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Ocular Phys > Block 11 > Flashcards

Block 11 Flashcards

1
Q

Monolayer of pigmented cells between choriocapillaris and outer segment of PR

A

RPE

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2
Q

Apical membrane of RPE faces which retinal layer

A

PR outer segments

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3
Q

General light absorption occurs where on the retina

A

Melanin in RPE

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4
Q

Blue light absorption is supplemented by what in the PRs

A

Lutein and zeaxanthin

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5
Q

The outer retina is exposed to what kind of environment

A

Oxygen rich

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6
Q

What layer of the retina creates a line of defense against oxidative damage

A

RPE

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7
Q

RPE contains high amounts of superoxide disputable and catalase

A

Enzymatic antioxidants

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8
Q

RPE accumulates lutein and zeaxanthin, ascorbate, alpha-tocopherol and beta-carotene

A

Nonenzymatic antioxidants

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9
Q

The RPE transports nutrients and metabolic end products between what 2 layers

A

PR and choriocapillaris

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10
Q

The transport of water by PR is driven by what

A

Active transport of Cl from retina to blood

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11
Q

Bull’s eye shaped lesion

A

Best’s vitelliform macular degeneration

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12
Q

Best’s vitelliform macular degeneration involves a reduction in transport of what

A

Reduction in epithelial Cl transport

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13
Q

The transport of lactic acid requires what

A

A tight regulation of the intracellular pH

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14
Q

What glucose transporters does the RPE containe

A

GLUT1 and GLUT3

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15
Q

Where does all-trans-retinal reduction to all-trans-retinol occur

A

PRs

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16
Q

Where does reisomerization of all-trans-retinol to 11-cis-retinal occur

A

RPE

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17
Q

Mutations in the genes of the visual cycle can cause what

A

Retinitis pigmentosa

Stargardt disease

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18
Q

Which is inherited, retinitis pigmentosa or stargardt disease

A

Retinitis pigmentosa

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19
Q

Phagocytosis is under what kind of control

A

Circadian

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20
Q

Every RPE cells faces how man PR in the fovea

A

23

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21
Q

How often is a whole outer segment of PR renewed

A

Every 11 days

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22
Q

Inability of the RPE to phagocytosis PR outer segment

A

Retinitis pigmentosa

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23
Q

A defect of RPE pR phagocytosis may also cause retinal degeneration in what patients

A

Usher type 1B patients

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24
Q

What 2 factors stabilize the endothelium of choriocapillaris

A

PEDF and VEGF

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25
Q

Which factor inhibits endothelial cell proliferation

A

PEDF

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26
Q

Which factor prevents endothelial cell apoptosis

A

VEGF

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27
Q

Factors that are essential for maintenance of the structural integrity of retina

A

TIMP1 and TIMP3

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28
Q

The most severe complication in age-related macular degeneration

A

Choroidal neovascularization

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29
Q

RPE cells secreted VEGF at a higher rate compared with RPE cells from eyes without neovascularization

A

Choroidal neovascularization

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30
Q

Tight junction between retinal pigment epithelium

A

Retina-blood barrier

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31
Q

Apical side of RPE toward

A

PR

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32
Q

Basolateral side of RPE faces

A

Choriocapillaris

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33
Q

Light detection by PR

Photon absorption by visual pigment on the discs of the outer segment

A

Photoreception

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34
Q

Visible light spectrum

A

400-700 nm

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35
Q

Dim light

A

Scotopic

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36
Q

Peripheral retina

A

Scotopic

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37
Q

Color

A

Photopic

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38
Q

Central retina

A

Photopic

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39
Q

Motion

A

Scotopic

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40
Q

Detail

A

Photopic

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41
Q

Which PR in scotopic

A

Rods

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42
Q

Which PR in photopic

A

Cones

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43
Q

Which PR are more sensitive

A

Rods

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44
Q

Which PR has a higher sensitivity to rapidly changing stimuli

A

Cones

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45
Q

Are there more rods or cones

A

Rods

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46
Q

Which are in the fovea

A

Cones

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47
Q

Peak absorption of rods

A

500-510 nm

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48
Q

Which PR converge to increase sensitivity

A

Rods

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49
Q

Which cones are in the fovea

A

Green (M) and red (L)

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50
Q

Unstable pigments that undergo a chemical change wen they absorb light

A

Photopigment

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51
Q

Opsin + 11-cis-retinal

A

Rhodopsin

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52
Q

Erythrolabe

A

Absorption max for red L cones

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53
Q

Chlorolabe

A

Absorption max for green M cones

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54
Q

Cyanolabe

A

Absorption max for blue S cones

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55
Q

Transformation of light into electrical and chemical signals that produces the perception of light

A

Phototransduction

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56
Q

Important channel in biochemical cascade

A 
CNG channel
(cGMP caged cation channel)
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57
Q

