Endo-cochlear potential is:
(A) +45 mV (B) --45mV (C) -60mV (D) +85 mV
(D) Ans: D.+85 mV(Ref Ganong 25/e p204, 24/e p203; Guyton I 3/e p677)Endocochlear potential:Cells in stria vascularis have a high concentration of Na, K ATPase.Exists all time between endolymph & perilymph.Positivity inside scala media & negativity outside.This is called endocochlear potential.Generated by continual secretion of positive potassium ions into scala media by stria vascularis.Normal: +85 mV