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Neuro 3000 > The Eye > Flashcards

The Eye Flashcards

1
Q

Dark current channels close and less Ca is entering. Ca inhibits the synthesis of cGMP by guanylyl cyclase and thus with less unerring guanylyl cyclase is more active and cGMP synthesis inc. Dark channel currents gradually open and depolarize cones so that they have a range through white they can function in the light

A

Light adaptation

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2
Q

Neural tissue at the back of the eye

A

Retina

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3
Q

Carry red-green and blue-yellow info

A

P and nonm-nonp ganglion cells

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4
Q

Respond to the opposite way the photoreceptors communicating with them do. Metabotropic glutamate receptors (light is preferred stimulus)

A

On type (sign inverting) bipolar cells

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5
Q

Fewer disks, contain red, blue, or green pigments

A

Cones

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6
Q

Only output cells, fire APs

A

Ganglion cells

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7
Q

The cornea uses this since there is air in front and fluid behind (aqueous humor)

A

Refraction

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8
Q

Bending of light when traveling from one medium to another

A

Refraction

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9
Q

What does it mean when we say our visual system doesn’t detect differences in absolute values?

A

Not great in uniformly light/dark environments

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10
Q

SLIDE 45

A

SLIDE 45

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11
Q

More sensitive to light bc rods more sensitive to low light, more photoreceptors per ganglion cell

A

Peripheral retina

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12
Q

What does the G protein (transducin) do when rhodopsin is hit by light?

A

Activates phosphodiesterase and reduces the level of cGMP

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13
Q

All the complex data we need to construct our perception of the world is gathered by this

A

Retina

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14
Q

How does light activate rhodopsin?

A

Light strikes retinal and changes its shape to linear and the color of rhodopsin changes

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15
Q

Distance between peaks

A

Wavelength

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16
Q

Are red on center, green off surround or green on center, red off surround. Red and green are opponent colors

A

P type cells

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17
Q

Release GABA as a NT

A

Horizontal cells

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18
Q

Transfer of light energy, compounds do this with light of specific wavelengths and reflect others

A

Absorption

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19
Q

Used in daylight (photopic) to detect color. Many more photons are required to activate these photoreceptors. Not very active in the dark

A

Cones

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20
Q

SLIDE 59

A

SLIDE 59

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21
Q

What happens when Na and Ca stop flowing into rhodopsin?

A

The cell is hyper polarized (more negative)

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22
Q

These photoreceptors and 1000x more sensitive to the others and are thus used for night vision (scotopic) and shut down in bright light

A

Rods

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23
Q

90% of the ganglion cells. Contact one to a few cone bipolar. They have, small concentric receptive fields, produce sustained slowly adapting responses, with a weak response to movement. Good at analyzing SHAPES

A

P type

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24
Q

Respond to light at 560 nm (l)

A

Red cones

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25
Q

Scotopic vs photopic vision

A

S - night vision. rods

P - day vision. cones

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26
Q

Light being bounced off of a surface

A

Reflection

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27
Q

SLIDE 35

A

SLIDE 35

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28
Q

Theory that brain assigns colors based on comparison fo cone readouts, more to it than this though including the color opponent process

A

Young-Helmholtz trichromacy theory

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29
Q

Light sensitive part of retina

A

Layer of photoreceptor outer segments

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30
Q

Xanthophylls here protect eye from near UV light and act as antioxidants

A

Macula

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31
Q

Ganglion cells that sustain APs for longer

A

P type

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32
Q

Overall cell response is to send information about light vs dark, red vs gree, blue vs yellow, movement, detail (like shapes)

A

Ganglion cells

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33
Q

There is usually poor contrast sensitivity at first, results from cones being hyper polarized at first due to dark current channels closing

A

Light adaptation

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34
Q

Response in center to one wavelength is cancelled by other wavelength (opponent only) in surround. This is similar to the center surround organization seen for light or dark except that specific cones are present in only the center or the surround

A

Color opponent cells

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35
Q

Respond to the same way the photoreceptors communicating with them do. Inotropic glutamate receptors (dark is preferred stimulus)

A

Off type (sign conserving) bipolar cells

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36
Q

Where the optic nerve exits the eye, blood vessels but no photoreceptors (blind spot)

A

Optic disc

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37
Q

SLIDE 46 and 47 and 48!!!

A

SLIDE 46 and 47 and 48!!!

