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Flashcards in physiology COPY Deck (32):
1

what does the vestibular system control

posture and balance

2

what makes up the vestibular system

series of fluid filled membranous tubes in the inner ear, embedded in the temporal bone
3 semi- circular canals
Utricle
saccule

3

where is the utricle

swelling at base that connects the semicircular canals

4

where is the saccule

swelling underneath utricle

5

which planes are the semicircular canals in

all at right angles - coronal, transverse, saggital

6

what is the ampulla

swelling at base that contains sensory hair cells

7

what do christae detect

rotational acceleration

8

what do the otolith organs detect (utricle and saccule)

linear acceleration

9

what are the sensory hair cells in the otolith organs called

maculae

10

which direction does the utricle and saccule detect

utricle - back / front tilt
saccule - vertical movement

11

what are the sensory cells of the semi circular canals called

ampulla

12

what are cristae

sensory receptors inside the ampulla, which have a flexible gelatinous structure called the cupula

13

what is the function of the cupula in the christae

stretches across entire width of ampulla and responds to movement of the endolymph fluid within the canals (cilia hair cells stretch width)

14

what produces the drag which bends the cupola and embedded cilia in the opposite direction of movement

inertia of endolymph

15

what are the 2 types of cilia hair cells

kinocilium
stereocilia

16

what happens if there is distortion towards and away from the kinocilium

towards - depolarisation and increased APs in vestibular nerve
away - hyper polarisation and decreased APs

17

where does integration of inputs of sensory receptors take place

cerebellum, unconsciously

18

how are maculae orientated in the utricle and saccule

utricle - horizontal
saccule - verticle

19

what is contained in the otolith membrane

otoliths (CaCO3 crystals) denser than endolymph

20

where do the 5 patterns that run in the vestibular nerve to the brain come from

3 from cristae in semi circular canals
2 from maculae in otolith organs

21

what is kinaesthesia

perception of movement and body position

22

what is the function of the tonic labyrinth reflex

keep the axis of the head in a constant relationship with the rest of the body (uses information from maculae ad neck proprioreceptors)

23

what is the function of the dynamic righting reflex

rapid postural adjustments that are made to stop you falling when you trip (long reflexes involving limb extensors)

24

why are the vestibular and visual apparatus so closely linked

- afferent fibres from semicircular canals project and connect to afferent fibres travelling to the extra-ocular nuclei
- vestibulocochlear fibres synapse to the nucleus of abducens, trochlear and occulomotor nerve

25

what is the function of the static reflex

image stays the right way up - when head tilts, eyes intort/ extort to compensate

26

what is the dynamic vestibular nystagmus reflex

series of saccadic eye movements that rotate the eye against the direction of rotation of the head and body so that the original direction of gaze is preserved despite head rotation (e.g roundabout)
direction of nystagmus = direction of rapid flick back

27

how is the caloric stimulation test set up

outer ear rinsed with cold or warm fluid - temperature difference from core goes through thin bone which sets up convention current for endolymph

28

depending on whether the fluid is warm or cold, which direction will the nystagmus be

cold - opposite side
warm - same

29

what is kinetosis

motion sickness - powerful maintained stimulation of vestibular system causes nausea/ vomitting, low BP, dizziness, sweating

30

when does kinetosis occur

when visual and vestibular inputs to cerebellum are conflicted

31

what is labyrinthitis

acute interference with normal vestibular function as a result of an infection

32

what is the cause of Menieres disease

overproduction of endolymph causing an increase in pressure