| air vesicles | One of the thin-walled saclike terminal dilations of the respiratory bronchioles, alveolar ducts, and alveolar sacs across which gas exchange occurs between alveolar air and the pulmonary capillaries. Synonym: alveoli pulmonis, alveolus, air cells, air vesicles, bronchic cells. (05 Mar 2000) |
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| air vessel | A vessel, cell, duct, or tube containing or conducting air; as the air vessels of insects, birds, plants, etc.; the air vessel of a pump, engine, etc. For the latter, see Air chamber. The air vessels of insects are called tracheae, of plants spiral vessels. Source: Websters Dictionary (01 Mar 1998) |
| air-bone gap | The difference between the threshold for hearing acuity by bone conduction and by air conduction. (05 Mar 2000) |
| air-conditioner lung | An extrinsic allergic alveolitis caused by forced air contaminated by thermophilic actinomycetes and other organisms. (05 Mar 2000) |
| air-gap radiography | Chest radiography with a space (at least 10 inches) between the subject and film. Instead of using a grid, this method uses the geometry and X-ray absorption by the air to remove scattered radiation. (05 Mar 2000) |
| air-gap technique | Chest radiography performed using a space between the subject and film instead of a grid to absorb scattered radiation; usually requires a target-film distance of 10 feet. (05 Mar 2000) |
| air-lock | <microscopy> An intermediate, enclosed chamber of a vacuum or pressure system through which an object may be passed without effectively changing the vacuum or pressure of the main body of the system. Reference here is to the vacuum of all electron microscopes. (05 Aug 1998) |
| airborne infection | A mechanism of transmission of an infectious agent by particles, dust, or droplet nuclei suspended in the air. (05 Mar 2000) |
| airborne radioactivity | <radiobiology> Radioactivity in any chemical or physical form that is dissolved, mixed, suspended or otherwise entrained in air. (16 Dec 1997) |
| airbrasive technique | A method of grinding, cutting tooth structure, or roughening the natural tooth surface or the surface of a restoration, by means of a device utilizing a gas-impelled jet of fine Al203 particles which, after striking the tooth, are removed by an aspirator. See: microetching technique. (05 Mar 2000) |
| aircraft | A weight-carrying structure for navigation of the air that is supported either by its own buoyancy or by the dynamic action of the air against its surfaces. (12 Dec 1998) |
| Aird, Robert | <person> U.S. Neurologist, *1903. See: Flynn-Aird syndrome. (05 Mar 2000) |
| airless lung | <radiology> Tumour, foreign body, mucous plug (12 Dec 1998) |
| airplane splint | A complicated splint that holds the arm in abduction at about shoulder level with the forearm midway in flexion, generally with an axillary strut for support. (05 Mar 2000) |
| airsacculitis | Inflammation of the mucous membrane of the air sacs of birds. (05 Mar 2000) |