The Ear Flashcards

1
Q

what do the semi circular canals of the ear measure

A

change in velocity, rotational acceleration in particular

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2
Q

in what situation do the semi circular canals give no output

A

once at constant velocity

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3
Q

what bone are the semi circular canals in, be specific

A

petrous part of the temporal bone

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4
Q

what is the fluid in the semi circular canals called

A

endolymph

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5
Q

give gibe differences for the constituents of the endolymph compared to plasma

A

endolymph lacks clotting factors and has much less protein

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6
Q

what connects all 3 semicircular canals

A

the vestibule

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7
Q

what is within the utricle of the ear that detects what orientation your head is in

A

the otoliths

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8
Q

which of the cupula and ampulla is above the other in the semi circular canal

A

the ampulla

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9
Q

what type of cell is all around the cupulla?

A

columnar cells

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10
Q

how are the stereocilia different to regular cilia in the way they work?

A

these stereocilia move first and then put a signal in, rather than the opposite of that

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11
Q

where do the signals go from the semicircular canals?

A

the cerebellum

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12
Q

what is physiological dizziness

A

it is the continuous flow of the endolymph in the semicircular canal after spinning has ended, the signals will be sent to the cerebellum and it will cause the contraction of the muscles on the side of the body that is are on the opposite side to the direction of lymph movement, but as you are no longer spinning you lose your balance and fall.

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13
Q

define dizziness

A

when the stereocilia of the semi circular cannals send signals to the cerebellum when there is no movement

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14
Q

what is labrynthitis

A

inflammation in the hair cells of the semicircular canals, so the stereocilia. that is often due to viral infection

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15
Q

what is vestibulitis

A

infection of the receptor cells in the semicircular canals’ cupula, the columnar cells

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16
Q

what is the function of the external ear

A

to transmit the sounds around the ear into the middle ear that starts at the tympanic membrane.

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17
Q

if a person has conductive hearing loss, what part of the ear is affected

A

the the external ear, whreby a barrier is stopping the sound getting from outside to the middle ear

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18
Q

what tube connects the atmosphere with the start of the middle ear (the tympanic membrane)

A

the external acoustic meatus

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19
Q

what is the internal acoustic meatus

A

this is a fissure in the skull through which CNs 7 and 8 travel

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20
Q

what is the boundary between the middle and inner ear

A

the oval window

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21
Q

what are the 2 main components of the inner eaar

A

the cochlea and the semicircular cannals

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22
Q

what part of the inner ear is the internal acoustic meatus intimate with

A

the cochlea

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23
Q

what does the eustacian tube link?

A

the middle ear to the pharynx

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24
Q

what is the purpose of the middle ear

A

to get the kinetic energy of the sound wave into the liquid part of the inner ear

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25
Q

what name is given to the chain that transmits the kinetic sound waves from the outer to middle ear

A

the ossicular chain

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26
Q

what part of the middle ear puts the vibrations into the inner ear, be specific

A

the footplate of the stapies into the oval window

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27
Q

what part of the ear is blocked in grommits?

A

the middle ear, due to its connection with the pharynx via the eustacian tube

28
Q

is the utricle or the saccule closest to the coclea?

A

the saccule

29
Q

what are the names given to each semicircular canal?

A

posterior, superior and horizontal/ lateral

30
Q

hwat is the purpose of the hair cells in the ear, what do they do, one word

A

transduction

31
Q

are shorter or longer fibres at the apex of the cochlea and what frequency do they detect

A

long and low frequency

32
Q

what type of map allows the brain to know which hair cells (at the apex of base) are vibrating more and so what frequency the sound wave is it?

A

the tonotropic map. as impulses from different regions along it go to different parts of the brain via the appropriate sensory neurones. so frequency is matched to position as there will be a greater oscilation in the hair cells of the appropriate frequency of the entering sound

33
Q

what is the order of the types of scala from top to bottom, in a cross section out of the coclea

A

scala vestibuli, scala media, scala typani

34
Q

which type of hair cell is more numerous in the ear

A

the inner hair cell

35
Q

what membrane forms the base of the scala media and where is it narrowest? the base or apex

A

the basilar membrane. the base. as the higher frequency sounds are able to vibrate this

36
Q

what provides the endolymph with constant k+ to form the unusual resting potential

A

stri vascularis

37
Q

which of the scala have alot of Na+ and K+

A

Na+=scala vestibule and tympani, K+= scala media

38
Q

what is the sensory organ of hearing called?

A

the organ of corti

39
Q

90% of the afferent fibres are from which type of hair cell?

