What is cardiac output?

Cardiac output refers to the volume of blood that is pumped by each ventricle of the heart in one minute. This measurement is crucial in understanding how effectively the heart is functioning to supply the body with oxygen and nutrients. It is a vital parameter in assessing cardiovascular health and fitness levels, particularly during exercise.

The correct answer reflects the fundamental definition of cardiac output, which is a combination of heart rate (the number of times the heart beats per minute) and stroke volume (the amount of blood ejected by the heart with each beat). Therefore, the relationship between these components allows for an understanding of how much blood is circulated throughout the body in a given timeframe.

While the option regarding the total blood volume ejected during exercise may seem relevant, it does not precisely define cardiac output, as cardiac output is a rate measured over time, not just a total volume. The choice about the amount of blood that returns to the heart refers to venous return, which is important but does not capture the definition of cardiac output itself. Lastly, while the concept of multiplying heart rate by stroke volume is correct in a quantitative sense to arrive at immediate cardiac output, the direct definition emphasizes the total volume of blood pumped by each ventricle in one minute.