In alveoli of the lungs, the air at the site of gas exchange, is separated from the blood by

(a) alveolar epithelium only

(b) alveolar epithelium and capillary endothelium

(c) alveolar epithelium, capillary endothelium and tunica adventitia

(d) alveolar epithelium, capillary endothelium, a thin layer of tunica media and tunica adventitia

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1 Answers

Correct Option (b) alveolar epithelium and capillary endothelium

Explanation:

The wall of the capillaries consists of only tunica internae which is made up of simple squamous endothelium. The wall of alveoli is also very thin, consisting of squamous epithelium.

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