How is cardiac output defined?

Cardiac output is defined as the amount of blood pumped out of a ventricle in one minute. This measurement is crucial in assessing the heart's efficiency and overall health. It provides a clear understanding of how well the heart is functioning to supply oxygenated blood to the body, which is essential for maintaining the metabolic needs of tissues and organs.

Cardiac output can be calculated by multiplying the stroke volume (the amount of blood ejected with each heartbeat) by the heart rate (the number of heartbeats per minute). It is typically expressed in liters per minute. This metric becomes particularly important in clinical settings to evaluate heart performance, especially during stress, exercise, or in cases of heart disease.

The other choices represent different aspects of cardiovascular physiology but do not define cardiac output. The volume of blood in the heart chambers speaks to preload but does not account for the rate of ejection. The rate of heart contractions per minute, also known as heart rate, is an important factor in cardiac output but fails to define the total volume output itself. Finally, pressure exerted by circulating blood relates more to blood pressure and vascular resistance than to cardiac output. Understanding these distinctions helps clarify the significance of cardiac output in the context of heart physiology.