Audio 1 Flashcards
The auditory system is designed to transform acoustic information into _______ and ultimately to ______
mechanical activity
electrochemical signals
The outer ear is made up
the pinna and external auditory meatus
The middle ear begins with the _______, and includes the ossicular chain (with all the associated muscles, ligaments, and tendons), and the Eustacian tube.
tympanic membrane
Sound is
long waves passing through medium
We get areas of rarefaction and compression over and over which translates into
pitch and frequency
The inner ear begins at the _______, and includes the :
oval window
cochlea and vestibular structures.
The pinna and ear canal provide a boost in
high frequency sound intensity~ External ear acoustic gain
middle ear is a ______, and consists of the ossicular chain that extends from the
mechanical system tympanic membrane (ear drum) to the oval window of the inner ear.
transmits sound pressure waves from air to fluid
middle ear mechanics
Three ways of middle ear impedence matching
area ratio
lever action
bucking of TM
Total gain of middle ear
31 dB, enough to overcome impedence mismatch
Area ratio principle:
go from Tympanic membrane with large area, same force, low pressure–>
smaller area, same force, HIGH pressure
Gives us 23 dB gain
Lever Action principle:
Length of malleus is longer then process of incus:
More distance, less force–> less distance, more force
~2dB gain
Ossicular chain: the length of the _____ is longer then the process of the _____
malleus
incus
Buckling of TM
The TM buckles when vibration occurs and applies almost twice the force to malleus
~6 dB
The inner ear is contained in the _______, and is encased in a bony structure called the osseous or bony labyrinth.
petrous apex of the temporal bone
The labyrinth consists of three continuous sections:
the vestibule, the cochlea, and the semicircular canals.
The initial point of communication between the middle and inner ears occurs at
the oval window of the vestibule where the stapes footplate abuts the oval window membrane
The core of the cochlea is the _______which is highly porous bone that allows passage of auditory nerve fibers as they travel from the internal auditory meatus to the hair cell synapse.
modiolus,
Extending from the modiolus into the osseous labyrinthine space is a bony shelf, or the
osseous spiral lamina
Spiral lamina provides partial division of the
cochlea, the upper:
the lower:
scala vestibuli
scala tympani
the scala vestibuli and scala tympani communicate at
helicotrema
spiral lamina is also the point of attachment for the basilar membrane, which is the lower border of the membranous labyrinth encasing the
scala media.
scala media bordered superiorly by _______ and inferiorly by the ________
Reissner’s membrane
basilar membrane
the organ of Corti located in
membranous labyrinth
stria vascularis in the membranous labyrinth is in charge of
metabolic environment of the scala media
–blood supply and ionic conc = cochlear battery (scala media very metabolically active)
The organ of Corti runs longitudinally along the length of the ______ and consists of many types of epithelial cells and structures.
basilar membrane
One row of _____and three rows of ______ are present, and the cell bodies are surrounded by supporting cells.
inner hair cells
outer hair cells
Perilymph is found in
with High
and Low
scala vestibuli
high Na
low K
endolymph is found in
with high
and low
scala media
K
Na
Hair cells are contacted by the dendrites of ______ whose cell bodies are in the spiral ganglion.
afferent bipolar neurons
The basilar membrane is like a
traveling wave
high frequency/pitch will get off at
the base or right away on basilar membrane
low pitch/frequency will get off basilar membrane at
apex or later
90-95% bipolar neurons contact ________ 5-10% contact _______.
inner hair cells;
outer hair cells
Many afferent fibers synapse on the same_____ , while single afferent fibers branch to synapse with _______.
inner hair cell
several outer hair cells
Efferent fibers have cell bodies in the _______ of the brainstem and synapse directly on outer hair cells and on the afferent fibers of inner hair cells.
superior olivary complex
concept that dif frequencies will displace basilar membrane at dif points
tonotopic organization
Inner and outer hair cells function as receptor cells that transduce mechanical movement into an
electrochemical signal to stimulate the auditory nerve.
passive transducers of auditory system
inner hair cells
Outer hair cells have microfilaments and microtubules along the length of the cell that give rise to ______
motile activity.
The motile properties of microfilaments on outer hair cells result in
increased basilar membrane motion and are responsible for the cochlear amplifier.
Rooted in the cuticular plate of each hair cell and projecting through the reticular lamina are bundles of actin filaments called ______, stiff hair-like structures that deflect with mechanical disturbances.
stereocilia
stiff hair-like structures that deflect with mechanical disturbances.
stereocilia
Stereocilia are connected to each other by filamentous ___________. These ensure that the connected stereocilia move as a unit when the longer stereocilia are deflected
cross-links and tip-links
Movement of the endolymph produces deflection of the :
sterocilia
Deflection of the stereocilia (in one direction) opens
ion channels of sterocilia– Positive ions flow inward, through open channels, depolarizing the hair cell
Once sterolia open up…positive ions flow in and
depolarize the hair cell causing NT release–> stim auditory nerve fibers
Endolymph in scala media is high in
K+~ 80mV
Inner hair cells have charge of
-45 mV bc the reticular lamina keeps them seperate
Perilymph in scala tympani has charge of
0 mV with low K+mV
Positive ions (K+) from endolymph flow in and \_\_\_\_\_\_ when tiplinks open
depolarize hair cells
We get depolarization during the _____
and hyperpolarization during the ______
upward phase
downward phase
Obstruction or anomoly at middle ear or external ear, something is blocking sound coming in d/t
Conductive hearing loss
Sensorineural hearing loss tends to be
permanent
Dysfunction of the cochlea and/or auditory nerve.
Sensorineural hearing loss:
Hearing is tested by measuring detection thresholds to stimuli. The detection thresholds are plotted on an
audiogram
