The Human Respiratory System · NCERT Biology

Which of the following is NOT part of the 'respiratory membrane' through which diffusion of gases occurs?

  1. Thin squamous epithelium of alveoli
  2. Endothelium of alveolar capillaries
  3. Basement substance between epithelium and endothelium
  4. Ciliated columnar epithelium of bronchioles
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Correct answer: Ciliated columnar epithelium of bronchioles

The diffusion membrane is made up of three layers: the thin squamous epithelium of alveoli, the endothelium of alveolar capillaries, and the basement substance in between. Ciliated columnar epithelium is part of the conducting zone, not the diffusion membrane.

Difficulty: Medium Question 13 of 20

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