The New Dictionary of Cultural Literacy, Third Edition. 2002.
blood pressure
The pressure of the blood against the walls of the blood vessels, especially the arteries. It is expressed in two figures, said to be one “over” the other: the systolic pressure, which is the pressure when the left ventricle of the heart contracts to push the blood through the body; and the diastolic pressure, which is the pressure when the ventricle relaxes and fills with blood. Blood pressure is affected by the strength of the heartbeat, the volume of blood in the body, the elasticity of the blood vessels, and the age and general health of the person. (Seecirculatory system.)
