Block 11 Flashcards
(175 cards)
1
Q
Monolayer of pigmented cells between choriocapillaris and outer segment of PR
A
RPE
2
Q
Apical membrane of RPE faces which retinal layer
A
PR outer segments
3
Q
General light absorption occurs where on the retina
A
Melanin in RPE
4
Q
Blue light absorption is supplemented by what in the PRs
A
Lutein and zeaxanthin
5
Q
The outer retina is exposed to what kind of environment
A
Oxygen rich
6
Q
What layer of the retina creates a line of defense against oxidative damage
A
RPE
7
Q
RPE contains high amounts of superoxide disputable and catalase
A
Enzymatic antioxidants
8
Q
RPE accumulates lutein and zeaxanthin, ascorbate, alpha-tocopherol and beta-carotene
A
Nonenzymatic antioxidants
9
Q
The RPE transports nutrients and metabolic end products between what 2 layers
A
PR and choriocapillaris
10
Q
The transport of water by PR is driven by what
A
Active transport of Cl from retina to blood
11
Q
Bull’s eye shaped lesion
A
Best’s vitelliform macular degeneration
12
Q
Best’s vitelliform macular degeneration involves a reduction in transport of what
A
Reduction in epithelial Cl transport
13
Q
The transport of lactic acid requires what
A
A tight regulation of the intracellular pH
14
Q
What glucose transporters does the RPE containe
A
GLUT1 and GLUT3
15
Q
Where does all-trans-retinal reduction to all-trans-retinol occur
A
PRs
16
Q
Where does reisomerization of all-trans-retinol to 11-cis-retinal occur
A
RPE
17
Q
Mutations in the genes of the visual cycle can cause what
A
Retinitis pigmentosa
Stargardt disease
18
Q
Which is inherited, retinitis pigmentosa or stargardt disease
A
Retinitis pigmentosa
19
Q
Phagocytosis is under what kind of control
A
Circadian
20
Q
Every RPE cells faces how man PR in the fovea
A
23
21
Q
How often is a whole outer segment of PR renewed
A
Every 11 days
22
Q
Inability of the RPE to phagocytosis PR outer segment
A
Retinitis pigmentosa
23
Q
A defect of RPE pR phagocytosis may also cause retinal degeneration in what patients
A
Usher type 1B patients
24
Q
What 2 factors stabilize the endothelium of choriocapillaris
A
PEDF and VEGF
25
Which factor inhibits endothelial cell proliferation
PEDF
26
Which factor prevents endothelial cell apoptosis
VEGF
27
Factors that are essential for maintenance of the structural integrity of retina
TIMP1 and TIMP3
28
The most severe complication in age-related macular degeneration
Choroidal neovascularization
29
RPE cells secreted VEGF at a higher rate compared with RPE cells from eyes without neovascularization
Choroidal neovascularization
30
Tight junction between retinal pigment epithelium
Retina-blood barrier
31
Apical side of RPE toward
PR
32
Basolateral side of RPE faces
Choriocapillaris
33
Light detection by PR
Photon absorption by visual pigment on the discs of the outer segment
Photoreception
34
Visible light spectrum
400-700 nm
35
Dim light
Scotopic
36
Peripheral retina
Scotopic
37
Color
Photopic
38
Central retina
Photopic
39
Motion
Scotopic
40
Detail
Photopic
41
Which PR in scotopic
Rods
42
Which PR in photopic
Cones
43
Which PR are more sensitive
Rods
44
Which PR has a higher sensitivity to rapidly changing stimuli
Cones
45
Are there more rods or cones
Rods
46
Which are in the fovea
Cones
47
Peak absorption of rods
500-510 nm
48
Which PR converge to increase sensitivity
Rods
49
Which cones are in the fovea
Green (M) and red (L)
50
Unstable pigments that undergo a chemical change wen they absorb light
Photopigment
51
Opsin + 11-cis-retinal
Rhodopsin
52
Erythrolabe
Absorption max for red L cones
53
Chlorolabe
Absorption max for green M cones
54
Cyanolabe
Absorption max for blue S cones
55
Transformation of light into electrical and chemical signals that produces the perception of light
Phototransduction
56
Important channel in biochemical cascade
```
CNG channel
(cGMP caged cation channel)
```
57
What does the CNG channel control
Na, K and Ca into the cell
58
In the dark, what is the RMP of rods
-50 mV
59
1st step in biochemical cascade
Photoisomerization of rhodopsin
60
Reduction of all-trans-retinal into all-trans-retinol occurs in
PR
61
Reisomerization of all-trans-retinol into 11-cis-retinal occurs in
RPE
62
The G protein involved in the biochemical cascade
Transducin
63
