Question

You have learnt in Physics that when volume increases, pressure decreases. How does this principle find a place in the process of breathing?

Answer 1

When we breathe in, the thoracic cavity expands increasing the volume of the air that fills it. This filling of air in the thoracic cavity decreases the pressure in the lungs. When we exhale out, thoracic cavity contracts, coming back to its normal shape and thus increasing the pressure in the lungs.

When the pressure in lungs is higher than the pressure around us, we are able to breathe in and if the pressure around us exceeds the pressure inside our lungs, it becomes difficult for us to breathe.

This is how Boyle's principle of pressure and volume works in the breathing process.