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Encyclopedia > Hair cell
Hair cell
Section through the spiral organ of Corti. Magnified. ("Outer hair cells" labeled near top; "inner hair cells" labeled near center.)
Gray's subject #232 1057
MeSH A08.663.650.250

Hair cells are the sensory cells of both the auditory system and the vestibular system in all vertebrates. In mammals, the auditory hair cells are located within the organ of Corti on a thin basilar membrane in the cochlea of the inner ear. They derive their name from the tufts of stereocilia that protrude from the apical surface of the cell, a structure known as the hair bundle, into the scala media, a fluid-filled tube within the cochlea. Mammalian cochlear hair cells come in two anatomically and functionally distinct types: the outer and inner hair cells. Damage to these hair cells results in decreased hearing sensitivity, i.e. sensorineural hearing loss. Image File history File links Gray931. ... The organ of Corti is the organ in the inner ear of mammals that contains auditory sensory cells, or hair cells. // Structure and function It has highly specialized structures that respond to fluid-borne vibrations in the cochlea with a shearing vector in the hairs of some cochlear hair cells. ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ... Senses are the physiological methods of perception. ... Cells in culture, stained for keratin (red) and DNA (green). ... The auditory system is the sensory system for the sense of hearing. ... The vestibular system, or balance system, is the sensory system that provides the dominant input about our movement and orientation in space. ... Typical classes Petromyzontidae (lampreys) Placodermi - extinct Chondrichthyes (cartilaginous fish) Acanthodii - extinct Actinopterygii (ray-finned fish) Actinistia (coelacanths) Dipnoi (lungfish) Amphibia (amphibians) Reptilia (reptiles) Aves (birds) Mammalia (mammals) Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns. ... Orders Subclass Multituberculata (extinct) Plagiaulacida Cimolodonta Subclass Palaeoryctoides (extinct) Subclass Triconodonta (extinct) Subclass Eutheria (excludes extinct ancestors) Afrosoricida Anagaloidea (extinct) Artiodactyla Carnivora Cetacea Chiroptera Cimolesta (extinct) Creodonta (extinct) Condylarthra (extinct) Dermoptera Desmostylia (extinct) Dinocerata (extinct) Embrithopoda (extinct) Hyracoidea Insectivora Lagomorpha Litopterna (extinct) Macroscelidea Mesonychia (extinct) Notoungulata (extinct) Perissodactyla Pholidota Plesiadapiformes... The organ of Corti is the organ in the inner ear of mammals that contains auditory sensory cells, or hair cells. // Structure and function It has highly specialized structures that respond to fluid-borne vibrations in the cochlea with a shearing vector in the hairs of some cochlear hair cells. ... Cross section of the cochlea. ... Cross section of the cochlea. ... A human ear (also called auricle or pinna) The ear is the sense organ that detects sound. ... Stereocilia are mechanosensing organelles of hair cells, which respond to fluid motion or fluid pressure changes in numerous types of animals for various functions, primarily hearing. ... Scala media is a endolymph filled cavity inside the cochlea, located in between the scala tympani and the scala vestibuli, separated by the basilar membrane and Reissners membrane(the vestibular membrane) respectively. ... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary...

Contents


Hair bundles as sound detectors

Research of the past decades has shown that outer hair cells do not send neural signals to the brain, but that they mechanically amplify low-level sound that enters the cochlea. The amplification may be powered by movement of their hair bundles, or by an electrically-driven motility of their cell bodies. The inner hair cells transform the sound vibrations in the fluids of the cochlea into electrical signals that are then relayed via the auditory nerve to the auditory brainstem and to the auditory cortex. Cross section of the cochlea. ... A schematic representation of hearing. ... The auditory nerve is the nerve along which the sensory cells (the hair cells) of the inner ear transmit information to the brain. ... The brain stem is the stalk of the brain below the cerebral hemispheres. ... Look up cortex in Wiktionary, the free dictionary. ...


