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BMS200 > wk 12, lec 1 > Flashcards

wk 12, lec 1 Flashcards

(86 cards)

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1
Q

3 parts of the auricle (pinna)

A

helix, lobule, tragus

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2
Q

function of auricle/ pinna

A

o Focuses sound waves onto tympanic membrane
o Changes the nature of sounds coming from different directions, emphasizes certain frequencies

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3
Q

what is the auditory meatus

A

opening of external auditory canal (ear hole)

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4
Q

what glands are in auditory meatus

A

o Ceruminous glands (modified apocrine sudoriferous glands) = ear wax

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5
Q

function of ceruminous glands

A

 Traps foreign substances, protects
-has fine hairs too

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6
Q

what is cerumen made of

A

anti microbial proteins, saturated FA, sloughed keratinocytes

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7
Q

where is tympanic membrane? what is is covered by?

A
  • Tympanic membrane is border between middle and outer ear
    o Fibroelastic CT covered externally with epidermis and internally by simple cuboidal epithelium
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8
Q

what is tympanic cavity? location? epithelium?

A
  • Tympanic cavity in in the petrous part of the temporal bone
    o Pseudostratified columnar epithelium lines eustachian tube and opens into nasopharynx
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9
Q

what does tympanic cavity open into? what happens if collapses and opens?

A

opens into nasopharynx
o Usually collapsed but opens when swallow or yawn to equalize pressure (i.e. pop ears on plane)

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10
Q

3 ossicles (little bones)

A

malleus, incus, stapes

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11
Q

malleus attaches to
incus attaches to
stapes attaches to

A

o Malleus
 Attaches to tympanic membrane and incus (synovial joint)

o Incus
 Attaches to malleus and stapes (synovial joint)

o Stapes
 Attaches to incus and oval window (ow= transition from middle to inner ear)

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12
Q

muscle in malleus and what CN

A

 Tensor tympani muscle dampens movement (CN V)

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13
Q

muscle in stapes and what CN

A

 Stapedius: dampens vibrations (CN VII)

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14
Q

the oscines function as?

A
  • Little bones as levers : amplify movements of tympanic membranae to oval window (TM has greater surface area than OW) and overcome acoustic impendence mismatch between air and water
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15
Q

what do ossicles help to overcome

A

acoustic impedance mismatch between air and water

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16
Q

where do vibrations get sent for action potentials

A

o Can send vibrations of fluid to cochlea and make action potentials = sound

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17
Q

cochlea- coiled how many times, has what

A
  • Cochlea- coiled 2.5 times, has sterovilli/cilia
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18
Q

3 parts of cochlea

A

scala vestibuli
scale tympani
scala media

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19
Q

scala vestibuli
scale tympani
scala media

which are filled with endolymph and perilymph

A

scala vestibuli- perilymph
scale tympani- perilymph
scala media- endolymph

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20
Q

what is Scala vestibule connected to, how is it separated from Scala media

A

 Connects with oval window

 Seperated from scala media by reissner’s membrane

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21
Q

what is Scala tympani connected to, how is it seperate from Scala media, what is it continuous with

A

 Connects to round window

 Separated from scala media by basilar membrane

 Continuous with scala vestibuli (communicated via helicotrema (tunnel))

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22
Q

how does Scala vestibule and tympani communicate

A

helicotrema (tunnel)

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23
Q

how does Scala media contact tectorial membrane

A

 Houses inner and outer hair cells (in basillar membrane) which contacts tectorial membrane

