2.45b Ventillation

1. Ventillation is the biological term for breathing.
2. Intercostal muscles are the muscles between the ribs.
3. The sternum has the ribs extended to the back bone.
4. There are internal intercoastal muscles which slope forward and the external intercoastal muscles run in the opposite direction.
5. When we inhale, there is a contraction of the external intercostal muscles.
6. This causes the thorax to rise and move outward, which increases the volume of the thorax.
7. This results in, a stretching of lung tissue with volume increase. The pressure decreases and air moves in.
8. When this occurs during exercise.
9. When we exhale the inyerbal intercostal muscles contract. the extrenal intercostal muscles relax.
10. The ribcage moves downward and in.
11. Volume reduces in the thorax.
12. this squeezes the alveoli tissue. This results in a pressure increases, forcing the air to move out.