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809 - Exam Block 2 > Physiology of Vision - Metz > Flashcards

Physiology of Vision - Metz Flashcards

(89 cards)

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1
Q

the retina of the eye is responsible for converting the _________ waves of light stimuli into _________

A

electromagnetic ; electrical signals

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2
Q

At a basic level, the photoreceptors of retina (eye) is capable of detecting two different qualities of light, what are they

A

brightness ; light

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3
Q

A large aperture would allow a ____ amount of light to pass through

A

large

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4
Q

a small aperture would allow a _____ amount of light to pass through

A

smaller

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5
Q

The pupil is an aperture that
controls the amount of light transmitted to the interior of the eye –> this process is controlled by the

A

autonomic nervous system

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6
Q

The iris is innervated by both the ______ and ______ divisions of the nervous system

A

sympathetic ; parasympathetic

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7
Q

When a bright light strikes the eye, the ________ nervous system facilitates _______
of the pupil via stimulation of the _______

** This reflex will occur bilaterally in both eyes, even if only one eye has been exposed to the high intensity light **

A

parasympathetic ; constriction ; circular muscles

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8
Q

When the eyes are exposed to a darker environment, the _______ nervous system
stimulates ______ of the radial muscles, leading to pupil ______

A

sympathetic ; constriction ; dilation

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9
Q

The pupillary reflex is important because it regulates the _______ falling upon the retina, and also protects the retina from overexposure to light

A

intensity of light

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10
Q

the aperture also affects the

A

depth of field (sharpness)

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11
Q

A large aperture will result in a larger ________ aka a larger
amount of blur in the background

A

depth of field

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12
Q

For closer vision, ciliary muscle ______ via ______ stimulation

A

contracts ; PS

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13
Q

for closer vision, tension on suspensory fibers is

A

reduced

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14
Q

for closer vision, the lens becomes more

A

spherical

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15
Q

for closer vision, the focal power is ______ for near vision

A

increased

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16
Q

_____ occurs when light passes between two different mediums

A

Refraction

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17
Q

To focus on closer objects, the eye must ______ its focal power through a process called ______

