Question

The alveoli contain specialized cells that secrete a phospholipoprotein complex known as pulmonary surfactant. The function of pulmonary surfactant is :

(a) to provide some rigidity to the alveoli to prevent lung collapse

(b) to decrease the surface tension of the alveoli, making it easier to expand them

(c) to facilitate the diffusion of O2 and CO2 by providing protein channels through which these gases flow

(d) to provide a sticky surface upon which dust and microbes are trapped and disposed of

Answer 1

Correct option: (b) to decrease the surface tension of the alveoli, making it easier to expand them

Explanation:

Thin layer of water on the inner surrface of alveoli serves to contract the alveoli and makes them behave like unfilled baloons that resist inflation. This would mean tremendous effort to inhale and expand the alveoli and therefore to overcome this cells of the alveoli secrete pulmonary surfactant to decrease the surface tension of water lining the alveoli.