ABSTRACT
The primary function of the heart is to deliver a sufficient volume of blood (oxygen and nutrients, etc.) to the tissues so that they may carry out their functions effectively. As the metabolic activity of a tissue varies, so will its need for blood. An important factor involved in meeting this demand is
cardiac output (CO)
or the volume of blood pumped into the aorta per minute. Cardiac output is determined by heart rate multiplied by stroke volume:
Cardiac output (CO) = heart rate (HR)
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stroke volume (SV)
An average adult at rest may have a heart rate of 70 beats per minute and a stroke volume of 70 ml per beat. In this case, the cardiac output would be:
CO = 70 beats/min
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70 ml/beat = 4900 ml/min
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5 l/min
This is approximately equal to the total blood volume in the body. Therefore, the entire blood volume is pumped by the heart each minute.
