Question

The figure given below shows the mechanism of breathing. Identify the stage (X) of breathing explained & A, B and C marked in the figure.

• A. X – Expiration, A– raised, B – decreased, C – relaxed
• B. X – Expiration, A – raised, B – increased, C – contracted
• C. X – Inspiration, A – raised, B – decreased, C – relaxed
• D. X - Inspiration, A– raised, B – increased, C – contracted

Answer 1

The correct option is D X - Inspiration, A– raised, B – increased, C – contracted

X – Inspiration, A – raised, B – increased, C – contracted.

The given figure shows the inspiration stage of breathing. Breathing is the process that moves air in and out of the lungs. Inspiration is an active process which is due to muscle contraction. During inspiration, the external intercostal muscles contract. This pulls the ribcage upwards. At the same time the diaphragm muscle contracts and flattens. This brings about the decrease in the pleural pressure and intrapulmonary pressure, which is less than the atmospheric pressure (negative pressure).There is an increase in the volume of the thoracic cavity, and it allows air to flow into the lungs.