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24 Cards in this Set
- Front
- Back
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retina
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the neural tissue and photo-receptive cells located on the inner surface of the eye
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where are rods and cones located?
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the retina
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rod
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-night vision
-do not detect colors |
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cones
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- used for day vision
- color vision - highest source of visual acuity |
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fovea
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the region of the retina that mediates the most acute vision
*only contains cones |
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blind spot
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area at the back of the eye where axons leave on the optic nerve towards the brain where NO receptors exist
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3 layers of the retina
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ganglion layer
bipolar layer photo-receptive layer |
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bipolar cells
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links info from photoreceptor cells to ganglion cells
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ganglion cells
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receives info from bipolar cells and transmits info to brain via axons traveling though the optic nerve
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light hyper-polarizes the cell and _______ the release of NTs by the photoreceptor
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decreases
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a decreases in the release of NTs causes the bipolar cell to _______ which triggers _______
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depolarize, the bipolar cell to release more NTs which depolarizes the membrane of the ganglion cell, increasing its rate of firing
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light ________ the photoreceptor
light _________ the bipolar cell |
hyper-polarize
depolarize |
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receptive field
depends on...? |
the part of the visual field that a neuron sees, the part in which light must fall for the neuron to be stimulated
a region of space in which the presence of a stimulus will alter the firing of that neuron *the location of the photo-receptors that provide it with visual info |
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info from photo-receptors located in the fovea come from a receptive field....
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the center, where the eye is looking
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info from photo-receptors located in the periphery of the retina come from a receptive field...
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located off to the side
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at the periphery of the retina...
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many receptors converge on a single ganglion cell bringing info from a large area of the retina
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at the fovea...
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there are equal number of ganglion cells and cones which provides more acute vision
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3 types of ganglion cells in frrogs
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ON (responded when light was on)
OFF(responded when light was off) ON-OFF(responded briefly to both) |
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in cats the receptive field is a circular center surrounded by a ring and stimulation of each has _____ effects
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contrary
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ON cells
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excited by light falling on the center
inhibited by light falling on the surrounding field **OFF cells respond oppositely |
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retina contains 2 kinds of color-sensitive ganglion cells
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red-green
yellow-blue |
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some color-sensitive ganglion cells respond in a __________ fashion
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center-surround
*means that the cell might be excited by red and inhibited by green in the center in their receptive field but show the opposite response in the surrounding ring |
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some ganglion cells serve as _________ detectors
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"black and white"
they do not see color, only encode relative brightness in center/surrounding area |
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order of cells
back of eye to front of eye |
1. photoreceptors
2. horizontal cells 3. bipolar cells 4. amarcine cells 5. ganglion cells |
