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Anatomy Final > Vision > Flashcards

Vision Flashcards

1
Q

name the two main processes involved in vision.

A
  1. light energy is transduced into neural activity

2. neural activity is processed by the brain

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2
Q

name the 4 things human visual systems permit light reflected off distant objects to be…

A
  1. localized relative to the individual within his or her environment
  2. identified based on size, shape, color, and past experience
  3. perceived to be moving (or not)
  4. detected in a wide variety of lighting conditions
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3
Q

light entering the eye is focused on the ________

A

retina

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4
Q

retina converts light energy into…

A

neural energy

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5
Q

axons of the retinal neurons are bundled to form the…

A

optic nerves

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6
Q

visual information is distributed to…

A

several brain structures that perform different functions

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7
Q

light rays must be ___ or ________ by the cornea

A

bent; refracted

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8
Q

what is the purpose of the refracting of light?

A

in order for it to focus on the retina

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9
Q

name the first sequence of event:

A
  1. light entering the eye is focused on the retina
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10
Q

name the second sequence of events:

A

retina converts light energy into neuronal activity

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11
Q

name the third sequence of events:

A

axons of the retinal neurons are bundled to form the optic nerves

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12
Q

name the fourth sequence of event:

A

visual information is distributed to several brain structures that perform different functions

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13
Q

define pupil

A

opening that allows light to reach retina

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14
Q

define iris

A

circular muscle that controls the diameter of the pupil

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15
Q

define aqueous humor

A

fluid behind the cornea

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16
Q

define sclera

A

the outermost layer of the eye

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17
Q

define extraocular muscles

A

attached to the eye and skull and allow movement

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18
Q

define conjunctiva

A

membrane inside the eyelid attached to the sclera

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19
Q

define optic nerve

A

axons of the retina leaving the eye

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20
Q

define cornea

A

transparent surface covering the iris and pupil

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21
Q

name the 6 muscles that surround the eye

A 
superior rectus m.
inferior rectus m.
medial rectus m.
lateral rectus m.
superior oblique m.
inferior oblique m.
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22
Q

another name for the optic disk is?

A

blind spot

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23
Q

the blood vessels of the eye originate where?

A

optic disk

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24
Q

the optic nerves leave through what?

A

optic disk

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25
Q

true or false: the optic disk contains photoreceptors.

A

false

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26
Q

define macula

A

area of the retina responsible for central vision

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27
Q

define fovea

A

center of the retina

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28
Q

where are most of the cones located at?

A

fovea

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29
Q

exactly where is the fovea located at?

A

the very center of the macula

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30
Q

the very center of the macula is located at

A

it’s the avascular zone just temporal to the optic nerve head

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31
Q

the fovea has a white dot called the…

A

foveal light reflex

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32
Q

name the things the fovea is responsible for.

A

for your color vision and the fine things you see

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33
Q

the small area just around the fovea is called the _____

A

foveola

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34
Q

define lens

A

transparent surface that contributes to the formation of images

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35
Q

what do ciliary muscles do?

A

change the shape of the lens and allow focusing

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36
Q

the vitreous humor is what than the aqueous humor?

A

more sticky than the aqueous humor

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37
Q

where is the vitreous humor located at?

A

between the lens and the retina

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38
Q

what is the main purpose of the vitreous humor?

A

to provide the eye with its spherical shape

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39
Q

the ______ is the innermost layer of cells at the back of the eye

A

retina

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40
Q

what is the main function of the retina?

A

transduces light energy into neural activity

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41
Q

name the 3 processes of image formation

A
  1. Refraction by the cornea
  2. Accommodation by the lens
  3. Pupillary light reflex
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42
Q

the refraction caused by the cornea aids in…

A

image formation

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43
Q

when refracting distant objects, light runs in…

A

parallel lines

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44
Q

light rays slow down because of what?

