- External intercostal muscles contract, whilst the internal intercostal muscles relax
- Ribs are pulled upwards and outwards, increasing the volume of the thorax
- Diaphragm muscles contract, causing it to flatten, further increases volume of the thorax.
- Increased volume of the thorax causes reduction of pressure in lungs
- Atmospheric pressure is now greater than pulmonary pressure and so air rushes into the lungs
THINK OF A DIFFUSION GRADIENT
1 of 2
- Internal intercostal muslces contract, whilst the external intercostal muslces relax
- Ribs move downwards and inwards, decreasing he volume of the thorax
- The diaphragm muscle relax, further decreasing the volume of the thorax
- Decreased volume of the thorax increases the pressure in the lungs
- The pulmonary pressure is now greater than atmospheric pressure and so air is forcced out of the lungs.
THINK OF DIFFUSION GRADIENT
2 of 2