Gas exchange in humans

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  • Created by: Görkem
  • Created on: 31-03-15 12:31

Gas exchange in humans

Gas Exchange in Humans:



How breathing works

Breathing in (inhaling) 1. Intercostal muscles contract, pulling the ribcage up and out 2. Diaphragm contracts moving down 3. The volume of the Thoracic Cavity increases 4. The pressure in the Thoracic Cavity decreases 5. Air is drawn into the lungs to equalize the pressure Inhaling is an active process, i.e. it requires energy for muscle contraction

Breathing out (exhaling)

1. Intercostal muscles relax, the ribcage moves inwards and down
2. Diaphragm relaxes moving up
3. The volume of the Thoracic Cavity decreases
4. The pressure in the Thoracic Cavity increases
5. Air leaves the lungs to equalize the pressure

The entire process is passive, i.e. no energy is required as there is no muscle contraction.

Alveoli and their adaptations for gas exchange:



- Alveolus is one cell thick
- Capillary wall is one cell thick
- Many alveoli produce a huge surface area
- Alveoli wall is moist
- Breathing maintains a high concentration gradient for O2 and

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