Look up exhalation or expiration in Wiktionary, the free dictionary.

Exhalation (or expiration) is the movement of air out of the bronchial tubes, through the airways, to the external environment during breathing.

Exhaled air is rich in carbon dioxide, a waste product of cellular respiration during the production of energy, which is stored in ATP.

Exhalation has a complementary relationship to inhalation; the cycling between these two efforts define respiration.

[edit] External links

• MeSH Exhalation
• Exhalation at eMedicine Dictionary
• Physiology at MCG 4/4ch2/s4ch2_14

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