How is cardiac output calculated?

Cardiac output is a key measure of the heart’s effectiveness in pumping blood throughout the body and is defined as the volume of blood the heart pumps per minute. It is calculated by multiplying the heart rate, which is the number of times the heart beats in one minute, by the stroke volume, the amount of blood ejected by the heart with each beat.

This foundational principle reflects the relationship between these two parameters; if either the heart rate or the stroke volume increases, the cardiac output will consequently increase. For instance, during physical activity, the heart rate typically rises, and this, coupled with a steady or slightly increased stroke volume, leads to an increased cardiac output to meet the body's enhanced demand for oxygen and nutrients.

The other options provided do not accurately represent the calculation of cardiac output. For example, multiplying heart rate by blood pressure does not yield a meaningful physiological parameter, as blood pressure is not directly related to how much blood is being pumped per minute. Similarly, including cholesterol levels in any calculation of cardiac output is inappropriate, as cholesterol is a substance found in the blood but does not directly influence the heart rate or stroke volume. Lastly, dividing heart rate by stroke volume does not yield cardiac output and lacks the correct relationship needed to measure this vital