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Neurobio > Lecture 8 - Vision > Flashcards

Lecture 8 - Vision Flashcards

1
Q

Where is the 3rd order neuron located along the visual pathway?

A

lateral geniculate nucleus of the thalamus

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2
Q

What are the 3 layers of the eyeball?

A
  1. sclera
  2. choroid
  3. retina
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3
Q

The sclera is continuous to the _____ _________

A

dura mater

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4
Q

What is the choroid?

A

a deep plexus of blood vessels like the choroid plexus deep to the sclera

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5
Q

What is the most inside part of the eye?

A

the retina

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6
Q

What does the conjunctive do?

A

fixes eyeball against our eyelid, part of the sclera

  • is a connective tissue
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7
Q

What is the limbus?

A

boundary of cornea and sclera

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8
Q

What is the ora serrata?

A

the end of the retina, not smooth

  • about 2/3 of the eyeball posteriorly
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9
Q

What is the lens?

A

a transparent layer of proteins, divides eyeball into anterior and posterior chambers

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10
Q

What is in the anterior chamber of the lens?

A

pigmented cells, secrete fluid drains into anterior chamber = aqueous humor

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11
Q

What is in the posterior chamber of the lens?

A

like glass, vitreous humor secreted by non-pigmented epithelia in the cell body

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12
Q

What happens when aqueous humor drainage is blocked?

A

glaucoma (other causes too)

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13
Q

What eye structures work on focusing and refraction of light?

A

cornea and lens

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14
Q

What eye structures work on brightness and quality?

A

iris and retina

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15
Q

What is the shape of the cornea?

A

convex anteriorly

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16
Q

What is the cornea for?

A

gross adjustment

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17
Q

What shape is the lens?

A

biconvex
- anterior convexity is adjustable

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18
Q

What is the job of the lens?

A

fine adjustment

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19
Q

What is a cataract?

A

layers of proteins that are transparent degrade with age so the transparency compromised

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20
Q

What happens with ciliary muscle contraction?

A

increases anterior convexity
- with CLOSE objects
- zonula fibers pull the lens out, build up biconvexity

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21
Q

What happens with ciliary muscle relaxation?

A

the anterior convexity is decreased
- with FAR AWAY objects
- relaxes ciliary muscles, pulls zonula fibers, stretches the anterior part of the lens
- more flat not so convex

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22
Q

What gives the pinhole effect?

A

the PUPIL

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23
Q

What two muscles control the dilation of the pupil?

A
  • pupillary dilator/dilator pupillae
  • pupillary sphincter/constrictor pupillae
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24
Q

What innervates the pupillary dilator?

A

sympathetic: superior cervical ganglia

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25
Q

What innervates the pupillary sphincter/constrictor?

A

CN III: ciliary ganglion

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26
Q

What does the retina do with strayed light?

A

absorbs it!
- reflection goes into the vitreous body, too much can cause you to not be able to see anything
- this absorbs light to get a clear image

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27
Q

What are photoreceptors?

A

rods and cones

NOT NEURONS

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28
Q

What do rods see?

A

black and white

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29
Q

What do cones see?

A

blue, red, and green

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30
Q

What is unique about the projection direction and processing direction of light?

A

opposite

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31
Q

What are bipolar neurons?

A

1st order neurons!

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32
Q

What is the ration of rods to bipolar neurons? Why is this important?

A

15~30:1

  • helps with gross image
33
Q

What is the ratio of cones to bipolar neurons? Why is this important?

A

1:1

  • acuity!
34
Q

What are ganglion cells?

A

2nd order neurons

35
Q

What do cones/rods release?

A

glutamate

INHIBITORY!!!

36
Q

What do pyramidal cells release in the cerebral cortex?

A

glutamate/aspartate

EXCITATORY

37
Q

What happens when glutamate is released in the eyes?

A

it inhibits functions of the bipolar neuron

38
Q

What is the macula?

A

part of the retina

  • lateral to the optic disc
  • around 5.5 mm diameter
39
Q

What can happen in the macula that can cause legally blindedness?

A

macular deceneration

  • cones died, acuity lost
  • can see things just without detail
40
Q

What is the fovea?

A

center of the macula in the retina
1.5mm diameter

41
Q

What is the foveola?

A

part of the fovea, very small 0.15mm diameter

42
Q

What is unique about the foveola?

