How does the elasticity of vessel walls affect blood pressure?

• A. Elastic walls lower the pressure
• B. Stiff and rigid vessel walls increase the pressure needed to push blood through
• C. Increased elasticity increases pressure
• D. Vessel wall elasticity has no effect on pressure

Answer: (B)

Elasticity, or compliance, of the vessel walls determines how much they can stretch when blood is pumped out of the heart. In elastic arteries, the walls expand during systole to store some of the stroke volume’s energy, then recoil to help keep blood flowing during diastole. This damping of pressure fluctuations keeps peak pressures in check and smooths flow. When the walls are stiff and less compliant, they don’t expand as much for the same amount of blood, so the pressure must rise more to push the blood through. That means higher systolic pressure and a larger pulse pressure. Over time, stiffer arteries raise the pressure the heart must generate to maintain flow.

So the idea is that reduced elasticity increases the pressure needed to move blood, which is why stiffer vessels raise blood pressure. Elastic walls don’t inherently lower pressure, nor does greater elasticity raise pressure, and there is a real effect of elasticity on pressure.