hearing Flashcards
why is endocochlear potential important
high conc. of K in endolymph allows for fast depolarization of the hair cell bodies which are surrounded by the perilymph (scala tympani)
helicotrema
connects the scala vestibuli and scala tympani at the apex
how do sound waves transduce through the cochlea
which types of channels join the tip links to the hair cells
TRPA 1 mechanic potassium channels
where are the stereocillia of the hair cells located
scala media (endolymph)
where is the cell body of the hair cells
scala tympani (perilymph)
describe transduction of hair cell depolarization
the movement of the basilar membrane causes hair cells in the stereocillia to move towards the tallest stereocillium, TRPA1 K channels open, the cell depolarizes, calcium channels downstream open, and neurotransmitter is released onto the spiral ganglion
how do motor proteins help with cochlear amplification
DOUBLE CHECK: outer hair cells have motor proteins which compress/elongate onto the basilar membrane and stimulate it to initiate a response from the inner hair cell
-help with sound waves (regardless of frequency) which do not have a high enough intensity
what are the two ways we decode auditory signals
phase locking and tonotophy/label lining
what is the central auditory pathway
spiral ganglion, ipsilateral auditory nerve, ipsilateral and contralateral superior olive, inferior colliculus, medial geniculate thalamus, primary auditory cortex
will a lesion below the superior olive cause binaural or monaural hearing loss
binaural
will a lesion above the superior olive cause monaural or binaural hearing loss
monaural
do the core regions play a significant role in distinguishing between sound wave frequencies from speech, environment, and music
no, only belt regions
which cortical regions respond to speech
left belt (also right but less)
which cortical regions respond to music
right belt mostly
which cortical regions respond to the environment
both right and left but moreso right
describe the MSO pathway
less than 2kHz; ; sound wave travels through both ears, ear closest to the sound fires action potential onto the ganglion cells/auditory nerve and reaches MSO. a little later, ganglion cells/auditory nerve from the farther ear also fires an action potential which travels to the MSO, at the coindicent neuron in the MSO, the largest signal is fired to the lateral geniculate nucleus
describe the LSO pathway
-more than 2000Hz
-occurs when the frequency of one signal is too large to measure interaural time differences
-the intensity of the first signal is echoed the other ear
-signals from both ears synapse on the inhibitory MNTB
-MNTB inhibits the other ear with a signal corresponding to the amplitude in the ipsilateral ear
-these net signals are sent to the LSO
-only one signal will actually be sent to the LSO unless the signal is coming from an equidistant point from both ears
how many genetic loci have been identified for hearing loss
300
what are the names of the ossicles
stapes, incus, malleus
infrasound
less than 20Hz
ultrasound
more than 20kHz
sound intensity for instant perforation of the eardrum
160dB
the auditory canal acts as a __________, enhancing sounds between _________kHz
closed tube resonator, 2-5kHz
compare the pressure of the oval window and tympanic membrane
the pressure at the oval window is 20x greater
what is the purpose of the round window
decompresses the acoustic energy that enters the cochlea via the stapes against the oval window (i think it stops the cochlea from popping)
attenuation reflex
when a loud sound (70-90dB) causes tympani and stapedius muscle to contract stopping movement of the ossicles
endolymph
high potassium, low sodium, most positive potential
-scala media
perilymph
high sodium, low potassium, lower potential than endolymph
-scala vestibuli and scala tympani
where are hair cells located
organ of corti
why is the helicotrema important/why do the scala vestibuli and scala tympani need to connect
allows for sound wave information to travel from the scala vestibuli to scala tympani so that basilar membrane can be stimulated/vibrated
cochlea narrows from _______ to ________
base to apex
basilar membrane widens from _________ to _________
base to apex
stiffness of the basilar membrane decreases from _______ to ________
base to apex
Broca’s aphasia
issues with language production but know what they want to say
Wernicke’s aphasia
can speak but it does not come out coherently at all
broadly speaking what is the left hemisphere imporant for
speech processing
broadly speaking what is the right hemisphere important for
processing of tonal stimuli and music
fun fact: we respond faster to speech than to music
did u know that cause that’s fun
