Why is surface tension significant in the alveoli?

• A. It helps in filtration of air
• B. It affects lung compliance
• C. It stores oxygen
• D. It prevents infections

Answer: (B)

Surface tension in the alveoli is significant primarily because it affects lung compliance, which is the ability of the lungs to stretch and expand during inhalation. The alveoli, which are tiny air sacs in the lungs, are lined with a thin layer of fluid that creates surface tension. This surface tension acts to resist the expansion of the alveoli.

When the surface tension is too high, it can make it more difficult for the lungs to inflate, reducing compliance. This is particularly important in conditions like respiratory distress syndrome, where reduced compliance can severely impair gas exchange. Surfactant, a substance produced by type II alveolar cells, plays a crucial role in reducing surface tension, thus enhancing lung compliance and facilitating easier breathing.

The other options are not accurate regarding the role of surface tension in the alveoli. Surface tension does not play a direct role in the filtration of air, nor does it store oxygen or prevent infections. Instead, its primary influence is on the mechanical properties of the lungs, particularly compliance, which is vital for effective ventilation and gas exchange.