A

hitting the cornea and aqueous humor

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45
Q

describe how light bends when it hits the cornea

A

perpendicular to the angle (radius of the cornea) between the curve of the cornea and the plane they are traveling on

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46
Q

define focal distance

A

it is the distance between the refractive surface and where the light rays converge

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47
Q

the focal distance is dependant on what?

A

the curvature of the cornea

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48
Q

accommodations by the lens avoids what?

A

blurry vision

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49
Q

when viewing an object within 9 meters, light rays…

A

do not travel in parallel

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50
Q

when viewing objects within 9 meters, what is most likely to happen to the light rays?

A

they will eventually diverge

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51
Q

what does the lens add?

A

refractive power

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52
Q

how do the lens add refractive power?

A

by changing its shape

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53
Q

when the ciliary muscles’ tension on the suspensory ligaments is released, what happens?

A

the lens becomes rounded

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54
Q

why is having the lens rounded important?

A

because the greater the curvature the greater the refraction

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55
Q

what do the pupils contribute to?

A

the optical qualities of the eye

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56
Q

the pupil adjusts for what?

A

for different light levels

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57
Q

what does pupillary light reflex contribute to?

A

simultaneous focusing on near and distant objects

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58
Q

what does accommodation do exactly?

A

it alters light rays that would otherwise run in parallel

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59
Q

when accommodation occurs, what is happening regarding the light rays?

A

they are no longer focused on the retina by the cornea

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60
Q

when the aperture of the pupil closes, what happens?

A

only light rays that are primarily in the center of the cornea and lens are allowed in

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61
Q

True or False: the light is focused after the aperture of the pupil is closed

A

false

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62
Q

define visual field

A

total space that can be viewed by the retina

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63
Q

what is the total degree of vision?

A

150 degrees

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64
Q

150 degrees can be divided into:

A

90 on temporal side

60 on the nasal side

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65
Q

the image on the back of the retina is…

A

reversed and inverted

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66
Q

define emmetropia

A

parallel light rays are focused on the retina without accommodation

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67
Q

emmetropia can also be called

A

normal vision

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68
Q

define hyperopia

A

the image is focused at a point behind the retina because the eyeball is too short

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69
Q

what is another term for hyperopia

A

farsightedness

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70
Q

hyperopia can be corrected how?

A

with a convex lens

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71
Q

define myopia

A

light rays converge in front of the retina because the eyeball is too long

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72
Q

how can myopia be corrected?

A

with concave lens

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73
Q

specialized cells of the retina do what?

A

convert light energy into neural activity

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74
Q

name the five main cell types found in the retina

A
  1. photoreceptors
  2. bipolar cells
  3. ganglion cell
  4. horizontal cells
  5. amacrine cells
75
Q

define photoreceptors

A

the only light sensitive cells in the retina

76
Q

photoreceptors are either…

A

rods or cones

77
Q

what do bipolar cells do?

A

connect photoreceptors to ganglion cells

78
Q

what do ganglion cells do?

A

fire action potential and send axons to the brain

79
Q

what do horizontal cells do?

A

receive inputs from photoreceptors and project laterally to bipolar cells

80
Q

what do amacrine cells do?

A

receive inputs from bipolar cells and project laterally to ganglion cells

81
Q

name the 5 layers of the retina from innermost to outermost

A
  1. ganglion cell layer
  2. inner plexiform layer
  3. bipolar layer (inner nuclear)
  4. outer plexiform layer
  5. photoreceptor layer (outer nuclear)
    pigmented layer
82
Q

the ganglion cell layer contains

A

cell bodies of the ganglion cells

83
Q

the inner nuclear layer contains

A

cell bodies of the bipolar cells

84
Q

the outer nuclear layer contains

A

cell bodies of the photoreceptors

85
Q

___________ are the only output cells

A

ganglion cells

86
Q

what can ganglion cells only do?

