Mechanism of breathing

 

1 Atmospheric pressure= 760mmHg

Pulmonary ventilation has three phase-

1. Inspiration

2. Expiration

3. Pause

Thoracic cavity expands

Lung volume increases

All pressure inside is decreased

Greater pressure outside cause flow of air into the lung.

When thoracic cavity contract

Lung volume decreases

All pressure inside is increased

Air flow out

Flow chart - pulmonary ventilation