If the stroke volume is 70 cm3 and the heart rate is 72 beats per minute, the cardiac output is about

Explanation

Cardiac output is stroke volume multiplied by heart rate, so 70 cm3 times 72 gives 5,040 cm3 per minute, which is about 5 dm3. That figure is close to the total blood volume of an adult, meaning the whole circulation passes through the heart roughly once every minute at rest. During heavy exercise both factors rise and the output can reach five times this value.