air sac(redirected from Air sacs)
Also found in: Dictionary, Thesaurus, Encyclopedia.
1. terminal dilation of the alveolar ducts, which give rise to alveoli in the lung; a small air chamber in the pulmonary tissue from which the pulmonary alveoli project like bays and into which an alveolar duct opens; Synonym(s): sacculus alveolaris [TA]
2. in birds, air-containing extensions of bronchi that connect with bone cavities.
Synonym(s): air sac
Farlex Partner Medical Dictionary © Farlex 2012
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, thin-walled enlargement in the trachea of an insect.
4. An inflatable pouch attached to the larynx in certain mammals, including the nonhuman great apes.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
air saca thin-walled extension to the lungs, present in the thorax, abdomen and bones of birds. Air sacs also occur as diverticula (outgrowths) of the TRACHEA in insects, where, as in birds, they are important in respiration.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005