Hårcells

Hårcells are specialized sensory receptor cells found in the auditory and vestibular systems of vertebrates. In the inner ear, they are crucial for hearing and maintaining balance. There are two main types: inner hair cells and outer hair cells. Inner hair cells are the primary sensory receptors for hearing, converting sound vibrations into electrical signals that are sent to the brain. Outer hair cells, on the other hand, act as amplifiers, actively changing their length to enhance the responsiveness and frequency selectivity of the inner hair cells.

In the vestibular system, hair cells located in the semicircular canals and otolith organs detect head movements and gravity. These movements cause the stereocilia, which are hair-like projections on the surface of the hair cells, to bend. This bending opens or closes ion channels, generating an electrical signal that is transmitted to the brain, providing information about spatial orientation and movement. Damage to hair cells, often caused by loud noise, certain medications, or aging, can lead to hearing loss and balance disorders, as these cells have a limited capacity for regeneration.