Cardiac Output (CO) is defined as:

Cardiac Output (CO) is defined as:

• A. The total volume of blood pumped by the left ventricle in one minute.
• B. The stroke volume times the heart rate.
• C. The amount of blood in the systemic circulation.
• D. The product of left ventricular pressure and heart rate.

Answer: (B)

Cardiac output is the amount of blood the heart pumps each minute, and the way it’s calculated is by multiplying how much blood is ejected with every beat (stroke volume) by how many beats occur each minute (heart rate). This gives CO in milliliters per minute. So, if a person ejects about 70 mL per beat at 70 beats per minute, the cardiac output is roughly 4,900 mL per minute (about 5 L/min). The idea that CO is simply the total volume the left ventricle pumps per minute is a true and descriptive way to think about it, and in healthy individuals the left and right ventricles deliver the same amount per minute, but the fundamental definition used in physiology and clinical practice is the product of stroke volume and heart rate. The other choices don’t define how much blood is moved per minute: one describes blood volume in the circulation, and the other mixes a pressure term with heart rate, which does not determine flow.

Cardiac output is the amount of blood the heart pumps each minute, and the way it’s calculated is by multiplying how much blood is ejected with every beat (stroke volume) by how many beats occur each minute (heart rate). This gives CO in milliliters per minute. So, if a person ejects about 70 mL per beat at 70 beats per minute, the cardiac output is roughly 4,900 mL per minute (about 5 L/min). The idea that CO is simply the total volume the left ventricle pumps per minute is a true and descriptive way to think about it, and in healthy individuals the left and right ventricles deliver the same amount per minute, but the fundamental definition used in physiology and clinical practice is the product of stroke volume and heart rate. The other choices don’t define how much blood is moved per minute: one describes blood volume in the circulation, and the other mixes a pressure term with heart rate, which does not determine flow.