Question

Explain the functional relationship between volume changes, pressure changes, and gas flow into and out of the lung during pulmonary ventilation.

Answer 1

Pulmonary ventilation can be simply called as breathing. It is the movement of the air in and out of the lungs called the inspiration and expiration. There occurs a relationship between the changes in the volume, pressure and airflow during pulmonary ventilation. During inspiration, the diaphragm will gets contracted and the volume inside the lungs will gets increased. According to Boyle's law, the volume and pressure is inversely proportional. That means if the volume of a container increases, the pressure inside the container will gets reduced and vice versa. In the case of lungs the increase in the volume will cause a decrease in the pressure. Inorder to maintain a constant pressure, the air from the atmosphere enters inside the lungs to maintain an equal pressure within the internal and external environment.

And during the process of expiration, the diaphragm will gets expanded. This will cause a decrease in the lung volume. And hence the pressure inside the lungs will gets increased ( because volume and pressure are inversely proportional). In order to maintain an equilibrium of pressure inside the lungs and the outer environment, the air inside the lungs will expel out.

A slight difference in pressure is sufficient enough to produce increased volume of gas flow.