What determines arterial blood pressure?

What determines arterial blood pressure?

• A. Cardiac output multiplied by peripheral resistance
• B. Heart rate only
• C. Stroke volume only
• D. Blood viscosity only

Answer: (A)

Arterial blood pressure reflects how much blood the heart pumps each minute and how much resistance the arterial system offers to that flow. The essential relationship is that mean arterial pressure is roughly the product of cardiac output and systemic vascular resistance. Cardiac output is the amount of blood ejected per minute, which depends on heart rate and stroke volume. Systemic vascular resistance comes mainly from the arteriolar radius: tiny changes in radius, driven by smooth muscle tone, cause large changes in resistance (radius to the fourth power is a key idea). Blood viscosity and vessel length also influence resistance, but they’re not as dynamic as arteriolar tone. So the best description is that arterial blood pressure is determined by cardiac output multiplied by peripheral (systemic vascular) resistance because it captures both how much blood is being moved and how hard it is to move it. Heart rate alone or stroke volume alone miss half of the picture, and viscosity alone doesn’t account for the pump-driven flow and the variable resistance of the arterial tree.

Arterial blood pressure reflects how much blood the heart pumps each minute and how much resistance the arterial system offers to that flow. The essential relationship is that mean arterial pressure is roughly the product of cardiac output and systemic vascular resistance. Cardiac output is the amount of blood ejected per minute, which depends on heart rate and stroke volume. Systemic vascular resistance comes mainly from the arteriolar radius: tiny changes in radius, driven by smooth muscle tone, cause large changes in resistance (radius to the fourth power is a key idea). Blood viscosity and vessel length also influence resistance, but they’re not as dynamic as arteriolar tone.

So the best description is that arterial blood pressure is determined by cardiac output multiplied by peripheral (systemic vascular) resistance because it captures both how much blood is being moved and how hard it is to move it. Heart rate alone or stroke volume alone miss half of the picture, and viscosity alone doesn’t account for the pump-driven flow and the variable resistance of the arterial tree.