Dictionary

arterial anastomosis A joining of two arteries. See also anastomosis.

arterial blood gas See ABG.

arterial tension See arterial pressure.

arteriogram An X-ray in which an injection of dye shows blood vessels.

arteriole A small branch of an artery that leads to a capillary. The oxygenated hemoglobin (oxyhemoglobin) makes the blood in arterioles (and arteries) look bright red.

arteriosclerosis Hardening and thickening of the walls of the arteries. Arteriosclerosis leads to heart attacks and strokes, as well as to peripheral vascular disease. Arteriosclerosis can be categorized as atherosclerosis, medial calcification, hypertensive, or arteriolar sclerosis. See also atherosclerosis; heart attack; stroke; peripheral vascular disease.

arteritis, cranial A serious disease characterized by inflammation of the walls of arteries, particularly those that supply blood to the head. Symptoms include headache, pain in the jaw when repetitively chewing, and tenderness of the scalp, usually over the inflamed arteries of the sides of the head (temporal area). Less specific symptoms include fatigue, low-grade…

arteritis, giant cell See arteritis, cranial.

appendix testis A small solid projection of tissue on the outer surface of the testis, which is a remnant of the embryologic mullerian duct.

apposition 1 The act of adding or accretion. Growth by apposition is characteristic of many tissues in the body by which nutritive matter from the blood is transformed on the surface of an organ into a solid unorganized substance. 2 The act of putting things in juxtaposition or side by side. To lose a pair…

apraxia The inability to execute a voluntary motor movement despite being able to demonstrate normal muscle function. Apraxia is not related to a lack of understanding or to any kind of physical paralysis; rather, it is caused by a problem in the cortex of the brain.

apraxia of speech A severe speech disorder characterized by an inability to speak or a severe struggle to speak clearly. Apraxia of speech occurs when the oral-motor muscles do not or cannot obey commands from the brain or when the brain cannot reliably send those commands. Apraxia of speech is caused by damage to the…