If it is GTP binding the the G protein
On
64
If it is GDP binding the the G protein
Off
65
Step 2 in the biochemical cascade
G protein activation
66
Step 3 in biochemical cascade
PDE6 activation
67
Activated PDE6 converts what
cGMP into GMP
68
How does PDE degrade cGMP
By hydrolyzing cGMP into 5'-GMP
69
Step 4 in biochemical cascade
Channel closing (CNG channel)
70
Opening of the CNG channels puts the PR at what
Resting dark-adapted state
71
Communication of rods with bipolar cells uses what NT
Glutamate
72
When there is light, is there more or less glutamate
Less glutamate released
73
Key molecule of biochemical cascade to keep CNG channel open
cGMP
74
Major energy producing pathways in the retina
Glycolysis
TCA (need O2)
Electron transport (need O2)
75
Which glucose transporter is used in the retina
GLUT3
76
When is lactic acid produced in the largest quantities
Sleep or condition with low oxygen levels
77
How does ascorbic acid protect the retina and lens
Blocks UV
Scavenges free radicals
Reduces O2 damage during inflammation
78
Compound that can protect the eye when endotoxin is exposed to the patient
Ascorbic acid/vitamin c
79
Aqueous glucose level is what percent of serum glucose level
80%
80
Vitreous to serum ratio of ascorbic acid
9:1
81
Junction between 2 nerve cells, consisting of a minute gap across which impulses pass by diffusion of a NT
Synapse
82
Excitatory NT in retina
Glutamate
83
Inhibitory NT in retina
GABA and glycine
84
More negative than RMP
Hyperpolarization
85
Less negative than RMP
Depolarization
86
In which layer of the retina do the horizontal cells provide lateral interactions
OPL
87
Bipolar cells transfer the light signals into which layer and onto what cells
IPL; amacrine and GC
88
Which cells transmit the signals to the visual centers of the brain
GCs
89
Which NT do cones use
Glutamate
90
Level of glutamate in the dark
High
91
Off cone bipolar and horizontal cells are _____ by light
Hyperpolarized
92
ON cone bipolar cells are _____ by light
Depolarizer
93
Off cone bipolar cells transfer signals onto
OFF GCs
94
on cone bipolar cells transfer signal onto
ON GCs
95
One cone connected to a midget bipolar cells connected to a midget ganglion cell
Midget system
96
NT in rods
Glutamate
97
Only one type of rod bipolar cell
ON rod bipolar cell
98
On rod bipolar cells are _____ by light
Depolarized
99
Classic rod pathway
Rods —> ON rod bipolar cells depolarized —> amacrine cells depolarized
- glutamate: ON cone bipolar cells —> ON GCs
- glycine : OFF cone bipolar cells —> OFF GCs
100
Glutamatergic neurons
Rods, cones, bipolar cells and most GCs
101
GABAergic and glycinergic neurons
Horizontal cells and most amacrine cells
102
Aging changes in the retina: nerve fibers within the ON
Decrease
103
Aging changes in the retina: optic cup diameter
Increases
104
Aging changes in the retina: ILM
Thickens
105
Aging changes in the retina: foveal reflex
Dimmer (bc of the thickened ILM)
106
Aging changes in the retina: total number of RPE cells
Decrease
107
Aging changes in the retina: lipofusin within RPE cells
Increases (drusen increases)
108
Aging changes in the retina: atrophy
Increases
109
Age-related retinal atrophy: Pigmentation in RPE/choroid decreases (can see normally hidden choroidal vessels)
Tigroid fundus
110
Age related retinal atrophy: peripheral RPE degeneration
Reticular degeneration
111
Which type of cells play a role in transmitting cones signal to GC
Cone bipolar
112
Which type of cells play a role in transmitting rod signal to GC
Rod bipolar and amacrine cells
113
What change does ON bipolar cells have with light
Depolarized
114
NT that bipolar cells have
Glutamate
115
When the center of a GCs receptive field is exposed to light, which type of GC is stimulated
ON center GC
116
A transparent, passive structure in the eye
Lens
117
Does the lens grow throughout life
Yes
118
Does the lens shed cells as it grows
No
119
2/3 of the lens is composed of what
Water
120
1/3 of the lens is composed of what
Protein
121
Water, protein and small amounts of other components contribute to the need to what
Tightly regulate energy metabolism that predominantly involves glucose metabolism
122
Most active energy metabolism in the lens (70%)
Anaerobic glycolysis
