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Why valves are present only in veins and not in arteries?
Good Question!

 Arteries and arterioles have thicker walls than veins and venules, respectively.  The increased amount of smooth muscle that is found in arteries gives them extra strength and elasticity to deal with the surges of blood from the heart.

    The smallest arterioles cannot have thick walls.  But they must also be able to deal with this pressure.  So, even the smallest arterioles do have some supportive smooth muscle.   Veins have valves within them to prevent backflow of blood.  Blood is allowed to go toward the heart, but it cannot fall back the other way.   These types of valves are especially important in getting blood back from places like your legs, all the way back to the heart.


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