A

increase ; accommodation

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18
Q

High concentration of photoreceptors in the

A

fovea

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19
Q

a relaxed ciliary muscle = a _____ lens

A

flat

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20
Q

a not-relaxed ciliary muscle = lens is

A

round

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21
Q

in myopia/near-sightedness - the axis of the eye is

A

too long

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22
Q

correction for myopia/near-sightedness = ____ lens that ____ the light

A

concave ; diverges

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23
Q

in hyperopia/far-sightedness - the axis of the eye is

A

too short

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24
Q

correction for hyperopia/far-sightednesss = ____ lens that ____ the light

A

convex ; converges

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25
in hyperopia/far-sightedness, the image is focused ____ the retina
behind
26
the lens becomes _____ elastic with age so the ability to accommodate _____
less ; decreases
27
Presbyopia causes difficulty seeing
near objections
28
to correct presbyopia = _____ lens that _____ the light
convex ; converges
29
uneven curvature of cornea and/or lens
astigmatism
30
an astigmatism = the image is _____ on the retina
unfocused
31
to correct an astigmatism = ____ lens that _____ the light
cylindrical ; appropriately focuses
32
the photoreceptors that are responsible for detecting light are in the _____ regions of the retina
deeper
33
The ganglion cells are the _____ of the retina, and their axon fibers are arranged in the _____
output ; optic nerve
34
Photoreceptors are
rods and cones
35
pigment epithelium absorbs
photons
36
rods and cones send _____ signals
electrical
37
The sensory receptors in the retina are called
photoreceptors
38
photoreceptors are responsible for converting the _______ signals from photons into the ______ signals of the nervous system
electromagnetic ; electrical
39
3 types of cones
red, green, blue
40
cones see ____ vision ; rods = ______ vision
color ; black & white
41
rods work best for ____ vision and cones work best for ____ vision (hint = what time)
night ; day
42
rods are ______ to low-light intensitity
sensitive
43
cones are not sensitive to
low-intensity light
44
rods are associated with _____ accuity
low
45
cones are associated with _____ accuity
high
46
rods are not present on the
fovea
47
cones are present on the
fovea
48
Both rods and cones contain outer segments comprised of
photoreceptor disks
49
Both rods and cones have inner segments which contain the
nucleus, mitochondria, and other cellular organelles
50
The base of the photoreceptors contain _______ that communicate with the _______ layer of the eye
synaptic bodies ; neural network
51
In these cellular membranes of the disks are embedded molecules of ______
photopigments
52
For rods, the photopigment is called ______
rhodopsin
53
The detection of light by the photopigment leads to the conversion of ______ to ______
11-cis-retinal ; all-trans-retinal
54
The conversion of 11-cis-retinal to all-trans-retinal leads to a complex signaling cascade that initiates several downstream effects via a
G-protein pathway
55
When rods are in a DARK environment, an enzyme in the cytosol called guanylyl cyclase continuously converts _____ into _____
GTP ; cGMP
56
When rods are in a DARK environment cGMP leads to activation of ________ channels in the plasma membrane of the _____ segment
non-selective cation channels ; outer
57
When rods are in a DARK environment The non-selective cation channels allow sodium molecules to diffuse down their electrochemical gradient from the extracellular fluid into the _____ of the ____
cytosol ; rod
58
When rods are in a DARK environment The movement of this Na+ into the cell produces a _____ of the cell
depolarization
59
When rods are in a DARK environment The depolarization of the cell stimulates the release of the neurotransmitter ______ from the _____ of the rod
glutamate ; synaptic end bulb
60
When rods are in a LIGHT environment When a photon of light is detected by a pigment in rods called ________ , the compound _________ is converted to _________
rhodopsin ; 11-cis retinal ; all trains retinal
61
When rods are in a LIGHT environment The conversion of 11-cis retinal to all trains retinal stimulates an associated G-protein called _________ to exchange its bound _____ for ______
transducin ; GDP ; GTP
62
When rods are in a LIGHT environment Once GDP is exchanged for GTP, the activated _____ subunit of the G-protein then dissociates from the _______
alpha ; beta-gamma complex
63
When rods are in a LIGHT environment The activated alpha subunit of the G-protein then dissociates from the beta-gamma complex leads to the activation of the enzyme ________________, which catalyzes the breakdown of _____ into ______
cGMP phosphodiesterase ; cGMP ; 5'GMP
64
When rods are in a LIGHT environment the breakdown of cGMP ; 5'GMP decreases the cytosolic levels of ______ , leading to closure of a _____ channel in the plasma membrane
cGMP ; non-selective cation
65
When rods are in a LIGHT environment The closure of the non-selective cation channel in the plasma membrane causes a drop in sodium _____ which leads to _______ of the plasma membrane, as the membrane potential become more ______ than at rest
influx ; hyperpolarization ; negative
66
In the dark, cGMP levels are _____, and this allows for the non-specific cation channels in the plasma membrane of the outer segment to be ____
high ; open
67
in the dark Sodium will be removed from the cytosol in the inner segment via a ______, leading to the "________"
sodium-potassium pump ; "dark current"
68
In the light, as the cGMP levels _____, cellular reactions lead to a _____ of these same non- specific cation channels
decrease ; closure
69
in the light, ____ sodium enters the cell, leading to a ______ of the plasma membrane and a ______ in the release of neurotransmitters from the ______
less ; hyperpolarization ; decrease ; synaptic end bulb
70
In the light the decrease in the release of neurotransmitters from the synaptic end bulb would ______ the release of ______ during exposure to light
decrease ; glutamate
71
the downstream effects of the neurotransmitter glutamate can be either ______ or ______, depending on the type of receptors activated on the bipolar or horizontal cells
excitatory ; inhibitory
72
The bases of the photoreceptors contain synaptic bodies that communicate with the neural network layer of the eye and is comprised of 3 cell types, what are they?
bipolar horizontal amacrine
73
Due to the thinness of the retina and the close proximity of these structures, the photoreceptors and interneurons can communicate effectively using _______
graded potentials
74
The ganglion cell layer is responsible for integrating all of the information from the ______ cells and sending ______ via their axons in the ______
upstream ; electrical signals ; optic nerve
75
The bases of the photoreceptors contain a synaptic body that releases neurotransmitters onto the ______ cells
bipolar cells
76
Rods are located at the ______ of the retina, and many rods synapse onto a _______ cell
periphery ; single bipolar
77
Rods have a high level of ______ with as many as 300 rods ______ onto a _____ cell
convergence ; converging ; single ganglion
78
Rods have a high level of convergence = this results a _____ sensitivity of rods, as light striking any of these rods could _____ the bipolar cell
higher ; activate
79
Rods have a high level of convergence - this results a higher sensitivity of rods - this arrangement also produces a _____ acuity in rods
lower
80
the clearness or sharpness of vision
acuity
81
there are relatively _____ cones that converge on a ____ cell
few ; ganglion
82
In the fovea, the ratio of cones to ganglion cells is almost _____
1:1
83
There are relatively few cones that converge on a ganglion cell. In the fovea, the ratio of cones to ganglion cells is almost 1:1. This allows for ________ of the color image, but ______ light sensitivity
greater sharpness/acuity ; lower
84
High sensitivity Low acuity
periphery of the retina
85
periphery of the retina has a ______ of rods and cones
mixture
86
periphery of the retina - many rods ______ onto a single ganglion cell
synapse
87
low sensitivity high acuity
center of the retina : fovea
88
cones only
center of the retina : fovea
89
1:1 ratio of cones to ganglion cells
center of the retina : fovea

809 - Exam Block 2 (16 decks)

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