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What Prevents Blood from Flowing Ba...

In the veins are valves that prevent the blood from flowing backwards. You can sometimes see them in action if you or an older person has veins close to the surface on their hands....
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Arteries take the blood away from the heart so valves r not needed in them but veins take the blood towards the heart so valves r needed
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Valves
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valves in the veins.
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It is under direct pressure from the heart, so arterial blood can only go one way. Veins contain tiny one way valves to keep the blood going in the correct direction.
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What Prevents Blood from Flowing Ba...

Answers.com > Wiki Answers > Categories > Science > Biology > Human Physiology > Circulatory System > Heart > What prevents blood from flowing back into ...
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supercool73, There is no valve, as such, but backflow is prevented by the opening of the tricuspid valve, thereby lowering the pressure in the right ...
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Like everything else, blood is subject to the forces of gravity. Yet blood sometimes must circulate against gravity -- moving "uphill" from your legs to your heart, ...
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