the auditory system Flashcards
what is a sound
repetitive vibrations in air
why can we hear?
an object vibrates -> producing changes in air pressure -> the air vibrates and travels in 3 dimensions -> we hear a sound
what is the amplitude of a sound
intensity difference in air pressure from the baseline to the peak of a wave (dB)
what is the amplitude of a sound measured in
dB - decibels
what is the wavelength of a sound
the distance from one peak wave to the next
what is the frequency of a sound
number of complete waves or cycles that pass by a given point in space every second
how is the frequency of a sound measured
hertz (Hz)
how is loudness/intensity of a sound determined
by amplitude
what is the pitch of a sound determined by
frequency
what is the timbre of a sound
the quality of a sound and is related to the characteristic of the sound wave
If sound if the vibration of air - in the eardrum, what picks up the vibrations primarily
malleus, the incus, and the stapes
after a sound vibrates the eardrum and then the malleus, the incus, and the stapes, where does the vibration then spread to
cochlea
in the cochlea, what is the vibration of air converted to
movement/vibration of fluids in the cochlea
in the cochlea, what is the vibration of sound captured by
hair cells
in the cochlea the physical vibration is transduced to what kind of energy
neural energy
what CN is the auditory vestibular nerve
CN VIII
what are the 3 ossicle bones in the middle ear
malleus, incus, stapes
in the middle ear, the 3 ossicle bones change the acoustic energy into what kind of energy
mechanical energy
where are the three ossicle bones located
middle ear
what type of energy is created by fluid motion in the inner ear
hydrodynamic energy
middle ear bones over come the loss of sound by doing what
increasing sound pressure
what is it called when the middle ear bones overcome the loss of sound by increasing sound pressure
impendence matching
what 2 structures does the inner ear contain
cochlea
labyrinth
in the inner ear, what system is the cochlea part of
auditory system
in the inner ear, what system is the labyrinth a part of
vestibular system
how many fluid filled cavities does the cochlea contain
3
Anatomy of the cochlea
reissner’s membrane separates scala vestibuli from _______
basilar membrane separates scala media from __________
transduction: organ of carti hair cells, basilar membrane to _________
reissner’s membrane separates scala vestibuli from scala media
basilar membrane separates scala media from scala tympani
transduction: organ of Corti hair cells, basilar membrane to tectorial membrane
what are hair cells otherwise known as
sterocilia
hair cells K+ current is (inwards/otwards)
inwards
why is it important to recycle K+ in the endolymph ?
K channels, transporters and gap junctions are critical for reconstituting K in the endolymph as mutations in these can result you becoming deaf
Hair cell transduction
depending on how a hair cell _____ the hair cell can release neurotransmitters
bends
Hair cell transduction
after neurotransmitters are released in the hair cells, where are they captured?
nerve fibers
the basilar membrane is flexible and vibrates in sync with ?
fluid motion
what characteristics of the basilar membrane determines the distance a particular frequency travels
width and flexibility of the basilar membrane
the width and flexibility of the basilar membrane determines what
the distance a particular frequency will travel
basis for tonotopy
different frequencies of sound waves activate hair cells in different
locations
basis for tonotopy
when hair cells bend most, they?
fire most
what neurotransmitter is associated with the auditory system
Glutamate
outer hair cells primarily get what kind of signal
efferent
inner hair cells primarily get what kind of signal
afferent signal
outer hair cells primarily get efferent inputs. They control …
stiffness, amplify membrane vibration
what hair cells can be known as a cochlear amplifier
outer hair cells
in outer hair cells, what are motor proteins composed of
prestin
in outer hair cells, motor proteins composed of prestin are capable of what
changing the length of the cell
outer hair cells respond to sound and respond by a change in length when depolarised/hyperpolarised
what happens when a OHC is depolarised
shortened
outer hair cells respond to sound and respond by a change in length when depolarised/hyperpolarised
what happens when a OHC is hyperpolarised
lengthen
auditory fibers of the eight nerve send branches to both ____ and ____ cochlear nucleus
dorsal and ventral
second order axons ascend contralaterally to innervate cells where
in the inferior colliculus
neurons in the ventral cochlear nucleus provide collateral branches to both ipsi and contralateral _____
superior olivary nuclei
auditory complex: what vs where
ventral (what/where)?
dorsal (what/where)?
ventral - what
dorsal - where
what is broca’s area used for
understanding language but unable to speak or write
what is wernicke’s area used for
speaks but cannot understand
what are the types of hearing loss
conductive
sensorineural
mixed
what is conductive hearing loss
processes that prevent sound from reaching the cochlea
what can cause conductive hearing loss
ruptured ear drum
abnormal growth obstructing ear flow
what is sensorineural hearing loss
processes that damage hair cells, spiral ganglion cells and/or the auditory nerve
what causes sensorineural hearing loss
noise, otoxic drugs, certain antibiotics
or liver/kidney disorders where you will be prescribed loop diuretics which target the NKCC1 transporter
what is mixed hearing loss
both conductive and sensorineural
what is the most common sensory deficit in the world
sensorineural hearing loss
is there a cure for age-related hearing loss?
no
what are some biological strategies for use in the inner hear that help combat hearing loss
gene therapy
stem cell therapy
molecular therapy
how do cochlear implants worl
bypass the nonfunctional or absent hair cells and directly stimulate spiral ganglion neurons
who would not be a candidate for a cochlear implant
patients who lack spiral ganglion neurons
what is tinnitus
perception of sound when no external stimulus is present
what is an example of someone with tinnitus
ringing in the ears
what are some things that make tinnitus worse
loud noises
alcohol
nicotine
caffeine
high sugar foods
sedatives, antidepressants, aspirin
high blood pressure
stress/fatigue
