What does cardiac output refer to?

Cardiac output is a critical measure of heart function and is defined as the volume of blood the heart pumps in one minute. This metric is essential for understanding how effectively the cardiovascular system delivers oxygen and nutrients to tissues throughout the body. It is typically calculated by multiplying the stroke volume—the amount of blood ejected by the heart in one contraction—by the heart rate (the number of heartbeats per minute).

This concept is vital in various medical scenarios, particularly in emergency situations where assessing the circulatory status of a patient can guide treatment decisions. Effective cardiac output ensures that all organs receive sufficient blood flow necessary for their function, and it is a key indicator of overall cardiovascular health.

The other options relate to different physiological concepts; for instance, the amount of blood ejected by the heart in one contraction pertains to stroke volume, not cardiac output. The total volume of blood in the body is a measure of blood volume, and the pressure exerted by the blood on the walls of blood vessels is referred to as blood pressure. Each of these measurements provides valuable information, but they do not define cardiac output directly.