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38
Q

This does most of the light bending for the eye

A

Cornea

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39
Q

What does light act as for a GPCR

A

Agonist

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40
Q

At back fo retina to absorb stray light, remove old discs, regenerate photopigment

A

Pigment epithelium

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41
Q

Peak minus trough

A

Amplitude

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42
Q

Respond to light at 530 nm (m)

A

green cones

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43
Q

The only light sensitive cells

A

Photoreceptors

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44
Q

The lens does this when looking at a distance and this when looking close up

A

Distance - flattens

Close up - more rounded

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45
Q

What range of intensity do photoreceptors work at? What does this mean?

A

100 fold range in intensity. At 1/10 of ambient light are maximally depolarized and at 10x ambient light are maximally hyperpolarized

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46
Q

Photoreceptors stop working and blindness in certain areas can result

A

Detached retina

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47
Q

Ganglion cells have these while photoreceptors do not. They function as an area of the visual field that feeds information a particular ganglion cells

A

Receptive fields

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48
Q

Information gathered in the retina is ultimately sent here

A

Primary visual cortex

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49
Q

5% of ganglion cells with some being color sensitive. Good with COLOR

A

non-m non-p type

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50
Q

Beyond on and off center, how are ganglion cells categorized?

A

P (midget) type
M (parasol) type
Non-M non-P

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51
Q

Said all colors created by mixing red, green, and blue light and the retina senses this. This was only a prediction at his time

A

Young

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52
Q

These photoreceptors communicate directly with bipolar cells

A

Center photoreceptors

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53
Q

Has more receptor cells per ganglion cell and more rods than cones

A

Peripheral retina

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54
Q

Transparent with no blood vessels

A

Cornea

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55
Q

Tough wall of the eyeball

A

Sclera

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56
Q

With small fields, carry info regarding fine detail

A

P type ganglion cells

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57
Q

Light is slowed by this in front of the cornea

A

Aqueous humor

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58
Q

Many disks and large amount of rhodopsin

A

Rods

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59
Q

Don’t fire APs. Respond by releasing more NT if depolarized and less NT if hyperpolarized

A

Bipolar cells

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60
Q

What are the two functions of the eye?

A
  1. camera like system to focus light on the retina

2. neural retina; generate a pattern of APs from the input of many photons striking photoreceptors

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61
Q

Failure of lens accommodation. Impairs close up vision needed for reading

A

Presbyopia

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62
Q

SLIDES 40 AND 41

A

SLIDES 40 AND 41

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63
Q

This is a type of electromagnetic radiation that exists on the EM spectrum that we see

A

Light

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64
Q

Involves both eyes (consensual) pupil of one does the same as the other (both dilate or constrict in light)

A

Pupillary light reflex

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65
Q

Can be thought of as all the bipolar cells communicating with them and they have receptive fields as well

A

Ganglion cells

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66
Q

Bipolar, amacrine, ganglion synaptic contacts of retina

A

Inner plexiform layer

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67
Q

Light hits behind retina, cant see close up (farsightedness)

A

Hyperopia

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68
Q

What type of receptor is rhodopsin?

A

GPCR (7 TM regions coupled with G protein inside cell)

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69
Q

Ability to distinguish between nearby points (20/20 = 0.83 degrees). Due to refractive power and spacing of photoreceptors

A

Visual acuity

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70
Q

Photoreceptor, bipolar, and horizontal cell layer contacts of retina

A

Outer plexiform layer

71
Q

Have no opponency bc receive input from all cone types in both center and surround

A

m type

72
Q

Membrane potential of rod outer segments in dark

A

-30 mV

73
Q

Light hits short of the fovea (retina), cant see far away (nearsightedness)

A

Myopia

74
Q

The complexity of this system allows for reading, art, and many of the abilities which are unique to humans

A

Visual

75
Q

Respond to light at 430 nm (s)

A

blue cones

76
Q

Outer nuclear layer cells

A

cell bodies of photoreceptors

77
Q

Extraocular muscle disorders that causes input from one eye to be suppressed

A

esotropia - cross eyed

exotropia - wall eyed

78
Q

How are cells organized in the retina?

A

In layers. Inner nuclear layer and outer nuclear layer (inner = closer to inside of eyeball)

79
Q

Only these fire APs while the others change Vm in smaller measured ways

A

Retinal ganglion cells

80
Q

How large is focal distance?

A

2.4 cm (the average diameter of an eyeball)

81
Q

These communicate to bipolar cells

A

Photoreceptors

82
Q

Analyze every point of the retinal surface

A

Several on type and off type ganglion cells

83
Q

How much do glasses correct?

