oxygen radical

radical

 [rad´ĭ-kal]

1. thorough or sweeping; directed to the cause or root of a morbid process.

2. a group of atoms that enters into and goes out of chemical combination without change and that forms one of the fundamental constituents of a molecule.

color radical chromophore.

free radical a radical that carries an unpaired electron; such radicals are extremely reactive, with a very short half-life.

oxygen radical a toxic metabolite of oxygen, such as superoxide or singlet oxygen, capable of damaging microorganisms and normal tissues.

Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

oxygen radical

Reactive oxygen metabolite Any molecule with an unpaired electron in its outer orbital which leads to an unstable and/or short half-life, which is capable of reducing or oxidizing other molecules. See Oxygen free radicals.

McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

oxygen radical

Hydrogen peroxide (H₂O₂) or the superoxide radical (O₂⁻) produced by the incomplete reduction of oxygen. Oxygen free radicals are released during the respiratory burst phase of phagocytosis by neutrophils and macrophages during inflammation. They cause direct cell damage, increase vascular permeability through damage to the capillary endothelium, and promote chemotaxis. Oxygen free radicals are normally contained by antioxidant protective measures; however, with severe inflammation they cause significant damage. They are believed to be responsible for much of the cellular damage involved in adult respiratory distress syndrome (ARDS), in which massive neutrophil aggregation and phagocytosis occur.

See also: radical

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