The endocochlear potential (ECP) in the scala media is approximately +80 mV and is generated by which structure?
- A Stria vascularis via an active ion transport mechanism (Na+/K+-ATPase in marginal cells) ✓
- B Spiral ganglion neurons via electrochemical coupling
- C Outer hair cells via prestin-driven electromotility
- D Reissner's membrane via passive diffusion of potassium
Correct answer: A. Stria vascularis via an active ion transport mechanism (Na+/K+-ATPase in marginal cells)
Explanation
The endocochlear potential of approximately +80 mV (the highest transepithelial potential in the body) is generated by the stria vascularis through active ion transport. The marginal cells of the stria vascularis use Na+/K+-ATPase and KCNQ1/KCNE1 potassium channels to secrete K+ into the endolymph and maintain its high K+ concentration and positive potential. This ECP, combined with the negative hair cell resting potential (~−70 mV), creates a driving force of ~150 mV for mechanoelectrical transduction. Prestin enables OHC electromotility but does not generate ECP.
Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.