The Auditory System

Question 1

what is the range of audible variation in air pressure?

Answer 1

20 Hz to 20,000 Hz

Question 2

What is ultrasound

Answer 2

sound above 20,000 Hz

Question 3

What is infrasound

Answer 3

sound below 20 Hz

Question 4

What can cause carsickness

Answer 4

infrasound

Question 5

what are the parts of the middle ear?

Answer 5

tympanic membrane, ossicles

Question 6

what are the ossicles

Answer 6

tiny bones which amplify the sound hitting the tympanic membrane

Question 7

how do the ossicles work

Answer 7

sound which hits the tympanic membrane moves the ossicles [malleus, incus, stapes] which knock on oval window

Question 8

what are stapedius and tensor tympani

Answer 8

tiny ear muscles which adapt to sound level to protect ear or understand speech better

Question 9

what is the attenuation reflex

Answer 9

muscle contraction of tensor tympani and stapedius in response to onset of loud sound (prevent ossicles from moving too much)

Question 10

where is endolymph located

Answer 10

in scala media, the middle compartment of the cochlea

Question 11

how is endolymph different than perilymph

Answer 11

it is 80 mV more positive because of the K+ content

Question 12

what is a tip link

Answer 12

extracellular filament which connects stereocilia to one another

Question 13

how does a tip link regulate potassium channels on hair cell cilia?

Answer 13

the tension of the tip link controls the opening of the mechanically gated potassium channels

Question 13

when the cilia are pointing straight up, the tension on the tip link causes

Answer 13

the mechanically gated channel to allow a small amount of potassium

Question 13

what function do motor proteins serve?

Answer 13

change the length of outer hair cells by compressing or expanding

Question 14

what is the result of the sterocilia bending to the left

Answer 14

the tip links open the mechanically gated potassium channels and the cell is depolarized

Question 14

The auditory component of cranial nerve VIII has most of it connections to these types of hair cells

Answer 14

Inner hair cells

Question 14

what is a tonotopic map?

Answer 14

a map of the basilar membrane and cochlear nucleus that shows which areas respond to which frequencies

Question 14

when does auditory information become binaural along its projection to the cortex?

Answer 14

Spiral ganglion -> Ventral cochlear nucleus -> [the superior olive] -> inferior colliculus -> MGN -> auditory cortex

Question 15

what is otoacoustics

Answer 15

measures what is actually heard by what comes back out of the ear - no need for patient input

Question 15

how do cochlear implants work

Answer 15

electrodes for specific frequencies are placed inside cochlea by using tonotopic map

Question 15

what is a conduction hearing impairment

Answer 15

an issue with the sound reaching the hair cells properly (infection in external canal, rupture of eardrum, ossicles issue)

Question 15

what is a sensory neural hearing loss

Answer 15

loss of hair cells or something inner ear damage - cochlear implant candidate

Question 15

how can ears ring?

Answer 15

tinnitus occurs when the tectorial membrane is not connected to stereocilia but loose and constantly vibrating