Zoology - Breathing and Exchange of Gases Question with Solution | TestHub

Mechanism of Normal inspiration:

A. Contraction of diaphragm$\to$Volume of the thoracic chamber in the anteroposterior axis increases.

B. The contraction of external intercostal muscles$\to$Ribs and the sternum are lifted up$\to$An increase in the volume of the thoracic chamber in the dorso-ventral axis.

C. Increase in the thoracic volume$\to$Increase in pulmonary volume$\to$Decrease in the intra-pulmonary pressure.

D. Intra-pulmonary pressure becomes less than the atmospheric pressure. This forces the air from outside to move into the lungs (inspiration).