Blood pressure (BP), sometimes referred to as arterial blood pressure, is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, blood pressure varies between a maximum (systolic) and a minimum (diastolic) pressure. The blood pressure in the circulation is principally due to the pumping action of the heart. Differences in mean blood pressure are responsible for blood flow from one location to another in the circulation. The rate of mean blood flow depends on the resistance to flow presented by the blood vessels. Mean blood pressure decreases as the circulating blood moves away from the heart through arteries and capillaries due to viscous losses of energy. Mean blood pressure drops over the whole circulation, although most of the fall occurs along the small arteries and arterioles. Gravity affects blood pressure via hydrostatic forces (e.g., during standing) and valves in veins, breathing, and pumping from contraction of skeletal muscles also influence blood pressure in veins.
The measurement blood pressure without further specification usually refers to the systemic arterial pressure measured at a person's upper arm and is a measure of the pressure in the brachial artery, major artery in the upper arm. A person’s blood pressure is usually expressed in terms of the systolic pressure over diastolic pressure and is measured in millimetres of mercury (mmHg), for example 140/90.
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... Regardless of site, blood pressure is related to the wall tension of the vessel according to the Young–Laplace equation (assuming that the thickness of the ...
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... A low sodium diet in Caucasians has a useful effect to reduce blood pressure, both in people with hypertension and in people with normal blood pressure ... people resulted in a decrease in systolic blood pressure by 5 mmHg, and in diastolic blood pressure by 2.70 mmHg ... In people with normal blood pressure, the corresponding decrease in systolic blood pressure was 2.03 mmHg and diastolic blood pressure 0.99 mmHg ...
Famous quotes containing the words pressure and/or blood:
“He who is of a calm and happy nature will hardly feel the pressure of age, but to him who is of an opposite disposition youth and age are equally a burden.”
—Plato (c. 427347 B.C.)
“Fit gravefellows you are for Lincoln, Brown
And Douglass and Toussaint. . . all whose rapt eyes
Fashioned a new world in this wilderness.
American earth is richer for your bones;
Our hearts beat prouder for the blood we inherit.”
—Dudley Randall (b. 1914)