How does the tunica media differ in veins compared with arteries?

How does the tunica media differ in veins compared with arteries?

• A. The tunica media is thicker in veins
• B. The tunica media is the same thickness in veins and arteries
• C. The tunica media is thinner in veins
• D. Veins lack tunica media

Answer: (C)

The main idea is how vessel walls adapt to pressure and flow control. The tunica media, the muscular middle layer, is thick in arteries because they experience high, pulsatile pressure from the heart. That thickness, rich in smooth muscle and elastic fibers, lets arteries constrict or dilate to regulate blood flow and maintain blood pressure between beats. In veins, pressures are much lower, so the middle layer is much thinner and contains less smooth muscle and elastic tissue. This makes veins more compliant and capable of storing a large volume of blood, with their walls relying more on the outer layer for structure and on surrounding muscles and valves to help move blood back to the heart. So the tunica media is thinner in veins than in arteries.

The main idea is how vessel walls adapt to pressure and flow control. The tunica media, the muscular middle layer, is thick in arteries because they experience high, pulsatile pressure from the heart. That thickness, rich in smooth muscle and elastic fibers, lets arteries constrict or dilate to regulate blood flow and maintain blood pressure between beats. In veins, pressures are much lower, so the middle layer is much thinner and contains less smooth muscle and elastic tissue. This makes veins more compliant and capable of storing a large volume of blood, with their walls relying more on the outer layer for structure and on surrounding muscles and valves to help move blood back to the heart. So the tunica media is thinner in veins than in arteries.