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24
Q

in the scala media what membrane so endolymph and perilymph dont mix

A

 Reissner membrane as barrier so endolymph and perilymph don’t mix

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25
what is for action potnetial in ear
organ of corti (in scala media)
26
organ of corti
site of transduction for vibration  action potential
27
where is organ of corti
* Stretches along basillar membrane * 4 rows of hair cells o Inner hair cells project into endolymph o Outer hair cells project into tectorial membrane in scala media
28
contents in endolymph vs perilymph
- Endolymph= high K+ - Perilymph = similar to CSF- low protein, mostly NaCl solution
29
steps to process of hearing
1. Sound waves enters external auditory canal 2. Stapes move inwards  oval window moves inwards  drop in pressure of scala vestibuli 3. Round window moves outwards (fluid not very compressible) and scala tympani pressure is now higher than scala vestibuli 4. Basillar membrane bends upward and organ of corti shears towards tectorial membrane 5. Hair bundle of outer hair cells tilt toward longer stereovilli 6. Transduction channels open in outer hair cells: K+ in  depolarize  receptor potential 7. Depolarize  contraction of prestin  contraction of outer hair cell (microseconds) 8. Basillar membrane moves upwards even more due to outer hair cell contraction 9. Endolymph moves beneath tectorial membrane 10. Inner hair cells bend towards longer stereovilli 11. Transduction channels open in inner hair cells  depolarize (K+ in, receptor potential) 12. VG Ca2+ channel open  release glutamate  depolarize afferent neuron a. Afferent cell bodies in spiral ganglion b. Bipolar neurons -dendrites contact inner hair cells
30
where is high frequency and low frequency detected in the ear
- High frequency detected near oval window - Low frequency detected near helicotrema
31
what is pitch based on
- Pitch based on what part of organ of corti detects the sound
32
differences in loudness is from
- Differences in loudness via how much basilar membrane vibrates o More movements  more displacement of stereovilli  more glutamate o Loudness= frequency of action potentials
33
types of sound waves/ compression waves
- Sinusoidal; alternate between compression and rarefaction
34
how does transduction happen in sound to get AP
- Movements of oval and round window cause deflections of basilar membrane and movement of hair cells o Frequency= where basilar membrane resonates the most o Amplitude= size of wave
35
2 types of equilibrium in the vestibular apparatus
static and dynamic
36
vestibular apparatus in ear for
balance
37
static vs dynamic equilibrium in ear
- Static o Detects position of head with respect to pull of gravity when body is not moving o Detects linear acceleration/ deceleration - Dynamic o Detects angular movements of head
38
where is vestibular system
in bony labryinth of inner ear
39
parts of vestibular system
- Three semicircular canals, two otolithic organs, utricle and saccule
40
what types of movement are the semicurcular canal and utricle and saccule for
o Semicircular = rotary acceleration and motion o Utricle and saccule= linear acceleration and static position
41
configuration of semicircular canals
- Semicircular canals in temporal bone in planes that are right angles (horizontal, anterior, posterior canals) - 3 pairs of canals work in push-pull fashion o 1 canal is stimulated, its partner is inhibited o Allows for sense of all directions of rotation  (i.e. right horizontal canal is stimulate by right rotation of head)
42
what does the ampulla of the semicircular canal have
(dilated part of canal) - Ampulla has crista ampullaris o Ridge of tissue on apical surface lined by vestibular hair cells (with 100 sterocilia and 1 long kinocilium) o Stereocilia and kinocilium have cupula (gelatinous covering)
43
in semicircular canal, when rotate head what happens to endolymph
- Rotation of head causes endolymph to move in opposite direction (bc inertia) o Deflects the cupula, bends stereocilia
44
3 canals of the semicircular canals
- Three canals at right angles to each other o Anterior canal: vertical in frontal plane  Detects yes nod o Posterior canal: vertical in sagittal plane  Detects side tilts o Lateral canal: horizontal  Detects no nod
45
anterior canal for
vertical in frontal plane  Detects yes nod
46
posterior canal for
vertical in sagittal plane  Detects side tilts
47
lateral canal for
horizontal  Detects no nod
48
what do the otolithic organs sense? what 2 organs are they?
