Test 2: Lecture 17 Auditory Flashcards
higher air pressure creates ___
condensation
lower air pressure creates ___
rarefaction
change is pitch changes ___
frequency
change in loudness changes
the amplitude (magnitude of the wave)
the peak to peak variation in pressure gives impression of ___
loudness
the frequency of the sinusoidal pressure wave will change the ___
pitch
cycles per sec = Hertz
sound is measured in
dB (decibels)
Bel is one log unit
measurement relative to 20 microPascals
0 dB is threshold for humans at 1-4 kHz
complex sound leads to the ___
combination of all sound waves into a sum sine wave that can be understood by the brain
auditory transduction
sound waves into electrical signals that can be interpreted by the brain
bones of the inner ear
auditory ossicles
malleus, incus and stapes
___ hold the inner ear bones in place
anterior malleal ligament
posterior incudal ligament
tendon of the tensor tympani muscle
footplate of the stapes sends vibrations into the ___
oval window of the bony labyrinth
bony labyrinth is filled with a fluid called ___
perilymph
flexibility of the ___ allows vibrations of the stapes to move the perilymph
round window
corridor to the round window is found in the spiral portion called the ___
cochlea
vibrations ascending to the apex of the cochlea by the
scala vestibuli
vibrations descending from the apex of the cochlea to the round window by the
scala tympani
___ is in between the scala vestibuli and the scala tympani
cochlear duct
cochlear duct is filled with
endolymph
membrane on top of the cochlear duct
reissners membrane
membrane below the cochlear duct
basilar membrane
___ is found on the basilar membrane of the cochlear duct
organ of corti
nerve impulses from the organ of corti to the brain are via the ___nerve
cochlear
hair cells within the organ of corti are covered by ___
tectorial membrane
lower frequencies vibrate the basilar membrane closer to the ___ of the cochlea
apex
higher frequencies vibrate the basilar membrane closer to the ___ of the cochlea
base
parts of the labyrinth
Bony
• series of channels in bone
• envelops membranous labyrinth
Membranous
• soft tissue contain sensory cells for hearing and balance
• dorsal is vestibular
– semi-circular canals, utricle, and sacculus
• ventral is auditory
– cochlea
movement of sound through the cochlea?
in through footplate of the stapes
up the scala vestibuli
down the scala tympani and out of the round window
another name for cochlear duct
scala media filled with endolymph
what part of the cochlear is filled with endolymph
and with perilymph?
endolymph → scale media (cochlear duct)
perilymph → scala vestibuli and scala tympani
apical surface sensory cells of the organ of corti are bathes in intracellular like ___
ionic environment → high K and low Na
there are ___ row of outer hair cells, and ___ row of inner hair cells in the organ of corti
3
1
hair cell are ___ cells
mechano-sensory
the afferent and efferent cells of the organ or corti are
afferent → inner
efferent → outer
hair cells
found in the organ of corti
characteristic sensory hairs or stereocilia on apical surface
» typical organized in 3 rows of descending height
communicate with overlying tectorial membrane
___ are essential to the transduction of sound
tip links on the stereocilla
will bind together the stereocilia of the hair bundle
deflection of hairs toward the tallest hair
depolarization
deflection of hairs away from the tallest hairs
hyperpolarization
asymmetric process excitatory
inhibitory
transduction channels are found near the tip of the ___ and are ___ channels
sterocilia
non-specific cationic channels
afferent fiber to the brain are made of __
inner hair cells contracted by ∼10
contract about 3 outer hair cells
specialized synapses to allow high and prolonged rates of synaptic transmission
outer hair cells
Both sensory and motor elements
• OHC are motile!
– contraction and elongation
• induced by voltage changes or inhibitory NT release
– modifies cochlear mechanics
– serves to sharpen cochlear frequency selectivity
– “cochlear amplifier”
loss of hearing is caused by ___
damage to hair cells
typical cause of sensorineural hearing loss
– drug insults (aminoglycosides)
– viral infection
– degeneration of genetic origin
– acoustic overstimulation
» break tip links or disrupt actin core - ineffective transduction
» hair cell death - excito-toxicity
acoustic overstimulation such as sat a concert will lead to ___
breaking tip links or disrupt actin core → can’t transduce wound
will eventually reform
middle ear muscles
tensor tympani
stapedius
___ collect and focus sound to the tympanic membrane
outer ear
