Where do auditory stimuli generate receptor potentials?

• A. The hair cells
• B. The auditory nerve
• C. The tympanic membrane
• D. The semicircular canals

Answer: (A)

Auditory stimuli generate receptor potentials in the hair cells of the organ of Corti. When sound causes the basilar membrane to move, the stereocilia atop hair cells bend, opening mechanically gated ion channels. This influx of ions produces a graded depolarization called a receptor potential, which leads to neurotransmitter release onto the auditory nerve fibers and ultimately fires action potentials that carry the sound information to the brain. The auditory nerve itself transmits those spikes, not receptor potentials. The tympanic membrane vibrates to transmit sound but does not generate receptor potentials itself, and the semicircular canals’ hair cells detect head rotation, not typical auditory signals.