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39 Cards in this Set
- Front
- Back
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The retina
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the nervous layer lining the inner surface of the globe behind the ora serratta only attached at ora serratta and the optic disc |
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The layers of the retina
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1 pigment epithelium 2 photoreceptors 3 external limiting membrane 4 outer nuclear layer 5 outer plexiform 6 inner nuclear layer 7 inner plexiform layer 8 ganglion cells 9 nerve fiber layer 10 internal limiting membrane |
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light entering the eye
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light comes in passes through the retina till it reaches the photoreceptors, in the photoreceptors the light is turned into electrical impulses
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the wiring system
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the electrical impulses pass through the 3 nerve cells 1 photoreceptor 2 bipolar cells 3 ganglion cells theses cells make up the optic nerve |
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pigment epithelium
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a single layer of flat hexagonal cells attached to Bruch's membrane, Allows transfer of nutrients from the choroid, blocks light
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Photoreceptors
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where the light is transformed into electrical impulses Rods and Cones |
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Rods 110 to120 million |
long slender cells containing the photopigment Rhodopsin, very sensitive to light, used for night vision and peripheral |
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Cones 5 to 6 million
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shorter, wider cells containing photopigment cells iodopsin. Provides color vison and daytime vision
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Outer limiting membrane
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a thin sheet (a mesh or net) formed by extensions of the ends of the supporting fibers of Muller cells (like a tree)
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Outer Nuclear Layer
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containes the rods and cone nuclei , The cones nuclei are arranged just below the limiting membrane, The rods nuclei are farther down and less regularly distributed
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Outer Plexiform
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made up of Photoreceptors, Axons and the synapses the form with the bipolar cells dendrites. there are also connections between the horizontal cells and the photoreceptors |
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Inner Nuclear Layer
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Contains the nuclei of the bipolar, fibers of Muller, horizontal , & amarine cells
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Inner Plexiform Layer
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contains the Synapses where the axon of the bipolar cells connect with the dendrites of the ganglion cells, projections from the amacrine cells also synapses with the ganglion cells
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Ganglion Cells Layer
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contain large rounded multipolar cells. The dendrites may be singular or branched. The passes into the nerve fiber layer. Becomes the optic nerve
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Nerve fiber layer
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contains bundles of nerves running parallel to the surface of the retina to the optic disc, retinal vessels mainly lie in this layer
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internal limiting membrane
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a thin layer formed by expended ends of the fibers of Muller
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Optic Disc
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Exit site of retinal nerve fibers from the eye, contains no rods or cones. The blind spot. relies heavely on the choroid for nutrients
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Macula luten
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small specialized central area of the retina, surrounding the fovea, millions of cones found in the macula and are responsible to daytime and color vision
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Fovea (most acute vision)
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central pit in the macula that contains a high concentration of cones and no retinal blood vessels |
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Retinis Pigmentosa |
a disease in which the rods are slowly destroyed and the reminder of the retina atrophies, the loss of rods initially effects the patients night vision and creates a mid-peripheral field loss. as the condition progresses the peripheral field is reduced |
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diabetic retinopathy
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blood vessels hemorrhage and new vessel grow can create retinal detachment and visual field losses
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Macular Degeneration (ARMD)
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a condition in which the cones in the macula are progressively deteriorate. there is a break down between Bruch's membrane and the pigment epithelium causing build up between the two layers called Drusion |
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Wet Macular Degeneration
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When blood builds up between Bruch's membrane and the pigment epthiluim
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Fluorescein Angiography
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When a fluorescein dye is injected to trace blood flow to the retina. Used to reveal retinal hemorrahages
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The Visual Pathway
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Comprised of the Axons of the retinal ganglion cells surrounded by pia, arachnoid, and dura sheaths
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The visual path way 8 steps
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1Intrabulbar potion 2 Intraorbital portion 3 Intra Cranial 4 Optic Chasma 5 Optic tract 6 Lateral Geniculate Body 7 Optic Radiations 8 Visual Cortex |
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Intrabulbar portion
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Nerve fibers pass through the sclera
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Intraorbital portion
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From the sclera to the Optical canal |
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Intra Cranial
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From the canal to the Chiasima
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Optic Chiasma
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nasal retinal fibers cross, temporal fibers do not, this enables stimulation of corresponding points of the two retinas send simultaneous messages to the visual centers on one side of the brain. |
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Optic Tract
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Carries nerve impulses from the chiasma to the Lateral Geniculate Body
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Lateral Geniculate Body
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A relay station for nerve impulses on their way to the visual cortex
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Optic Radiations
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Nerve fiber bundles whose cell bodies lie in the lateral geniculate body. Their axons fan out and terminate at the visual cortex |
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The visual cortex
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Lies in the striated area on either side of the calacarine fissure in the occipital lobe. Information from the eye is sifted, coordinated and interpreted
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Three photosensitive pigment cones
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Blue Green Red |
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Trichromat
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Normal color vision Possesses all three pigments |
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anomalous trichomat
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a partial deficiency of one of the three pigments protanaomaly -red deuteranomaly-green tritanomaly- blue |
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Dicromat
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a complete deficiency of one of the pigments Protanopia-red deuteranopia-green tritanopa-blue |
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Monochromat
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sees shades of gray |
