Lecture 20 Flashcards

1
Q

Describe the vestibular sense

A
  • Not major component of consciousness
  • Only aware in case of malfunctions or overstimulation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are symptoms of a malfunctioning or overstimulated vestibular sense?

A
  • Vertigo
  • Nausea
  • Dizziness
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How many Peripheral Apparati are there in the vestibular system?

A

2
- One per ear

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What can happen when you lose the vestibular peripheral apparatus on one ear?

A
  • You will adapt to using the other
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Why do we have a vestibular apparatus in each ear?

A
  • Gives better resolution of the code
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is required to use the vestibular input to make inferences about body position in space?

A

Information from
- Skin
- Vision
- Proprioception

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the different directions of movement in the vestibular system?

A
  • Pitch (y-axis): anterior/posterior (front/back)
  • Roll (x-axis): coronal
  • Yaw (z-axis): Rotational
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where does the Vestibular System Reside?

A

Inner Ear
- Very close to the cochlea
- Next to very dense bone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the vestibular system innervated by?

A
  • Cranial Nerve VIII: Vestibulocochlear Nerve
  • Afferent axons go to receptors in vestibular system and auditory system
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the bony labyrinth

A
  • Bunch of tunnels and holes carved out of the petrous temporal bone
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where is the Bony Labyrinth Located?

A
  • Petrous Temporal Bone
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where is the Bony Labyrinth Located?

A
  • Petrous Temporal Bone
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is be between the membranous and bony labyrinth?

A

Fluid
- Perilymph

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the membrane within the tunnels of the bony labyrinth called?

A
  • Membranous labyrinth
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the Membranous Labyrinth filled with?

A
  • Endolymph
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Where does the membranous labyrinth sit?

A
  • Floats inside the bone
  • thin layer of fluid separating it from bone
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the 3 semicircular canals?

A
  • Anterior
  • Posterior
  • Horizontal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What happens to the anterior and posterior canals?

A
  • Join together
  • Merge within the vestibule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What goes through the 3 semicircular canals?

A
  • membranous semicircular ducts
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the Ampulla?

A
  • slight swelling in the tubes of the vestibular system
  • contain hair receptors for semicircular ducts
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What connects up with the cochlea?

A
  • Continuous fluid-filled tubing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the two otolith organs?

A
  • Saccule
  • Utricle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Where are the otolith organs located?

A
  • vestibule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What does the vestibule contain?

A
  • Otolith Organs
  • Hair Receptors
  • Membranous sac that are specialized
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the ducts and vestibule embedded in?

A
  • Solid, dense petrous temporal bone
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Why are the ducts and vestibule embedded in solid, dense petrous temporal bone?

A
  • So acceleration is transferred directly into the vestibular system
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How is the vestibular on one-side compared to the other?

A
  • They are perfectly mirrored
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What does each side of the vestibular system contain?

A
  • 3 semicircular canals
  • 3 semicircular ducts
  • swellings that contain otolith organs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

How are the semicircular ducts orientated?

A

Orthogonal on Each Other
- at right angles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What does the orientation of the semicircular ducts do?

A
  • allows them to work in pairs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What plane is the horizontal duct in?

A
  • Slightly off horizontal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

How can you line up the horizontal ducts in the horizontal plane?

A
  • tilt head down
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

How are the anterior ducts orientated with one another?

A
  • 90 degrees orthogonal to each other
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

How would you line up the anterior ducts with the other anterior ducts?

A

turn head 45 degrees to one side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

How are the posterior and anterior ducts orientated?

A
  • 90 degrees from anterior canal on one side is aligned with the posterior duct
35
Q

What does the orientation of the semicircular ducts make?

A
  • a perfect 3D plot
36
Q

What are Hair Cells in the Vestibular and auditory systems?

A
  • Receptors
37
Q

What sticks out of the top of every Hair Cell?

A
  • Cilia
38
Q

What are the 2 types of Hair Cells?

A
  • Kinocilium
  • Stereocilia
39
Q

Describe Kinocilium

A

Celia
- Tall
- thick
- Rigid Cilia
- 1 per cell

40
Q

Describe Stereocilia

A

Cilia of Hair Cells
- 40-70 per cell
- increase in length from one end of cell towards kinocilium
- Shortest are further from kinocilium

41
Q

Are the Hair Cells polarized? Why?

A

Yes
- morphological axis of polarity
Why
- Something about the way the hairs move that is critical

42
Q

What is the Hair Cell Connected to?

A
  • Afferent Neurons
  • Sits on top of afferent sensory axon
43
Q

What happens when you bend the stereocilia toward the kinocilium?

A
  • depolarize, would drop more Neurotransmitters out of it
44
Q

What happens when you push the stereocilia away from the kinocilium?

A
  • Hyperpolarize
45
Q

How does the hair cell depolarize?

A
  • Stereocilia bends towards the kinocilium
46
Q

How does the hair cell hyperpolarize?

A
  • Stereocilia bends away from kinocilium
47
Q

What kind of receptor are hair cells?

A
  • mechanoreceptors
48
Q

What causes the change in the membrane potential of the hair cells?

