Wednesday hearing and balance Flashcards
fluid in the inner ear is the only fluid in the body that is high in
potassium
Do babies make sounds from their ears?
yup
what is primarily responsible for sending the signals from the ear to the brain
inner hair cells
What is primarily responsible for the active process of hearing i.e. giving off acoustic emissions
outer hair cells
What part of the ear usually limits what you can hear?
middle ear
not the cochlea
small amount of fluid build up in middle ear. what happens?
large amount, what happens?
small amount - increase in stiffness, cannot hear lower frequencies
large amount - increase in mass, cannot hear higher frequencies
pitch hearing range.
range where we hear really well?
100Hz - 20KHz
real well - 500Hz - 5KHz
Clinical audiogram
x and y axis
y axis -
100 on bottom, 0 on top
100 is loudest
these numbers refer to amount dBs “lost” in hearing.
if you score a 50, you need 50 more decibles than normal in order to hear a certain frequency of sound
x axis -
frequency - 8kHz is max.
amount of clinical hearing loss if you loose the middle ear? what type of hearing loss is this?
40-65dB loss across all frequencies
conductive hearing loss
type of hair cells in utricles
type of hair cells in ampules
maculae
cristal
What ever direction you are accelerating your head towards, the canal in that direction is ________
depolarizing
turn head to the right, right canal depolarizes.
Decelerate and come to a stop? left canal now depolarizes
Dix-hallpike procedure is done when a patient is looking to the left.
What structure depolarizes, what structure hyperpolarizes?
what is this test used to diagnose?
Depolarization of the left posterior semicircular canal
hyperpolarization of the right anterior SC canal
diagnoses:
benign paroxysmal positional vertigo
What is defective in BPPV
oticonia fall off of the insides of the semcircular canal and build up (usually) in the posterior canals of the inner ear
type 1 vs type 2 hair cells in the ear.
in the cochlea
type 1 - inner - 90 percent of afferent fibers go to these hair cells. One afferent to one hair cell. each hair cell gets many afferents (3-5). Supported by surrounding cells
type 2 - outer - an afferent that goes to a type 2 cell may go to other type 2 cells. each connection is not as secure (not as redundant) Has contractive properties like a muscle cell. Sends less sensory info to the brain and it is less precise. Create a feedback loop, the cells move up and down when they hear something, this makes the steriocillia keep vibrating.
mechanoreceptor, both have stereocillia
Where in the cochlea are low pitched sounds detected?
Where in the cochlea are high pitched sounds detected?
apex
base
In older people, what causes a rushing water type sound
brain normally filters out static noise made by the ear, it may stop doing this in older people
where do hair cells sit?
basilar membrane of the cochlea
endolymph and perilymph
z
Where are the steriocilia of the hair cell sitting?
endolymph (scala media)
what comes down into a hair cell when transduction channels open?
Potassium, comes from the endolymph
chemical and electrical forces on potassium inside a neuron
” “ in a hair cell of the ear
[K] inside > [K] outside, wants to move out
electrical makes it want to move in
Chemical wins, K moves out
[K] outside > [K] inside
electrical potential makes it want to come in even MORE
K moves in
What is meant by the “active process” of the ear
When the outer hair cell contract contributing to the transduction of sound signals in the cochlea
Why is the ear most sensitive in the 500Hz to 5kHz range?
Because of the actions of the middle ear
What type of hair cells have kinocilium?
Vestibular
auditory hair cells ditch kinocilium during development
what type of channel is the primary transduction channel in the ear?
mechanical
if you move the stereocillia towards the kinocilia is the de- or hyper- polarization
depolarization, causes influx of potassium
