Air sac

Air sac is an anatomical term with several meanings:Pulmonary alveolus, informally known as an air sac, one of innumerable spherical outcroppings of the respiratory bronchioles in the mammalian lung, the primary sites of gas exchange with the bloodan anatomical structure continuous with the trachea found in some insects which can be used to actively pump air throughout the bodyan anatomical structure unique to the dinosaur and bird respiratory systems that allows unidirectional flow of air into the lungs and through the body
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An alveolus (plural: alveoli, from Latin alveus, "little cavity"), is an anatomical structure that has the form of a hollow cavity. Mainly found in the lung, the pulmonary alveoli are spherical outcroppings of the respiratory bronchioles and are the primary sites of gas exchange with the blood. Alveoli are particular to mammalian lungs; different structures are involved in gas exchange in other vertebrates.
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Air sac n. A tiny, thin-walled, capillary-rich sac in the lungs where the exchange of oxygen and carbon dioxide takes place. [more]Air sac - Community and Resources

Noun
1. a tiny sac for holding air in the lungs; formed by the terminal dilation of tiny air passageways
(synonym) alveolus, air cell
(hypernym) sac
(part-holonym) lung
2. any of the thin-walled extensions of the tracheae of insects
(hypernym) sac
(part-holonym) insect
3. any of the membranous air-filled extensions of the lungs of birds
(hypernym) sac
(part-holonym) bird

One of the spaces in different parts of the bodies of birds, which are filled with air and connected with the air passages of the lungs; an air cell.

  

ALVEOLO. SACCO AEREO