Question

Why veins are thin walled but arteries are thick walled

Answer 1

To withstand the pressure of the blood coming out from the heart, arteries need thick walls. The returning blood in the veins is under low(er) pressure. Because of the lower pressure, vein walls are thinner. However, veins also have one-way stop valves to keep blood from flowing backwards.

Answer 2

Arteries are thick walled because the pressure of blood under arteries are very high compared to that of veins . Therefore arteries are thick walled and veins are thin walled .