MHT CET Medical202622 April 2026Morning ShiftBiologyBreathing and Exchange of GasesActual
In the lungs, the alveolar air is separated from blood by ______.
Options
- Aa layer of squamous epithelium and smooth muscles.
- Ba layer of squamous epithelium and a layer of transitional epithelium
- Ctwo layers of simple squamous epithelium
- Dtwo layers of tunica externa, interna and tunica media
Correct answer
C. two layers of simple squamous epithelium
Step-by-step solution
The diffusion membrane in the lungs is composed of three major layers: the thin squamous epithelium of alveoli, the endothelium of alveolar capillaries, and the basement substance in between them. The endothelium of the alveolar capillaries is also a type of simple squamous epithelium. Therefore, the alveolar air is separated from the blood by two layers of simple squamous epithelium. Answer: two layers of simple squamous epithelium