Cardiac output is defined as:

Cardiac output is defined as:

• A. The amount of blood per beat
• B. The pressure of circulating blood on the walls of blood vessels
• C. The need for extra oxygen after strenuous exercise
• D. The amount of blood pumped out of the heart in one minute

Answer: (D)

Cardiac output is the total volume of blood the heart pumps per minute. It’s determined by heart rate (how many beats per minute) and stroke volume (how much blood is ejected with each beat), so you can think of it as heart rate times stroke volume. The description given matches this idea: the amount of blood pumped out of the heart in one minute. The other ideas refer to different concepts—blood per beat is stroke volume, the pressure on vessel walls is blood pressure, and needing extra oxygen after strenuous exercise relates to oxygen uptake/oxygen debt, not the total minute-by-minute output.

Cardiac output is the total volume of blood the heart pumps per minute. It’s determined by heart rate (how many beats per minute) and stroke volume (how much blood is ejected with each beat), so you can think of it as heart rate times stroke volume. The description given matches this idea: the amount of blood pumped out of the heart in one minute. The other ideas refer to different concepts—blood per beat is stroke volume, the pressure on vessel walls is blood pressure, and needing extra oxygen after strenuous exercise relates to oxygen uptake/oxygen debt, not the total minute-by-minute output.