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Question
Explain the mechanism of breathing.
Solution
- The process of taking air into the lungs is called inspiration or inhalation.
- During inspiration, the sternum is pushed up and outward and the diaphragm is pulled down.
- This increases the volume of the thoracic cavity and the pressure decreases.
- The air outside the body flows into the lungs. Here exchange of gases takes place between the air and the blood.
- The process of expelling air from the lungs is called expiration or exhalation. Upon exhalation, the lungs recoil to force the air out of the lungs.
- The intercostal muscles relax, returning the chest wall to its original position. During exhalation, the diaphragm also relaxes, moving higher into the thoracic cavity.
- This increases the pressure within the thoracic cavity relative to the environment.
- Air rushes out of the lungs due to the pressure gradient. This movement of air out of the lungs is a passive event.
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