BIO 12 UNIT 4: Study Notes
INHALATION AND EXHALATION & BREATHING INTERACTIONS
- INHALATION: Entrance of air into the lungs
- Active
- Controlled by medulla oblongata in the brain--> sends nerve impulses to the diaphragm and ribs
- Lungs expand (inflate)
- Pleural membranes stretch (allows lungs to freely expand)
- Intercostal rib muscles contract to move ribs up and out
- Ribs move up and out increasing thoracic cavity size and decreasing pressure (lower than atmospheric [air] pressure: high (in external air) to low (in body lungs))--> air enters body
- Diaphragm contracts to increase thoracic cavity size and decrease pressure
- Thoracic Cavity size INCREASES
- Thoracic Cavity pressure DECREASES
- EXHALATION: Exit of air from the lungs
- Passive
- Lungs compress (deflate)
- Pleural membranes relax (constricts lung expansion)
- Intercostal rib muscles relax to move ribs in and down
- Ribs move down and in decreasing thoracic cavity size, increases thoracic cavity pressure (higher than atmospheric [air] pressure: high (in body lungs) to low (external air))--> air leaves body
- Diaphragm relaxes to decrease thoracic cavity size and increase pressure
- Thoracic Cavity size DECREASES
- Thoracic Cavity pressure INCREASES
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