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
