The most important factor in the return of blood flow back to the heart is __________.

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    skeletal muscle contraction
    the pumping of the heart
    high pressure
    valves in the veins

asked May 30, 2013 in Biology by anonymous
    

1 Answer

0 votes
skeletal muscle contraction
answered May 31, 2013 by Bioshare ~Top Expert~ (34,070 points)



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