​Air sacs in the lungs provide continual one-way flow of fresh, oxygen-rich air.

A) ​fish respiration
B) ​amphibian respiration
C) ​mammalian respiration
D) ​bird respiration
E) ​insect respiration

Air Sacs

Specialized structures in birds that extend from the lungs, facilitating efficient gas exchange and buoyancy.

Bird Respiration

The process by which birds exchange gases, notably featuring a unique system of air sacs that provides them with a continuous flow of air through their lungs for high efficiency.