Medical Dictionary: Hypertension

Hypertension is an insidious disease. Because it has no symptoms or warning signs, 30% of the people who have the condition don't realize it. This medical dictionary covers the terms used in the report, Hypertension: Controlling the 'Silent Killer', and includes details on hypertension and blood pressure symptoms, treatment, causes, medications, and tests.

aldosterone: A hormone secreted by the adrenal glands that signals the kidneys to conserve sodium and water; the result is higher blood pressure.

angiotensin: A protein that increases blood pressure by constricting blood vessels and stimulating the release of aldosterone. The inactive form is angiotensin I, and the active form is angiotensin II.

antihypertensives: Medications used to treat high blood pressure.

arterial resistance: The pressure that the artery walls exert on blood flow; in general, the less elastic the arteries, the greater the arterial resistance and the higher the blood pressure.

atherosclerosis: Thickening of the inner layer of artery walls from the buildup of debris, such as fats and cholesterol, from the bloodstream; this narrows the passageway and diminishes blood flow.

autonomic nervous system: The part of the nervous system that controls involuntary processes, such as heartbeat and breathing. Its two arms are the sympathetic and parasympathetic nervous systems.

coronary artery disease: Narrowing or blockage of the arteries that supply blood to the heart muscle. The condition can cause angina and heart attack.

diabetes: A disorder in which blood glucose (sugar) levels are elevated.

diastolic pressure: The second (bottom) reading of a blood pressure measurement, which reflects the pressure in the arteries between heartbeats.

epinephrine: A chemical released by the sympathetic nervous system that constricts blood vessels and increases heart rate; also called adrenaline.

essential hypertension: High blood pressure for which there is no known underlying cause; also called primary hypertension.

heart failure: A condition in which the heart loses its ability to efficiently pump blood throughout the body.

isolated systolic hypertension: A form of hypertension characterized by elevated systolic blood pressure and normal diastolic pressure.

labile hypertension: Blood pressure that frequently fluctuates between normal and abnormal during the course of a day, often within only a few minutes.

left ventricular hypertrophy: Thickening of the left ventricle, the chamber of the heart that pumps blood to the body.

malignant hypertension: A dangerous type of hypertension marked by an unusually sudden rise in blood pressure to very high levels, often accompanied by headache, blurred vision, and seizures.

neurotransmitters: Chemicals released by nerve cells that transmit messages to other nearby cells.

norepinephrine: A neurotransmitter that constricts blood vessels.

pulse pressure: The difference between your systolic and diastolic blood pressures. May help predict heart disease risk.

renal artery stenosis: Narrowing of an artery that supplies blood to the kidney.

renin: An enzyme released by the kidney that stimulates production of angiotensin.

resistant hypertension: Blood pressure that remains persistently elevated despite drug therapy and lifestyle changes.

secondary hypertension: High blood pressure that has an identifiable, often correctable, cause.

systolic pressure: The first (top) number of a blood pressure measurement, which reflects pressure in the arteries when the heart contracts.

vasoconstrictors: Substances that constrict blood vessels.

vasodilators: Substances that widen blood vessels.

white-coat hypertension: Blood pressure elevations that occur in response to visits to a doctor’s office.