5. Physiology of the Auditory and Vestibular Systems Flashcards
Where is endolymph found?
What is the K+ concentration like?
Does it bathe the apical or basal end of hair cells?
Within the cochlear duct and membranous labyrinth.
High [K+].
Bathes apical end.
Where is perilymph found?
What is the K+ concentration like?
Does it bathe the apical or basal end of the hair cells?
Between the membranous and bony labyrinth.
Low [K+].
Bathes basal end.
What fluid is in the scala media?
Endolymph
What fluids are in the scala tympani and scala vestibuli?
Perilymph
Higher frequencies have maximal motion at which region of the basilar membrane?
Lower frequencies?
Higher - at base.
Lower - apical part.
Near the oval window the basilar membrane is narrow and stiff. What sounds are absorbed best here?
High frequency sounds
Distal from the oval window the basilar membrane is wide and flexible. What sounds are absorbed best here?
Low frequency sounds
What kind of receptors are hair cells?
Mechanoreceptors
What causes an influx of K+ into the hair cells?
A deflection toward the kinocilium
What are the 2 factors that cause influx of K+ into the hair cell?
Large endolymphatic potential (high K+ conc in the cell).
Large electrochemical gradient (scala media has high + charge).
What NT is secreted once the hair cells are depolarized?
Glutamate
What happens when the stereocilia are deflected away from the kinocilia?
The cell is hyperpolarized
What ion causes depolarization of the hair cells?
What does depolarization cause the entry of?
What channel does it use?
K+
Ca++
TRPA1
Main function of scala vascularis:
Maintain electrochemical properties of endolymph
How many rows of inner hair cells?
What is their function?
1 layer.
Primary source of auditory info.
How many rows of outer hair cells?
Main function(s)?
3 layers.
Amplifier, otoacoustic emissions,
Where do hair cells receive afferents?
Where do they receive efferents?
Afferents from spiral ganglia.
Efferents from superior olivary complex.
What neuron fibers do inner hair cells use?
What neuron fibers do outer hair cells use?
Type I
Type II
Dorsal cochlear nuclei function:
To integrate acoustic info w/ somatosensory info for localization of sound.