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Dr. Andrew Rynne

Family Physician

Exp 50 years

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Blood flow from point a to b

why does blood flow from point a to b ?
Tue, 15 Dec 2009
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Everybody's answer above is correct. They only neglected to mention that the reason the blood does not flow backward is, the veins have one-way valves. When the heart contracts the valves in the veins open and the blood flows forward. When the heart expands to receive more blood, the valves in the veins close so that the blood does not flow back from the way it came.
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