Question

In lungs, the air is separated from the venous blood through

• A. squamous epithelium + endothelium of blood vessel
• B. transitional epithelium + tunica externa of blood vessel
• C. squamous epithelium + tunica media of blood vessel
• D. none of the above

Answer 1

The correct option is A

squamous epithelium + endothelium of blood vessel

The correct option is A.

Explanation for the correct option:

1. The diffusion membrane present in the lungs is very thin and has a dense network of blood capillaries which helps in diffusion.
2. The two layers of the diffusion membrane are the squamous epithelium of the alveolar walls of the lungs and the endothelium of the blood vessel.

Explanation for the incorrect options:

Option B:

1. The transitional epithelium is not found in the lungs.
2. It is present in the kidneys.

Option C:

1. The tunica media is the thickest layer of the arterial wall and hence not suitable for diffusion.
2. It is also not present in the lungs.

Option D:

1. The separation of oxygen is done through diffusion membrane made up of endothelium and squamous epithelium, as told in the first option.

Final Answer: The endothelium and squamous epithelium separates the oxygen from the blood in the lungs.