Biochemistry of Vision Flashcards
(95 cards)
1
Q
retina
A
ora serrata - anterior edge
nonsensory retinal pigment
epithelium -can inject
sensory retina
2
Q
sensory retina
A
macula lutea
fovea centralis
optic disk
3
Q
anatomic axis
A
doesn’t line up
4
Q
visual axis
A
to fovea centralis
- most acute vision
- image directly projected here
5
Q
macula lutea
A
surrounds fovea centralis
6
Q
optic disk
A
where optic nerve arises
-retinal vessels present
7
Q
cell types of retina
A
neurons
retinal pigment epithelium
neuron support cells
8
Q
photoreceptor cells
A
rods and cones
9
Q
neurons of retina
A
outer - photoreceptors
- interneurons
- retinal ganglion cells
10
Q
retinal pigment epithelial cells
A
outermost layer
-separate retina from choroid
11
Q
mueller cells
A
support cells from inner to outer membrane of retina
12
Q
choreocapillaris
A
closest choroid to retina
13
Q
inner portions of retina
A
too far for diffusion from choroid
-so instead get blood from retinal blood vessels
14
Q
slide of retina
A
look for cell nuclei
-easy to see different layers
15
Q
ganglion cell layer
A
larger cells
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
17
Q
photoreceptor cell segments
A
inner and outer
-both in exterior of eye
18
Q
inner segment of photoreceptor
A
rich in organelles
19
Q
outer segment of photoreceptors
A
flat membranous disks with photopigment
-continuous turnover - move exteriorly
20
Q
rods
A
light of differing intensity
around periphery of retina
rhodopsin
21
Q
cones
A
blue, green, red
COLOR
fovea
contain iodopsin
22
Q
rhodopsin
A
in rods
23
Q
iodopsin
A
in cones
24
Q
internal photoreceptor matrix
A
important
- provides nutrition to photoreceptor and remove waste
- including shed membranous disks
cycling proteins - interstitial retinal binding protein
25
interstitial retinal binding protein
transports retinol to RPE and retinal to the photoreceptor
26
RPE
retinal pigment epithelium
- contains melanin granules
- phagocytose shed disks
- retinol re-isomerization enzyme
11-cis retinal to retinol
27
rods end in?
end in rod sperule
- dendrites of bipolar cells
- neurites of horizontal cells
28
cones end in
cone pedicle
-dendrites of bipolar cells
neurites of horizontal cells
29
neurite
ether dendrite or axon?
30
proteins in photoreceptor
photopsin
- cones iodopsins
- rods rhodopsin
31
chromophore
11-cis retinal
| -combine with the photopsin to form the iodopsin
32
red, green, blue stimulated together
seen as white light
33
photobleaching
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
34
photopigment
acts as GPCR when stimulated
-GMP from cGMP
**reduced cGMP levels**
35
high cGMP
photoreceptor off
- activates sodium channels
- dark = open sodium channels
36
decreased cGMP
close sodium channels
due to photoreceptor activation
37
visual cycle
bleaching and cycling between retinoids
38
all-trans-retinol
converted to all trans-retinal in RPE
| -which can be cycled
39
leber congenital amaurosis type 2
group of mutations in RPE65
- isomerohydrolase
- converts all trans retinol to 11 cis retinal
in RPE
loss of vision results
autosomal recessive
40
bipolar cells
receive impulse from photoreceptor cell
| -rod and cone varieties
41
diffuse cone bipolar
input from multiple cells
42
midget cone bipolar
input from single cell
only in cones
thought to be involved in visual acuity (1:1 ratio)
43
diffuse ganglion cells
contact with several bipolar cells
44
midget ganglion cells
contact with single bipolar cells
**possibly better acuity
45
association neurons
integrate signals
- amacrine cells - end ??
- horizontal cells - end on cone pedicles and rod spherules
46
mueller cells
span retina
47
microglia
present in all layers
48
visual axis of cornea
a fovea
49
central depression
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
macular degeneration
breakdown of macula
51
macular edema
inflammation at macula
not maculitis
52
inflammation optic disk
pappil edema
53
optic nerve
convergence of axons of retinal ganglion cells
myelination begins at optic disk
54
blind spot
absence of photoreceptors at the optic nerve
| -only axons
55
avascular structure
fovea centralis
-don't want to impede the movement of light
thickness diminished - can get nutrients from choroid
56
vascular structure
optic disk
57
choroid
outer retinal blood supply
58
central retinal artery
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
photoreceptors and horizontal cells
NO blood from central retinal atery
| --they get blood from choroid
60
retinal detachment
photoreceptor layer from RPE layer
-hemorrhage in that area
between brooks membrane and RPE
decreased diffusion of outer segments
-lose vision
61
retinal tear
vitreous can leak in and cause retinal detachment
62
diabetic retinopathy
complication of diabetes
| -after 15-20 years
63
pathology of diabetic retinopathy
```
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
preproliferative phase
increased size and number of intraretinal hemorrhages
- no vision loss
- vision loss due to macular edema
65
proliferative phase
formation of new blood vessels
-can protrude into vitreous
- clouded vision
- detached retina
can extend to other structures of eye
66
fundoscopy
opthalmoscopy
-for examining retina
requires dilation of pupil
- to see better picture of entire retina
67
non-proliferative DR
exudates and hemorrhage
68
tortuous arteries
VEG-F signaling
69
proliferative DR
with NEOVASCULARIZATION
tufts of arteries - new growth
larger hemorrhaging
70
fluorescein angiography
dye into vein in patients arm
-retinal photograph captures fluorescence
can visualize hemorrhage and neovascularization
**see blood supply
allows earlier intervention
71
optical coherence tomography
used to create cross section of retina
| -retinal thickness increases in DR and macular edema
72
Tx for non-proliferative
blood glucose control
| blood pressure control
73
diastolic BP
may be better predictor of progression
74
photocoagulation
possible in retina due to presence of absorptive pigment epithelial cell layer
75
panretinal
for proliferative DR
| -across large diameter
76
focal laser
for non-proliferative DR
| -directed to microvascular events
77
vitrectomy
removal of vitreous humor
can be physical removal or enzymatic
78
pars plana
area for injecting eye
| between retina and ciliary body
79
glucocorticoid injections
reduce neovascularization
complication - increased IOP
80
VEG-F inhibitor
to stop vascular growth
81
primary
no known cause
| or congenital/genetic
82
corneo-irideal angle
obstruction - closed angle glaucoma
83
open angle glaucoma
no angle closure
-increased IOP
primary - congenital
secondary - particulate matter, episcleral venous pressure
84
tonometry
measure pressure to depress cornea
85
slit-lamp examination
low power microscope with high intensity, focused light
examine cornea, iris, lens, cornea, extraocular tissues
86
iridocorneal angle measure?
with gonioscope lens
87
large bright space in optic disk
decreased retinal ganglion cells
88
cup-to-disk ratio
rim - axons
| cup - central retinal a and v
89
whitening of rim
death of retinal ganglion cells
90
margin changes of rim
death of retinal ganglion cells or inflammation
91
cup diameter changes
horizontal diameter should be less than half horizontal diameter of disk
1:2 ratio
loss of RGC axons, signs of optic cupping
92
Tx of optic cupping
increase aqueous outflow
-decreased aqueous production
laser trabeculoplasty
trabeculectomy
93
drainage of aqueous
trabecular meshwork > canal of schlemme
94
angle closure glaucoma
primary - anatomical predisposition
-pupillary block
secondary - inflammation, neovascular, contraction of tissue
95
exam questions
no image identification
| -be able to understand the results of an image
