Cochlear Electrophysiology Flashcards
Scala media is filled with what kind of liquid? What is the voltage of the liquid?
-Endolymph, +80 mV
Scala vestibuli is filled with what kind of liquid? What is the voltage of the liquid?
-Perilymph, 0 mv
Scala tympani is filled with what kind of liquid? What is the voltage of the liquid?
-Perilymph, 0 mV
What is the resting voltage of the outer and inner hair cells?
- OHCs: -70 mV
- IHCs: -45 mV
Why is it important to have a potential difference across scala media and hair cells?
- 125-150 mV potential difference between the endolymph and inside of the HCs creates a large voltage gradient, which drives K+ ions into the cell when ion channels are open
- In accordance with the Davis Battery Theory
What is the source of the endocochlear potential? What types of cells help generate it?
-Ion pumps of the stereocilia
Where are the ion channels on the stereocilia?
-In the tip-links at the superior-most portion of the stereocilia
Stereocilia must be fast enough to do what?
-Facilitate fast enough ion transfer for high frequencies
What are the cochlear potentials? Which respond to stimuli?
- Resting potential:
- Endocochlear potential
- Intracellular potential
- Active potentials:
- Cochlear microphonic
- Summating potential
- Compound action potential
-Active potentials respond to stimuli
Which potential mimics the stimulus fine structure? Is it more like AC or DC?
- CM
- AC
Which potential mimics the stimulus envelope? Is it more like AC or DC?
- SP
- DC
Where is the compound action potential generated?
-Spiral ganglion of the ANFs
What goes up to higher frequencies, the cochlear microphonic or the inner hair cell potential?
-CM
What cells produce OAEs?
-OHCs
