Answers

2015-07-07T19:46:25+08:00
It is because the pump of the heart.

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2015-07-07T20:13:45+08:00
Oxygen from the lungs, enters the heart through the left atrium exit through the left ventricle, pass the oxygen to the arteries, and then to the capillaries where the exchange of gases takes place . pass the carbon dioxide to the veins and enters the right atrium exit to the right ventricle and goes back to the lungs. where thelungs is responsible for the exhalation of carbon dioxide
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