hearing and equilibrium Flashcards

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1
Q

what is the function of the ears?

A

hearing and equilibrium

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2
Q

what are the mechanoreceptors and where are they located?

A

they are the hair cells and are located in fluid-filled membranous/ labyrinth

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3
Q

what is the fluid in the membranous?

A

endolymph- surrounds hair cell
perilymph- circulates around labyrinth

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4
Q

what does the outer ear consist of?

A

auricle
auditory canal
tympanic membrane

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5
Q

what does the middle ear consist of?

A

tympanic cavity
auditory ossicles- malleus, incus, stepes
pharyntympanic or auditory tube

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6
Q

what is the auditory tube?

A

it connects the middle ear to the nasopharynx

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7
Q

What does the inner ear consist of?

A

fluid-filled bony labyrinth lined in the membrane - membranous labyrinth
cochlea, vestibule, semicircular canals

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8
Q

what is sound?

A

air pressure waves
wavelength (distance between waves) pitch of sound
amplitude(height) is the loudness

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9
Q

what is frequency?

A

measured in hz = waves/msec
increased frequency= higher pitch
hertz

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10
Q

what is amplitude?

A

wave height measured in decibals dB
increased amplitude=louder

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11
Q

what are the mechanoreceptors?

A

located in spiral organs (organ of corti) of cochlea
receptors called hair cells

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12
Q

what happens when stereocilia on cells bend?

A

mechanically gated ion channels open and an action potencial occurs

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13
Q

explain how the ion channels open for an action potencial to occur?

A

bending of the stereocillia causes mechanically gated k channels to open, k concentration is high in endolymph so k flows in and depolarization occurs

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14
Q

what are the steps in hearing?

A
  1. sound waves cause tympanic m to vibrate
  2. ossciles amplify vibrations
  3. stapes pushes against oval window creating waves in perilymph
  4. pressure waves in tympanic duct moves bassilar m.
  5. cilia of hair cells in cochlear duct bend as they touch tectorial membrane causing depolarization
  6. wave energy dsicepated at round window
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15
Q

what does the flexibility of the basilar membrane varies in length causes what?

A

causes different hair cells to respond to sounds of different pitch

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16
Q

what is equilibrium?

A

in the inner ear and consists of vestibular aparatus

17
Q

what are the two parts of the vestibular aparatus?

A

vestibule- utricle and saccule
semicircular canals

18
Q

what are the two types of equilibrium?

A

static equilibrium from vestibules
head position with respect to gravity and liner acceleration
dynamic equilibrium from semicircular canals
roatational movement of head in space

19
Q

what does reflexive mean?

A

means we are only aware of it when things go wrong
our maintenance of equilibrium is reflexive

20
Q

what are the sensory receptors involved in equilibrium

A

hair cells with are mechanoreceptors

21
Q

what is a maculae?

A

it is in vestibule and is in epithelial patches of walls of utricle and saccule
hair cells have to respond to positional changes in relation to gravity

22
Q

what do the utricle and saccule do in the maculae?

A

utricle- detects movement in horizontal plane
eg. tilting head linear acceleration
saccule- detects movement in changes vertical plane
eg. being upside down

23
Q

what are the hair cells in macculae embedded in?

A

jelly-like otolithic membrane which makes it weighted

24
Q

how does equilibrium work in maculae?

A

crystals of calicium cabronate otoliths add weight to otolithic membrane
membrane slides in the direction of gravity
hair cells stereocilia bend
mechanically gated ion channels open and depolarization occurs

25
Q

what is crista ampulee?

A

aspect of equilibrium in the semicircular canals

26
Q

where are the hair cells in crista ampulee?

A

they project into the cupuia which is a hap of gelatinous material

27
Q

describe how crista ampulee works?

A

roation of head moves the endolymph
capula moves
sterocilia bend
action potencial created

28
Q

what detects rotation?

A

3 semicircular canals orriented in 3 different planes (ampulla at the base of each canal) detect rotation in different planes

29
Q

what is the sensory pathway for equilibrium?

A

goes from the vestibular nerve
to vestiocochlear nerve
to vestibular nuclei in medulla oblongata
(motion sickness drugs depress these centers)
can go to either cerebellum or extraocular eye muscles
which sends messages to skeletal position or back to the vestibulocochlear nerve used to stabilize image