What is the purpose of the Endocochlear potential?
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What is the purpose of the Endocochlear potential?
The endocochlear potential (EP) of +80 mV in cochlear endolymph is essential for audition and controlled by K+ transport across the lateral cochlear wall composed of two epithelial barrier layers, the syncytium containing the fibrocytes and the marginal cells.
What is the Endolymphatic potential?
Endolymphatic Potential (EP) The endolymphatic potential is a positive standing potential (70-100 mV) that can be measured from the scala media referenced to ground. The EP reflects flux of K+ ions through the stria vascularis into the scala media.
What is stria Vascularis?
The stria vascularis, composed of marginal, intermediate, and basal cells, is responsible for maintaining the ion composition of the endolymph and producing an endocochlear potential (EP) in the scala media [1,2].
How endocochlear potential is produced?
It is commonly accepted that the endocochlear potential (EP) of the cochlea is generated by an electrogenic transport of potassium into scala media by the marginal cells of stria vascularis.
What is the Summating potential?
This ‘summating potential’ (SP) is a d.c. change related to. the root-mean-square of the acoustic pressure, integrated over one or two. waves. It increases up to injurious sound pressure levels.
How is endocochlear potential generated?
What is microphonic potential?
The cochlear microphonic is a receptor potential believed to be generated primarily by outer hair cells. Its detection in surface recordings has been considered a distinctive sign of outer hair cell integrity in patients with auditory neuropathy.
What is modiolus in ear?
The modiolus is a conical shaped central axis in the cochlea. The modiolus consists of spongy bone and the cochlea turns approximately 2.75 times around the central axis in humans. The cochlear nerve, as well as spiral ganglion is situated inside it.
What is the spiral ganglion?
The spiral (cochlear) ganglion is a group of neuron cell bodies in the modiolus, the conical central axis of the cochlea. These bipolar neurons innervate the hair cells of the organ of Corti.
How does the ionic composition of endolymph generate endocochlear potential?
Endolymph is created from perilymph. The endocochlear potential is the sum of two potentials: a positive potential caused by active secretion of K+ by the stria vascularis (120mV) and a negative potential created by the passive diffusion of K+ ions from the hair cells (40mV), which can be visualised after an anoxia.
What is the difference between cochlear microphonic and action potential?
The cochlear microphonic and the summating potential (SP) are generated by the hair cells of the organ of Corti, whereas the compound action potential (AP) of the auditory nerve represents the summed synchronized response of many individual nerve fibers.
How do you say modiolus?
noun, plural mo·di·o·li [moh-dahy-uh-lahy, muh-].
What is a modiolus quizlet?
Modiolus. the central core of bone within the cochlea. It forms the axis of the cochlear spiral, which coils for 2.75 turns.
Where is ganglion Spirale?
the cochlea
…of nerve cell bodies, the spiral ganglion, located in the modiolus of the cochlea. The neurons of the spiral ganglion are called bipolar cells because they have two sets of processes, or fibres, that extend from opposite ends of the cell body.
What is meant by a Tonotopic map?
Tonotopic maps are a striking feature of the mammalian auditory cortex and underlie the representation of complex sounds, such as speech. This spatial separation of frequencies originates in the inner ear, where high frequencies are processed in the base of the cochlea and low frequencies in the apex.
What is the endocochlear potential generated by?
stria vascularis
It is commonly accepted that the endocochlear potential (EP) of the cochlea is generated by an electrogenic transport of potassium into scala media by the marginal cells of stria vascularis.
Where is the endocochlear potential?
The endocochlear potential (EP; also called endolymphatic potential) is the positive voltage of 80-100mV seen in the cochlear endolymphatic spaces. Within the cochlea the EP varies in the magnitude all along its length.
What is cochlear microphonic?
How is cochlear microphonic measured?
You can measure cochlear microphonics with a standard ABR electrode montage. But you will get the strongest signal with the electrodes positioned as close to the site of generation as possible. The most used electrodes for this purpose are the gold foil TipTrodes or TM-trodes.
