Explain how the heart could compensate for changes in peripheral resistance. Which statement best reflects the described mechanism?

Explain how the heart could compensate for changes in peripheral resistance. Which statement best reflects the described mechanism?

• A. When there is a higher heart rate, peripheral resistance is higher to have the same volume of blood moving through the blood vessels.
• B. Peripheral resistance decreases as heart rate increases.
• C. Heart rate changes do not affect flow.
• D. Preload is the sole determinant of flow.

Answer: (A)

The main idea is that blood flow is determined by the pressure gradient across the systemic circuit and the resistance of the vessels (flow equals the pressure difference divided by resistance). To keep the amount of blood moving steady when peripheral resistance changes, the heart can adjust cardiac output by changing heart rate (and stroke volume). If resistance rises, increasing heart rate raises arterial pressure, boosting the pressure gradient so that flow stays more constant despite the higher resistance. This coordinated change between heart rate and vascular resistance is how the system maintains a steady volume of blood moving through the vessels. The mechanism reflects how autonomic adjustments can raise heart rate and, often, vascular tone to preserve perfusion when resistance changes.

The main idea is that blood flow is determined by the pressure gradient across the systemic circuit and the resistance of the vessels (flow equals the pressure difference divided by resistance). To keep the amount of blood moving steady when peripheral resistance changes, the heart can adjust cardiac output by changing heart rate (and stroke volume). If resistance rises, increasing heart rate raises arterial pressure, boosting the pressure gradient so that flow stays more constant despite the higher resistance. This coordinated change between heart rate and vascular resistance is how the system maintains a steady volume of blood moving through the vessels. The mechanism reflects how autonomic adjustments can raise heart rate and, often, vascular tone to preserve perfusion when resistance changes.