Final answer:
Arteries are thicker than veins due to the presence of a thicker and more elastic muscular layer, which allows them to withstand high pressure and maintain their shape.
Step-by-step explanation:
Arteries are thicker than veins because they have a thicker and more elastic muscular layer. This allows arteries to withstand the high pressure of blood pumped from the heart and maintain their shape. Veins, on the other hand, have thinner walls and less smooth muscle, as their primary function is to transport blood back to the heart at lower pressure. The thicker walls of arteries also help to distribute blood evenly throughout the body, while the thinner walls of veins allow for the expansion and contraction needed to accommodate changes in blood volume and pressure.
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