exam one (audio & vestibular) Flashcards
passage of sound
auditory receptors in cochlea, brain stem neurons, MGN, auditory cortex
audible variations in air pressure
sound
what is the audible range in humans
20-20,000 Hz
perception of sound frequency (low pitch = low frequency, high pitch = higher frequency)
pitch
higher intensity is perceived as _____ than low intensity
louder
a high amplitude is a ___ sound and low amplitude is ___ sound
loud, soft
by age 65 ___ of hair cells are gone
40%
sound waves move through the ear in what order
sound waves, tympanic membrane, ossicles, oval window, cochlear fluid, and sensory neuron response
what is the function of the ossicles and what are they called
sound amplification by putting pressure on oval window; malleus, incus, stapes
reflexive response where onset of loud sound causes two middle ear muscles to contract (these rigid muscles diminish amplification of ossicles)
attenuation reflex
fluid in outer tubes of cochlea (scala vestibuli and scala tympani), ion concentrations?
perilymph; low K+ and high Na+
fluid in inner ear tube of cochlea (scala media); ion concentration?
endolymph; high K+ and low Na+
response of the ____ ____ to sound establishes a place code in different locations of membrane are maximally deformed by different sound frequencies
basilar membrane
higher frequencies ____ faster; low frequencies make it further along the basilar membrane
dissipate
on the basilar membrane, there are stereocilia extending into tectorial membrane (because basilar membrane moves)
outer hair cells
just below the tectorial membrane the __ ____ ___ have stereocilia extending into the endolymph
inner hair cells
bending of the basilar membrane moves hair cells relative to ___ ____ bending the ____
tectorial membrane, stereocilia
sound bends the basilar membrane upward which results in the stereocilia bending _____; this is the final step of the mechanical message
outward
there are more outer or inner hair cells
outer
once the mechanically gated channels are open the K+ ions move in which ____ the hair cell membrane
depolarize
the bending of the basilar membrane opens mechanicaly gated ___ channels
K+
Once the hair cell membrane is depolarized ____ has an influx and GLU is released onto ___ ___ ___
Ca2+ , spiral ganglion cells
one spiral ganglion cell then synapses with ____ ____ hair cells but it synapses with only one ____ hair cell
numerous outer; inner
one inner hair cells synaposes with only one spiral ganglion cell, true or false?
false
sound amplification done the outer hair cells is known as ____ ___
cochlear amplifier
outer hair cells have a motor protein called ___ which allows the hair cell to compress and expand; it is driven by acetylcholine neurons (brain stem)
prestin
prestin essentially helps the outer hair cell to exaggerate the bending of the ___ ___
basilar membrane
without prestin the “wave” will go the same distance down basilar membrane but loses its ___ ___
loud frequency
electrode placement of cochlear implants serves to
reserve tonotopic map
each cochlear nucleus receives input from ___ ear (medulla)
one
neurons are first present in the ___ ___ (medulla)
superior olive
what is the pathway after the spiral ganglion cells from the inner ear
auditory nerve takes it to the cochlear nucleus to the superior olive
from the medulla where does sound travel as an action potential
it is taken by the lateral lemniscus to the inferior colliculus (mid brain)
the superior olive is ____
binaural (sound sharing)
from the inferior colliculus sound goes to what structure in the thalamus
MGN to the auditory cortex
everything after the medulla (superior olive) is information from both ears, true or false
true
encoding sound intensity (loudness) can be done by the ___ ___ of individual neurons
firing rate
as intensity increases so does amplitude of basilar membrane movement, this causes the membrane potential to more rapidly become _____ and ______
depolarized and hyperpolarized
the membrane becoming hypoerpolarized and depolarized rapidly increases number of action potentials by the ___ ____ ___
spiral ganglion cells
another approach encoding loudness is to look at the total number of ____ ____; the more hair cells activated by larger area of basilar membrane vibrating, the broader the frequency range (to which spiral ganglion cells still respond)
active neurons
frequency at which neuron is most responsiveness
characteristic frequency
firing of auditory nerved correspond to a particular ____ of the sounds wave, which is called phase locking
phase
the pinna allows us to have ____ sound localization
vertical
interaural time delay (time taken for a sound to reach second ear) is most effective localization strategy for ____ frequency
low
interaural intensity difference (head casts a sound shadow, reducing sound intensity) is the most effective localization strategy for ____ frequency sounds
high
the impulses of sound reach olivary neuron at the same time and ____ to produce an action potential that indicated perception of sound
summate
axons leaving the MGN project to A1 of the primary auditory cortex where organization called ____ is maintained by Hz
tonotopy
if there was a uniltateral lesion of the A1 compared to V1 what would happen and why?
The ability to hear would be mostly unaffected (except precise localization) because cross talk happens sooner and both ears get the same stimuli
what are the otolith organs and what do they do
utricle and saccule; movement (acceleration and tilt of head)
the semicircular canals function to maintain
position
hair cells of the otolith organs are embedded in the _____ (sensory epithelium)
macula
the cilia which project out of the epithelium are capped by ____ crystals
otoconia
the macula hairs respond to ___ ___ through the bending of the cillia
head tilt
what benefit is there to have three semicircular canals
they are three different directions and sense all possible head-rotation angles
head rotation causes _____ of hair cells in semicircular canal on one side and ____ of hair cells on the other side, this is called?
excitation, inhibition and push-pull arrangement
the auditory/vestibular nerve goes from the cochlea to the ____ then the limb and neck motor neurons
medulla
reflex that keeps line of sight fixed on visual target when head is in motion
the vestibulo-ocular reflex
how does the vestibulo-ocular reflex work
senses rotation of head and rapidly commands movement of eyes in opposite direction
