Lecture 35 - Vestibular system Flashcards Preview

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Flashcards in Lecture 35 - Vestibular system Deck (39):
0

What are the tasks of the vestibular system?

Senses head movements
Maintain visual axes when head is moving
Send motor commands to trunk and limb muscles to maintain balance

1

What is the task of the auditory system?

Transduce vibration into electrical activity

2

What are three sections of the membranous labyrinth?

Utricle - Saccule - Semicircular ducts

3

What is the function of the utricles?

Monitor and activate response to linear acceleration of horizontal movements

4

What is the function of the saccule?

Monitor and activate response to linear acceleration of vertical movements

5

What is the function of the Semicircular ducts?

Monitor and respond to angular acceleration of head in all planes

6

What is the orientation of the semicircular ducts?

Anterior - Lateral - Posterior

7

What neural structure is associated with the vestibular system?

Scarpa's ganglion - vestibular ganglion

8

What is the electrolyte composition of the perilymph?

Increased Na concentration

9

What is the electrolyte composition of the endolymph?

Increased potassium concentration

10

What are three main structures in an ampulla?

Crista - Cupula - Hair cells

11

What are the three main structures of the hair cells?

Stereocilia - Kinocilium - Afferent/Efferent fibers

12

What fluid are the hair cells sitting in?

Endolymph

13

What happens within the ampulla when the endolymph is moving?

Bends cupula, which in turns tilt the stereocilia and kinocilium

14

What structure contains the ampullas?

Semicircular ducts

15

What structure are the hair cells embedded into?

Crista

16

What are the structures in the otolithic organs?

Otolithic membrane, Otoconia, Macula, Striola

17

What are the two otolithic organs?

Utricle and saccule

18

What is moved with the head is moved within the otolith organs?

Cap of statoconia movies, causing bending of the hair cells

19

What happens in the otolith organs when the sterocilia bend toward the kinocilium?

Hair cells depolarize

20

What molecular structure is linked to the depolarization of the hair cells?

Tip link

21

What does the tip link do?

Opens mechanically gated K+ channels
More voltage gated calcium channels open
Increase glutamate release

22

What happens in the semicircular ducts when the stereocilia are deflected towards kinocilium?

Apical K+ channels open
Depolarization of the cell membrane
Calcium channels open
Synaptic vesicles to open

23

What nerve is affected when the hair cells are depolarized?

Afferent nerve firing is increased

24

What happens when the stereocilia deflected away from kinocilium?

Decreased firing rate

25

What are the four vestibular nuclei?

Superior - Inferior - Medial - Lateral

26

What is VOR?

Vestibular reflex with the function of keeping the eyes on an object when the head is in motion relative to that object

27

How is the VOR carried out?

Contraction of the extra-ocular eye muscles required to keep that image of that object focused on the fovea

28

What happens when there is a lesion on the vestibular portion of the CN VIII, vestibular apparatus, or nuclei?

Perception of moving when not

29

What are the components of the spiral organ?

Outer hair cells
Inner hairs
Inner hair cell

30

Where is low frequency sound processed?

Towards the helicotrema

31

Where is high frequency sound processed?

Toward the oval window

32

What scala interacts with the oval window?

Vestibuli

33

What scala interacts with the round window?

Tympani

34

What is a sound wave?

Pressure displaces scala vestibuli which displaces cochlear duct and spiral organ

35

What projects into the tectorial membrane?

Stereocilia

36

What nerve goes into the scala tympani?

Cochlear nerve through the spiral ganglion

37

How does a hair cell depolarize?

Hair cells bend towards the kinocilia
Opens the mechanically gated potassium channels
More Ca2+ voltage gated open
Glutamate released

38

What is auditory information delivered to and processed in?

Auditory cortex