Inner hair cells – from sound to nerve signal

The deflection of the hair-cell stereocilia opens mechanically gated ion channels that allow any small, positively charged ions (primarily potassium and calcium) to enter the cell. Unlike many other electrically active cells, the hair cell itself does not fire an action potential. Instead, the influx of positive ions from the endolymph in Scala media depolarizes the cell, resulting in a receptor potential. This receptor potential opens voltage gated calcium channels; calcium ions then enter the cell and trigger the release of neurotransmitters, mainly glutamate, at the basal end of the cell. The neurotransmitters diffuse across the narrow space between the hair cell and a nerve terminal, where they then bind to receptors and thus trigger action potentials in the nerve. In this way, the mechanical sound signal is converted into an electrical nerve signal. The repolarization in the hair cell is done in a special manner. The perilymph in Scala tympani has a very low concentration of positive ions. The electrochemical gradient makes the positive ions to flow through channels to the perilymph. Nerve fiber innervation is much more dense for inner hair cells than for outer hair cells. A single inner hair cell is innervated by numerous nerve fibers, whereas a single nerve fiber innervates many outer hair cells. Inner hair cell nerve fibers are also very heavily myelinated, which is contrast to the unmyelinated outer hair cell nerve fibers. Stereocilia are mechanosensing organelles of hair cells, which respond to fluid motion or fluid pressure changes in numerous types of animals for various functions, primarily hearing. ... Stretch-activated or stretch-gated ion channels are ion channels which open their pores in response to mechanical deformation of a neurons plasma membrane. ... Ion channels are present in the membranes that surround all biological cells. ... General Name, Symbol, Number potassium, K, 19 Chemical series alkali metals Group, Period, Block 1, 4, s Appearance silvery white Atomic mass 39. ... General Name, Symbol, Number calcium, Ca, 20 Chemical series alkaline earth metals Group, Period, Block 2, 4, s Appearance silvery white Atomic mass 40. ... A. A schematic view of an idealized action potential illustrates its various phases as the action potential passes a point on a cell membrane. ... Receptor potential is the transmembrane potential difference of a sensory cell. ... Voltage-dependent calcium channels (VDCC) are a group of voltage-gated ion channels found in neurons and glial cells with a permeability to the ion Ca2+, which plays a role in the membrane potential. ... Neurotransmitters are chemicals that are used to relay, amplify and modulate electrical signals between a neuron and another cell. ... Glutamate is the anion of glutamic acid. ... In phylogenetics, basal members of a group are subgroups that diverged very early from the others. ... Neurotransmitters are chemicals that are used to relay, amplify and modulate electrical signals between a neuron and another cell. ... In biochemistry, a receptor is a protein on the cell membrane or within the cytoplasm or cell nucleus that binds to a specific molecule (a ligand), such as a neurotransmitter, hormone, or other substance, and initiates the cellular response to the ligand. ...


Outer hair cells – acoustical pre-amplifiers

In mammalian outer hair cells, the receptor potential triggers active vibrations of the cell body. This so-called somatic electromotility consists of oscillations of the cell’s length, which occur at the frequency of the incoming sound and in a stable phase relation. Outer hair cells have evolved only in mammals. They have not improved hearing sensitivity, which reaches similarly exquisite values also in other classes of vertebrates. But they have extended the hearing range from ca 11 kHz (maximum in some birds) to ca 200 kHz (maximum in some marine mammals). They have also improved frequency selectivity (frequency discrimination), which is of particular benefit for humans, because it enabled sophisticated speech and music.


The molecular biology of hair cells has seen considerable progress in recent years, with the identification of the motor protein (prestin) that underlies somatic electromotility in the outer hair cells. This is a list of gene families or gene complexes, that is sets of genes which occur across a number of different species which often serve similar biological functions. ... Prestin is the motor protein of the outer hair cells of the inner ear of the mammalian cochlea. ...


Hair-bundle motors

Results in recent years further indicate that mammals apparently also have conserved an evolutionarily earlier type of hair-cell motility. This so-called hair-bundle motility amplifies sound in all non-mammalian land vertebrates. It is effected by the closing mechanism of the mechanical sensory ion channels at the tips of the hair bundles. Thus, the same hair-bundle mechanism that detects sound vibrations also actively “vibrates back” and thereby mechanically amplifies weak incoming sound.


References

  • Coffin A, Kelley M, Manley GA, Popper AN. Evolution of sensory hair cells. In: GA Manley, AN Popper, RR Fay. Evolution of the Vertebrate Auditory System, Springer-Verlag, New York 2004, pp 55-94.
  • Kandel ER, Schwartz JH, Jessell TM. Principles of Neural Science, 4th ed., pp.590-594. McGraw-Hill, New York (2000). ISBN 0-8385-7701-6
  • Manley GA. Advances and perspectives in the study of the evolution of the vertebrate auditory system. In: GA Manley, AN Popper, RR Fay. Evolution of the Vertebrate Auditory System, Springer-Verlag, New York 2004, pp 360-368.
  • Fettiplace R and Hackney CM (2006), "The sensory and motor roles of auditory hair cells," Nature NeuroSci. 7:19-29.

Eric Richard Kandel (born November 7, 1929) is a psychiatrist, a neuroscientist and professor of biochemistry and biophysics at Columbia University. ... Principles of Nerual Science cover First published in 1981, Principles of Neural Science is a neuroscience textbook edited by Eric R. Kandel, James Schwartz, and Thomas Jessell. ...

