Question

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

Hint:

Remember: \textbf{Inspiration} is for \textbf{In}creasing volume. When the chest cavity gets bigger, the pressure inside drops, and air is sucked \textbf{in}. Expiration is the opposite.

Answer 1

Interpretation of Diagrams

Diagram A – Inspiration (Inhalation): Air enters the lungs as shown by arrows pointing inward. The diaphragm contracts and flattens downward, while the rib cage moves upward and outward. This increases the volume of the thoracic cavity.

Diagram B – Expiration (Exhalation): Air leaves the lungs as shown by arrows pointing outward. The diaphragm relaxes and arches upward, while the rib cage moves downward and inward. This decreases the volume of the thoracic cavity.

Changes during Inspiration and Expiration

Feature	Inspiration (Active Process)	Expiration (Passive Process)
Diaphragm	Contracts and flattens	Relaxes and arches upwards
External Intercostal Muscles	Contract	Relax
Ribs and Sternum	Move upwards and outwards	Move downwards and inwards
Volume of Thoracic Cavity	Increases	Decreases
Pressure in Lungs	Decreases (becomes negative compared to atmosphere)	Increases (becomes positive compared to atmosphere)
Movement of Air	Air rushes into the lungs	Air is forced out of the lungs