Avian Respiratory System

Birds do not have a diaphragm and bird lungs do not expand or contract like the lungs of mammals. Avian lungs are unique in that the air flows in only one direction, rather than in and out as in other vertebrates.

Bird anatomy has been Prepared to allow for their flying. The skeletal system of birds is light and their breathing systems have been Built to provide the bird its high oxygen needs. Birds have air sacs distributed throughout much of their bodies through which air moves in and out. Air sacs are thin-walled (only one or two cell layers thick) structures that are built into the body cavity, wings and leg bones. The air sacs are the Ingenious structures through which the continuous, unidirectional, efficient flow of air passes as part of the unique aviary respiratory system.