Dictionary

ACE Angiotensin converting enzyme. ACE converts an angiotensin to its activated form, angiotensin II, enabling it to function. Angiotensin II constricts blood vessels and elevates blood pressure.

ACE inhibitor A drug that inhibits ACE. Using an ACE inhibitor relaxes the arteries, not only lowering blood pressure but also improving the pumping efficiency of a failing heart and improving cardiac output in patients with heart failure. ACE inhibitors are therefore used for blood pressure control and congestive heart failure. ACE inhibitors include benazepril…

acentric chromosome A chromosome that is lacking a centromere (a specialized region of the chromosome to which spindle fibers attach during cell division). As a result, an acentric chromosome is lost when the cell divides. See also centromere.

aceruloplasminemia See ceruloplasmin deficiency.

acetabulum The cup-shaped socket of the hip joint. The acetabulum is a feature of the pelvis. The head (upper end) of the femur (thighbone) fits into the acetabulum and articulates with it, forming a ball-and-socket joint.

acetaminophen A nonaspirin pain reliever or analgesic. Acetaminophen may be given alone to relieve pain and inflammation or it may be combined with other drugs, as in some migraine medications, which contain acetaminophen, a barbiturate, and caffeine.

acetone A volatile liquid used as an industrial solvent. Acetone is also one of the ketone bodies that is formed when the body uses fat instead of glucose (sugar) for energy. The formation of acetone is usually a sign that cells lack insulin or cannot effectively use the insulin that is available, as occurs in…

acetone breath The breath of a person with excessive acetone in their body. Acetone breath smells fruity and is a telltale sign of significant diabetes. See also diabetes mellitus.

acetylcholine A neurotransmitter released by nerves that is essential for communication between the nerves and muscles.

acetylsalicylic acid See aspirin.

achalasia A disease of the esophagus that mainly affects young adults. Abnormal function of nerves and muscles of the esophagus causes difficulty swallowing and sometimes chest pain. Regurgitation of undigested food can occur, as can coughing or breathing problems related to entry of food material into the lungs. The underlying problems are weakness of the…

Achilles tendon One of the longest tendons in the body, a tough sinew that attaches the calf muscle to the back of the heel bone (calcaneus). The name comes from Greek mythology: The hero Achilles was invulnerable to injury except for his heel, which proved his downfall when it was pierced by Paris’s arrow. It…