579
A
ABCD rule a system for self-determining the presence
of melanoma; stands for Asymmetry, Border irregularity,
Color, and Diameter
abdominal aorta term for the left aorta when it reaches
the abdomen
abdominal cavity space bounded by the abdominal
walls, the diaphragm, and the pelvis
abdominopelvic cavity (ab-DAHM-i-noh-PEHL-vik)
continuous internal opening that includes the abdominal
and pelvic cavities
abduction movement of a body segment away from the
body in the frontal plane
abnormal contractility condition an abnormal
heartbeat; arrhythmia
absorption the movement of food molecules from the
small intestine into the blood
acceleration the change in velocity of the object to which
a force is applied
accessory reproductive organs glands and structures
other than the ovaries and testes, which are needed for
reproduction, such as the prostate gland and vestibular
glands
accommodation the process through which contraction
of the muscles of the ciliary body makes the lens thicker
acetabulum (as-eh-TAB-yoo-lum) deep socket within
each coxal bone that receives the head of the femur to
form the hip joint
acetylcholine (a-SEE-til-KOH-leen) a neurotransmitter
acid substance that, when added to water, increases its
hydrogen ion concentration
acquired immune defi ciency syndrome (AIDS) a
disease in which the immune system is greatly weakened
due to infection with HIV, making a person more
susceptible to rare cancers and opportunistic infections
acromegaly (ak-roh-MEG-a-lee) a rare condition in which
the anterior pituitary hypersecretes growth hormone,
causing an increase in overall body size; gigantism
acromioclavicular joint (a-KROH-mee-oh-kla-VIK-yoo-lar)
joint between the acromion process of the scapula and
the clavicle
acromion (a-KROH-mee-ahn) bone projection on the top
lateral side of each scapula
acrosomal enzymes (AK-roh-sohm-al) enzymes
contained in the tip of a sperm’s head that allow it to
digest the protective glycoproteins surrounding an oocyte
actin a common protein that is the building block for
microfi laments and for thin fi laments in muscle cells
action potential the electric charge produced in nerve or
muscle fi ber by stimulation
active immunity immunity in which the blood plasma
cells in the body make antibodies as a result of previous
exposure to a disease or a vaccine
active process a process that requires the use of
muscles
active transport type of membrane transport that
requires energy
acute the term used to describe an injury caused by a
single force
acute bronchitis a temporary infl ammation of the
mucous membranes that line the trachea and bronchial
passageways; causes a cough that may produce mucus
acute lymphocytic leukemia (ALL) the most common
form of leukemia in adults over 70 years of age;
characterized by overproduction of lymphocytes
acute myeloid leukemia (AML) the most common form
of leukemia in adults; develops when the bone marrow
produces too many myeloblasts
adaptive immune system see immune system
Addison’s disease a condition caused by hyposecretion
of adrenal corticoid hormones that causes muscle
atrophy, a bronze skin tone, low blood pressure, kidney
damage, hypoglycemia, severe loss of fl uids and
electrolytes, and a general feeling of weakness
adduction movement of a body segment closer to the
body in the frontal plane
adenoid see pharyngeal tonsil
adenosine triphosphate see ATP
adipocyte (AD-i-poh-sight) a fat cell
adipose tissue a type of tissue that is almost entirely fat
cells
adrenal cortex outer layer of the adrenal glands, which
itself has three layers that secrete steroid hormones
adrenal glands a pair of glands that sits on top of the
kidneys; consists of the adrenal cortex and adrenal medulla
adrenaline a hormone that is secreted by the adrenal
medulla and is involved in the body’s fi ght-or-fl ight
response; epinephrine
adrenal medulla the part of the adrenal glands that
functions as a part of the nervous system; it secretes
the hormones epinephrine and norepinephrine
(catecholamines) during the fi ght-or-fl ight response
adrenocorticotropin (ACTH) (a-DREE-noh-KOR-ti-koh-
TROH-pin) a tropic hormone secreted by the anterior
pituitary that acts on the adrenal cortex to stimulate the
release of glucocorticoid hormones like cortisol
adult onset diabetes see type II diabetes mellitus
afferent lymphatic vessel vessel that carries lymph into
a lymph node
afferent nerves sensory transmitters that send impulses
from receptors in the skin, muscles, and joints to the
central nervous system
afferent pathway the route on which informational
messages travel from a receptor to a control center
agglutination (ah-GLOO-ti-NAY-shun) the process by
which red blood cells clump together, usually in response
to an antibody; can block small blood vessels and cause
hemolysis
agonist (AG-un-ist) role played by a skeletal muscle to
cause a movement
agranulocytes (ay-GRAN-yoo-loh-SIGHTS) white blood
cells whose cytoplasm lacks granules
albinism (AL-bi-nizm) an inherited condition that prevents
the normal production of melanin
aldosterone (al-DAHS-ter-ohn) a steroid hormone
produced in the adrenal cortex that regulates salt and
water balance in the body by stimulating the kidneys
to absorb sodium and water from urine and eliminate
potassium
Glossary