Answer to Question #167597 in Zoology for Silverstone

Question

How is the respiratory system of birds modified to meet their high oxygen 

requirement? How is it different from the respiratory system of mammals?

Answer 1

The respiratory system of birds facilitates efficient exchange of carbon dioxide and oxygen via continuous unidirectional airflow and air sacs.

The avian respiratory system is physically distinct from the mammalian respiratory system, both in structure and in its ability to exchange gas as efficiently as possible.

The bird’s respiratory system consists of paired lungs, which contain static structures with surfaces for gas exchange, and connected air sacs, which expand and contract causing air to move through the static lungs. A breath of oxygen-rich inhaled air remains in the respiratory system for two complete inhalation and exhalation cycles before it is fully spent (used) and exhaled out the body.

The efficiency of the avian respiratory system is owed in part to its unidirectional nature and the structure of its parabronchial system (the smaller passages within the lungs). The air capillaries in the walls of the parabronchial system have a much larger overall surface area than that found in the mammalian respiratory system. The greater the surface area, the more oxygen and carbon dioxide can be passed between blood and tissues, which makes for more efficient breathing.

Reference : https://asknature.org/strategy/respiratory-system-facilitates-efficient-gas-exchange/