Which cell type in the spiral organ of Corti converts mechanical vibrations (shearing of stereocilia) into electrical signals, and what opens the ion channels responsible for depolarization?

• A Outer hair cells; K+ influx from endolymph via mechanically-gated tip link channels
• B Inner hair cells; K+ influx from endolymph via mechanically-gated tip link channels ✓
• C Inner hair cells; Na+ influx from perilymph
• D Supporting (pillar) cells; ATP-gated channels

Explanation

Inner hair cells (IHCs) are the primary sensory transducers of hearing, responsible for converting sound vibrations into neural signals transmitted to CN VIII. The stereocilia on IHCs are connected at their tips by tip links (composed of cadherin-23 and protocadherin-15). When the basilar membrane vibrates and shears the tectorial membrane against the stereocilia, the tip links mechanically open MET (mechanotransduction) channels. Endolymph (high K+) flows into the cell via these channels due to the electrochemical gradient (endocochlear potential), depolarizing the cell and triggering afferent neurotransmitter release. Outer hair cells (OHCs) amplify basilar membrane motion via electromotility (prestin protein).

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.