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An Sc 310 > Lec 11 - Ear, Hearing, and Equilibrium > Flashcards

Lec 11 - Ear, Hearing, and Equilibrium Flashcards

1
Q

what are the two fxns of the ear

A

-hearing and eq

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2
Q

what is the outer ear made of and what is its fxn

A

-pinna and external auditory meatus (ear canal)
-for collecting sound waves and sending them to tympanic membrane

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3
Q

what is the middle ear made of and what is its fxn

A

-tympanic membrane, ossicles (malleus, incus, stapes), oval window, round window
-for amplification of sound waves to prepare them for transmission from an air to a fluid enviro

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4
Q

what is the inner ear made of, and what is it for

A

-cochlea, vestibular apparatus
-for transduction of sound energy (cochlea is for hearing and vestib app is for eq)

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5
Q

what is the eustachian (auditory) tube for

A

-maintain eq of pressure
-connects the airfield of middle ear w the pharynx in the throat
-normally collapsed and opens only for a short period of time to balance middle ear pressure w atmospheric air

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6
Q

what are sound waves

A

-mechanical waves caused by motion of air molecules

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7
Q

how do molecules move during sound waves and how does it transmit energy

A

-molecules do not move from og position but instead bump into adjacent molecules to transfer energy, causing more molecules to collide
-energy is transmitted in waves that radiate away from vibrating object
-sound waves spread in three dimensions

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8
Q

how are intensity and pitch measured

A

-intensity (loudness): amplitude of sound waves measured in dB
-pitch: frequency of waves measured in waves/sec (Hz)

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9
Q

what frequency do humans hear at

A

20 -20,000 Hz

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10
Q

sound is the brain’s interpretation of what

A

-frequency and amplitude

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11
Q

what is the diff b/w low and high frequency waves

A

-low correspond to low pitch sounds
-high correspond to high pitch sounds

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12
Q

what physical aspect of a wave does amplitude correspond to, what is loudness an interpretation of

A

-wave height
-sound intensity

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13
Q

what is the diff b/w infrasound, ultrasound, and acoustic sounds, which animals hear what

A

-infra waves have too low frequency for humans to hear (whales, elephants, hippos), below 20 Hz
-acoustic are what humans can hear
-ultrasound waves have too high frequency for humans to hear (bats, dogs, birds, insects), above 20,000 Hz

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14
Q

what adverse affects does exposure to infrasound waves cause, how are ppl usually exposed to them

A

-headache, concentration difficulties, moods, depression, sleep disorder
-occupation may expose indivs

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15
Q

what evidence is there that exposure to radiofrequency waves from 5G increase the risk of coronavirus

A
  1. causes morphologic changes in RBC that can lead to hypercoagulation
  2. impairs microcirculation and reduces RBC and hemoglobin lvls causing hypoxia
  3. leads to immune system dysfxn (immunosuppression, autoimmunity, hyperinflammation)
  4. increases oxidative stress on cells leading to increased prodn of free radicals causing damage
  5. increases intracellular Ca2+ which is essential for viral entry, repln, and release, and promotes pro-inflammatory pathways
  6. makes heart arrhythmias and cardiac disorders worse
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16
Q

how do a dog and cat’s hearing range compare to a humans

A

-dogs hear 40 - 60,000 Hz
-cats hear 55 - 79,000 Hz
-dog’s can hear 4x the distance that humans can and can recognize sounds faster
-cats can hear higher pitched sounds and can hear ultrasonic sounds that rodents use

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17
Q

what causes the tympanic membrane to vibrate

A

sound waves

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18
Q

what is the first lvl of sound amplification and transduction, what are the sound waves converted to

A

-ossicles
-mechanical vibrations

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19
Q

what is the second lvl of sound amplification and transduction, what are the vibrations converted to

A

-oval window (smaller than tympanic membrane)
-fluid waves

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20
Q

what is the third lvl of transduction, what are the fluid waves converted to

A

-bending of hair cells in cochlea
-electrical signals

21
Q

what is the fourth lvl of transduction

A

-electrical signals releasing NTs

22
Q

what is the fifth lvl of transduction, through what nerve is info transmitted to brain

A

-NTs binding to primary auditory neurons causing APs
-vestibulocochlear nerve (nerve VIII)

