Flashcards in The Auditory System Deck (24):
What is presbycusis?
natural hearing loss of old age
Name 2 ototoxic drugs.
How do you feel ear pain from loud sounds? Where are the pain sensors?
Free nerve endings in the tympanic membrane.
Can sound be broken down into simple frequencies? What part of your body does this?
Yup. The cochlea.
Why does the sound need to get amplified by the tympanic membrane and bones?
so the sound can get into the water...
Where are the outer hair cells / tectorial membrane?
The scala media
What is the scala media filled with? Notable ionic concentrations?
Endolymph, high in K+ <-- which is unusual. (You still have those ion concentrations from CTB memorized, right?)
What are the scala vestibuli and scala tympani filled with? Notable ionic concentrations?
Paralymph, high in Na+.
Which hair cells have afferent synapses? What happens if you lose them?
Inner hair cells. If you lose them, you're deaf.
Which hair cells have efferent synapses? What happens if you lose them?
Outer hair cells. If you lose them, hearing sensitivity is (greatly) decreased.
Where are the channels used in auditory receptor cells located?
At the tips of stereocilia on the hair cells, connected by tip links...
What makes the channels used in auditory receptor cells open? Result?
Movement of endolymph in the right direction -> ion channels pulled open due to stereocilia being different lengths. Ion influx causes action potential... auditory info.
Why don't hair cells use GPCRs for auditory info?
GPCRs are too slow.
What are the hair cells sitting on?
the basilar membrane
Where do low freq. sounds go in the basilar membrane?
Where do high freq. sounds go in the basilar membrane?
What's sitting on top of the hair cells?
the tectorial membrane
What signal do low freq. sounds produce?
Depolarization at frequency matching sound
What signal do high freq. sounds produce?
How do the physical properties of the basilar membrane vary along its length?
Narrow and stiff at base (for high freqs)
Wide and floppy at apex (for low freqs)
Are there unmyelinatd auditory afferents?
Yes... Type II fibers... but what they do... ???
What's the significance of a specific area in the basilar membrane having a frequency for which the threshold for activation is lowest?
That's the frequency that the hair cells in that area respond to.
Why might you want working outer hair cells when you're at the bar?
So you can modulate hearing such that you tune into the frequencies of the lucky person you're trying to pick up, reducing background noise.