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ANP Final - Will > Lec 19 > Flashcards

Lec 19 Flashcards

1
Q

What are the three divisions of the ear and their purposes?

A

The External and middle ear are for hearing only, but the internal ear is for hearing as well as balance.

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1
Q

What are the three parts of the outer ear? What are their functions?

A
  1. Auricle/pinna is cartilage and funnels sound waves
  2. The lobule is the lobe and lacks cartilage
  3. The external acoustic meatus is where the sound waves go and is a canal in the temporal bone that is lined with skin, sebaceous glands, and ceruminous glands.
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2
Q

What is cerumen? What does it do?

A

It is earwax and protects the ear from germs, dirt, dust etc. and waterproofs the ear as well.

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3
Q

What is the name of the structure that transfers sound waves from the external acoustic meatus to the ossicles?

A

The tympanic membrane

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4
Q

What is the middle ear?

A

It is an air filled cavity

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4
Q

What is the structure of the tympanic membrane?

A

Is a thin layer of connective tissue covered with skin on the outer ear side, and mucosa on the middle ear side.

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4
Q

What is otitis media?

A

An infection of the middle ear.

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4
Q

What two openings are medial to the middle ear?

A

The oval window next to the stapes and the round window inferior to that

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4
Q

What tube links the middle ear with the nasopharynx?

A

The pharyngotympanic tube.

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4
Q

What are the names of the three ear bones in order of outermost to innermost?

A
  1. Malleus
  2. Incus
  3. Stapes
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5
Q

What condition is required for the tympanic membrane to vibrate in terms of pressure?

A

Pressure must be equal on both sides of the tympanic membrane.

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6
Q

What is the eardrum?

A

The tympanic membrane

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7
Q

What two tiny muscles contract to limit ossicular vibration?

A

The tensor tympani and the stapedius

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8
Q

What are the two divisions of the inner ear?

A

The bony labyrinth and the membranous labyrinth.

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9
Q

What three structures are a part of the bony labyrinth?

A

The cochlea, semicircular canals, and vestibules

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10
Q

What fills the bony labyrinth?

A

Perilymph (similar to CSF)

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11
Q

What are membranous labyrinth structures?

A

They are a series of membranous sacs within the bony labyrinth.

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12
Q

What fills the membranous labyrinth structure sacs?

A

potassium-rich endolymph is a ICF like fluid

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13
Q

What do the fluid in the inner ear do?

A

conduct sound vibrations as well as respond to changes in position/acceleration

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14
Q

What are the two sacs of the vestibule called?

A

The utricle (superior) and saccule (inferior)

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15
Q

What structures do the vestibule sacs associate with?

A

The utricle associates with the semicircular canals and the saccule associates with the cochlea

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16
Q

What is a main function of the vestibule sacs?

A

They monitor head position by containing equilibrium receptors called maculae that respond to gravity.

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17
Q

What do the semicircular ducts separate?

A

The semicircular canals and the utricle of the vestibule

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18
Q

Why is the end of the semicircular canals swollen? What is this structure called?

A

It houses equilibrium receptors. The ampulla is the swollen end of the canal, and the receptors are called crista ampullaris.

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19
Q

What do the crista ampullaris monitor?

A

The angular movements of the head.

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20
Q

What is the bony pillar in the cochlea called?

A

The modiolus

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21
Q

What does the cochlear duct lead to?

A

The cochlear apex

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22
Q

What is the spiral organ hearing receptor?

A

The organ of corti

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23
Q

What is the composition of the three cochlear chambers? Describe them

A

The cochlear duct (scala media with endolymph) is in the middle, with the Scala vestibuli (perilymph, continuous with oval window/vestibule), and the Scala tympani (perilymph, cont. with round window) on each side.

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24
Q

What allows the two perilymph ducts to be continuous?

A

The helicotrema

25
Q

Where does the spiral organ sit?

A

The basilar membrane

26
Q

What is the shape of the basilar membrane? How does this affect its receptivity to pitch?

A

The basilar membrane is thick and narrow at the beginning (good for high pitched sounds), and wider and thinner as it nears the cochlear apex (better for low pitched sounds).

27
Q

What is the structure of the spiral organ?

A

There is one inner hair cell and three outer hair cells sandwiched between the basilar membrane and the tectorial membrane.

28
Q

What nerve innervates the cochlea?

A

The vestibulocochlear nerve

29
Q

What is the order of transmission of sound in the inner ear?

A

Sound waves go from the vestibuli and tympani scalas to the cochlear duct, where it is picked up by the spinal organ

30
Q

What are the two part of a sound wave?

A

Compression and rarefaction

31
Q

What is the range of human hearing?