What does the CNG channel control

A

Na, K and Ca into the cell

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58
Q

In the dark, what is the RMP of rods

A

-50 mV

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59
Q

1st step in biochemical cascade

A

Photoisomerization of rhodopsin

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60
Q

Reduction of all-trans-retinal into all-trans-retinol occurs in

A

PR

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61
Q

Reisomerization of all-trans-retinol into 11-cis-retinal occurs in

A

RPE

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62
Q

The G protein involved in the biochemical cascade

A

Transducin

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63
Q

If it is GTP binding the the G protein

A

On

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64
Q

If it is GDP binding the the G protein

A

Off

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65
Q

Step 2 in the biochemical cascade

A

G protein activation

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66
Q

Step 3 in biochemical cascade

A

PDE6 activation

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67
Q

Activated PDE6 converts what

A

cGMP into GMP

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68
Q

How does PDE degrade cGMP

A

By hydrolyzing cGMP into 5’-GMP

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69
Q

Step 4 in biochemical cascade

A

Channel closing (CNG channel)

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70
Q

Opening of the CNG channels puts the PR at what

A

Resting dark-adapted state

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71
Q

Communication of rods with bipolar cells uses what NT

A

Glutamate

72
Q

When there is light, is there more or less glutamate

A

Less glutamate released

73
Q

Key molecule of biochemical cascade to keep CNG channel open

A

cGMP

74
Q

Major energy producing pathways in the retina

A

Glycolysis
TCA (need O2)
Electron transport (need O2)

75
Q

Which glucose transporter is used in the retina

A

GLUT3

76
Q

When is lactic acid produced in the largest quantities

A

Sleep or condition with low oxygen levels

77
Q

How does ascorbic acid protect the retina and lens

A

Blocks UV
Scavenges free radicals
Reduces O2 damage during inflammation

78
Q

Compound that can protect the eye when endotoxin is exposed to the patient

A

Ascorbic acid/vitamin c

79
Q

Aqueous glucose level is what percent of serum glucose level

A

80%

80
Q

Vitreous to serum ratio of ascorbic acid

A

9:1

81
Q

Junction between 2 nerve cells, consisting of a minute gap across which impulses pass by diffusion of a NT

A

Synapse

82
Q

Excitatory NT in retina

A

Glutamate

83
Q

Inhibitory NT in retina

A

GABA and glycine

84
Q

More negative than RMP

A

Hyperpolarization

85
Q

Less negative than RMP

A

Depolarization

86
Q

In which layer of the retina do the horizontal cells provide lateral interactions

A

OPL

87
Q

Bipolar cells transfer the light signals into which layer and onto what cells

A

IPL; amacrine and GC

88
Q

Which cells transmit the signals to the visual centers of the brain

A

GCs

89
Q

Which NT do cones use

A

Glutamate

90
Q

Level of glutamate in the dark

A

High

91
Q

Off cone bipolar and horizontal cells are _____ by light

A

Hyperpolarized

92
Q

ON cone bipolar cells are _____ by light

A

Depolarizer

93
Q

Off cone bipolar cells transfer signals onto

A

OFF GCs

94
Q

on cone bipolar cells transfer signal onto

A

ON GCs

95
Q

One cone connected to a midget bipolar cells connected to a midget ganglion cell

A

Midget system

96
Q

NT in rods

A

Glutamate

97
Q

Only one type of rod bipolar cell

A

ON rod bipolar cell

98
Q

On rod bipolar cells are _____ by light

A

Depolarized

99
Q

Classic rod pathway

A

Rods —> ON rod bipolar cells depolarized —> amacrine cells depolarized

  • glutamate: ON cone bipolar cells —> ON GCs
  • glycine : OFF cone bipolar cells —> OFF GCs
100
Q

Glutamatergic neurons

A

Rods, cones, bipolar cells and most GCs

101
Q

GABAergic and glycinergic neurons

A

Horizontal cells and most amacrine cells

102
Q

Aging changes in the retina: nerve fibers within the ON

A

Decrease

103
Q

Aging changes in the retina: optic cup diameter

A

Increases

104
Q

Aging changes in the retina: ILM

A

Thickens

105
Q

Aging changes in the retina: foveal reflex

A

Dimmer (bc of the thickened ILM)

106
Q

Aging changes in the retina: total number of RPE cells

A

Decrease

107
Q

Aging changes in the retina: lipofusin within RPE cells

A

Increases (drusen increases)

108
Q

Aging changes in the retina: atrophy

A

Increases

109
Q

Age-related retinal atrophy: Pigmentation in RPE/choroid decreases (can see normally hidden choroidal vessels)

A

Tigroid fundus

110
Q

Age related retinal atrophy: peripheral RPE degeneration

A

Reticular degeneration

111
Q

Which type of cells play a role in transmitting cones signal to GC

A

Cone bipolar

112
Q

Which type of cells play a role in transmitting rod signal to GC

A

Rod bipolar and amacrine cells

113
Q

What change does ON bipolar cells have with light

A

Depolarized

114
Q

NT that bipolar cells have

A

Glutamate

115
Q

When the center of a GCs receptive field is exposed to light, which type of GC is stimulated

A

ON center GC

116
Q

A transparent, passive structure in the eye

A

Lens

117
Q

Does the lens grow throughout life

A

Yes

118
Q

Does the lens shed cells as it grows

A

No

119
Q

2/3 of the lens is composed of what

A

Water

120
Q

1/3 of the lens is composed of what

A

Protein

121
Q

Water, protein and small amounts of other components contribute to the need to what

