Question

Interpret the given diagrams A and B. Enlist the changes occurring during inspiration and expiration. 

Hint:

Inspiration is an active process requiring muscle contraction, whereas expiration is a passive process due to muscle relaxation.

Answer 1

The given diagrams represent pulmonary ventilation, specifically inspiration (A) and expiration (B). 

Diagram A - Inspiration (Inhalation): 
- The diaphragm contracts and moves downward. 
- The rib cage expands as the intercostal muscles contract. 
- The volume of the thoracic cavity increases, reducing pressure inside the lungs. 
- Air rushes into the lungs due to the pressure difference. 
Diagram B - Expiration (Exhalation): 
- The diaphragm relaxes and moves upward. 
- The rib cage moves downward and inward as intercostal muscles relax. 
- The volume of the thoracic cavity decreases, increasing pressure inside the lungs. 
- Air is pushed out of the lungs.