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blood pressure
the pressure of the blood against the walls of any blood vessel. The term usually refers to the pressure of the blood within
the arteries (arterial blood pressure), which is the result of factors such as the pumping action of the heart, resistance to the flow of blood in the arterioles, the elasticity of artery walls, the blood volume and extracellular fluid volume, and the blood's viscosity (thickness). At each pulsation, arteries expand to absorb the increase in blood pressure. As the heart relaxes in preparation
for another beat, the aortic valves close to prevent blood from flowing back to the heart chambers, and the artery walls spring back, forcing the blood through
the body between contractions. In this way the arteries act as dampers on the pulsations and thus provide a steady flow of
blood through the blood vessels.
Copyright 2007. An Elsevier publication. All rights reserved.
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