lecture 17 (test 2) Flashcards

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1
Q

role of the outer ear

A
  • funnels sound
  • conducts sound vibrations
  • prevents damage to the tympanic membrane
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2
Q

what is the role of the pinna

A
  • part of the outer ear
  • channels sound to the eardrum
  • lined with wax secreting glands that protect the ear
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3
Q

the middle ear is made up of the …

A

malleus
incus
stapes

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4
Q

malleus

A

“hammer”
attached to eardrum
head connected to the incus

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5
Q

incus

A

“anvil”

the shaft is connected to the stapes

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6
Q

stapes

A

oval shaped footplate makes a tight connection with the oval window

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7
Q

the function of the middle ear

A

conduct vibration to the inner ear

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8
Q

eustachian tube

A

equalizes pressure across eardrum

connects the ear to the back of the throat

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9
Q

the lever effect

A

joints between bones are hinged

movement of the long part of incus creates a greater force on the incus

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10
Q

the condensation effect

A

sound collected my tympanic membrane and channeled through the ossicles

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11
Q

surface area or the eardrum is ______ than the oval window

A

18 times bigger

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12
Q

muscles in the middle ear

A
tensor tympani (attached to malleus)
stapedius (attaches to stapes)
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13
Q

what activates the middle ear muscles and when

A

motor neurons in response to loud sounds

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14
Q

what does tensing middle ear muscles do

A

reduce ossicle movement

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15
Q

middle ear muscle reflex has a ______ delay

A

200ms (arent activated in time for loud sudden noises)

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16
Q

3 canals of inner ear

A

vestibular canal
typanic canal
middle canal

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17
Q

3 canals of inner ear separated by what

A

basilar membrane and Reissner’s membrane

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18
Q

sound transmission from the middle ear to the inner ear

A

1) displacement of stapes on oval window, increases pressure in the vestibular canal
2) pressure gradients transmitted across resiner’s membrane into middle canal
3) causes movement of the basilar membrane, on which the transduction apparatus sits
4) increased pressure on the tympanic membrane is relieved by the outward movement of the round window

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19
Q

where is the organ of Corti located

A

along the top of the basilar membrane

20
Q

how does the organ of Corti work

A

recieves vibrations from basilar membrane

21
Q

what is the organ of Corti mad of

A

a scaffold of the cells that supports the specialized neurons called hair cells

22
Q

arch of Corti separates into ____ and _____

A

the inner and outer portion

23
Q

the organ of Corti is arranged in what matter

A

bilaterally symmetrical

24
Q

tectorial membrane attaches where

A

at the end of the tallest stereocilia

25
Q

inner hair cells

A

single row
transform vibrational energy to electrical energy
innervated by the afferent auditory nerve fibers
the inner side of arch of Corti

26
Q

outer hair cells

A

3 rows

the outer side of arch of Corti

27
Q

the tectorial membrane is a

A

gelatinous structure

28
Q

what happens when stereocilia are flexed

A

release of neurotransmitters

29
Q

stereocilia bend in which direction

A

the direction of the force

30
Q

a traveling wave causes the basilar membrane to move _________ and _______

A

up and down

31
Q

which direction do hair cells and tectorial membrane move and what is it called

A

the opposite, shearing force

32
Q

what is the result of the shearing force

A

ion channels open

33
Q

what are tip links

A

fine filaments that run parallel to the plane of bilateral symmetry

34
Q

how are inner hair stereocilia arranged

A

tallest to shortest

35
Q

steps to auditory transduction

A

1) displacement of hair bundles towards tallest stereocilia
2) tip links open cation-selective channels
3) entry of cation (mainly K+) depolarizes the hair cell
4) voltage-gated Ca2+ channels open and allow Ca2+ entry
5) Neurotransmitter (glutamate) released onto cochlear nerve fibers that innervate the hair cells
6) AP in cochlear nerve carry info to higher processing areas

36
Q

what is mechanoelectrical conduction

A
mechanical displacement converted to an electrical signal
is fast (10 μs) 
is sensitive (hair cell movements detected on atomic nm scale)
37
Q

sensory recptors of the auditory system

A

hair cells

38
Q

how do we detect greater amplitude in the cochlea

A
  • HOW MUCH BASILAR MEBRAN MOVES UP AND DOWN
  • the tympanic membrane will move farther
  • greater deflection of basilar and tectorial membranes
  • greater shearing force
  • greater depolarization and more neurotransmitters released
39
Q

place code

A
  • a complex tone will cause the basilar membrane to vibrate where each of its harmonics frequencies that make up the complex sound
40
Q

vibrations start at what end of the basilar membrane

A

base

41
Q

the base is for what frequency

A

high

42
Q

apex is for what frequency

A

low

43
Q

which end of the basilar membrane is wider

A

apex

44
Q

what frequencies are stimulated earlier in a complex sound

A

higher

45
Q

when will the sound be heard

A

when vibration reaches the apex

46
Q

tonotopic map

A

how frequencies are mapped on the basilar membrane

47
Q

what acts like a Fourier analyzer in the ear

A

basilar membrane