Which two factors together determine the pressure gradient in the cardiovascular system?

Which two factors together determine the pressure gradient in the cardiovascular system?

• A. Force of ventricular contraction and peripheral resistance
• B. Blood viscosity and heart rate
• C. Cardiac output and venous return
• D. Aortic diameter and blood velocity

Answer: (A)

The pressure gradient in the circulation is set by two opposing forces: how hard the heart pushes and how much resistance the vessels offer. When the ventricles contract forcefully, they generate higher pressure in the aorta, increasing the gradient to push blood through the systemic circulation. At the same time, the peripheral vessels provide resistance; the greater this resistance, the higher the pressure the heart must generate to maintain flow. This relationship is often summarized as mean pressure difference roughly equal to cardiac output times total peripheral resistance. So the two factors that determine the gradient together are the force of ventricular contraction (driving the pump) and peripheral resistance (the opposition to flow).

The pressure gradient in the circulation is set by two opposing forces: how hard the heart pushes and how much resistance the vessels offer. When the ventricles contract forcefully, they generate higher pressure in the aorta, increasing the gradient to push blood through the systemic circulation. At the same time, the peripheral vessels provide resistance; the greater this resistance, the higher the pressure the heart must generate to maintain flow. This relationship is often summarized as mean pressure difference roughly equal to cardiac output times total peripheral resistance. So the two factors that determine the gradient together are the force of ventricular contraction (driving the pump) and peripheral resistance (the opposition to flow).