Question

 Diffusion of gases occurs in the alveolar region only and not in the other parts of respiratory system. Why?

Answer 1

because there are 300 million alveoli in our lungs. Only diffusion can meet the requirements of it.

Answer 2

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$\red\longmapsto\:$ Alveoli are made up of single cell layered epithelium which is provided with blood capillaries.so it is the respiratory area part where diffusion takes place.

$\red\longmapsto\:$ where as the trachea, bronchi and broncioles have multilayered walls without capillary network.So these tubes are only air conducting parts where diffusion does not occur.

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