The Respiratory System and Gas Exchange | Back to Top

When the rib muscles relax, the rib cages moves in and down. The combined effect of these actions is to put pressure on the expanded thoracic cavity. ... When this material is detected at the back of the mouth, it is swallowed or coughed up and expectorated (spit out). ... Asthma narrows the airways by causing allergy-induced spasms of ... ................
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