hårcellen

Hårcellen, also known as the hair cell, is a specialized sensory receptor cell found in the auditory and vestibular systems of vertebrates. These cells play a critical role in converting mechanical stimuli—such as sound waves and head movements—into electrical signals that the nervous system can interpret.

Hair cells are named for their distinctive bundle of stereocilia, which resemble tiny hairs protruding from their apical surface. These stereocilia are highly sensitive to mechanical displacement, allowing them to detect vibrations and positional changes. In the cochlea of the inner ear, hair cells are responsible for hearing, while in the vestibular system, they contribute to balance and spatial orientation.

The structure of hair cells includes a basal body, a cell body, and an apical tuft of stereocilia. When mechanical forces cause these stereocilia to bend, ion channels in their membranes open or close, leading to changes in membrane potential. This process generates receptor potentials that, if strong enough, trigger the release of neurotransmitters, ultimately sending signals to the brain via auditory or vestibular nerves.

Hair cells are non-dividing and cannot regenerate in humans, making them particularly vulnerable to damage from loud noise, aging, or certain toxins. Conditions such as hearing loss or vestibular disorders often result from the degeneration or dysfunction of these cells. Research into hair cell regeneration and protection remains an active area of biomedical study, with potential implications for treating hearing and balance impairments.

Their sensitivity and specificity make hair cells essential for auditory perception and equilibrium, highlighting their importance in both physiological function and clinical medicine.