Medical Definition of depolarization
: loss of polarization; especially : loss of the difference in charge between the inside and outside of the plasma membrane of a muscle or nerve cell due to a change in permeability and migration of sodium ions to the interior … partial depolarization of the ventricular tissue resulting from rapid conduction of the electrical impulse from the atrium to the ventricle …—Mark S. Link, The New England Journal of Medicine, 11 Oct. 2012
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