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Flashcards in Vestibular System Deck (28)
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1

What does the vestibular system control?

Posture and balance

2

Where is the vestibular system found?

Inner ear (labyrinths embedded in temporal bone)

3

What does the vestibular apparatus consist of?

3 semicircular canals
Utricle
Saccule

4

What are the utricle and saccule collectively known as?

Otolith organs

5

What do the otolith organs detect?

Linear acceleration
Encode info about position of head

6

What is the function of the utricle?

Back/front head tilting

7

What is the function of the saccule?

Vertical movement

8

What do the semicircular canals detect?

Rotational acceleration

9

Where are the sensory cells located in the semicircular canals?

Ampulla (base of ssc)

10

What are cristae?

Sensory receptors consisting of capula which stretch across ampulla and respond to movement of endolymph fluid

11

What are found in the capula?

Cilia of hair cells which directly synapse with sensory neurons of vestibular nerve

12

What do the hair cells in the scapula detect?

Rotational acceleration

13

How do the hair cells respond to rotational acceleration?

Endolymph inertia produces drag, bends the capula and cilia in opposite direction to movement
Sudden stop- endolymph still moves, sense of movement and dizziness

14

What are the 2 types of cilia?

Kinocilium
Stereocilia

15

What is the effect of cilia distortion in direction of kinocilium?

Depolarisation and increased APs in vestibular nerve

16

What is the effect of cilia distortion in direction away from kinocilium?

Hyperpolarisation and decreased discharge of APs in vestibular nerve

17

What is the sensory apparatus of the utricle and saccule known as?

Maculae

18

How are the maculae different within the otolith organs?

Utricle - orientated on horizontal plane
Saccule - orientated on vertical plane

19

What is the tonic labyrinthine reflex?

Keeps head axis in constant relationship with rest of body

20

What is the dynamic righting reflex?

Rapid postural adjustments that are made to stop you falling when you trip

21

What is vertigo?

Perception of movement in the absence of movement

22

What symptoms are associated with Meniere's disease?

Vertigo
Nausea
Nystagmus
Tinnitus

23

What are the CaCO3 crystals found in the otolith membrane called?

Otoliths

24

What detects head tilting?

Macula in utricle

25

What does head tilting cause?

Otoliths and otolith membrane move, distorts jelly and moves cilia

26

What is static reflex?

Eyes intort/extort to compensate for head tilting so image stays the right way up

27

What is dynamic vestibular nystagmus?

Eye movements that rotate the eye against direction of rotation of head and body so that direction of gaze is preserved

28

How is vestibular function tested?

Post rotatory nystagmus
Caloric stimulation