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Neuro Mini Exam > Biochemistry of Vision > Flashcards

Biochemistry of Vision Flashcards

1
Q

retina

A

ora serrata - anterior edge

nonsensory retinal pigment
epithelium -can inject

sensory retina

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2
Q

sensory retina

A

macula lutea
fovea centralis
optic disk

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3
Q

anatomic axis

A

doesn’t line up

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4
Q

visual axis

A

to fovea centralis

  • most acute vision
  • image directly projected here
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5
Q

macula lutea

A

surrounds fovea centralis

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6
Q

optic disk

A

where optic nerve arises

-retinal vessels present

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7
Q

cell types of retina

A

neurons
retinal pigment epithelium
neuron support cells

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8
Q

photoreceptor cells

A

rods and cones

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9
Q

neurons of retina

A

outer - photoreceptors

  • interneurons
  • retinal ganglion cells
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10
Q

retinal pigment epithelial cells

A

outermost layer

-separate retina from choroid

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11
Q

mueller cells

A

support cells from inner to outer membrane of retina

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12
Q

choreocapillaris

A

closest choroid to retina

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13
Q

inner portions of retina

A

too far for diffusion from choroid

-so instead get blood from retinal blood vessels

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14
Q

slide of retina

A

look for cell nuclei

-easy to see different layers

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15
Q

ganglion cell layer

A

larger cells

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16
Q

layers in order of signal transduction

A 
pigment epithelial cells
photoreceptor cells
outer limiting membrane
outer nuclear layer
outer plexiform layer
inner nuclear layer
inner plexiform layer
ganglion cell layer
optic nerve fibers
inner limiting membrane
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17
Q

photoreceptor cell segments

A

inner and outer

-both in exterior of eye

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18
Q

inner segment of photoreceptor

A

rich in organelles

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19
Q

outer segment of photoreceptors

A

flat membranous disks with photopigment

-continuous turnover - move exteriorly

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20
Q

rods

A

light of differing intensity
around periphery of retina

rhodopsin

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21
Q

cones

A

blue, green, red

COLOR

fovea

contain iodopsin

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22
Q

rhodopsin

A

in rods

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23
Q

iodopsin

A

in cones

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24
Q

internal photoreceptor matrix

A

important

  • provides nutrition to photoreceptor and remove waste
  • including shed membranous disks

cycling proteins - interstitial retinal binding protein

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25
Q

interstitial retinal binding protein

A

transports retinol to RPE and retinal to the photoreceptor

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26
Q

RPE

A

retinal pigment epithelium

  • contains melanin granules
  • phagocytose shed disks
  • retinol re-isomerization enzyme

11-cis retinal to retinol

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27
Q

rods end in?

A

end in rod sperule

  • dendrites of bipolar cells
  • neurites of horizontal cells
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28
Q

cones end in

A

cone pedicle
-dendrites of bipolar cells
neurites of horizontal cells

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29
Q

neurite

A

ether dendrite or axon?

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30
Q

proteins in photoreceptor

A

photopsin

  • cones iodopsins
  • rods rhodopsin
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31
Q

chromophore

A

11-cis retinal

-combine with the photopsin to form the iodopsin

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32
Q

red, green, blue stimulated together

A

seen as white light

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33
Q

photobleaching

A

photopigment absorbs photon of light and changes confirmation

photopigment contains protein and 11-cis retinal

  • change from cis to trans
  • also changes the opsin it is associated with

acts as GPCR

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34
Q

photopigment

A

acts as GPCR when stimulated
-GMP from cGMP

reduced cGMP levels

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35
Q

high cGMP

A

photoreceptor off

  • activates sodium channels
  • dark = open sodium channels
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36
Q

decreased cGMP

A

close sodium channels

due to photoreceptor activation

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37
Q

visual cycle

A

bleaching and cycling between retinoids

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38
Q

all-trans-retinol

A

converted to all trans-retinal in RPE

-which can be cycled

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39
Q

leber congenital amaurosis type 2

A

group of mutations in RPE65

  • isomerohydrolase
  • converts all trans retinol to 11 cis retinal

in RPE

loss of vision results

autosomal recessive

40
Q

bipolar cells

A

receive impulse from photoreceptor cell

-rod and cone varieties

41
Q

diffuse cone bipolar

A

input from multiple cells

42
Q

midget cone bipolar

A

input from single cell

only in cones

thought to be involved in visual acuity (1:1 ratio)

