I’m Deaf Flashcards
What does the pinnacle do?
Collect sound
What are the names of the three ossicles?
Malleus, incus, and stapes
What is the eardrum called?
Tympanic membrane
What do the ossicles do for the tympanic membrane?
Creates movement and causes more pressure to vibrate the cochlear fluid than the air could provide (amplifier)
What are the three fluid filled chambers in the cochlea called?
Scala vestibuli, Scala media, Scala tympani
What separates the Scala vestibuli and Scala media?
Reissner’s membrane
What separates the Scala media and Scala tympani?
Basilar membrane
Where is the organ of corti?
On the basilar membrane (media side)
What is the importance of the organ of corti?
It contains the auditory receptor cells
What hangs over the organ of corti that helps stimulate the hair cells?
Tectorial membrane
What are the chambers that contain perilymph?
Scala vestibuli and Scala tympani
What are the chambers that contain endolymph?
The Scala media
What are the ion concentrations in the perilymph?
High Na+ Low K+
What are the ion concentrations in the endolymph?
High K+ and Low Na+
What causes the ionic difference?
Stria vascularis
What is the helicotrema?
Hole at the apex of the basilar membrane that connects vestibuli and tympani
Where does the stapes push on the cochlea?
Oval window
What is a tonotopic map?
A place code on the basilar membrane that produced maxes amplitude deflection
What do the tips of stereocilia of hair cells touch?
Tectorial membrane
What do the outer hair cells bend in response to?
Tectorial membrane
What do the inner hair cells bend in response to?
Moving endolymph
Stereocilia have ____ gated ion channels
Mechanically
What causes when the hair cells are bent the correct way?
K+ channels are forced open which depolarizes the cell
Once hair cell is depolarized, what happens?
Ca2+ enters and causes NT transmission onto a nerve cell
What is the ratio of outer hair cells to inner hair cells?
3:1
What do the inner and outer hair cells communicate to?
Spiral ganglion cells
What percent of spiral ganglion neurons communicate w/ inner hair cells?
95%
One inner hair cell usually has ____ spiral ganglion attached
10
How many spiral ganglion receive input from several outer hair cells?
1
What is the purpose of outer hair cells?
Amplifying movement of the basilar membrane w/ low intensity sounds
What protein is responsible for outer hair movements?
Prestin
What happens if there’s no Prestin?
Near deafness
What is the central auditory pathway?
Ventral cochlear nuclei -> superior olive -> inferior colliculus -> MGN -> Aud cortex
When do binaural neurons first appear?
Superior olive
What do the Olivary nucleus use to travel to the inferior colliculus?
Lateral lemniscus pathway
IC projects to the ____
MGN in the thalamus
The MGN project to the ____
Auditory cortex
What is the characteristic frequency of a hair cell?
What frequency it is most responsive to
Does greater amplitude of a sound cause more of less depolarization?
More, which leads to APs being fired at an increased rate
What kind of sound produces basilar membrane movements over a longer distance? (Aka activates more hair cells)
Intense sounds
What is loudness correlated with?
Number of active neurons and firing rates
What encodes sound frequencies at <200Hz?
Phase locking (fire an AP at same cycle as sound)
How are intermediate frequencies encoding with?
Phase locking and tonotopy
What is the volley principle?
Intermediate sound frequencies display a pooled phase lock manner
At <5 kHZ, what encodes sound frequencies?
Tonotopy
What is interaural time delay?
Time diff from sound to hit one ear compared to another
What is used to compare differences in each ear for continuous low tones? (20-2k Hz)
Time it takes for each CYCLE to hit the ear
What is used to compare differences in each ear for continuous high tones (2k-20k Hz)?
Compared INTENSITY of the sound compared to both ears, whichever side is more intense is where the sound is coming from
What determines vertical sound localization?
Reflection from the pinna
How is the A1 structured?
Tonotopically
Where do MGN neurons terminate in A1?
Layer 4
What do Layers 2 and 3 of A1 contain?
Small pyramidal cells
What do Layers 5 and 6 contain?
Mostly pyramidal cells
