Answers

2016-07-19T19:15:07+08:00
A hollow muscular organ that pumps the blood through the circulatory system by rhythmic contraction and dilation. In vertebrates there may be up to four chambers (as in humans), with two atria and two ventricles.
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2016-07-19T19:21:33+08:00
The organ inside the chest that sends the blood around the body.
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