Exhalation

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Exhalation (or expiration) is the movement of air out of the bronchial tubes, through the airways, to the external environment during breathing. Exhalation is initiated by a decrease in volume and positive pressure exerted upon the intrapleural space upon relaxation of the diaphragm. The positive pressure generated, relative to atmospheric pressure, allows airflow from the alveoli to the mouth and outside air.

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

Exhalation has a complementary relationship to inhalation (or inspiration), the cycling between these two efforts define respiration.

[edit] During exercise

During exercise, exhalation becomes an active process. Internal intercostals and abdominal muscles contract during forced expiration. This causes rapid exhalation. The contraction of muscles is an active process.

See also: Lung

exhalation is part of the respiratory system... its rather important to breathe!