A

produce action potentials

87
Q

light travels through the other cell layers in order to…

A

reach the photoreceptors

88
Q

at the back of the eye is a pigmented epithelium that…

A

absorbs any light not absorbed by the photoreceptors

89
Q

there are two kind of photoreceptors based on

A

appearance and function

90
Q

name the two kinds of photoreceptors

A

rods and cones

91
Q

rods are…

A

long, cylindrical and have many disks

92
Q

cones are

A

shorter, tapering outer segment, and has relatively fewer disks

93
Q

rods are _____ to colors

A

not sensitive

94
Q

rods are sensitive to

A

shades of grey and low light vision

95
Q

where can rods be found?

A

macula

96
Q

rods have a much higher…

A

pigment concentration

97
Q

rods are ________________ to light than cones

A

1000x more sensitive

98
Q

rods function in what kind of condition?

A

scotopic conditions

99
Q

scotopic means

A

nighttime

100
Q

name the pigment all rods have

A

rhodopsin

101
Q

rhodopsin is a

A

purple pigment that when the eye is exposed to right light, it becomes bleached (inactive), after interval of darkness, it returns to color

102
Q

cones are used in what kind of condition

A

photopic

103
Q

there are ___ types of cones

A

3

104
Q

the three types of cones see what colors

A

blue
green
red

105
Q

where can cones be found?

A

primarily in the fovea centralis and macula

106
Q

cones use the visual pigment of __________

A

iodopsin

107
Q

in the central retina, there is correspondence between…

A

photoreceptor and ganglion

108
Q

in the peripheral retina, many photoreceptors do what?

A

converge on a single output ganglion cell

109
Q

which is more sensitive to light: central or peripheral retina?

A

peripheral retina

110
Q

photoreceptors transduce what?

A

light energy into changes in membrane potential

111
Q

the first step in phototransduction, starts with events at…

A

G-protein coupled receptors

112
Q

the binding of a neurotransmitter activates what?

A

G-proteins

113
Q

G-protein activation stimulates…

A

various effector enzymes

114
Q

the enzymes alters what?

A

the intracellular concentration of cytoplasmic second messengers

115
Q

the 2nd messengers either directly or indirectly alters…

A

membrane ion channels which alter membrane potential

116
Q

name the events during phototransduction

A

light stimulation of photopigment activates G-proteins
G-proteins activate various effector enzymes
enzymes decrease intracellular concentrations of 2nd messengers (cGMP)
change in 2nd messenger concentration closes a Na+ channel

117
Q

in complete darkness there is a steady influx of

A

Na+

118
Q

the steady flow of Na+ does what?

A

depolarizes the photoreceptor membrane and thus NT is released

119
Q

what is a general term for this?

A

dark current

120
Q

Na+ channels responsible for this current are gated by…

A

cGMP (cyclic guanosine monophosphate)

121
Q

where is cGMP produced?

A

in photoreceptors

122
Q

thus, Na+ stays open in the ___

A

dark

123
Q

why is it that in the dark, the Na+ stay open?

A

levels of cGMP rise, and keep the gates open

124
Q

when light enters, cGMP is converted to

A

GMP (phosphodiesterase hydrolyxes cGMP)

125
Q

the membrane ______________ in response to light

A

repolarizes

126
Q

thus in the light, Na+ channels do what?

A

close

127
Q

rhodopsin is

A

a photopigment

128
Q

where is rhodopsin located?

A

in stacked disks in the outer segment of the rods

129
Q

what is rhodopsin comprised of?

A

retinal and opsin

130
Q

what does opsin do?

A

absorbs light

131
Q

photoreceptors no longer respond at…

A

particular light intensities

132
Q

the activation of rods by light does what to photopigment?

A

it bleaches it

133
Q

cones are contain what?

A

opsin

134
Q

the 3 kinds of opsin found in cones can be activated by

A

blue, green, red

135
Q

what results from equal activation of all three

A

white

136
Q

only _______ cells fire action potentials

A

ganglion

137
Q

axons of ganglion cells form the ______

A

optic nerve

138
Q

in response to dark, photoreceptors are depolarized and release NT called

A

glutamate

139
Q

photoreceptors make _______ contact with bipolar cells

A

synaptic

140
Q

how do photoreceptors contact bipolar cells?

