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34 Cards in this Set
- Front
- Back
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retina
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contains photoreceptors & other neurons |
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cornea |
curved outer layer of eye; bends light rays & forms image on retina |
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refraction |
bending light rays by change in density of medium (ex. cornea, lens of eyes) |
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lens |
helps focus image on retina |
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ciliary msucle |
controls shape of lens |
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accommodation |
contraction of ciliary muscles to cause nearer/farther images to come into focus |
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myopia |
nearsightedness |
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transduction |
conversion of light energy into neural activity |
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rods |
work well in low light; insensitive to color; more numerous in periphery; low acuity
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cones
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works well in bright light; allows us to see color; high acuity; more numerous in fovea |
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bipolar cells |
receive input from rod/cone photoreceptors & synapse on ganglion cells |
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ganglion cells |
receive signal from bipolar cells; axons for optic nerve |
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occipital cortex |
striate cortex |
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LGN |
lateral geniculate nucleus |
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receptive field |
stimulus region & features that affect activity of cell in sensory system |
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light always . . . |
hyperpolarizes photoreceptors |
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on - center bipolar cells |
excited by light b/c it receives less glutamate; glutamate inhibits this cell |
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off - center bipolar cells |
inhibited by light because it receives less glutamate; glutamate excites this cell |
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on - center gannglion cells |
depolarized/excited by on - center bipolar cell when light hits its center; fires nerve impulse to report "light" to visual centers |
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off - center ganglion cells |
depolarized/excited by off - center bipolar cells when light hits periphery; fires nerve impulse to report "dark" to visual centers |
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on - center/off - surround |
concentric receptive field where stimulation of center excites cell but stimulation of surround inhibits it |
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off - center/on - surround |
concentric receptive field where stimulation of surround excites it but stimulation of center inhibits it |
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lateral inhibition |
when interconnected neurons inhibit their neighbors bu producing contrast at edges of regions (ex. when one bipolar is active, it inhibits its neighbors) |
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firing rate (on - center ganglion cell) |
increased
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firing rate (off - center ganglion cell) |
decreased |
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ataxia |
spatial disorientation where patient can't accurately reach for objects using sight as guide |
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myopia |
nearsightedness; eyeball is too long; images form in front of retina |
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optic disc |
where blood vessels & ganglion cell axons leave eye; blind spot |
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visual acuity |
measure of how much detail we see; sharper in center of visual field |
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fovea |
center region of retina |
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rhodopsin
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photopigment recognized by rods
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phototopic system |
cone receptors; low sensitivity; high acuity; rapid response time; |
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scotopic system |
rod receptors; high sensitivity; low acuity; slow response time |
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iris |
gives eyes color |
