Explain the process of inspiration under normal conditions.

Explanation

Inspiration involves intaking of fresh air in the ling alveoli. In man, inspiration is an active process and involves contraction of two types of inspiratory muscles.
Phrenic muscles contract and flatten the diaphragm which increases the thoraciccavity anteroposteriorly.
External intercostal muscles, present between the ribs, contract and move the ribs outward, forward and upward due to which thoracic cavity increases dorsoventrally as well as laterally. increase in thoracic cavity decreases the interapulmonary pressure than the atmospheric pressure and the fresh air rushes into the lungs through the respiratory tract on the principle of diffusion.