43
Q

diffuse ganglion cells

A

contact with several bipolar cells

44
Q

midget ganglion cells

A

contact with single bipolar cells

**possibly better acuity

45
Q

association neurons

A

integrate signals

  • amacrine cells - end ??
  • horizontal cells - end on cone pedicles and rod spherules
46
Q

mueller cells

A

span retina

47
Q

microglia

A

present in all layers

48
Q

visual axis of cornea

A

a fovea

49
Q

central depression

A

fovea centralis

surrounded by macula

flattening of cells at an angle to allow more light in**

greatest visual discretion
-mostly cone photoreceptors

low light vision here = bad

50
Q

macular degeneration

A

breakdown of macula

51
Q

macular edema

A

inflammation at macula

not maculitis

52
Q

inflammation optic disk

A

pappil edema

53
Q

optic nerve

A

convergence of axons of retinal ganglion cells

myelination begins at optic disk

54
Q

blind spot

A

absence of photoreceptors at the optic nerve

-only axons

55
Q

avascular structure

A

fovea centralis
-don’t want to impede the movement of light

thickness diminished - can get nutrients from choroid

56
Q

vascular structure

A

optic disk

57
Q

choroid

A

outer retinal blood supply

58
Q

central retinal artery

A

rises from optic nerve head
-maintenance of inner retina

branches to three layers of capillaries
-run posterior to inner limiting membrane, within the nerve fiber layer

59
Q

photoreceptors and horizontal cells

A

NO blood from central retinal atery

–they get blood from choroid

60
Q

retinal detachment

A

photoreceptor layer from RPE layer
-hemorrhage in that area

between brooks membrane and RPE

decreased diffusion of outer segments
-lose vision

61
Q

retinal tear

A

vitreous can leak in and cause retinal detachment

62
Q

diabetic retinopathy

A

complication of diabetes

-after 15-20 years

63
Q

pathology of diabetic retinopathy

A 
microaneurysms
cotton-wool spots - loss of vasculature
retinal veins - dilated and tortuous
retinal arteries - white / nonperfused
selective loss of pericytes - from retinal capillaries
apoptosis of capillary endothelial cells
64
Q

preproliferative phase

A

increased size and number of intraretinal hemorrhages

  • no vision loss
  • vision loss due to macular edema
65
Q

proliferative phase

A

formation of new blood vessels
-can protrude into vitreous

  • clouded vision
  • detached retina

can extend to other structures of eye

66
Q

fundoscopy

A

opthalmoscopy
-for examining retina

requires dilation of pupil
- to see better picture of entire retina

67
Q

non-proliferative DR

A

exudates and hemorrhage

68
Q

tortuous arteries

A

VEG-F signaling

69
Q

proliferative DR

A

with NEOVASCULARIZATION

tufts of arteries - new growth
larger hemorrhaging

70
Q

fluorescein angiography

A

dye into vein in patients arm
-retinal photograph captures fluorescence

can visualize hemorrhage and neovascularization

**see blood supply

allows earlier intervention

71
Q

optical coherence tomography

A

used to create cross section of retina

-retinal thickness increases in DR and macular edema

72
Q

Tx for non-proliferative

A

blood glucose control

blood pressure control

73
Q

diastolic BP

A

may be better predictor of progression

74
Q

photocoagulation

A

possible in retina due to presence of absorptive pigment epithelial cell layer

75
Q

panretinal

A

for proliferative DR

-across large diameter

76
Q

focal laser

A

for non-proliferative DR

-directed to microvascular events

77
Q

vitrectomy

A

removal of vitreous humor

can be physical removal or enzymatic

78
Q

pars plana

A

area for injecting eye

between retina and ciliary body

79
Q

glucocorticoid injections

A

reduce neovascularization

complication - increased IOP

80
Q

VEG-F inhibitor

A

to stop vascular growth

81
Q

primary

A

no known cause

or congenital/genetic

82
Q

corneo-irideal angle

A

obstruction - closed angle glaucoma

83
Q

open angle glaucoma

A

no angle closure
-increased IOP

primary - congenital
secondary - particulate matter, episcleral venous pressure

84
Q

tonometry

A

measure pressure to depress cornea

85
Q

slit-lamp examination

A

low power microscope with high intensity, focused light

examine cornea, iris, lens, cornea, extraocular tissues

86
Q

iridocorneal angle measure?

A

with gonioscope lens

87
Q

large bright space in optic disk

A

decreased retinal ganglion cells

88
Q

cup-to-disk ratio

A

rim - axons

cup - central retinal a and v

89
Q

whitening of rim

A

death of retinal ganglion cells

90
Q

margin changes of rim

A

death of retinal ganglion cells or inflammation

91
Q

cup diameter changes

A

horizontal diameter should be less than half horizontal diameter of disk
1:2 ratio

loss of RGC axons, signs of optic cupping

92
Q

Tx of optic cupping

A

increase aqueous outflow
-decreased aqueous production

laser trabeculoplasty
trabeculectomy

93
Q

drainage of aqueous

A

trabecular meshwork > canal of schlemme

94
Q

angle closure glaucoma

A

primary - anatomical predisposition
-pupillary block

secondary - inflammation, neovascular, contraction of tissue

95
Q

exam questions

A

no image identification

-be able to understand the results of an image

Neuro Mini Exam (7 decks)

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