L15 - Vision & Balance(LA) Flashcards Preview

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Flashcards in L15 - Vision & Balance(LA) Deck (38)
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1

T/F: Visual system has direct access to vestibular nuclei (involved in balance)

T

2

Vection is an illusion of self-motion while stationary caused by? What types?

Moving visual scenes
Liner: like in a train
Circular: sitting in a rotating cylinder

3

What happens when we rotate at a constant velocity?

The sense of rotation is gradually replaced by a sense that the world is rotating around us.

4

If you place someone in a centrifuge - what do they associate verticality with? Gravity, centrifugal force, resultant force?

Resultant
*It is not gravity but FORCE in general with which we align our notion of what is "vertical"

5

!How do we sense force? (4)

-Pressure on feet
-Other body parts may take weight
-Muscle reactions to maintain uprightness
-MAJOR SOUCE: vestibular apparatus inside inner ear

6

!What are the 3 main sources of orientation info?

1) Visual orientation info
2) Proprioceptive info (joint position, muscle force (via sensors in tendons))
3) Vestibular system

7

_ semicircular canals that sense? _ otolith organs that sense? Both in inner ear (each side of the head) found in?

3 - Rotation, angular acceleration
2 - Linear acceleration
Petrous portion of temporal bone (hardest bone in skull - but still vulnerable to infection)

8

!How can vestibular system be disrupted?

Deaf people lack the system, may be destroyed by gentamycin or related antibiotics, viruses

9

What is affected if vestibular system is disrupted?

Swimming (disrupts proprioceptive and visual sources of "up" info), standing on one foot, walking in the dark

10

What is presbycusis?

Hearing loss

11

What happens to vestibular organs when excessive physical activity occurs?

Damage to vestibular organs. High impact aerobics can injure otoliths

12

Bony labyrinth of vestibular system contains?

Perilymph

13

Membranous labyrinth of vestibular system contains?

Endolymph

14

Vestibular nerve is part of CN_

8 - same as auditory nerve but different termini

15

Where do hair cells of all the labyrinth organs send their output to?

Vestibular nuclei in brainstem

16

Cell bodies of vestibular nerve cluster in?

Vestibular ganglia of Scarpa (a swelling of the vestibular nerve within the internal auditory meatus)

17

Where does vestibular nerve send efferent input to?

Hair cells

18

The 2 otolith organs (fluid filled sacs) are called?

-Utricle is joined to the 3 semicircular canals
-Saccule is a separate little pouch
*Oto (ear) lith (stone) - they are crystals of Ca2CO3

19

Sensory hair cells embedded into otolith organs where the otoliths are embedded on top of it

Sensory hair cells embedded into otolith organs where the otoliths are embedded on top of it

20

Auditory transduction
Bending towards kinocilium - depol
Away - Hyperpol

Auditory transduction
Bending towards kinocilium - depol
Away - Hyperpol

21

Responses of kinocillium saturate when cilia are bent more than _ microns?

0.5 microns - about the width of a cilium

22

What happens to otolith organs when airplane loses altitude in downdraft suddenly?

-Saccular up/down otoliths stimulated
-Utricular otoliths no longer press on hair cells

23

Where are endolymph found?

Semicircular canals are filled with endolymph

24

Each semicircular canal has a bulge called?

Ampulla

25

Hair cells detect inertia of? Otoliths? Canals?

Hair cells - Internal contents
Otoliths - otoliths itself
Canals - Endolymph

26

Cupula

Gelatinous mass on top of crista (thickened zone of epithelium) that contains hair bundles in the same orientation. Bending one direction hyperpol (away from kinocilium), other direction depol (towards kinocilium).

27

During head rotation, the endolymph pushes on the?

Cupula

28

Vestibular nerve transmits info about head rotation to vestibular nuclei in the medulla ipsilaterally or contralaterally?

Ipsilaterally

29

Vestibulo-ocular reflexes

Keep eyes still when head moves

30

Vestibulo-spinal reflexes

Enables skeletomuscular system to compensate for head movement and for head to be kept still while body moves