What does cardiac output (CO) measure?

Cardiac output (CO) is a critical physiological measurement as it represents the amount of blood ejected by either the left or right ventricle of the heart per minute. This value is significant because it reflects the efficiency of the heart as a pump and indicates how well it can meet the body's demands for blood during various activities, including exercise and rest.

The calculation of cardiac output involves two main components: stroke volume (the amount of blood ejected with each heartbeat) and heart rate (the number of beats per minute). Therefore, understanding cardiac output is essential for assessing cardiovascular health and performance, especially in clinical exercise physiology contexts.

Other choices describe related but distinct concepts. The volume of blood in the arteries pertains to a specific location in the circulatory system and does not encompass the dynamic aspect of blood being pumped per minute. The amount of blood in the veins indicates what is being stored rather than what is actively circulated. While heart rate is a component of cardiac output, it does not capture the actual volume of blood being circulated, thus lacking the complete picture provided by cardiac output itself.