Question

Co-relate this setup with the working of the human respiratory system. Here rubber sheath represents the diaphragm. Select the events that occur when diaphragm contracts or rubber sheath is pulled.

• A. Pressure inside the lungs is reduced.
• B. Pressure inside the lungs is increased.
• C. Size of lungs increases.
• D. Size of lungs decreases.

Answer 1

Answer: (A), (C)

Size of lungs increases.

When the diaphragm contracts (rubber sheath is pulled) the volume of lungs increases since the pressure decreases. Air rushes into the lungs and lungs expand. When the diaphragm relaxes (rubber sheath is pushed upwards), it pushes air out of the lungs.