-oh-migh-AHP-a-thee)
heart failure caused by infection and weakening of the
myocardium, or heart muscle