What is the primary function of outer hair cells and inner hair cells in the cochlea?

What is the primary function of outer hair cells and inner hair cells in the cochlea?

• A. Outer hair cells detect sound; inner hair cells amplify basilar membrane vibrations.
• B. Outer hair cells amplify basilar membrane vibrations; inner hair cells transduce vibrations into neural signals.
• C. Both outer and inner hair cells transduce vibrations equally; outer hair cells only adjust endolymph composition.
• D. Inner hair cells amplify vibrations; outer hair cells transduce signals to the auditory nerve.

Answer: (B)

The main concept is the distinct roles of outer and inner hair cells in hearing. Outer hair cells act as mechanical amplifiers: they change their length in response to voltage changes, thanks to prestin, which boosts the motion of the basilar membrane and enhances sensitivity and frequency selectivity. Inner hair cells are the primary sensory transducers: their stereocilia deflect with the basilar membrane’s motion, mechanotransduction channels open, and this converts vibration into neural signals by releasing neurotransmitter onto auditory nerve fibers. So the function described—outer hair cells amplifying basilar membrane vibrations and inner hair cells transducing vibrations into neural signals—best captures how the cochlea converts sound into neural information.

The main concept is the distinct roles of outer and inner hair cells in hearing. Outer hair cells act as mechanical amplifiers: they change their length in response to voltage changes, thanks to prestin, which boosts the motion of the basilar membrane and enhances sensitivity and frequency selectivity. Inner hair cells are the primary sensory transducers: their stereocilia deflect with the basilar membrane’s motion, mechanotransduction channels open, and this converts vibration into neural signals by releasing neurotransmitter onto auditory nerve fibers. So the function described—outer hair cells amplifying basilar membrane vibrations and inner hair cells transducing vibrations into neural signals—best captures how the cochlea converts sound into neural information.