2.45a Ventillation

1. Ventillation is the biological term for breathing
2. It is associated with gas exchange in the lungs
3. This process is largely under the conrtol of the diaphragm.
4. Alveoli is the site of gas exchange.
5. In the walls of the alveoli there would be protein molecules which are called elastin. They stretch. When we stretch the elastic and release them, they would go back to their original shape and size.
6. The diaphragm forms a dome shape pointing up to the thorax when it is relaxed.
7. When we inhale we have a contraction of the diaphragm, which causes it to shorten and flatten and move down.
8. The diaphragm is a sheet of muscle extending from the front edge of the ribcage to the back edge of the ribcage.
9. This increases the volume of the thorac which increases the volume of the lung. This increases the pressure falling in the alveoli and the space increases. Soon, the pressure decreases and air moves into the thorax.
10. When we exhale, the diaphragm has to be relaxed.
11. The diaphragm will go back to the dome shape if it is relaxed. It moves up because of the elastin.
12. When the diaphragm relaxes the elastin is recoiled.
13. This reduces the volume of the alveoli which increases pressure in the alveoli.
14. This forces the alveoli gas out of the lung.