Cardiac output is:

Cardiac output is:

• A. The heart rate alone.
• B. The volume of blood pumped by the heart per minute.
• C. The volume of blood pumped by the heart per beat.
• D. The resistance of the systemic circulation.

Answer: (B)

Cardiac output is the amount of blood the heart ejects into the circulation each minute. It is calculated as heart rate (beats per minute) times stroke volume (volume ejected per beat), so CO = HR × SV. This ties the frequency of beats to how much blood is delivered with each beat, giving a measure of the overall pumping capacity. Think of it this way: the heart can beat quickly or slowly, and each beat can eject a larger or smaller amount of blood. The product of those two factors gives the total volume moved per minute. On average, resting cardiac output is about 5 liters per minute in a healthy adult, and it can increase substantially with exercise as both heart rate and stroke volume typically rise. The other ideas aren’t what CO represents. Heart rate alone counts how often the heart beats but not how much blood is moved with each beat. The volume pumped per beat is the stroke volume, which is only part of the picture. Systemic vascular resistance describes afterload and influences how hard the heart has to work to eject blood, but it does not equal the amount pumped per minute.

Cardiac output is the amount of blood the heart ejects into the circulation each minute. It is calculated as heart rate (beats per minute) times stroke volume (volume ejected per beat), so CO = HR × SV. This ties the frequency of beats to how much blood is delivered with each beat, giving a measure of the overall pumping capacity.

Think of it this way: the heart can beat quickly or slowly, and each beat can eject a larger or smaller amount of blood. The product of those two factors gives the total volume moved per minute. On average, resting cardiac output is about 5 liters per minute in a healthy adult, and it can increase substantially with exercise as both heart rate and stroke volume typically rise.

The other ideas aren’t what CO represents. Heart rate alone counts how often the heart beats but not how much blood is moved with each beat. The volume pumped per beat is the stroke volume, which is only part of the picture. Systemic vascular resistance describes afterload and influences how hard the heart has to work to eject blood, but it does not equal the amount pumped per minute.