The Auditory System Flashcards
what is the range of audible variation in air pressure?
20 Hz to 20,000 Hz
What is ultrasound
sound above 20,000 Hz
What is infrasound
sound below 20 Hz
What can cause carsickness
infrasound
what are the parts of the middle ear?
tympanic membrane, ossicles
what are the ossicles
tiny bones which amplify the sound hitting the tympanic membrane
how do the ossicles work
sound which hits the tympanic membrane moves the ossicles [malleus, incus, stapes] which knock on oval window
what are stapedius and tensor tympani
tiny ear muscles which adapt to sound level to protect ear or understand speech better
what is the attenuation reflex
muscle contraction of tensor tympani and stapedius in response to onset of loud sound (prevent ossicles from moving too much)
where is endolymph located
in scala media, the middle compartment of the cochlea
how is endolymph different than perilymph
it is 80 mV more positive because of the K+ content
what is a tip link
extracellular filament which connects stereocilia to one another
how does a tip link regulate potassium channels on hair cell cilia?
the tension of the tip link controls the opening of the mechanically gated potassium channels
when the cilia are pointing straight up, the tension on the tip link causes
the mechanically gated channel to allow a small amount of potassium
what function do motor proteins serve?
change the length of outer hair cells by compressing or expanding
what is the result of the sterocilia bending to the left
the tip links open the mechanically gated potassium channels and the cell is depolarized
The auditory component of cranial nerve VIII has most of it connections to these types of hair cells
Inner hair cells
what is a tonotopic map?
a map of the basilar membrane and cochlear nucleus that shows which areas respond to which frequencies
when does auditory information become binaural along its projection to the cortex?
Spiral ganglion -> Ventral cochlear nucleus -> [the superior olive] -> inferior colliculus -> MGN -> auditory cortex
what is otoacoustics
measures what is actually heard by what comes back out of the ear - no need for patient input
how do cochlear implants work
electrodes for specific frequencies are placed inside cochlea by using tonotopic map
what is a conduction hearing impairment
an issue with the sound reaching the hair cells properly (infection in external canal, rupture of eardrum, ossicles issue)
what is a sensory neural hearing loss
loss of hair cells or something inner ear damage - cochlear implant candidate
how can ears ring?
tinnitus occurs when the tectorial membrane is not connected to stereocilia but loose and constantly vibrating
