How do hair cells convert movement into electrical signals?

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human sensory reception Human sensory reception.

Hair cells in the organ of Corti convert mechanical sound vibrations into electrical signals through a process of transduction driven by shearing forces.

When the basilar membrane vibrates, it creates shearing forces between the reticular lamina and the tectorial membrane, causing the stereocilia at the top of the hair cells to bend. This movement triggers the following sequence:1

Ion Channel Activation: When stereocilia bend toward their tallest point, ion channels open, allowing potassium ions to flow into the cell from the endolymph.1
Depolarization: This influx of ions depolarizes the hair cell. Conversely, bending in the opposite direction closes the channels, hyperpolarizing the cell.1
Neurotransmitter Release: The depolarization stimulates the base of the hair cell to release neurotransmitters.1
Signal Transmission: These chemicals are absorbed by nerve fibres at the base of the cell, which then transmit electrical signals along the cochlear nerve.1

This process is sensitized by a steep electrical gradient, known as the endocochlear potential, maintained between the endolymph and the perilymph.1