adrenal glands Hormone-producing (endocrine) glands that rest atop each kidney and secrete several hormones, including adrenaline (which increases heart rate and raises blood pressure) and aldosterone (which regulates the levels of potassium and sodium).
adrenaline (epinephrine) Hormone produced by the adrenal glands that increases heart rate and blood pressure by narrowing (constricting) blood vessels. An important hormone secreted in stressful situations as part of the body’s fight-or-flight response. aldosterone Hormone secreted by cortex or outer portion of the adrenal glands; regulates potassium secretion and the retention of salt and water by the kidneys.
anemia A reduction in the normal amount of hemoglobin or the number of red blood cells in the circulation.
aneurysm A bulging out (protrusion) or blistering in a major blood vessel at a point where there is a weakness in the vessel wall.
angina A pressure or an intense chest pain resulting from a reduced oxygen supply to the heart muscle.
angiogram An X-ray of blood vessels or other part of the cardiovascular system.
angiography A diagnostic procedure in which a contrasting dye is injected into the bloodstream to make blood vessels or heart chambers visible on an X-ray image.
angioplasty Therapeutic procedure in which a catheter with a deflated balloon at the tip is inserted into a narrowed artery. The balloon is then inflated at the site of narrowing to widen it.
angiotensin A blood chemical that constricts blood vessels, thereby raising blood pressure,
angiotensin-converting enzyme (ACE) inhibitors Drugs that inhibit the action of angiotensin and that are used to treat high blood pressure or congestive heart failure.
anemia may be a symptom of iron deficiency, chronic bleeding, or some other underlying disorder.
anorexia The medical term for loss of appetite.
antiarrhythmics A group of drugs used to treat irregular heartbeats (arrhythmias).
anticoagulants Drugs that suppress the blood-clotting process.
anticonvulsants Drugs used to treat seizures.
antihypertensives Drugs used to lower high blood pressure.
anxiety Feelings of apprehension and uneasiness.
aorta he largest artery in the body. It receives blood from the left ventricle of the heart; the blood is then distributed through a branching system of arteries to all parts of the body.
aortic regurgitation (insufficiency) Failure of the aortic valve to close properly, allowing some blood to flow back into the left ventricle with each heartbeat instead of forward into the circulation.
aortic stenosis A narrowing or stiffness of the aortic valve causing an obstruction to blood flow; this results in an increased workload for the heart.
aortic valve The valve that controls the flow of blood between the aorta and the left ventricle, the heart’s major pumping chamber.
aphasia Loss of the ability to speak, usually as a result of injury or disease of the brain.
arrhythmia Deviation from the normal heartbeat rhythm because of a disturbance in the electrical impulses to the heart.
arterial lumen The channel of an artery through which blood flows.
arteries Blood vessels that carry oxygenated blood away from the heart to all parts of the body.
arterioles The smallest arteries, which distribute blood to the capillaries.
arteriosclerosis A condition in which the walls of arteries thicken and lose elasticity; commonly called “hardening of the arteries.” See atherosclerosis.
arteriovenous malformation A tangle of arteries and veins without the capillaries that normally connect the two.
ascites A collection of excess fluids in the abdominal cavity.
atheroma A collection of fatty plaque. It is a common pathologic event of atherosclerosis.
atherosclerosis A form of arteriosclerosis resulting from the buildup of fatty substances called plaque on the walls of the arteries, causing a reduction in blood flow.
atresia The absence of a normal body passage or opening (orifice) from an organ or other part of the body.
atrial fibrillation An abnormal heart rhythm (arrhythmia) in which the heart’s atria contract at an excessive and irregular rate.
atrial septal defects Abnormal congenital openings in the wall dividing the heart’s upper chambers.
atrial septum A thin wall dividing the heart’s left and right atria or upper chamber.
atrioventricular It is the small mass of conduction tissue, located between the upper and lower chambers of the heart, through which electrical impulses pass, controlling heart rhythm pass.
atrium (plural = atria) One of the two upper chambers of the heart. The left atrium receives newly oxygenated blood from the lungs. The right atrium receives deoxygenated blood from various parts of the body.
autonomic nervous system The involuntary nervous system that controls unconscious body functions such as heart rate and blood pressure.