The diagram shows how air pressure inside the lungs changes during one full breathing cycle. Atmospheric pressure is $101\,\text{kPa}$. At which point on the diagram do the ribs start to move downwards?
- AA
- BB
- CC
- DD
Biology 0610 · IGCSE · Gas exchange in humans
The diagram shows how air pressure inside the lungs changes during one full breathing cycle. Atmospheric pressure is $101\,\text{kPa}$. At which point on the diagram do the ribs start to move downwards?