Medical Definition of antioxidant. : any of various substances (as beta-carotene, vitamin C, and alpha-tocopherol) that inhibit oxidation or reactions promoted by oxygen and peroxides and that include many held to protect the living body from the deleterious effects of free radicals.
An action potential is a very rapid change in membrane potential that occurs when a nerve cell membrane is stimulated. Specifically, the membrane potential goes from the resting potential (typically -70 mV) to some positive value (typically about +30 mV) in a very short period of time (just a few milliseconds).
: Level I: Reviewing Facts and Terms (Bloom's Taxonomy: Comprehension) 42) All of the following must occur before a second action potential can begin, EXCEPT. A) the Na+ and K+ ions that moved in/out of the cell must move back to their original compartments.