Which vessels have a thicker wall, arteries or veins?

• A. Arteries have a thicker wall because they have to pump more blood
• B. Veins have a thicker wall because they return blood to the heart
• C. Both have the same wall thickness
• D. Capillaries have thicker walls

Answer: (A)

Arteries have thicker walls because they must withstand the high pressure generated when the heart pumps blood into the arterial system. Their walls contain a thick muscular layer with elastic fibers (the tunica media) that allows them to stretch as blood pulses through and then rebound, helping to push blood forward and maintain blood pressure between heartbeats. Veins operate at much lower pressure, so their walls are thinner and less muscular, with valves often helping return blood to the heart. Capillaries have the thinnest walls, just a single layer of endothelial cells, to enable efficient exchange of gases, nutrients, and wastes. So the thicker-walled vessels are arteries.