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Stories about: respiration

Top 8 Respiratory Diseases Oxygen enters into our bloodstream through the lungs, while the toxic carbon dioxide is also expelled through them. We call this process breathing. The lungs have a system of tubes called bronchia. Bronchia ramify into gradually smaller tubes that can be as thin as a human hair. At the end of the thinnest tubes, call... 14 January 2008 14:06 GMT