Part 2

Question 1

who is the judge

Answer 1

the vestibular system

Question 2

can the vestibular system be consciously controlled

Answer 2

no

Question 3

responsibilities of the vestibular system

Answer 3

assess movement of the head relative to gravity and the horizon to maintain posture control
stability of images on fovea during head motion
resolves inter-sensory conflicts

Question 4

components of vestibular system

Answer 4

sensorial organs
vestibular nuclei
cerebellum (supervisor)
projections to brainstem, inner ear and cortex

Question 5

what are the sensorial organs

Answer 5

utricle, saccule, Semi-circular canals

Question 6

what motions of head can vestibular system encode

Answer 6

acceleration, decelerations and tilt

Question 7

why are inner ears the judge

Answer 7

because they are internally referenced and don’t rely on the environment to determine since they are incased by bone and only are influenced by gravity

Question 8

when do the otic placodes develop from germinate epithelium

Answer 8

22 days of embryonic life

Question 9

explain anteroventral part of otocyst development

Answer 9

first utricle maculae (week 5E) then Saccule maculae (late week 5E) then cochlear fields are segregated (week 6E)

Question 10

what are maculae used for?

Answer 10

they are used to encode information

Question 11

what part is developed first vestibular or hearing

Answer 11

vestibular

Question 12

how many sensors are on each ear and explain

Answer 12

5. Each ear has 1 ampullae for each of the 3 SCC, 1 utricle and 1 saccule

Question 13

how do vestibular hair cells work

Answer 13

they convert mechanical displacement into electrical signals which are transmitted by vestibular afferent nerves
50-100 stereocilia and a kinocilium extend into either the otolithic membrane or the cupula
- mechanic deflection opens channels at tip of sterocilia creating depolarizing potential

Question 14

what are kinocilium

Answer 14

tallest filament in bunch
- disappear in hair cells after birth but vestibular hair cells keep them

Question 15

vestibular hair cells are activated

Answer 15

when tip links bend towards kinocilium

Question 16

vestibular hair cells are inhibited when

Answer 16

tip links bend away from kinocilium

Question 17

Type 1 afferent nerve ending

Answer 17

flask shaped (chalice shaped)
1-4 hair cells per nerve ending
irregular afferents: rapid detection of head motion, Vestibular ocular reflex initiation and angular vestibular ocular reflex

Question 18

Type 2 afferent nerve ending

Answer 18

Cylindrical (Button shaped)
- multiple hair cells per nerve ending
regular afferents senstive to a broad spectrum range of motion

Question 19

what is the resting firing rate of type I and II afferent nerve endings

Answer 19

70-100 spokes/ second

Question 20

what is the excitation rate of type I and II afferent nerve endings

Answer 20

400 spikes/sec

Question 21

what is the inhibition rate of type I and II afferent nerve endings

Answer 21

0

Question 22

anatomical components of semi-circular canals

Answer 22

filled with endolymph
each has own ampulla (sensor/detector of motion)
ampulla contains crista ampullaris
cupula itself is the gelatinous component of crista ampullaris
- ampulla connects utricle with SCC

Question 23

what are the angular acceleration pairs

Answer 23

superior/anterior
posterior/inferior
lateral/horizontal

Question 24

superior/anterior

Answer 24

look towards front 45 degrees and highest

Question 25

posterior/inferiror

Answer 25

look towards back 45 degrees and lowest (gravity wise)

Question 26

lateral/horizontal

Answer 26

almost horizontal 30 degrees

Question 27

what are the vertical canals

Answer 27

posterior/ inferior and superior/anterior - they are perpendicular to each other

Question 28

what canal encodes axial rotation

Answer 28

lateral

Question 29

what canal encodes flexsion/extension

Answer 29

anterior duct

Question 30

what canal encodes lateral bending

Answer 30

posterior duct

Question 31

what direction does fluid move compared to motion

Answer 31

opposite direction of motion due to inertia

Question 32

when are hair cells activated

Answer 32

when endolymph fluid is in motion

Question 33

location of ampula for anterior scc

Answer 33

at front

Question 34

location of ampula for posterior scc

Answer 34

back

Question 35

what is crus communae

Answer 35

where the anterior SCC canal back and front of posterior SCC are fused together - open together towards inner ear close to utricle

Question 36

why are static postion changes not encoded by cupula

Answer 36

bc cupula spefic gravity is = to endolymph and only acceleration or deceleration is coded - in gravitational fields not responsive to static postion changes of the head

Question 36

location of ampula for horizontal SCC

Answer 36

is at front and opens independently at inner ear - no crus communae

Question 37

when is motion of liquid (gel) and activation of HC maximal

Answer 37

when SCC rotate around perpendicular axis

Question 38

when is motion of liquid (gel) and activation of HC minimal

Answer 38

when SCC rotate around longitudinal axis

Question 39

how do we get the perception of head rotation

Answer 39

from integrating info from all 6 SCC and nerve centers analyzing activations and inhibitions, encoding head motion in 3 planes of space

Question 40

Edwald's second law

Answer 40

In Horizontal SCC: displacement towards the ampulla= greater VOR response than by acceleration which causes displacement away from ampulla

Question 41

ampullopetal

Answer 41

towards ampulla

Question 42

ampullofugal

Answer 42

away from ampulla

Question 43

Edwalds third law

Answer 43

Vertical SCC: displacement away from ampulla= Greater VOR responses produced than by acceleration which causes displacement towards the ampulla