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Esdin LS 2 Lec 4 Sensory

To hit the neural layer protection eye muscle

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Unformatted text preview: see 10 4/21/13 Fibrous Layers thick layer, for protection, ensures that light rays travel in the right direction to hit the neural layer protection, eye muscle attachment fluid aqueous humor, fluid Cornea fibrous vitreous humor, fluid 6 eye muscles attached to the eye allow mobility of the eye Sclera the white in the eyes, protection thick layer, muscle attached here lens blood vessels, brings nutrients, nourishes the eye Vascular Layer Ciliary muscles controls shape of lens changes size of pupil Iris pigmented layer smooth muscle Pupil opening size determines the amount of light Zonular fibers connective fibers Choroid light bounces off this at the back light bounces off the choroid plexus then back to the retina 11 4/21/13 Vascular Layer •  Choroid very very dark –  Pigmented layer that contain blood vessels •  Ciliary muscles •  Zonular fibers –  Hold the lens in place •  Iris Accommodation focusing •  The ciliary muscles allow objects to be focused on the retina no matter how near or distant they are •  The lens can change shape 12 4/21/13 Accommodation Distant objects are focused on the retina neural layer The lens changes shape to make the light rays bend more and focus on the retina How Does Accommodation Occur? •  When an object is far, the ciliary muscles are relaxed, the zonular fibers become tight, causing the lens to flatten •  When an object is near, the ciliary muscles are contracted, the zonular fibers become loose, causing the lens to be rounded 13 4/21/13 Accommodation Ciliary muscles relaxed Zonular fibers are pulled Lens flat to focus distant objects Ciliary muscles contracted Zonular fibers are loose Lens thick to focus near objects Iris radial smooth muscles contract, pupil dilates Dim light Radial smooth muscles Circular smooth muscles Pupil Bright light circular smooth muscles contract, pupil is constricts red eye : look up why this happens 14 4/21/13 Neural Layer Retina Retina •  The retina contains photoreceptors to receive the light and send it to the brain through the optic nerve •  Contains the fovea centralis (high visual rods and cones scattered here acuity) the part of the eye that we want to aim the light for (the reason accommodation happens) 15 4/21/13 Retina •  Have different types of cells –  Ganglion cells first action potential; typical neuron –  Amacrine strengthen allow them to be integrated together (am & horiz) –  Bipolar –  Horizo...
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