Tag Archives: hair cells

Stereocilia Inner Ear

In the inner ear, stereocilia are the mechanosensing organelles of hair cells, which respond to fluid motion in numerous types of animals for various functions, including hearing and balance. They are about 10–50 micrometers in length. (text source Wikipedia)

Stereocilia from the Inner Ear.  Some rights reserved from Zeiss microscopy (link)

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Inner ear hair cells

The sensations of hearing and balance rely on hair cells, a family of cells located in the inner ear. Crucial to their function are tip links, strings of protein that physically connect the cilia or “hairs” found on these cells.  When the cilia move in response to sensory stimuli — head movement or the vibration of sound, for example—tension is applied to the tip links, which begins a process that ultimately sends nerve impulses to the brain.

Tip links are composed of two different types of proteins called cadherins, which connect in the middle to make one long string. Mutations in these proteins often result in congenital deafness and balance disorders. Scientists have only recently made strides toward understanding the nature of these cadherins, especially at their connection to each other—hypothesized to be the first area to break under stress. (from Harvard.edu)

Image courtesy of Corey lab (link)

Inner ear hair cells, the very cells that convert a mechanical stimulus like sound or head movement into neural signals. Here you can see the mechanosensitive cilia bundles of three cells; the rest of each cell is below the visible surface.

Additional information (michaeldmann.net link)

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Cochlea

A scanning electron micrograph of a cross-section through the cochlea, false colored to reveal the distinct functional units of the mammalian organ for hearing.

Image from Cell.com       By Bechara Kachar, NIDCD/NIH        (larger image here)

SEM of a cross-section through the cochlea, false colored to reveal the distinct functional units of the mammalian organ for hearing: mechanosensory hair cells (blue), supporting cells (pink), and highly specialized extracellular matrix structures (ECM, green). Although all hair cells in the cochlea have similar organization and the same basic function, the broad range of sensitivity and exquisite frequency selectivity of each hair cell depends on its micromechanical properties and its relationship to the local architecture. (from cell.com)

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Hair Cells

Hair cells are the sensory receptors of both the auditory system and the vestibular system in all vertebrates. The auditory hair cells are located within the organ of Corti on a thin basilar membrane in the cochlea of the inner ear.


Image from Wellcome images, Credit Dr. David Furness, Creative Commons (link)

Hair cell of inner ear
A scanning electron microscope image of the sensory hair bundle of an inner hair cell from a guinea pig’s hearing organ in the inner ear.
Vibrations made by sound cause the hairs to be moved back and forth, alternately stimulating and inhibiting the cell. When the cell is stimulated
it causes nerve impulses to form in the auditory nerve, sending messages to the brain.

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