3.2 MECHANISM OF BREATHING

Breathing is a mechanical process. It is the movement of air into and out of the lungs. The force that drives air into the lungs comes from ordinary air pressure.

The lungs themselves neither draw in air nor push it out. The expansion and contraction of the lungs is accomplished by the diaphragm, and by intercostal muscles. The mechanism of breathing consists of two phases: 1. Inspiration or inhalation 2. Expiration or exhalation.