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Histology > The Ear > Flashcards

The Ear Flashcards

1
Q

what does the helicotrema connect?

A

the scala vestibuli to the scala tympani

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2
Q

what is the ductus reuniens?

A

small duct connecting the saccule to the cochlear duct

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3
Q

what is the vestibular membrane (reissner’s membrane)

A

roof of the cochlear duct that is composed of two simple squamous epithelial sheets separated by a basal lamina

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3
Q

What is the organ of corti responsible for?

A

hearing

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3
Q

do the bases of the hair cells in the organ of corti rest on the basilar membrane?

A

NO

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4
Q

what membrane are the stereocilia embedded in in the sensory maculae?

A

otolithic membrane

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5
Q

where does blood supply to the inner ear arise from?

A

the labyrinthine artery

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6
Q

what is the cupula? how does it function in sensation?

A

it is a gelatinous membrane that encapsulates the stereocilia and kinocilia. Acts like a sail: if the head rotates, the endolymph moves within the semicircular duct to push against and deviate the cupula resulting in deflection of the stereoclila; direction of deviation determines the polarity of the receptor potential

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6
Q

what does the tectorial membrane of the organ of corti contain?

A

keratin like protein

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6
Q

can hypothyroidism lead to hearing loss?

A

yes

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8
Q

what is the spiral ligament

A

outside wall of the cochlea that is made of dense CT

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9
Q

How does the kinocilium location determine functional polarity?

A

if the stereocilia are tilted TOWARD the kinocilium = depolarization; if the stereocilia are tilted AWAY from the kinocilium = hyperpolarization

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9
Q

what is the function of the otoliths?

A

increase the mass of the membrane surface to augment the effect of accelerating forces on the membrane and thus on the stereocilia

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10
Q

what compartments are part of the osseous labyrinth? what compartments of the cochlear are part of the membranous labyrinth?

A

scala vestibuli + scala tympani = osseous scala media = membranous

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11
Q

what causes K+ channels in the stereocilia to open?

A

mechanoreception via connection of stereocilia to the adjacent stereocilia

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11
Q

what supports the hair cells bases in the organ of corti?

A

phalangeal cell and a process of the phalangeal cell surrounding the apex of the hair cell

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12
Q

what inserts on the oval window of the vestibule?

A

stappes

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13
Q

what is located on one end of each semicircular canal?

A

the ampulla (swelling)

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14
Q

what is the boney central axis of the cochlea?

A

modiolus (towards modiolus = inner, away from modiolus = outer)

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15
Q

what is the stria vascularis?

A

pseudostratified, vascularized, epithelium that secretes endolymp

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15
Q

what is the structure of kinocilum

A

9 doublet microtubules; immotile; longest stereocilia is adjacent to the kinocilium

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16
Q

pendred syndome

A

genetic disorder causing hearing loss in children (SLC26A4 = carrier gene

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17
Q

what is the osseous spiral lamina?

A

spiraling shelf off of the modiolus that indents the inner edge of the cochlea

17
Q

what are the sensory areas of the inner ear?

A
  1. crista ampullaris (of semicircular ducts) 2. sensory maculae (of utricle and saccule) 3. organ of corti (of cochlear duct)
17
Q

what are the two types of hearing loss? what are the main differences?

A
  1. conductive losses = disruption in the conductive pathway of soundwaves traveling (ie: disruption of tympanic membrane) 2. sensorineural loss = loss of hair cells of VIII nerve fibers
18
Q

what is motion sickness caused by?

A

over stimulation of the utricle/saccule

19
Q

what forms the floor the cochlear duct?

A

the basilar membrane; the organ of corti is located on it

20
Q

How does the organ of corti transmit sound?

A

the cohclear duct hair cells transduce mechanical energy into sound frequency, and the frequency response is represented as a continuous gradient along the organ of corti.

22
Q

what is the function of the organ of corti:

A

to transduce auditory signals

24
Q

what type of cells are found in the spiral ganglion?

A

bipolar

26
Q

what is perilymph high in? low in? vs endolymph

A

peri = high in Na low in K+ endo = high in K+ low in Na

27
Q

what are the two types of cells on the crita ampularis?

A

both columnar epithelium: 1. supporting cells = have secretory granules; tall columnar 2. sensory hair cells = stereocilia and kinocilia are embedded in gelatinous membrane (cupula) which acts like a sail

28
Q

what happens if sensory cell of the ear is depolarized

A

it will release more neurotransmitter on VIII afferent processes and cause an increase in signal to the vestibular or auditory centers of the brain

29
Q

where are neurotransmitters released from in the inner tunnel (of organ of corti)

A

spiral ganglion cells

31
Q

what is the function of the utricle and saccule?

A

detection of linear acceleration (tripping over something)

33
Q

what is the vestibular aqueduct

A

small boney channel that connects to the vestibule

33
Q

what keeps the endolymph and perilymph from mixing?

A

the occluding zonules of the cells lining the membranous labyrinth

34
Q

what is the crista ampullaris? where is it found?

A

a sensory structure in the ampulla (swelling at end of semicircular canal); detects rotational movements of the head

34
Q

what is vertigo? what is it caused by

A

dizziness; caused by disturbances of vestibular function such as infection of the vestibule or lesions of the central or peripheral nervous system

35
Q

the modiolus contains fibers for what nerves?

A

VIII + peripheral ganglion (spiral ganglion) for auditory system

36
Q

what is menieres disease?

A

swelling of the membranous labyrinth leading to dizziness (vertigo) tinitus (ringing of ears) and low frequency hearing loss

38
Q

what is the membranous labyrinth? what is it derived from?

A

it is a continuous series of epithelially lined membrane channels derived from the otocyst containing endolymph

39
Q

presbyacusis

A

poor high frequency perception due to age related loss of hair cells at the basal turn of the cochlea

40
Q

what is the membranous labyrinth composed of?

A

1.semicircular ducts 2. utricle 3. saccule 4. endolymphatic duct and sac 5. cochlear duct

42
Q

what does the otolithic membrane contain?

A

crystalline includes (otoliths) in its surface

43
Q

what cells line the inner tunnel of the organ of corti?

A

pillar cells

44
Q

where is perilymph secreted from?

A

the blood vessels in the CT of the ossesous labyrinth

45
Q

what does the vestibule connect anteriorly? posteriorly?

A

anteriorly: cochlea posteriorly: semicircular canals

47
Q

where is the sensory maculae located?

A

in the utricle and saccule

48
Q

how do the hair cells at the base of the organ of corti transduce sound vs those at the apex of the cochlea?

A

base = transduce highest frequencies apex = transduce lowest frequencies

50
Q

what does the scala vestibuli connect with?

A

oval window ( to cochlea)

52
Q

what does the scala tympani connect with?

A

round window ( to cochlea)

53
Q

what is prominent in the pillar cells and the phalangeal cells? what is the significance of their structure?

A

microtubules and intermediate filaments; This allows for the pillar and phalangeal cells to form a rigid RETICULAR LAMINA in which the apical portions of the hair cells are locked via zonular adherens and zonula occludens junctions

54
Q

why is it important that the basilar membrane upon which the organ of corti rests is collagenous and not rigid?

A

because sound causes compression of waves in the perilymph which shifts the two rigid plates to the deviate the stereocilia and produce receptor potntials in the sensory cells

55
Q

what is unique to the hair cells of the organ or corti

A

don’t have a kinocilium, have a basal body instead

56
Q

What do all of the sensory areas of the inner ear contain?

A
  1. sensory hair cells with sterocilia an single kinocilum (or basal body in the auditory cells)

Histology (24 decks)

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