Human Anatomy and Physiology

Difference between inspiration and expiration?

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Answer

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Wiki User
05/08/2009

This occurs within the respiratory system. During inpiration, the intercostal muscles contract, the diaphragm descends, and the rib cage rises. The thoracic cavity volume increases, stretching the lungs, and the intrapulmonary volume increases. This causes the intrapulmonary pressure to drop. Air flows into the lungs until the intrapulmonary pressure equals the atmospheric pressure. During expiration the intercostal muscles relax, the diaphragm rises, and the rib cage descends. The thoracic cavity volume decreases, causing the the lungs to recoil, and the intrapulmonary volume decreases. This causes the intrapulmonary pressure to rise, and the air flows out of the lungs until the intrapulmonary pressure equals the atmospheric pressure.