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Old 28 September 2007, 04:39 PM
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Eddylizard Eddylizard is offline
Join Date: 15 June 2006
Location: Tonbridge, Kent, UK
Posts: 17,857

Originally Posted by Spamamander View Post
My completely uneducated guess would have to do with the thickness of the vessel walls. Arteries do not need to have thick walls, as blood is forced through them by the heart, so you can see the color of the blood within. Veins have thick walls to force the blood back to the heart, so they are not transparent and you instead see the color of the venous walls.
Actually arteries have thicker walls than veins, to cope with the greater pressure of arterial blood. Just as a fire hose is made of thicker material than a garden hose. Veins play no part in pumping the blood back to the heart, that's achieved by the residual pressure from blood following behind and a series of one-way valves inside the veins preventing it flowing back

ETA A better written explanation.

Last edited by Eddylizard; 28 September 2007 at 04:47 PM.
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