Inner Ear Review 2

Question 1

Why is IMM important

Answer 1

helps to overcome loss of the sound wave coming in acoustically

Question 2

these cells are the first row of supporting cells only for the OHC’s, all the way up to the stereocilia

Answer 2

Dieter cells

Question 3

these support the whole structure of the organ of corti

Answer 3

Hensen’s cells

Question 4

help create the tunnel in organ of corti

Answer 4

outer and inner pillars

Question 5

picks up info and carries it away

Answer 5

afferent/sensory

Question 6

going to the motor unit

Answer 6

efferant/motor

Question 7

Explain sound process to this point

Answer 7

Sound is funneled by the pinna into the EAC striking the TM (acoustic) - Ossicles vibrate (mechanical) and increase in energy due to IMM - footplate rocks into oval window in the scala vestibuli - Wave gets released through the scala tympani at the round window - wave also stimulates the BM at the best frequency releasing neuro chemicals to be sent to the brain (electro-chemical)

Question 8

connects the scala media of cochlea to the saccule

Answer 8

ductus reuniens

Question 9

this attaches to the membraneous portion running through the vestibular aqueduct to the sac to empty into the dura in the brain

Answer 9

endolymphatic duct

Question 10

The cell bodies for cochlear fibers of CN VIII are

Answer 10

spiral ganglia

Question 11

The cell bodies for vestibular fibers of CN VIII are

Answer 11

scarpa’s ganglia

Question 12

the thin passageway that connects the saccule to the cochlear duct is:

Answer 12

ductus reuniens

Question 13

fluid inside the ductus reuniens?

Answer 13

endolymph

Question 14

how many vestibular sensory epithelial areas are there in one ear?

Answer 14

5

Question 15

how many vestibular sensory epithelial areas are there in one head?

Answer 15

10

Question 16

List the areas where you find the sensory epithelium with vestibular hair cells within the inner ear?

Answer 16

3 ampullae (anterior, posterior, lateral), utricle, saccule

Question 17

How do the waves travel from the stapes footplate?

Answer 17

1. across reissner’s membrane where the fluid pushes down from vestibuli to tympani and then out the round window
2. entire length of the BM is displaced (regardless of pressure) but due to stiffness gradient of BM, the frequency of the wave will dictate which organ of corti along the BM will be max displaced

Question 18

endolymph is high in

Answer 18

potassium

Question 19

ST, SV and CSF are high in

Answer 19

sodium

Question 20

Are compositions of perilymph in ST and SV the same?

Answer 20

No, SV has higher potassium and lower sodium

Question 21

What is endocochlear potential

Answer 21

endolymph has low calcium content and held at a positive voltage (80-85 mV) and only found in the cochlear duct

Question 22

Where do we find the highest EP?

Answer 22

highest at the basal turn and decreases towards the apex

Question 23

What is EP dependent on?

Answer 23

metabolism and ion transport

Question 24

If there is anoxia or occluded blood supply with ion transport inhibitors (diharetics), what happes to EP

Answer 24

rapidly falls and becomes negative

Question 25

What is the site of EP generation

Answer 25

stria vascularis

Question 26

What is the most common inherited cause of sensorineural deafness?

Answer 26

defects in genes that code for connexin proteins that form gap junction

Question 27

ion transporters of stria vascularis are the same as those in what

Answer 27

kidney

Question 28

concentration in solutions

Answer 28

millimolar

Question 29

process of the hair cells turning mechanical energy into a potential change

Answer 29

potassium in through stereocilia, calcium in through cell wall channels, carries glutamate+ out to CN8 afferent ganglion

Question 30

Process of the sensory system receptors

Answer 30

External stimulus — accessory structure — sensory receptor cell — synapse — sensory neuron — synapse

Question 31

What are the specialized sensory neurons for our hearing system?

Answer 31

OHC IHC

Question 32

What does it mean to have "graded" sensory receptor cells

Answer 32

Amplitude modulated (increased stimulus intensity = increased voltage change)

Question 33

Simplified sound transmission process:

Answer 33

1. Sound strikes the tympanic membrane 2. Bones vibrate 3. Oval window moves fluid in the scala vestibule 4. The fluid pushes on the respective location of the basilar membrane and activates the movement of the tectorial membrane 5. The stereocilia are activated to open ion channels 5. Waves are dissipated back into the middle ear space through the round window

Question 34

what lays on top of the outer hair cells steriocillia?

Answer 34

Tectorial membrane

Question 35

what supplies blood and oxygen to the cochlea?

Answer 35

stria vascularis

Question 36

ratio of outer to inner hair cells

Answer 36

3 outer to 1 inner

Question 37

the cochlea is ______ organized

Answer 37

tonotopically

Question 38

high frequencies are at the

Answer 38

base

Question 39

the OHC only enhance sounds from _________ dB

Answer 39

0-40 dB

Question 40

what do the sereocilia sit on?

Answer 40

cuticular plate

Question 41

What is depolarization?

Answer 41

make something more positive inside of hair cells from -45 mV to 0mV excitatory process

Question 42

What is hyperpolarization?

Answer 42

make something more negative overshoots and goes from -45 ot -65 mV inhibitory in neural transmission