A

through horizontal cells

141
Q

bipolar cells, in response to the glutamate released by photoreceptors are either…

A

depolarized or hyperpolarized

142
Q

so in darkness, the glutamate released by the photoreceptor causes…

A

EPSP in bipolar cell

143
Q

if the bipolar cell is classified as “ON” it

A

hyperpolarizes when there is no light and depolarize when there is light

144
Q

name the 2 types of ganglion cells

A

M type ganglion (large)

P-type ganglion (small)

145
Q

the signals goes from the retina to the

A

LGN (lateral geniculate nucleus) of the thalamus

146
Q

the signal moves from the LGN towards

A

primary visual cortex

147
Q

the signals moves from the primary visual cortex to

A

other cortical areas

148
Q

name the 3 connections between the eyes and brain

A

optic nerve
optic chiasm
optic tract

149
Q

left and right visual worlds are processed

A

contralaterally

150
Q

information about the left visual field is processed by the

A

right side of the brain

151
Q

information about the left that is seen by the right eye

A

does not cross over

152
Q

the image is…

A

inverted and reversed

153
Q

objects in the temporal part of the left hemifield are focused onto the

A

nasal retina of the left eye

154
Q

objects in the nasal part of the right hemifield are focused on the

A

temporal retina of the left eye

155
Q

fibers from the nasal retinas always…

A

cross over at the optic chiasm

156
Q

if its seen by the nasal world, it __________________ cause it already did switched by being seen by the opposite eye’s temporal retina

A

never decussates

157
Q

if ultimately seen by the temporal retinas, they…

A

do not cross over because they are already viewing the opposite world

158
Q

thus, when you view something from the nasal visual field, the image will be seen by the…

A

opposite eye’s temporal retina

159
Q

if an image is seen by the temporal visual field, the image will be seen by the….

A

same side’s nasal retina

160
Q

the primary target of the optic tract is

A

the LGN

161
Q

10% of the optic tract goes to the

A

superior colliculus in the midbrain

162
Q

name the other 2 places the optic tract will travel to.

A

hypothalamus (SCN-circadian rhythm)

pretectum-reflex control of the pupil and lens

163
Q

the lateral geniculate nucleus (LGN) is part of the

A

dorsal thalamus

164
Q

the LGN is arranged in ___ layers

A

6

165
Q

Layers 1 + 2 are the most

A

ventral

166
Q

layers 1 + 2 contain….

A

large neurons

167
Q

layers 1 + 2 are referred to as

A

magnocellular LGN layers

168
Q

Layers 3 -6 contain what?

A

small neurons

169
Q

what are layers 3-6 referred to as?

A

parvocellular LGN layers

170
Q

how is the information from the 2 eyes kept separate?

A

they are projected to different layers of the LGN

171
Q

the nasal retinal sees the temporal part of the hemifields and the information…

A

crosses over

172
Q

Nasal retina projects to which layers?

A

1,4,and 6

173
Q

temporal retina projects to which layers?

A

2, 3, and 5

174
Q

Layer IV is subdivided into 3 separate layers….

A

IV A, B, and C

175
Q

LGN projects primarily to which layer?

A

layer IVC

176
Q

Layer IVC is divided into 2 tiers:

A

Alpha

Beta

177
Q

alpha corresponds with

A

movement

178
Q

beta corresponds with

A

color

179
Q

Magnocellular LGN layers project to

A

IVC alpha

180
Q

Parvocellular LGN layers project to

A

IVC beta

181
Q

Beta = blue =

A

color

182
Q

Beta = blue = color = pigment =

A

P type

183
Q

M type cells are large and they project to the magnocellular layers:

A

1 or 2

184
Q

P type cells are small and they project to the parvocellular layers:

A

3, 4, 5, or 6

Anatomy Final (12 decks)

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