8.5 hearing

Question 1

3 ossicles?

Answer 1

malleus
incus
stapes

Question 2

dwscribe the pathway of the sound until oval window

Answer 2

oval window -> scala vestibuli -> helicotrema -> scala tympani -> round window

Question 3

where does the organ of corti located?

Answer 3

in the scala media

Question 4

describe sound

Answer 4

longitudinal wave

330 m/s

Question 5

describe pure tone

Answer 5

single frequency
sinusoid wave
not normally produced in nature

Question 6

dwscribe the intensity of sound

Answer 6

determined by the amount of pressure, measured by dB

Question 7

how can we measure dB?

Answer 7

dB= 20xlog(actual pressure/reference pressure)

Question 8

what does the referance pressure equal to?

Answer 8

20 microPascals

Question 9

what is the purpose of the middle ear? how?

Answer 9

increase in the intensity of sound

bcs oval window is 10-20 times smaller than tympanic membrane

Question 10

describe the structure of hair cells-

Answer 10

modified eputhelial cells with stereocilia on the apical surface.

Question 11

what happens to the hair cells apon stimulation?

Answer 11

they secrete Glu on their basal side

Question 12

what causes the stereocilia to bend?

what will happen then?

Answer 12

mechanical stimulus

causes channels to open -> potassium influx -> depol -> VGCaC open -> Glu exocytosis -> AP

Question 13

which hair cells are the primary auditory R?

Answer 13

inner hair cells

Question 14

where can we find the perilymph?

Answer 14

scala tympani + scala vestibuli

Question 15

K
Na
conc in the perilymph?

Answer 15

K- 2 nM

Na- 140 nM

Question 16

endolymph K and Na conc

Answer 16

K- 150 nM

Na- 1 nM

Question 17

what produces the endolymph? and where?

Answer 17

by the stria vascularis

in the cochlea

Question 18

what is the difference in voltage btw endolymph and membrane potential of the hair cells?

Answer 18

endolymph: +80 mV

hair cells: -40 mV

Question 19

why is the large electrochemical gradient btw endolymph and hair cells important?

Answer 19

bcs both contain a lot of potassium
so we need another help in generating a difference btw them that will lead to charge difference! so K ions will be driven from the endolymph to the hair cells

Question 20

what family does the channel on stereocilia belong to?

Answer 20

Transiant Receptor Potential (TRP) A1 family

Question 21

describe the Transiant Receptor Potential (TRP) A1

Answer 21

nonspecific cation channels

Question 22

what does contraction of the outer hair cells require?

Answer 22

Prestin
it is a motor protein
does not need ATP

Question 23

where will the higher frequency sound reach in the chochlea?

Answer 23

not far away. only low frequency will reach the apex

Question 24

Broadmann area?

Answer 24

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