A

20-20000Hz

32
Q

In what Hz range can humans pick up pitch differences?

A

1500-4500Hz

33
Q

What are decibels and how are they calculated?

A

It is a measurement of amplitude and is a logarithmic scale.

34
Q

How does our perception of sound line up with decibel readings?

A

We perceive a difference of 10dB(x10 the sound energy) as only a doubling of volume

35
Q

What are some common decibel readings?

A

50 is normal conversation, 70 is a busy restaurant, and 120 is a concert

36
Q

Which cochlear hair cells are most important? What is their structure?

A

Inner cochlear hair cells have stereocilia embedded in the tectorial membrane, with hair connected by tip links.

37
Q

How does transduction occur in the inner cochlear hair cells?

A

The cells are mechanically gated, and when hair pivot towards the highest hair, some gates open that allow K and Ca to enter, depolarizing the cell and releasing NT glutamate which excites the cochlear nerve.

38
Q

When tip links are loose in the inner cochlear hair cells, what is happening?

A

Ion gates are closing

39
Q

What is the role of the three outer hair cells?

A

They are postulated to deal with support and protection. They seem to polarize/depolarize and stretch/contract in response to basilar membrane movement. They amplify some basilar membrane movement, and stiffen in response to loud noises which protects the inner hair cells.

40
Q

What are the first two steps of the auditory pathway?

A

Sound signals pass from the spiral ganglion in periphery to the cochlear nuclei in the brain stem.

41
Q

Where are auditory signals sent after the cochlear nuclei?

A

Either the superior olivary nuclei for localization of sound, or the inferior colliculi to the auditory reflex center, and then after those to the auditory cortex.

42
Q

Where is pitch percieved?

A

The primary auditory cortex

43
Q

describe desiccation in the auditory pathway

A

It only happens to some pathways, so both cortices receive input from both ears

44
Q

How does the superior olivary nuclei localize sound?

A

It determines relative loudness and timing reaching individual ears

45
Q

What three inputs help the balance system?

A

Head balance organs, visual cues, and proprioceptive cues

46
Q

What is the balance receptor system called?

A

vestibular apparatus

47
Q

What do the receptors in the vestibule measure?

A

static equilibrium (acceleration/position/gravity)

48
Q

What do the semicircular canal receptors measure?

A

head rotation

49
Q

Why do the semicircular canal receptors measure head rotation? What is this called?

A

Dynamic equilibrium can be measured as the semicircular canal has crista ampullaris that face three planes of direction.

50
Q

Where are macula located?

A

In the utricle and saccule

51
Q

What do the macula consist of?

A

Supporting cells and hair cells

52
Q

What is the makeup of a macular hair cell?

A

It has stereocilia and one kinocilium each embedded in otolithic membrane

53
Q

What is otolithic membrane?

A

It is a jelly mass that is studded with Calcium carbonate crystals (otoliths)

54
Q

Why do utricular hairs respond to forwards/backwards/tilting motions?

A

The utricular macule is horizontal, so the hair stand straight up and when it is bent through the forwards/backwards motion it depolarizes the nerves.

55
Q

Why do saccular hairs respond to vertical movement?

A

The saccular macule is vertical, so the hair point sideways and bend during these up and down motions.

56
Q

What fibers are wrapped around the hair cells?

A

Vestibular nerve fibers

57
Q

What happens when stereocilia bend towards the kinocilium?

A

It depolarizes the nerve.

58
Q

What happens when stereocilia bend away from the kinocilium?

A

The nerve hyperpolarizes, and a lot less action potentials happen.

59
Q

What kind of information do the macula give us?

A

Information on changes in head positioning.

60
Q

What type of vestibular receptor cell is found in semicircular canals and is stimulated by rotational (changes in velocity of rotational) movements?

A

Crista Ampullaris

61
Q

What is the makeup of a crista ampullaris?

A

It is a hair cell stuck in a gel-like mass: the cupula

62
Q

How is the nerve arrangement in the crista ampullaris?

A

It is encircling the base of each hair cell.

63
Q

What is the gel of the crista ampullaris called?

A

The cupula

64
Q

Why do each set of semicircular canals have opposite ducts on opposite sides of the head?

A

The comparison of the two (when one hyperpolarizes the other depolarizes) gives us information on direction.

65
Q

What fluid bends the cupula inside a crista ampullaris?

A

Endolymph fluid

66
Q

Where does information from the vestibular system go? Why?

A

It goes straight to the cerebellum/brain stem allowing the body to respond reflexively.

67
Q

What information does the brain nuclei integrate? What does it do with this information?

A

Vestibular/visual/somatic and automatically commands eyes/body movements through vestibulospinal tracts.

ANP Final - Will (15 decks)

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