where are the hair cells of the cochlear duct located
Hair cell Hair cells are the sensory receptors of both the auditory system and the vestibular system in the ears of all vertebrates. Through mechanotransduction, hair cells detect movement in their environment.[1] In mammals, the auditory hair cells are located within the spiral organ of Corti on the thin basilar membrane in the cochlea of the inner ear. They derive their name from the tufts of stereocilia called hair bundles that protrude from the apical surface of the cell into the fluid-filled cochlear duct. Mammalian cochlear hair cells are of two anatomically and functionally distinct types, known as outer, and inner hair cells. Damage to these hair cells results in decreased hearing sensitivity, and because the inner ear hair cells cannot regenerate, this damage is permanent.[2] However, other organisms, such as the frequently studied zebrafish, and birds have hair cells that can regenerate.[3][4] The human cochlea contains on the order of 3,500 inner hair cells and 12,000 outer hair cells at birth.[5]
Stereocilia (inner ear) As acoustic sensors in mammals, stereocilia are lined up in the organ of Corti within the cochlea of the inner ear. In hearing, stereocilia transform the mechanical energy of sound waves into electrical signals for the hair cells, which ultimately leads to an excitation of the auditory nerve. Stereocilia are composed of cytoplasm with embedded bundles of cross-linked actin filaments. The actin filaments anchor to the terminal web and the top of the cell membrane and are arranged in grade of height.[2] As sound waves propagate in the cochlea, the movement of endolymph fluid bends the stereocilia. If the direction of movement is towards the taller stereocilia, tension develops in the tip links, mechanically opening transduction channels near the tips. Cations from the endolymph flow into the cell, depolarizing the hair cell and triggering the release of neurotransmitters to nearby nerves, which send an electrical signal to the central nervous system.
Auditory system There are far fewer inner hair cells in the cochlea than afferent nerve fibers â€“ many auditory nerve fibers innervate each hair cell. The neural dendrites belong to neurons of the auditory nerve, which in turn joins the vestibular nerve to form the vestibulocochlear nerve, or cranial nerve number VIII.[32] The region of the basilar membrane supplying the inputs to a particular afferent nerve fibre can be considered to be its receptive field.
Tactile corpuscle They are distributed on various areas of the skin, but concentrated in areas especially sensitive to light touch, such as the fingers and lips.[3][4][5][6][7] More specifically, they are primarily located in glabrous skin just beneath the epidermis within the dermal papillae.[8]