Lecture 16- The ear: hearing and balance Flashcards

1
Q

what is hearing?

A

our brains perception of sound energy

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2
Q

what is sound transduction?

A

conversion of mechanical energy of sound waves to electrical energy

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3
Q

what is pitch?

A

our interpretation of frequency

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4
Q

what is loudness/ volume?

A

our perception of intensity/ amplitude of sound waves

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5
Q

what does the processing of sound tell us?

A

tells us about distance direction and movement

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6
Q

what are sound waves?

A

compressed air

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7
Q

what structures are in the external ear? 3

A

pinna: directs sound waves into the ear
external auditory canal
tympanic membrane

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8
Q

what structures are in the middle ear? 4

A

ossicles (malleus, incus, stapes)
eustachian tube (connects to pharynx/throat)

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9
Q

what structures are in the inner ear? 5

A

semicircular canals
vestibular apparatus
oval window
cochlea
nerves

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10
Q

what are the two different large overall structures of the inner ear?

A

bony labyrinth
membranous labyrinth

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11
Q

what is the difference between bony labyrinth and membraneous labyrinth?

A

membranous labyrinth is located within bony labyrinth
membranous labyrinth is filled with fluid

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12
Q

what does the membranous labyrinth contain?

A

cochlear duct with organ or corti
3 semicircular ducts with 1 crista ampullaris in each
utricle/saccule with 1 macula in each

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13
Q

what happens when you hear sounds? what is the process?

A
  1. sound waves strike the tympanic membrane and vibrates
  2. vibration is transferred to the 3 bones of the middle ear
  3. vibrations of the oval window create fluid waves within the cochlea
  4. fluid waves cause hair cells to bend and ion channels to open which causes neurotransmitter release
  5. neurotransmitter release onto sensory neurons creates AP that travel through cochlear nerve to brain
  6. energy from waves transfers across the cochlear duct into the tympanic duct, then brought back into middle ear at the round window
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14
Q

what is the process of hearing sounds through the cochlea in simple terms? Old Vegetables Help Tame Rabbits

A

oval window
vestibular duct
helicotrema (end of cochlea)
tympanic duct
round window

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15
Q

what does the cochlear nerve do?

A

transmits action potentials from the primary auditory neurons to cochlear nuclei in the medulla on their way to the sensory cortex

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16
Q

what are the 3 ducts that the cochlea has? what are they made of?

A

vestibular duct (contains perilymph that is extracellular fluid or plasma)
tympanic duct (contains perilymph that is extracellular fluid or plasma)
chochear duct (contains endolymph that has a high concentration of K+)

17
Q

what is the organ or corit? where is it located?

A

receptor organ of hearing
cochlear duct

18
Q

what structures are included in the organ of corti?

A

tectorial membrane
hair cells
nerve fibres
basilar membrane

19
Q

what is the structure of the hair cells?

A

stereocilia (look like toes) the tallest stereocilia is called the kinocilium (big toe) on the stereocilia are K+ channel proteins that are mechanically gated
connected by tiplinks

20
Q

what does happens when hair cells bend toward kinocilium?

A

excitatory: more channel proteins open, K+ entry depolarizes cell, thus have more action potential FREQUENCY which release more neurotransmitters

21
Q

what happens when hair cells bend away from kinocilium?

A

inhibition: channels close, less K+ entry, cell hyperpolarizes, frequency of AP decreases, thus less neurotransmitters released

22
Q

the basilar membrane has variable sensitivity to sound wave frequency along its length, describe the high frequency side and low frequency side

A

high pitch: stiff thicker region near round window
low pitch: flexible skinny region near helicotrema (end of cochlea)

23
Q

when sound leaves the cochlea what is the process through the brain?

A

vestibulocochlear nerve
medulla
midbrain
thalamus
cortex
OR
vestibulocochlear nerve
cerebellum

24
Q

what is conductive hearing loss?

A

loss of ability of ossicles to transmit vibration to oval window (external or middle)

25
Q

what is sensorineural hearing loss?

A

loss of ability of hair cells to respond to the movement of tectorial membrane generate electrical signals (middle ear)

26
Q

what is central hearing loss?

A

loss of ability of neural pathways from vesitibubchoclear nerve to CNS (stroke)

27
Q

where is the utricle/ saccule located in the inner ear?

A

inside vestibular apparatus/ vestibule

28
Q

what are the 2 compartments of the vestibular apparatus?

A

otolith organs
semicircular canals

29
Q

what does teh otolith organs consist of? 2

A

macula (sensory organ)
saccule/ utricle (detects linear acceleration and head position)

30
Q

what are the structures of the macula?

A

otoliths (crystals that move in response to gravitational forces)
gelatinous otolith membrane

31
Q

what do the semicircular canals consist of?

A

superior (sensitive to rotational acceleration)
horizontal (sensitive to rotational acceleration)
posterior (sensitive to rotational acceleration)
crista ampullaris

32
Q

what does the crista ampullaris do?

A

provides information about rotation of head
they rest on top of utricle and saccule

33
Q
A