What does cardiac output measure?

Cardiac output measures the amount of blood ejected by the heart in one minute. It is a crucial parameter in assessing the heart's efficiency in pumping blood throughout the body and is typically calculated by multiplying the stroke volume (the volume of blood ejected with each heartbeat) by the heart rate (the number of beats per minute). This measurement is vital for understanding how well the circulatory system is functioning, particularly during different levels of physical activity and overall health.

In contrast, the other options focus on different aspects of physiological measurements. The volume of blood ejected in one contraction refers specifically to stroke volume, not total output per minute. Total lung capacity pertains to respiratory capacity and does not relate to cardiac function. Oxygen consumption at rest is indicative of metabolic rates but does not directly measure cardiac output. Thus, understanding that cardiac output integrates both the volume of blood pumped and the frequency of heartbeats over time helps highlight its significance in evaluating cardiovascular health.