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How do the walls of veins differ from the walls of arteries?

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Illustration of a human heart cross-section showing four chambers-left and right atria and ventricles-with labeled major blood vessels. An inset highlights cardiac muscle tissue, showing myocytes and intercalated disks. — human cardiovascular system The human heart is both a pump and a muscle. Its four chambers move blood efficiently, while cardiac muscle cells joined by intercalated disks synchronize each contraction.

In the human cardiovascular system, the walls of veins and arteries both consist of three layers—the tunica intima, tunica media, and tunica adventitia—but they differ significantly in structure to accommodate different physiological demands.123

Key differences include:

Wall Thickness and Composition: Arteries have thicker, more muscular, and more elastic walls to withstand the high pressure generated by the heart. In contrast, veins have thinner, more compliant walls because they transport blood under substantially lower pressure.132
Tunica Media: The middle layer of an artery is rich in muscle and elastic fibers, which allow the vessel to expand and recoil with each heartbeat. In veins, this layer is thinner and contains less muscle and elastic tissue, with a higher proportion of collagen fibers.132
Valves: Many veins, particularly those in the limbs, contain valves formed by folds in the tunica intima to prevent the backflow of blood. These valves are absent in arteries.23
Elastic Membrane: The elastic membrane lining found in the tunica intima of arteries is absent in veins.2
Lumen Size: Veins generally have larger internal diameters (lumens) than arteries.23