A

the inner hair cell. so the inner hair cells do most of the hearing

40
Q

the outer hair cells mainly have efferent or afferent nerves connected to them?

A

efferent

41
Q

wha 2 ways can the stereocilia be damaged and start to break off?

A

listening to v loud sounds like music and certain antibiotics damage them

42
Q

where does the auditory cord go to from the cochlea

A

to the thalamus

43
Q

how many times that the cochlea curve round the modeolus (ie the central axis of the spiral)

A

5 times.

44
Q

through which scala do the vibrations move 1.up the cochlea 2.down the cochlea

A

1.scala vestibule 2.scala tympani

45
Q

what membrane is vibrated by the movement of the endolymph and what do the hair cells compress against due to this?

A

the basilar membrane, the tectorial membrane

46
Q

describe how k+ causes a signal to be sent along the cochear nerve

A

at the apical portion (tectoral membrane bit) of the hair cell, K+ flows into the cell, this depolarises it and so Ca2+ channels at the base of the hair cell (nearer the basilar membrane) open. so vesucles containing neurotransmitter are released from the cell into the nerves, resulting in an action potential to be sent from there. It is the high concentration of K+ just outside the apical surface that allows for this. the fact that the area surroundng the lower portion of the hair cell has low K+ means that the K+ flows out and so the cell is now repolarised.

47
Q

what makes the use of K+ in the cochlea so unique?

A

it is used for both de and repolarisation. de- at the top and re- at the bottom. so when the endolymph flows up, depolarisation occurs and when it flows down, repolarisation occurs

48
Q

what actually allows the entry of K+ at the apical side of the hair cell

A

tip links, so when the hair cell moves, the tip link is stretched and so the K+ channels open, allowing flow of potassium in down a conc gradient

49
Q

what 2 things distinguish a loud from a quiet sound?

A

the firing rate of the nerves and the number of nerves recruited, so temporal and spatial summation

50
Q

what are the 3 types of cochlear nuclei in the brains cortex (specifically part of the temporal lobe)

A

the lateral,dorsal and ventral cochlear nuclei

51
Q

what does the superior olive do in terms of sound detection

A

the localisation of sound

52
Q

does the medial superior olive do low or high frequency analysis

A

low frquency

53
Q

do the dorsal or ventral collicular nuclei project to the inferior colliculus

A

dorsal

54
Q

what property of sound makes your ear less able to distinguish the frequencies

A

the louder the sound

55
Q

what is the main purpose of the outer hair cells and what other thing also does this role?

A

amplification of sound, the difference in surface area between the tympanic membrane and oval window that increases the pressure of the sound waves

56
Q

what protein is responsible for the shape change in the outer hair cells and what is its shape dependent on

A

prestin. voltage, because the afferent nerve fibres from the inner hair cells are directly linked to efferent fibres going to the outer hair cells, so that the outer hair cells can then amplify whatever sound signals are detected by the inner hairs cells

57
Q

does a problem in the visual cortex of the occipital lobe affect the nystagmus reflex?

A

no, because it all happens in the brain stem

58
Q

what is the series of signals involved in a nystagmus ( which nuclei)

A

from the semicircular canal, via the vestibular nerve, to the 8th nerve nucleus then to the 6th nerve nucelus on the contralateral side. this will send an impulse to the 3rd nerve nucleus of the opposite eye. the 3rd nerve nucleu then operates the medial rectus and the 6th nerve nucleus operates lateral rectus on the eye at the same side of that nucleus

59
Q

when using water to test for brainstem death, which semicircular canal is made vertical?

A

the horizontal semicircular canal

60
Q

is the nystagmus away or towards the ear with the a. cold water being poured in 2.warm water being poured in

A

a. away 2.towards

61
Q

which 2 nerve nuclei are in the pons and which one is in the midbrain that are involved in the nystagmus?

A

pons= 6th and 8th midbrain=3rd

62
Q

which semicircular canal allows nystagmus, in normal conditions, whereas the other 2 don’t

A

horizontal

63
Q

what allows the 2 eyes to move in the same direction in a nystagmus

A

the fact that the 6th nerve nucleus operates lateral rectus of the ipsilateral side but send impulses to the 3rd nerve nucleus of the opposite eye via crossover

64
Q

what 2 muscles of the middle ear alter the stiffness of the ossicular chain

A

the stapedius and tensor tympani

65
Q

which part o fthe ear have endolymph that detects the position of the head and linear acceleration

A

the utricle and saccule

66
Q

what 4 areas have endolymph and what 2 areas have perilymph

A

endolymph: semicircular canals, the utricle and the saccule and scala media. perilymph is the scala tympani and scala media.