air sacair sac
any of the air-filled cavities in a bird's body, having connections to the lungs
- An air-filled space in the body of a bird that forms a connection between the lungs and bone cavities and aids in breathing and temperature regulation.
- See alveolus.
- A saclike, thin-walled enlargement in the trachea of an insect.
- An inflatable pouch attached to the larynx in certain mammals, including the nonhuman great apes.