Explain how the structure of an artery is adapted to withstand and regulate the high-pressure blood flow it receives from the heart.

Arteries have a thick tunica media composed mainly of smooth muscle and elastic fibres, which gives the wall strength to resist the high pressure from the heart and prevents rupture. The abundant elastic fibres allow the artery to stretch when a pulse wave passes and then recoil, dampening the pulse and maintaining a more continuous flow. The smooth muscle can contract (vasoconstriction) or relax (vasodilation), thereby regulating the diameter of the lumen and the blood flow to different tissues. The lumen is relatively narrow compared to the wall thickness, and the inner surface is lined with a smooth endothelium that reduces friction and promotes efficient flow.