Answers

2015-09-01T14:47:58+05:30
atrium are upper chamber of heart.
send blood to ventricle.
walls are thinner .
blood pressure is low
does not have valves.

ventricles are lower chamber of heart.
receives blood from atrium.
walls are thicker.
blood pressure is high.
have valves.
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2015-09-01T18:47:50+05:30
Atrium are on top, send blood to ventricle.walls are thinner 
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