Which statement best defines blood pressure?

• A. The heart rate multiplied by stroke volume
• B. The pressure of the blood in the circulatory system
• C. The amount of blood pumped per minute
• D. The oxygen content of arterial blood

Answer: (B)

Blood pressure is the pressure of the blood in the circulatory system—the force that blood exerts on the walls of the arteries as the heart pumps. This definition captures what is being measured when we say someone has high or low blood pressure. It is not the product of heart rate and stroke volume (that combination yields cardiac output, the amount of blood moving per minute), nor the total amount of blood pumped per minute by itself, nor the oxygen content of arterial blood (which reflects oxygenation, not pressure). Blood pressure results from how much blood the heart ejects with each beat and how much resistance the arteries provide, and it’s influenced by factors like blood volume and arterial elasticity. In practice we express it as systolic over diastolic pressure (measured in mmHg), reflecting the peak pressure during heartbeats and the pressure between beats.