air sac

American  

noun

1. a sac containing air.

2. alveolus.

3. any of certain cavities in a bird's body connected with the lungs.

4. a saclike dilation of the wall of a trachea in many insects.

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air sac British  

noun

1. any of the membranous air-filled extensions of the lungs of birds, which increase the efficiency of gaseous exchange in the lungs

2. any of the thin-walled extensions of the tracheae of insects having a similar function

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air sac Scientific  

1. 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.

2. See alveolus

3. A saclike enlargement in the trachea of an insect.

4. A baglike piece of skin or tissue below the jaw of certain animals, such as the bullfrog and orangutan, that can be inflated to increase sound production.

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Etymology

Origin of air sac

First recorded in 1820–30

Example Sentences

A micro CT scan - that produces 3D images - revealed the contents of the egg, complete with the air sac.

From BBC • Feb. 11, 2024

This work confirms that the early dinosaurs did not have these extensive air sac systems, says Ohio University paleontologist Patrick O'Connor, who was not involved in the new study.

From Scientific American • Mar. 31, 2023

“Every breath we take has to be expertly conveyed from the tip of the nose to the last air sac in the lungs,” Merati said.

From Seattle Times • Apr. 6, 2021

From the posterior air sac, air enters the lungs, and the anterior air sac in front of the lungs.

From Textbooks • Jan. 1, 2015

Physalia; a b air sac with crest c, m bunches of individuals, n central tentacles, t t expanded tentacles.

From Seaside Studies in Natural History Marine Animals of Massachusetts Bay. Radiates. by Agassiz, Alexander