A
  • cones only, highest visual acuity
43
Q

What is foveation?

A

fixes the fovea on the target objects

44
Q

What does the ganglion cell axon bundle form?

A

the optic nerve

45
Q

What is the blind spot?

A

has no photoreceptors
- happens worse with a retina injury/stroke

46
Q

What is the visual pathway to the V1?

A

left optic nerve to optic chiasm to left optic tract to left latearl geniculate

47
Q

What axons form the left optic nerve?

A

both nasal and temporal

48
Q

What happens with the axons at the optic chiasm?

A

crosses over (axons)

49
Q

What are the axons doing at the left optic tract?

A

temporal and nasal axons run together

50
Q

What is the lateral geniculate?

A

3rd order neuron in the thalamus, projects to V1

51
Q

What is the parallel process?

A

pathway through thalamus mainly for us to not see something but still perform

  • such as reaching for a bottle you know is there but not looking up to grab it
52
Q

What is the geniculostriate pathway?

A

lateral geniculate nucleus to V1
- STRIPED, the mitochondria show up as stripes with staining

53
Q

What makes up the 2 parts of the geniculostriate pathway?

A
  1. superior projection fibers in the parietal lobe for the inferior quadrant
  2. inferior projection fibers in the temporal lobe, Meyer’s loop for the superior quadrant
54
Q

What projects to 60% of posterior V1?

A

Macula

55
Q

What is the retinotopy?

A

spatial information conserved
- presentation of the world in your mind

56
Q

How is the iris controlled by visceral motors when sunlight is too strong?

A

sphincter pupillae activated by CNII, decreases light into the eyeball

57
Q

What are the visual hemifields?

A

each eye has a right and left component

58
Q

Where is the temporal space?

A

in the nasal retina

59
Q

Where is the nasal space?

A

in the temporal retina

60
Q

What is the binocular field?

A

crossover of the left and right hemifields when looking forward

61
Q

What is the optic nerve responsible for?

A

the vision of the eye, ipsilateral nasal and temporal retinas

62
Q

What happens at the optic chiasm?

A

decussation or crossover of bilateral nasal retina tracts

63
Q

What happens at the optic tract?

A

vision of both visual hemifields
- ipsilateral temporal and contralateral nasal retina

64
Q

If there is an impairment at the optic nerve what happens?

A

blind of the eye: CN II

65
Q

What happens if there is an impairment at the optic chiasm?

A

tunnel view: optic chiasm

66
Q

What happens if there is an imparment at the optic tract?

A

homonymous hemianopia

67
Q

What happens if there is an impairment on the optic radiation?

A

superior quadrantoanopia: Myer’s loop

68
Q

What happens if there is an impairment at the geniculostriate pathway?

A

homonymous hemianopia

69
Q

Where do the parallel projection pathways go through?

A

not through the thalamus

70
Q

What are parts of the tectopulvinar pathway?

A
  • pretectal area and superior colliculus
  • pupillary light reflex
  • visual association area: dorsal stream
71
Q

What happens if there are issues with the dorsal stream?

A

blindsight/riddoch’s phenomena

  • pts with an occipital stroke cant see one side
72
Q

What is in the hypothalamus in the parallel projection pathway?

A

suprachiasmatic nuclei

73
Q

What does the suprachiasmatic nuclei do?

A

relay for circadian rhythm

74
Q

Is CNII afferent or efferent? Where does it go in the pupillary light reflex pathway?

A

afferent, specific ganglion cells, NO PHOTORECEPTORS

  • to bilateral CNIII parasympathetic nucleus
75
Q

Is CNIII efferent or afferent? What does it do?

A

efferent

  • constricts bilateral pupils
76
Q

What happens if you shine a flashlight in one eye and it constricts but the other does not?

A

the CN III on the side that doesnt constrict is nonfunctional

77
Q

What happens when one the flashlight is shined into one eye and both pupils constrict, then into the other and they dilate?

A

on the side that the flashlight causes to dilate CN II is nonfunctional

78
Q

Axon bundles from which side of the nasal and temporal retina are in the left optic nerve, optic chiasm, and right optic tract?

A
  • left optic nerve: both left nasal and temporal retina
  • optic chiasm: bilateral nasal retina ganglia axons
  • right optic tract: right temporal and left nasal retina ganglion axons

Neurobio (10 decks)

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