Mechanism of Breathing
# Inhalation/Inspiration
- Diaphragm contracts and becomes flatter (typically dome-shaped)
- Digestive organs pushed down
- (External) intercostal muscles contract
- Ribcage rises
- Volume of thorax increases
- Pressure inside thorax decreases below atmospheric pressure
- Air is forced into the lungs
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# Exhalation/Expiration
- Diaphragm relaxes
- Diaphragm pushed up by displaced organs underneath
- (External) intercostal muscles relax
- Ribcage falls
- Volume of thorax decreases
- Pressure inside thorax increases above atmospheric pressure
- Air is forced out of the lungs
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| Feature | Inhalation | Exhalation |
|---|---|---|
| Diaphragm | Contracts + flattens | Relaxes, becomes dome shaped |
| Digestive Organs | Pushed Down | Push Diaphragm up |
| Intercostal Muscles | Contract | Relax |
| Ribcage | Rises | Falls |
| Chest Cavity | Volume increases | Volume decreases |
| Thorax | Pressure decreases | Pressure increases |
| Air | Forced IN | Forced OUT |