air sac

air sac
noun
1. a tiny sac for holding air in the lungs; formed by the terminal dilation of tiny air passageways
• Syn: ↑alveolus, ↑air cell
• Derivationally related forms: ↑alveolate (for: ↑alveolus)
• Hypernyms: ↑sac
• Part Holonyms: ↑lung
2. any of the thin-walled extensions of the tracheae of insects
• Hypernyms: ↑sac
• Part Holonyms: ↑insect
3. any of the membranous air-filled extensions of the lungs of birds
• Hypernyms: ↑sac
• Part Holonyms: ↑bird

* * *

noun
1. : a cavity in the pollen grain of pines
2.
a. : one of the spaces in different parts of the bodies of birds that are air-filled and connected with the air passages of the lungs and usually with cavities in the bones and that serve to reduce the specific gravity of the body and assist respiration by the great increase of surface thus exposed to the air as well as by providing a space for the residual air so that the lungs may be completely filled with fresh air at each respiration
b. : paired bladderlike backward extensions of the branchial cavity of certain Indian fishes that are lined with vascular tissue and serve as accessory breathing organs
c. : the internal subumbrellar portion of the specialized inverted pneumatophore in siphonophores that contains air and keeps the colony afloat
3. : a thin-walled dilation of a trachea occurring in many insects
4. : a pulmonary alveolus

* * *

1. a sac containing air.
2. alveolus (def. 2).
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.
[1820-30]

* * *

air sac,
1. an alveolus: »

The air from the bronchial tubes flows into millions of air sacs, called alveoli, which make up the spongelike mass of each lung (Arthur C. Guyton).

2. an air-filled space in different parts of the body of a bird, connected with the lungs. It aids in breathing and in regulating body temperature.
3. a thin-walled enlargement in the trachea of an insect, resembling a sac.

* * *

n. a lung compartment containing air; an alveolus
■ an extension of a bird's lung cavity into a bone or other part of the body

Useful english dictionary. 2012.

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Look at other dictionaries:

  • Air sac — 1. (Anat.) 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. [1913 Webster] 2. An {alveolus}. [PJC] …   The Collaborative International Dictionary of English

  • 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 secondary sites of gas exchange with the blood… …   Wikipedia

  • air sac — n ALVEOLUS (b) * * * 1. in birds, one of the air filled cavities connected with the air passages of the lungs and usually with cavities in the bones; they assist in respiration and lower the body s specific gravity. Domestic fowl have one or two… …   Medical dictionary

  • air sac — n. any of the air filled cavities in a bird s body, having connections to the lungs …   English World dictionary

  • air-sac — airˈ sac noun 1. An alveolus, or the cluster of alveoli, at the termination of a bronchiole in the lungs 2. An outgrowth of the lung in birds, helping respiration or lightening the body 3. In insects, a dilatation of the trachea • • • Main Entry …   Useful english dictionary

  • air sac — air′ sac n. 1) anat. alveolus 2) 2) orn any of certain cavities in a bird s body connected with the lungs • Etymology: 1820–30 …   From formal English to slang

  • air-sac disease — noun : a serious inflammatory condition of the air sacs of poultry * * * air sac disease «AIR SAK», chronic respiratory disease in domestic fowl …   Useful english dictionary

  • air sac — 1. a sac containing air. 2. alveolus (def. 2). 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. [1820 30] * * * ▪ anatomy       any of the air filled extensions… …   Universalium

  • air sac — gas bladder, a thin membranous, sometimes alveolated sac in the dorsal portion of the abdominal cavity. Contains a varying mixture of gases, not identical to the composition of air. May be one, two or three chambered. May be connected to the gut… …   Dictionary of ichthyology

  • air sac — /ˈɛə sæk/ (say air sak) noun 1. a sac containing air. 2. any of certain cavities in a bird s body connected with the lungs. 3. a saclike dilatation of an insect trachea …  

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