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16 Cards in this Set
- Front
- Back
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Fluid content of the bony labyrinth? Of the membraneous labyrinth?
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Perilymph and endolymph, respectively.
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What does the perilymph most closely resemble, composition-wise? The endolymph?
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Perilymph is like CSF, while endolymph resembles intracellular fluid.
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Meniere's disease
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Vertigo, nausea, tinnitus from the endolymphatic blockage of the membraneous labyrinth
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General structure of a hair cell
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One end in endolymph: Kinocilia (tallest cilia) and descending badly named microvilli (stereocilia) embedded in gelatinous material
Other end in perilymph, synaptically connected to afferents that lead to CN 8 |
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What part of the m. labyrinth does not contain kinocilium? What is the fxn of that part of the ear?
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Organ of Corti in the cochlea. Hearing.
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How does this hair cell business work?
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Mechanical (shear) forces in the gelatinous material that hair cell microvilli are embedded in generate a receptor potential via transduction
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Why are the TJs between hair cells so important?
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They keep the endolymph separate from CN 8. Potassium concentration in the endolymph is so high the nerve would be destroyed otherwise.
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Hair cell transduction in a nutshell
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Deflection of the hair bundle causes K-channels to open, K to flow inward from endolymph, depolarizing the hair cell. The depolarization of the hair cell opens Ca channels in the basal part of the cell, causing an excitatory neurotransmitter to synapse with CN 8
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Innervation to the tensor tympani? Purpose of TT?
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Motor from 5. Diminish vibrations through tympanic membrane
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Innervation to stapedius? Purpose of stapedius?
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CN VII, diminish vibration of stapedius
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Spiral ganglion
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Within the modolius. Contains the cell bodies of the auditory primary afferent fibers.
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What is the stria vascularis
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The specialized portion of the cochlear duct that produces most of the endolymph in the labyrinth
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Tunnel of Corti. Contents?
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Perilymphatic space that separates the inner from outer hair cells in the organ of corti. The TC contains fibers of CN 8
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What stimulates the outer hair cells in the organ of corti? The inner?
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Endolymph flowing over the tectorial membrane. Inside, the endolymph stimulates the inner hair cells directly.
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Analogy of tonotopic organization
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Similar to somatotopic organization, only via frequencies, not by body parts
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Different purposes of inner versus outer hair cells?
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INNER ARE THE MOST IMPORTANT FOR MOST ALL TRANSMISSION. However, at the threshold of hearing, the outer hair cells can modulate, specify, and ACTIVELY amplify difficult-to-differentiate sounds.
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