5 Describe the role of the basilar membrane and the hair cel

5. Describe the role of the basilar membrane and the hair cells of the organ of Corti in transducing sound waves into electrical signals and determining the perceived frequency of a sound.

Solution

1 Ans The hair cells of the organ of Corti are arranged in four rows along the length of the basilar membrane. Individual hair cells have multiple strands called stereocilia. The bottom of these cells are attached to the basilar membrane, and the stereocilia are in contact with the tectorial membrane Inside the cochlea, sound waves cause the basilar membrane to vibrate up and down. This creates a sharing force between the basilar membrane and the tectorial membrane, causing the hair cell stereocilia to bend back and forth. This leads to internal changes within the hair cells that creates electrical signals. Auditory nerve fibers rest below the hair cells and pass these signals on to the brain. So, the bending of the stereocilia is how hair cells sense sounds. Outer hair cells have a special function within the cochlea. When the stereocilia are bent in response to a sound wave, an electromotile response occurs. This means the cell changes in length. So, with every sound wave, the cell shortens and then elongates. This pushes against the tectoral membrane, selectively amplifying the vibration of the basilar membrane. This allows us to hear very quiet sounds.