FreeRadicals_and_ReactiveOxygenSpecies

FreeRadicals_and_ReactiveOxygenSpecies - The Physiology of...

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1 The Physiology of Hyperbaric Oxygen Therapy Free Radicals and Reactive Oxygen Species I. Introduction – Definition, Source, function and Purpose A. Definition of free radicals and r eactive o xygen s pecies (ROS). 1. Reactive oxygen species (ROS) are highly reactive ions and “free radicals” (chemicals containing atoms with an unpaired electron in its outer orbit) involving oxygen molecules. 2. “Free radicals” are present that do not contain oxygen, but ROS refers to free radicals containing oxygen molecules. 3. Characteristics: a. Short lived b. Unstable c. React with other molecules to achieve stability B. Source of ROS’s 1. Byproduct of cellular respiration (presence of redox cycling compounds). 2. Synthesized by enzyme systems – phagocytic cells, neutrophils and macrophage (NADPH oxidase, myeloperoxidases). 3. Exposure to ionizing radiation 4. Smoking, herbicides, pesticides, fried foods, etc. 5. Production: a. Chain reaction, a free radical steals an electron from a nearby compound forming a new free radical. Free radicals may steal electrons from cellular structures or molecules. b. By normal cellular respiration – electron transport system – often oxygen is the terminal electron acceptor in the cell mitochondria Æ ROS c. Figure on production of common free radical species.
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2 C. Function and purpose 1. Necessary for production of some hormones (thyroxine). 2.
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This note was uploaded on 01/16/2012 for the course BI 200 taught by Professor Potter during the Fall '11 term at Montgomery College.

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FreeRadicals_and_ReactiveOxygenSpecies - The Physiology of...

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