A
  • a movement of the hairs
49
Q

What does the movement of the stereocilia relative to the kinocilium determine?

A
  • The leakiness of the membrane
50
Q

What kind of background discharge does the 8th afferent nerve have?

A
  • High
  • NT dropping out of the hair cells constantly
  • spontaneous firing at 100Hz
51
Q

How does the magnitude of the bending of the stereocilia determine the leakiness of the membrane?

A
  • the more it bends the more it changes it
  • higher bend towards kinocilium = higher leakiness
  • higher bend away from kinocilium = less leakiness
52
Q

What does the leakiness of the hair cell mean?

A
  • How much NT is being released
53
Q

What happens to the firing rate of the hair cells when there is nothing pushing against the kinocilium?

A
  • Normal firing rate
54
Q

Where do the hair cells congregate?

A

Ducts
- Ampullae (swelling)
Otolith Organs
- Macula

55
Q

What is the crista ampullaris of the ampullae?

A
  • All hair cells are orientated in the same direction
  • Kinocilium on one side with stereocilia staircase down
56
Q

What is the Macula?

A
  • Sensory Region of the Otolith Receptors
57
Q

How are the hair cells orientated in the macula? Why?

A

very specific pattern
- so hair cells will deform in different proportions

58
Q

What is the specific pattern of the macula hair cells?

A
  • lined up with axis of morphology in many directions
  • line in the middle of the macula called the striola
59
Q

What is the line in the middle of the macula called?

A
  • Striola
60
Q

How does the macula work?

A
  • depolarized/hyperpolarized during movement
  • the specific hair cells that are changed tells the direction distortion
  • Can sheer in any direction
  • deals in planes
  • mirrored on other side
61
Q

What planes of movement do the hair cells in the utricle work in?

A
  • Lateral motion
  • forward/backward (redundant plane)
62
Q

Where is the kinocilium located in the utricle?

A
  • closest to the striola
63
Q

Where are the cilia located in the Utricle?

A
  • sticking straight up from floor
  • Vertical and oriented in horizontal plane
  • Kinocilium close to striola
64
Q

What does the movement of hair cells mean in the Utricle?

A
  • Towards the striola = depolarization
65
Q

How are the hair cells orientated in the Saccule?

A
  • On the walls
  • Hairs stick out horizontally
  • Kinocilium furthest from striola
66
Q

What causes depolarization in the Saccule?

A
  • Movement of hairs away from striola
67
Q

What are some key structural features of the Otoliths?

A
  • Hair Cells: project up into the overlying membrane
  • Otolithic Membrane: overlying membrane
  • Otoconia: small crystals, imbedded in membrane
68
Q

What are Otoliths sensitive to?

A
  • Linear Acceleration
69
Q

What are Otoconia? What do they do?

A

Otoconia
- Small Crystals imbedded in Otolithic Membrane
Do
- Give mass to otolithic membrane

70
Q

How does the otolithic membrane cause bending?

A
  • Otoconia give mass
  • Gravity pulls membrane down
71
Q

What does the shifting of the otolithic membrane do?

A
  • causes cilia to move
  • Pulls stereocilia towards or away from kinocilium depending on the orientation
72
Q

What happens if acceleration is constant?

A
  • the shearing stops
73
Q

How does polarization work in the Utricle?

A
  • sheering in the horizontal plane will cause hyperpolarization or depolarization
  • Picks up linear acceleration in the horizontal plane
74
Q

How does polarization in the Saccule work?

A
  • Movement in forward/backward and up/down will cause hyperpolarization or depolarization (same time)
75
Q

How is 3D linear acceleration covered by the Otoliths?

A
  • Utricle and Saccule are mirrored on each side
76
Q

What is different about hair cells in the Ampullae compared to the Macula?

A

Ampullae
- all orientated in same way
- Either hyperpolarize or depolarize
Macula
- Oriented in different ways
- Hyperpolarized and Depolarized at same time

77
Q

What is the Cupula?

A
  • Gelatinous material that welds across the duct
  • Membrane that divides the ducts in two
78
Q

Where do the hair cells of the ampullae project?

A
  • The Cupula
79
Q

What causes the bending of the cilia in the ampullae? how?

A

What
- Movement of the fluid (endolymph)
How
- Endolymph has natural inertia
- Rotation cause fluid to lag behind
- Fluid pushes against cupula
- Cilia bends

80
Q

What happens when you spin your head to one side?

A

Moves right away
- membranous duct
- cupula
- hair cells
Does not move right away
- endolymph

81
Q

What does the movement of endolymph measure?

A
  • angular acceleration in any direction in 3D
82
Q

What happens when you spin at constant velocity?

A
  • Fluid stops bending the cupula, and hair cells go back to normal
  • afferent goes back to normal firing rate
83
Q

How do the Hair Cells in the vestibular system work in pairs?

A
  • Morphological axis of polarity
  • when one side depolarizes, the other hyperpolarizes
84
Q

Why does the fluid lag behind the rest of the vestibular structure?

A
  • The structure is attached to bony system, fluid is not attached