Innerhårcellerna

Innerhårcellerna, or inner hair cells, are sensory receptor cells located in the cochlea of the mammalian inner ear. They are one of two types of hair cells, the other being outer hair cells, and play a critical role in translating mechanical vibrations from sound waves into electrical signals that the auditory nerve can interpret. Inner hair cells are arranged in a single row along the basilar membrane, whereas outer hair cells form three rows.

The structure of an inner hair cell consists of a short apical segment that bears highly specialized stereocilia, a slender basal segment that contains the cell’s nucleus and organelles, and a basolateral membrane that forms synaptic connections with type I spiral ganglion neurons. The orientation and height of the stereocilia bundle create a graded response to deflection of the basilar membrane, opening mechanically gated ion channels primarily permeable to potassium and calcium ions. This depolarization triggers neurotransmitter release at the synaptic base, mainly glutamate, which activates postsynaptic receptors on auditory nerve fibers.

Inner hair cells are essential for the perception of frequency and intensity of sound. Because they have a limited capacity for regeneration in mammals, damage from noise exposure, ototoxic drugs, aging, or genetic mutations can lead to permanent hearing loss or balance disorders. Research into stem cell therapy, gene editing, and pharmacological protection is ongoing to preserve or restore the function of these cells.