[Campbell Biology P.992] What is the primary function of surfactant in the mammalian respira... | Practice Question

What is the primary function of surfactant in the mammalian respiratory system, and what is a known consequence of its deficiency?

  • A: To trap airborne pathogens and move them towards the pharynx; deficiency leads to increased susceptibility to infections.
  • B: To increase the surface area of the alveoli for gas exchange; deficiency causes reduced lung capacity.
  • C: To reduce the surface tension in the fluid lining the alveoli, preventing their collapse; deficiency causes respiratory distress syndrome (RDS).
  • D: To facilitate the transport of oxygen-poor blood to the alveoli; deficiency results in poor oxygenation of blood.

Explanation

The text explicitly states, “The film of liquid that lines alveoli is subject to surface tension, an attractive force that has the effect of minimizing a liquid's surface area... alveoli would be expected to collapse under high surface tension. It turns out, however, that these air sacs produce a mixture of phospholipids and proteins called surfactant... which coats the alveoli and reduces surface tension.” It also links surfactant deficiency to “respiratory distress syndrome RDS , a life-threatening disease of newborns.”