Blood pressure

The blood pressure is the pressure of the blood within the arteries. It is produced primarily by the contraction of the heart muscle. It's measurement is recorded by two numbers. The first (systolic pressure) is measured after the heart contracts and is highest. The second (diastolic pressure) is measured before the heart contracts and lowest. A blood pressure cuff is used to measure the pressure. Elevation of blood pressure is called "hypertension." (see hypertension).

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blood pressure n pressure exerted by the blood upon the walls of the blood vessels and esp. arteries, usu. measured on the radial artery by means of a sphygmomanometer, and expressed in millimeters of mercury either as a fraction having as numerator the maximum pressure that follows systole of the left ventricle of the heart and as denominator the minimum pressure that accompanies cardiac diastole or as a whole number representing the first value only <a blood pressure of 120/80> <a blood pressure of 120> abbr. BP

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the pressure of blood against the walls of the main arteries. Pressure is highest during systole, when the ventricles are contracting (systolic pressure), and lowest during diastole, when the ventricles are relaxing and re-filling (diastolic pressure). Blood pressure is measured - in millimetres of mercury - by means of a sphygmomanometer at the brachial artery of the arm, where the pressure is most similar to that of blood leaving the heart. The normal range varies with age, but a young adult would be expected to have a systolic pressure of around 120 mm and a diastolic pressure of 80 mm. These are recorded as 120/80.

Individual variations are common. Muscular exertion and emotional factors, such as fear, stress, and excitement, all raise systolic blood pressure (see hypertension). Systolic blood pressure is normally at its lowest during sleep. Severe shock may lead to an abnormally low blood pressure and possible circulatory failure (see hypotension). Blood pressure is adjusted to its normal level by the sympathetic nervous system and hormonal controls.

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1. the pressure of blood against the walls of any blood vessel. 2. the pressure of the blood on the walls of the arteries, dependent on the energy of the heart action, the elasticity of the walls of the arteries, and the volume and viscosity of the blood. The maximum or systolic blood pressure occurs near the end of the stroke output of the left ventricle of the heart. The minimum or diastolic blood pressure occurs late in ventricular diastole. Mean blood pressure is the average of the blood pressure levels, and basic blood pressure is that during quiet rest or basal conditions. See also hypertension and hypotension.