23
Q

outline how sound moves through the ear

A

-sound waves hit tympanic membrane and become vibrations which go through the ossicles
-the stapes hits the oval window creating fluid waves in the cochlea
-fluid waves bend the hair cells which open ion channels and release NTs
-NTs bind to sensory neurons and cause APs that go through cochlear nerve to brain

24
Q

how does energy from the sound waves dissipate

A

-moves across cochlear duct to tympanic duct and dissipate to middle ear

25
Q

where does sound energy get converted into APs

A

cochlea

26
Q

what is the generic name for the: scala vestibuli, scala tympani, scala media

A

-vestibular duct
-tympanic duct
-cochlear duct

27
Q

where is perilymph found

A

-scala vestibuli
-scala tympani

28
Q

where is endolymph found, what ion does it contain

A

-scala media
-K+

29
Q

what are hair cells, where are stereocilia found, what are the hair cells surrounded by

A

-receptor cells for sound
-stereocilia are tips embedded in tectorial membrane and placed short to tall
-endolymph

30
Q

what connects stereocilia so they can move tgt

A

-tip links which are protein bridges

31
Q

what does mechanical stress resulting in bending of the tip links cause in both the tall and short direction of stereocilia

A

-tall: K+ channels open causing depol
-short: K channels close causing hyperpol

32
Q

why is K the ion that causes depol, what does Ca2+ do

A

-bc the conc is so high in the endolymph
-Ca enters hair cells and causes glutamate (NT) to be released into the synapse w an afferent sensory neuron

33
Q

T or F: no APs happen at rest in hair cells

A

-false
-low frequency APs are constantly generated at rest due to K moving in

34
Q

what does intensity coding measure, how

A

-loudness
-amplitude is reflected by the amt of deflection and opening of ion channels in stereocilia

35
Q

what does frequency coding measure, how

A

-pitch of sound
-based on where on the basilar membrane the deflection occurs

36
Q

what is the basilar membrane

A

-membrane that is stiff and narrow near its attachment b/w round and oval windows
-widens and becomes flexible near distal end

37
Q

how do low frequency and high frequency waves affect the basilar membrane

A

-high create max displacement of the basilar membrane close to the oval window
-low travel along the length of the membrane and create max displacement near flexible distal end

38
Q

how does the basilar membrane code the frequency of sound waves

A

-based on their location along the membrane

39
Q

where do the hair cells synapse onto, what nerve do their axons make up

A

-afferent axons of cranial nerve VIII
-cochlear nerve (one hair cell per one cochlear nerve fibre)

40
Q

how does sound move through the neural pathways of the cochlear nerve, second order neuron, third order neuron, auditory cortex

A

-cochlear nerve enters brainstem and synapses w a second order neuron
-this neuron goes to the medial geniculate nucleus of they hypothalamus where it synapses onto a third order neuron
-the third order goes to the auditory cortex which has a frequency map that corresponds to the basilar membrane

41
Q

how are the semicircular canals oriented in relation to each other

A

-perpendicular

42
Q

what type of movement does the anterior, posterior, and lateral canal detect

A

-anterior: head up and down
-posterior: head up and down to side
-lateral: head side to side

43
Q

what kind of acceleration does the vestib apparatus and the otolith organs (utricle and saccule) monitor

A

-vestib: rotational
-organs: linear

44
Q

where are the hair cells located in the semicircular canal

A

-ampulla

45
Q

how does the semicircular canal detect rotational acceleration

A

-hairs move in opp direction to movement bc its like the initial push of the fluid, if you move right the fluid is gonna hit the wall going left until it can catch up

46
Q

what are the utricle and saccule, what movement do they each detect, where are their hair cells located

A

-bulges b/w semicircular canals and cochlea
-utricle detects fwd/bkwd motion, and saccule detects up/down
-hair cells located in gelatinous material covered by otoliths

47
Q

what nerve goes to the cortex, what two nerves is it made of

A

-cranial nerve VIII (aka vestibulocochlear nerve)
-made of vestib nerve for eq and cochlear nerve for hearing

48
Q

what nerve goes to the cerebellum, where does it synapse to, where do the collateral pathways go

A

-vestibular nerve
-synapse in vestibular nuclei of medulla or run w/out synapsing to cerebellum (site of eq processing)
-collateral pathways run from medulla to cerebellum or up through retic formation and thalamus

An Sc 310 (7 decks)

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