A

By a few diopters

84
Q

Between the cornea and lens (nourishes cornea)

A

Aqueous humor

85
Q

How must retinal change for activation and deactivation of rhodopsin?

A

Activate - cis to trans (straighten)

Deactivate - trans to cis (gets its bend back)

86
Q

How does contrast affect perception of light and dark?

A

Lighter surrounds and darker surrounds can influence the perception of the center shade

87
Q

Information gathered in the retina that isn’t sent to the primary visual cortex goes to areas involved with what?

A

Areas influencing biological rhythms, eye movement, control of the pupillary light reflex and shape of the lens

88
Q

Good reference point, retina is thin here, where we have our best vision

A

Fovea

89
Q

Loss of peripheral and night vision due to degeneration of photoreceptors (though to be genetic disorder controlled by about 100 different genes)

A

Retinitis pigmentosa

90
Q

Muscles controlling pupil size and show the eye color

A

Iris

91
Q

What creates he best resolution?

A

Low photoreceptor to ganglion cell ration (best in fovea)

92
Q

With low resolution and large receptive fields, carry info regarding movement

A

M type ganglion cells

93
Q

20/10 vision?

20/30 vision?

A

10 - yours is better than most

30 - yours is worse than most

94
Q

These communicate to ganglion cells

A

Bipolar cells

95
Q

Clouding of the lens usually fixed with lens removal and replacement with artificial lens

A

Cataract

96
Q

This also bend light (12 diopters) and helps to form sharp images of close objects (within 9 meters)

A

Lens

97
Q

Can also be designated on center and off center cells like bipolar cells

A

Ganglion cells

98
Q

This occurs when moving form light to dark and takes about 20 minutes

A

Dark adaptation

99
Q

4 parts of photoreceptors

A
  1. outer segment
  2. inner segment
  3. cell body
  4. synaptic terminal
100
Q

Poor for details but can see faint stars

A

Peripheral retina

101
Q

These types of animals can see UV while these can see infrared

A

UV - some fish

Infrared - snakes

102
Q

Results from pupil dilation, adjustment of retinal circuitry, the synthesis of new unbleached rhodopsin (11 trans retinal converted back to 11 cis retinal)

A

Dark adaptation

103
Q

What causes the membrane potential in rods?

A

Special Na channels (dark current) opened by cGMP made by guanylate cyclase, continuously made in the dark

104
Q

The retina sticks to it and it helps to nourish photoreceptors

A

Pigment epithelium

105
Q

Light that hits a surface and is transferred into it with no reflection or refraction

A

Absorption

106
Q

Almost half of the cortex is devoted to this in some form

A

Vision

107
Q

These photoreceptors communicate with horizontal cells

A

Surround photoreceptors

108
Q

Intermediate light levels when both cones and rods are involved in vision

A

Mesotopic

109
Q

More of these = work better in low light

A

Rods

110
Q

These photoreceptors are more present in the peripheral vision

A

Rods

111
Q

These photoreceptors are more present in the central vision

A

Cones

112
Q

Changing lens shape, ciliary muscles contract, lens becomes rounder, more curved

A

Accommodation

113
Q

Light reduces the level of this leading to this occurring in rods

A

Reduces level of cGMP, Na channels close, rods hyperpolarize in light. Light is like an agonist

114
Q

Can be easily transplanted since it has no blood vessels

A

Cornea

115
Q

Increased intraocular pressure from pushing on the optic nerve

A

Glaucoma

116
Q

Most of the light we see is this

A

Reflection

117
Q

Have blue on center, yellow off surround or yellow on center, blue off surround. Blue and yellow are opponent colors

A

non m-non p

118
Q

How do the different sensitivity of cones create a picture?

A

Combine to produce right signal for response

119
Q

Central vision, important for fine vision

A

Macula

120
Q

What causes channels in cones to eventually open in light

A

Lack of Ca entering, more cGMP produced

121
Q

Loss of central vision which occurs in 25% of people over age 65

A

Macular degeneration

122
Q

Nearsightedness, correct with concave lens

A

Myopia

123
Q

Jelly-like fluid inside the eyeball

A

Vitreous humor

124
Q

He showed how RGCs responses affected by horizontal and bipolar cells

A

Dowling

125
Q

What causes bad vision underwater with no goggles?

A

Light bending occurring at the cornea

126
Q

How many photoreceptors vs bipolar cells vs ganglion cells?

