Neuro II > 40 Vision > Flashcards

40 Vision Flashcards

(67 cards)

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1
Q

Incoming light is focused on:

A

fovea

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2
Q

As an image enters the eye, it is:

A
  1. refracted by the cornea
  2. inverted through the pupil
  3. refracted by the lens
  4. projected onto fovea
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3
Q

The lens refraction abilities are controlled by:

A

ciliary muscles (under SNS and PNS control)

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4
Q

Function of sclera?

A

protective layer for the retina and the choroid


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5
Q

Function of choroid?

A

vasc bed which provides blood flow and nutrients to the photoreceptors and RPE cells

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6
Q

The retinal blood flow is supplied by:

A
  1. central retinal artery (enters through optic nerves)

2. choroid

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7
Q

The cell bodies of the photoreceptors are located in:

And project to:

A

outer nuclear layer

outer plexiform layer

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8
Q

The photoreceptors signal through:

to:

A

through the outer plexiform layer to the bipolar cells

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9
Q

Cell bodies of bipolar cells are located:

A

in the inner nuclear layer

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10
Q

The final layer of neurons in the retina are:

A

retinal ganglion cells (located in the ganglion cell layer)

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11
Q

Function of retinal pigmented epithelial cells?

A

support the photoreceptors and provide nutrients

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12
Q

Line outermost surface of retina?

A

photoreceptors

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13
Q

Function of interneurons?

A

help in convergence of the image from the millions of photoreceptors to hundreds of bipolar cells to tens of ganglion cells

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14
Q

Types of interneurons?

A

horizontal cells and amacrine cells

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15
Q

Coalesce to form optic nerve head?

A

ganglion cell axons

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16
Q

Blind spot =

A

optic nerve head

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17
Q

Structure of fovea?

A

radially displaced retinal layers

allows for minimal distortion of the image

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18
Q

Main functions of retinal pigmented epithelial cells?

A
  1. separate the vascular choroid from the neural retina
  2. phagocytose rod outer segments every 10 days
  3. absorb some of the light that comes to the photoreceptors
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19
Q

Macular degeneration results when:

A

blood vessels damage the RPE + break through their barrier –> grow into macular region of the eye

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20
Q

Light detection/transduction occurs in:

A

outer segment of rods

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21
Q

What are spherules?

A

synaptic vesicles in rods

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22
Q

Cones are (shorter/longer) and (bigger/smaller) than rods.

A

shorter, smaller

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23
Q

How is color “seen”?

A

recognized by a unique combo of L-, M- and S-cones

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24
Q

Blue cones?

A

S

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25
Green cones?
M
26
Red cones?
L
27
Carried on the X-chromosome?
M-cone and L-cones
28
Function of photoreceptors?
absorb quanta of light and convert to elec signal
29
Occurs in rods/cones in response to light?
hyperpolarization
30
Reaction caused by light entering?
converts 11-cis-retinal to all-trans retinal
31
Activates rhodopsin? | Then what happens?
all-trans retinal 1. Active rhodopsin can activate GTP 2. activates cGMP PDE by removing inh subunit 3. 

Active PDE decr cGMP levels enough to hyperpolarize mem = close Na and Ca channels
32
What repolarizes the membrane?
1. calcium pumped out through the Na/Ca exchanger 2. Ca reduced in the membrane --> cGMP levels rise = re-polarize the membrane to pre-stimulus levels
33
How do proteins return to pre-activation?
1. Slowly, rhodopsin is de-P 2. Slowly, all-trans-retinal converted back to 11-cis-retinal 3. Rhodopsin kinase re-P rhodopsin (which is bound by arrestin)
34
What removes arrestin from rhodopsin?
conversion of 11-cis-retinal to all-trans-retinal
35
Once photoreceptors have processed the light, the signal is passed along to:
bipolar cells
36
Detect major changes in activity levels at bipolar-ganglion cell synapse?
amacrine cells
37
Location of cone bipolar cells? Location of rod bipolar cells?
center of retina periphery
38
Help converge the signals from multiple rod photoreceptors to fewer rod bipolar cells?

Horizontal cells
39
Alpha ganglion cells have most input from:d
rods | *participate little in color perception
40
Structure of alpha ganglion cells?
extensive dendritic trees, large axons
41
Alpha ganglion cells project to:
magnocellular layer of the lateral geniculate nucleus
42
Function of alpha ganglion cells?
help locate the object in space

43
Function of beta ganglion cells?
fine texture and colors
44
Beta ganglion cells project to:
parvocellular regions in the LGN

45
Structure of beta ganglion cells?
small receptive field | small dendritic arbors
46
What does not occur in the fovea?
convergence
47
Ratio of | cone : cone bipolar cell : ganglion cell
1:1:1
48
Why do humans have a crisp image representation?
no horizontal or amacrine cell interactions in the fovea
49
Why is image reverse and inverted?
pinpoint effect of pupil
50
Decussates in optic chiasm?
ganglion cell axons (nasal fibers)
51
How are fibers radiating to primary visual cortex organized?
retinotopically
52
The L visual field is processed in the (R/L) visual cortex
R
53
Which visual image does not cross?
temporal
54
The M pathway originates from: | Projects to:
magnocellular ganglion cells lateral geniculate layers 1/2 --> 4C alpha in the cortex
55
What is the function of 4C alpha in the cortex?
space info
56
The P pathway originates from: | Projects to:
parvocellular ganglion cells lateral geniculate layers 3-6 --> 4C beta in the cortex
57
What is the function of 4C beta in the cortex?
form info
58
Etiology of diabetic retinopathy?
1. changes in vasc (due to incr angiogenic and decr angiostatic growth factors) 2. changes in neurons (loss of photoreceptors + ganglion cells)
59
A retinal image of advanced macular degeneration shows:
hyperfluorescence and areas of no vascularity
60
Leading cause of blindness in older people? Leading cause of blindness in working age adults?
AMD DR
61
Etiology of AMD?
damage to choroidal vasculature breaks through the RPE cells and damages the macula --> Central vision = lost due to damage of macula
62
AMD or DR? | genetic component
both
63
AMD or DR? | Loss of central vision
AMD
64
AMD or DR? | loss of all vision
DR
65
AMD or DR? | choroid NV
AMD
66
AMD or DR? | retinal NV
DR
67
Cause of AMD?
Age** Smoking Genetics Changes in angiogenic/static factors
Neuro II
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