External links

  • Hair Cells at the University of Montpellier
Sensory system - Auditory system - edit
Outer ear: Pinna | Ear canal 

Middle ear: Eardrum | Ossicles (MalleusIncus & Stapes) | Stapedius | Tensor tympani | Eustachian tube This article or section may be confusing for some readers, and should be edited to be clearer or more simplified. ... The auditory system is the sensory system for the sense of hearing. ... The outer ear is the external portion of the ear and includes the eardrum. ... Juzzah is a loser Boom, Headshot Bergamin and Gerald died The pinna (Latin for feather) is the visible part of the ear that resides outside of the head. ... Anatomy of the human ear. ... For an alternative meaning, see ear (botany). ... The tympanic membrane, colloquially known as the eardrum, is a thin membrane that separates the external ear from the middle ear. ... The ossicles (also called auditory ossicles) are the three smallest bones in the human body. ... The malleus is hammer-shaped small bone or ossicle of the middle ear which connects with the incus and is attached to the inner surface of the eardrum. ... This article refers to a bone in the mammalian ear. ... The stapes or stirrup is the stirrup-shaped small bone or ossicle in the middle ear which attaches the incus to the fenestra ovalis, the oval window which is adjacent to the vestibule of the inner ear. ... The stapedius is the smallest striated muscle in the human body. ... The tensor tympani muscle arises from the auditory tube and inserts onto the handle of the malleus, damping down vibration in the ossicles and so reducing the amplitude of sounds. ... Anatomy of the human ear. ...


Inner ear: Cochlea (Scala vestibuliScala media & Scala tympani) | Oval window | Helicotrema | Round window | Basilar membrane | Reissner's membrane | Organ of Corti | Hair cells | Stereocilia The inner ear comprises both: the organ of hearing (the cochlea) and the labyrinth or vestibular apparatus, the organ of balance located in the inner ear that consists of three semicircular canals and the vestibule. ... Cross section of the cochlea. ... Scala vestibuli is a perilymph filled cavity inside the cochlea of the inner ear. ... Scala media is a endolymph filled cavity inside the cochlea, located in between the scala tympani and the scala vestibuli, separated by the basilar membrane and Reissners membrane(the vestibular membrane) respectively. ... Scala tympani is the name of one of the perilymph filled cavities in the cochlear labyrinth. ... The helicotrema is the part of the cochlear labyrinth where the scala tympani and the scala vestibuli meet. ... The round window is one of two membranes that separates the inner ear from the middle ear. ... Cross section of the cochlea. ... Reissners membrane is a membrane inside the cochlea of the inner ear, it separates scala media from scala vestbuli and together with the basilar membrane it creates a compartment in the cochlea filled with perilymph, which is important for the function of the organ of Corti inside the scala... The organ of Corti is the organ in the inner ear of mammals that contains auditory sensory cells, or hair cells. // Structure and function It has highly specialized structures that respond to fluid-borne vibrations in the cochlea with a shearing vector in the hairs of some cochlear hair cells. ... Stereocilia are mechanosensing organelles of hair cells, which respond to fluid motion or fluid pressure changes in numerous types of animals for various functions, primarily hearing. ...


Brain: Cochlear nerve VIII → Cochlear nuclei → Superior olivary nuclei → Inferior colliculi → Medial geniculate nuclei → Primary auditory cortex Comparative brain sizes In animals, the brain, or encephalon (Greek for in the head), is the control center of the central nervous system. ... The Cochlear nerve (n. ... The vestibulocochlear nerve is the eighth of twelve cranial nerves and also known as the auditory nerve. ... The cochlear nuclei consist of: (a) the lateral cochlear nucleus, corresponding to the tuberculum acusticum on the dorso-lateral surface of the inferior peduncle; and (b) the ventral or accessory cochlear nucleus, placed between the two divisions of the nerve, on the ventral aspect of the inferior peduncle. ... // Anatomy The superior olivary nucleus (or superior olive) is a small mass of gray substance situated on the dorsal surface of the lateral part of the trapezoid body. ... The paired inferior colliculi together with the superior colliculi form the eminences of the corpora quadrigemina. ... The medial geniculate nucleus is a nucleus of the thalamus that acts as a relay for auditory information. ... The primary auditory cortex is the region of the brain that is responsible for processing of auditory (sound) information. ...


  Results from FactBites:
 
Hair cell - Wikipedia, the free encyclopedia (762 words)
Hair cells are the sensory cells of both the auditory system and the vestibular system in all vertebrates.
In mammals, the auditory hair cells are located within the organ of Corti on a thin basilar membrane in the cochlea of the inner ear.
The inner hair cells transform the sound vibrations in the fluids of the cochlea into electrical signals that are then relayed via the auditory nerve to the auditory brainstem and to the auditory cortex.
Hair cell (208 words)
Hair cells are the sensory cells of the auditory system that are found within the cochlea's organ of Corti.
Modern research has shown that outer hair cells are motile and responsible for stimulus compression and amplification, while the inner hair cells are responsible for transforming the input sound stimulus into a series of action potentials that are relayed via the auditory nerve to the brainstem and auditory cortex.
The influx of positive ions increases the receptor potential of the cell, which in turn, triggers the release of neurotransmitter at the basal end of the cell, via the opening of voltage gated calcium channels.
  More results at FactBites »

 
 

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