Utricle and the saccule - Otolithic organs sense: static equilibrium and linear accelerations and decelerations
49
position of utricle and saccule
- Sac like structures in the vestibule (bony chamber between cochlea and semicircular canals) o Saccule is vertical, utricle is horizontal
50
what are macula in the article and saccule
- Macula: plaque like mound of neurosensory tissue (similar to crista ampullaris) o Made of 3: neurosensory hair cells, supporting cells, otolithic membrane (gelatinous cover)
51
what is the otolithic membrane covered in (urticle and saccule) and what's the reason
o Otolithic membrane covered in otoliths or otoconia (calcium carbonate crystals) which make it denser than endolymph
52
what happens to otolithic membrane in linear acceleration or deceleration
- In linear acceleration or deceleration the otolithic membrane slides bc inertial lag o Sliding over macula deflects hair cell sterocilia producing sensory signal
53
what are the chemicals in nose and mouth that activate chemoreceptors
- Chemoreceptors activated by chemicals in mucus in nose (odorants) and saliva in mouth (tastants)
54
how many taste buds in papilla of tongue
- 5000 taste buds in papilla on tongue
55
4 types of papillae
1. fungiform papillae 2. circumvallate papillae 3. foliate papillae 4. filiform papillae
56
which papilla lacks taste buds
filiform papillae
57
fungiform papillae
tip of tongue  5 taste buds at apex (tip of papillae)
58
circumvallate papillae
- V shape on back of tongue
59
foliate papillae
posterior edge  Circumvallate and foliate have 100 taste buds at papillae sides
60
filiform papillae
rough; detect food textures  Lack taste buds
61
where are taste buds found
- In tongue, soft palate, epiglottis, pharynx
62
how many taste receptors
- 50-100 taste receptor cells with microvilli at apex and receptors for tastants
63
how many nerve fibers for taste buds
- Innervated by 50 nerve fibers which each get input from 5 taste buds
64
how are taste cells made; how long is lifespan
- Basal cells differentiate into taste cells and have 10 day lifespan
65
purpose (2) of saliva
- Saliva is solvent for tastants (dissolves) o Also secrete bicarbonate for help swallowing
66
how to dissolve tastants
saliva
67
5 tastes
salt, sweet, sour, bitter, umami (via CNS bc each taste cell receptor cell connects to specific gustatory axon)
68
how is salt tasted
o Epithelial sodium channels (ENaC) --> depolarize via Na+
69
how is sour tasted
o H+ proton --> ENaC permits proton entry o H+ blocks K+ channels o Hyperpolarize cyclic nucleotide gated cátion channels
70
how is sweet tasted
o GPCRs: T1R2 and T1R3 o Via natural sugar and sacchari
71
how is bitter tasted
o Warn Against poison o i.e. quinine blocks K+ channesl o i.e. strychnine binds T2R (GPCR)
72
how is umami tasted
o T1R1 and T1R3 o Activate truncated metabotropic glutamate receptor (mGluR4)
73
where is olfactory epithelium
upper nasal cavity
74
what do olfactory sensory neurons do
- Oflactory sensory neurons – bipolar neuron for signal transduction of odorant  receptor potential o Dendrite goes into nasal cavity with 6-12 cilia
75
where does axon of olfactory nerve go
- Axons form olfactory nerve – traverse the cribiform plate of ethmoid bone to reach olfactory bulbs
76
how to detect doors
- Supporting cells secrete mucus to get good envo to detect odors
77
how do odorant's dissolve
- Odorants dissolve in mucus and bind receptor on cilia of olfactory sensory neurons
78
how often do olfactory neurosn get repalced
- Basal stem cells replace olfactory neurons; 1-2 month lifespan
79
what do the GPCRs in olfactory do
o Result in Cl- and Ca2+ channels opening
80
what's in the olfactory bulb
- In olfactory bulb, the olfactory sensory neurons axons synapse on primary dendrites of mitral and tufted cells, forming distinctive olfactory glomeruli
81
each neuron and each door have what
- Each neuron has 1/400 olfactory genes - Each odorant can bind an array of receptors
82
how to identify an odorant's
- Central olfactory system decodes the receptor-cell activity pattern to identify the odorant
83
otoscleoris is
- Abnormal bone deposition in middle ear o Around rim of oval window at footplate of stapes o Both ears affected
84
genes or other cause in otosclerosis
autosomal dominant; bony overgrowth o Measles infection?
85
steps in otorscllerosis
o Fibrous ankylosis of footplate  bony overgrowth  anchor to oval window
86
what does otosclerosis cause? severe?
- Hearing loss due to immobilization of oval window - Usually not severe derangement but can progress to hearing loss

BMS200 (46 decks)

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