15. Describe how the structure of the bird respiratory system provides the energy the bird needs for flight.

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.

Birds do not have a diaphragm; instead, air is moved in and out of the respiratory system through pressure changes in the air sacs. ... Bird lungs do not expand or contract like the lungs of mammals. In mammalian lungs, the exchange of oxygen and carbon dioxide occurs in microscopic sacs in the lungs, called 'alveoli.'

Air sacs are found as tiny sacs off the larger breathing tubes (tracheae) of insects, as extensions of the lungs in birds, and as end organs in the lungs of certain other vertebrates. They serve to increase respiratory efficiency by providing a large surface area for gas exchange.

How do birds respire?

Some birds can sing while they fly! ... When the bird takes a second breath, the air in the lungs is sucked into the cranial air sacs -caudal thoracic, cervical, and clavicular. The cranial air sacs act as a holding chamber which provides a small back flow of air into the lungs during expirations.

Explanation:

your answer should be c) enjoy!

it is either c or d and i know for sure it is not a or b