A

Tightly regulate energy metabolism that predominantly involves glucose metabolism

122
Q

Most active energy metabolism in the lens (70%)

A

Anaerobic glycolysis

123
Q

What energy path is secondary producing NADPH and is 5-10% of the lens energy

A

HMP Shunt

124
Q

The rest of the energy (outside of anaerobic glycolysis and HMP shunt) is derived from

A

Metabolism of lactic acid and glucose in lens epithelium (TCA and ETC)

125
Q

The 2 dominant source of energy in the lens

A

Anaerobic glycolysis and HMP shunt

126
Q

Transport of glucose among cells is accomplished via

A

Gap junctions

127
Q

How does the lens get glucose since it has no blood supply

A

From posterior or anterior surface connecting with other mediums (ex: aqueous humor)

128
Q

Glucose is takin into cells via

A

Facilitated transport

129
Q

How does the lens rid of waste

A

Via diffusion to aqueous and then to the blood

130
Q

The epithelial cells are located where in the lens

A

Anterior pole

131
Q

What do the epithelial cells of the lens generate

A

The secondary fibers in the cortex

132
Q

Which surface of the lens has an upside down y suture

A

Posterior

133
Q

What happens to sutures as we age

A

They get more branches (up to 12)

134
Q

How much of the total power of the eye is the lens

A

1/3 (15D)

135
Q

2/3 of the lens is composed of

A

Water

136
Q

1/3 of the lens is composed of

A

Proteins

137
Q

3 types of proteins in the lens

A 
Water soluble (crystallins)
Urea soluble (crystallins and cytoskeletal)
Insoluble (membrane proteins)
138
Q

What is the main water soluble protein in the lens

A

Alpha crystallins

139
Q

90 of the proteins in the lens

A

Crystallins (water soluble)

140
Q

What proteins helps keep the lens transparent and give it a higher refractive index

A

Alpha crystallins

141
Q

Molecular chaperon of the lens

A

Alpha crystalline

142
Q

Where is the refractive index higher in the lens, nucleus or cortex

A

Nucleus

143
Q

How is water pumped out of the lens

A

From anterior surface through Na/K pump

144
Q

How is water pulled into the lens

A

From the back surface through osmotic pressure

145
Q

Where does mitosis of secondary fiber cells of the lens occurs

A

Germinative zone of anterior lens epithelium

146
Q

Where do lens fibers migrate after mitosis

A

Through transition zone and into the equator (elongation begins)

147
Q

Primary protector against oxidative damage in the lens

A

Glutathione

148
Q

Is ascorbic acid highe rin lens or aqueous

A

Lens

149
Q

Hofstetter’s formula solves what

A

How much accommodation someone has left due to their age

150
Q

Hofstetter’s formula

A

15-1/4(age)

151
Q

Type of cataract: decline of glutathione making fibers susceptible to oxidative damages

A

Nuclear cataract

152
Q

Type of cataract: fibers lose organelles and gain yellow-brown pigment

A

Nuclear cataract

153
Q

Type of cataract: decrease in glutathione activity, increase in Ca, Na and water

A

Cortical cataract

154
Q

Type of cataract: epithelial cells migrate from equatorial region and accumulate at posterior pole

A

Posterior subcapsular cataract

155
Q

How much does the lens thicken each year

A

.22mm per year

156
Q

Which surface of the lens increases

A

Anterior

157
Q

Does the radius of curvature of the lens increase or decrease with age

A

Decrease

158
Q

Which way does the lens move with age

A

Anteriorly

159
Q

Type of cataract: increase in sorbitol production - increase water uptake - lens swell - depletion of NADPH and cant reduce free radicals - protein polymerization

A

Diabetic cataract

160
Q

Unusual changes in Rx may indicate

A

Uncontrolled diabetes

161
Q

Changes in osmolarity of lens causes changes in

A

Thickness
Radius of curvature
Rx

162
Q

What type of light does the lens absorb to protect the retina

A

UV

163
Q

Type of protein does the lens contain the most

A

Crystallins

164
Q

Where does Na/K pump located to help pump out water

A

Anterior epithelium

165
Q

What is the driving force of water entering the lens from the back

A

Osmotic pressure

166
Q

Which part is responsible for the formation of secondary lens fibers

A

Anterior epithelium

167
Q

What type of changes in the lens are caused by accumulation of sorbitol

A

Cataract

Rx changes

168
Q

Single pigmented epithelium of retina

A

RPE

169
Q

Help outer retina get nutrition and remove waste

A

RPE

170
Q

Concentration of VEGF in healthy eyes

A

Low

171
Q

With AMD, levels of VEGF

A

Higher

172
Q

where is VEGF produced

A

RPE

173
Q

Is the CNG channel open or closed after the biochemical cascade

A

Closed

174
Q

When the CNG channel is closed, the is NT increased or decreased

A

Decreased

175
Q

Excitatory cells

A

Ganglion and amacrine (use glutamate)

Ocular Phys (5 decks)

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