Mechanism of Breathing · NCERT Biology

Anatomically, the lungs are situated in an air-tight thoracic chamber. This setup is essential because:

  1. Lungs lack a muscular mechanism to change their own volume
  2. It prevents airborne pathogens from entering the bloodstream directly
  3. It maintains constant body temperature around the heart and lungs
  4. It provides rigid structural support so the ribs can grow larger
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Correct answer: Lungs lack a muscular mechanism to change their own volume

Since lung tissue is not muscular, it cannot expand or contract on its own. The air-tight thoracic chamber ensures that any change in the volume of the thoracic cavity is directly reflected in the pulmonary volume.

Difficulty: Medium Question 8 of 20

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