123
What energy path is secondary producing NADPH and is 5-10% of the lens energy
HMP Shunt
124
The rest of the energy (outside of anaerobic glycolysis and HMP shunt) is derived from
Metabolism of lactic acid and glucose in lens epithelium (TCA and ETC)
125
The 2 dominant source of energy in the lens
Anaerobic glycolysis and HMP shunt
126
Transport of glucose among cells is accomplished via
Gap junctions
127
How does the lens get glucose since it has no blood supply
From posterior or anterior surface connecting with other mediums (ex: aqueous humor)
128
Glucose is takin into cells via
Facilitated transport
129
How does the lens rid of waste
Via diffusion to aqueous and then to the blood
130
The epithelial cells are located where in the lens
Anterior pole
131
What do the epithelial cells of the lens generate
The secondary fibers in the cortex
132
Which surface of the lens has an upside down y suture
Posterior
133
What happens to sutures as we age
They get more branches (up to 12)
134
How much of the total power of the eye is the lens
1/3 (15D)
135
2/3 of the lens is composed of
Water
136
1/3 of the lens is composed of
Proteins
137
3 types of proteins in the lens
```
Water soluble (crystallins)
Urea soluble (crystallins and cytoskeletal)
Insoluble (membrane proteins)
```
138
What is the main water soluble protein in the lens
Alpha crystallins
139
90 of the proteins in the lens
Crystallins (water soluble)
140
What proteins helps keep the lens transparent and give it a higher refractive index
Alpha crystallins
141
Molecular chaperon of the lens
Alpha crystalline
142
Where is the refractive index higher in the lens, nucleus or cortex
Nucleus
143
How is water pumped out of the lens
From anterior surface through Na/K pump
144
How is water pulled into the lens
From the back surface through osmotic pressure
145
Where does mitosis of secondary fiber cells of the lens occurs
Germinative zone of anterior lens epithelium
146
Where do lens fibers migrate after mitosis
Through transition zone and into the equator (elongation begins)
147
Primary protector against oxidative damage in the lens
Glutathione
148
Is ascorbic acid highe rin lens or aqueous
Lens
149
Hofstetter’s formula solves what
How much accommodation someone has left due to their age
150
Hofstetter’s formula
15-1/4(age)
151
Type of cataract: decline of glutathione making fibers susceptible to oxidative damages
Nuclear cataract
152
Type of cataract: fibers lose organelles and gain yellow-brown pigment
Nuclear cataract
153
Type of cataract: decrease in glutathione activity, increase in Ca, Na and water
Cortical cataract
154
Type of cataract: epithelial cells migrate from equatorial region and accumulate at posterior pole
Posterior subcapsular cataract
155
How much does the lens thicken each year
.22mm per year
156
Which surface of the lens increases
Anterior
157
Does the radius of curvature of the lens increase or decrease with age
Decrease
158
Which way does the lens move with age
Anteriorly
159
Type of cataract: increase in sorbitol production - increase water uptake - lens swell - depletion of NADPH and cant reduce free radicals - protein polymerization
Diabetic cataract
160
Unusual changes in Rx may indicate
Uncontrolled diabetes
161
Changes in osmolarity of lens causes changes in
Thickness
Radius of curvature
Rx
162
What type of light does the lens absorb to protect the retina
UV
163
Type of protein does the lens contain the most
Crystallins
164
Where does Na/K pump located to help pump out water
Anterior epithelium
165
What is the driving force of water entering the lens from the back
Osmotic pressure
166
Which part is responsible for the formation of secondary lens fibers
Anterior epithelium
167
What type of changes in the lens are caused by accumulation of sorbitol
Cataract
| Rx changes
168
Single pigmented epithelium of retina
RPE
169
Help outer retina get nutrition and remove waste
RPE
170
Concentration of VEGF in healthy eyes
Low
171
With AMD, levels of VEGF
Higher
172
where is VEGF produced
RPE
173
Is the CNG channel open or closed after the biochemical cascade
Closed
174
When the CNG channel is closed, the is NT increased or decreased
Decreased
175
Excitatory cells
Ganglion and amacrine (use glutamate)
