Answers

2015-10-23T21:19:43+08:00
Gas exchange happens when you inhale and exhale.we take in the oxygen and emit carbon dioxide
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2015-10-23T22:38:25+08:00

when a person inhales, the rib cage expands to allow mixture of gases enter to the lungs, the pressure within increases it will then be followed by exhalation to release gases which are not needed  by the body together with carbon dioxide, the release is with the help of intercostal muscles and diaphraghm 
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