hearing Flashcards
(39 cards)
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