A

100 mil to 10 mil to 1 mil (convergence of info)

127
Q

Consist of a center and a surround. They have small in the center of the retina and large in the periphery

A

Receptive fields

128
Q

Average amount of bending by the cornea (depends on curvature of cornea)

A

42 diopters

129
Q

Membrane attaching eyelids to sclera

A

Conjunctiva

130
Q

Area seen by eyes when looking forward

A

Visual field

131
Q

SLIDE 34

A

SLIDE 34

132
Q

What property of light equates to higher energy?

A

Higher frequency

133
Q

Specialized for high resolution and color (no rods). Overlying cells grow off to the side and light has a clearer path to the photoreceptors

A

Fovea

134
Q

Parallel streams of info leave the eye via what

A

Optic nerve

135
Q

Constriction of pupil causes this

A

Increases depth of focus

136
Q

More energy is required to bleach these which leads to them staying working during the day

A

Cones

137
Q

Path of light in the retina

A

Passes through several layers (mostly transparent) to reach photoreceptors

138
Q

Provide input to subcortical areas to synchronize response to light changes

A

ipRGCs

139
Q

Use melanopsin, depolarize in light, large dendritic fields, dendrites sensitive to light

A

Intrinsically photosensitive ganglion cells (ipRGC)

140
Q

Control the response of central photoreceptors

A

Horizontal cells

141
Q

These contract to make the lens rounder, more curved, in accommodation of the lens

A

Ciliary muscles

142
Q

5% of the ganglion cells. Synapses with many bipolar. They have large concentric receptive fields, have transient rapidly adapting responses, respond to movement across fields, and low contrast stimuli. Good at analyzing MOVEMENT

A

M type

143
Q

Light that hits a surface and bends

A

Refraction

144
Q

Farsightedness, correct with convex lens

A

Hyperopia

145
Q

Enhances the ability to detect contrasts and edges moving across the boundaries of the center surround

A

Same stimulus in the center and surround producing opposite effects

146
Q

What is the visual range of light for humans?

A

400-700 nm

147
Q

Why is light bent when it goes to the cornea?

A

It is moving from one medium (air) to another (liquid)

148
Q

Modify the pathway of photoreceptors to bipolar to ganglion

A

Horizontal and amacrine cells

149
Q

The degree to which light is bent is measured in these

A

Diopters

150
Q

How many rods and how many cones?

A

rods - 5 mil

cones - 92 mil

151
Q

Ganglion cells that are sensitive to color

A

P type and some non m-non p

152
Q

Eye muscles that assist with eye movement

A

Extraocular muscles

153
Q

What must happens for rhodopsin to send another signal

A

Must be unbleached

154
Q

Produced by retina-brain stem connections, dilate/constriction of pupils in light

A

Pupillary light reflex

155
Q

What is retinal derived from?

A

Vitamin A

156
Q

Work on these 4 animals helped in eye discoveries

A

Crabs, frogs, cats, and monkeys

157
Q

What does reduces levels of cGMP cause in rhodopsin?

A

Dark current (cGMP channels) close and the flow of Na and Ca into the photoreceptor is reduced

158
Q

Occurs after moving from dark to light. Takes 5-10 minutes

A

Light adaptation

159
Q

Why are dashboard lights red?

A

To only affect cones so we don’t bleach our rods and become unable to see in the dim light

160
Q

Waves per second

A

Frequency

161
Q

3 key structures of the retina

A
  1. optic disc
  2. macula
  3. fovea
162
Q

Has the effect of producing opposing responses to the same stimulus depending on whether it is striking the center or the surround

A

Receptive fields

163
Q

Our visual system detects differences in this but not this

A

Differences in light intensity but not absolute values

164
Q

Controls the shape of the lens

A

Ciliary muscle

165
Q

SLIDE 50!!!

A

SLIDE 50!!!

166
Q

Gets nourishment from the aqueous humor since it has no blood vessels

A

Cornea

167
Q

Respond to light at 500 nm. Don’t do day vision

A

Rods

168
Q

Total absorption of light

A

Black

169
Q

Inner nuclear layer cells

A

bipolar, horizontal, amacrine

170
Q

What happens when light hyperpolarizes rods?

A

-30 mV to -65 mV (more NT release to less NT release)

171
Q

What happens when photons strike the GCPR rhodopsin?

A

Retinal is bleached (cis to trans)

172
Q

This allows for detection of a single photon is the rhodopsin GPCR

A

Amplification

173
Q

Dark part of the eye bc of retinal pigments

A

Pupil

Neuro 3000 (15 decks)

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