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1、EYEThe eye is an extension of the brainEye brain proxomitylCan you see : lthe optic nerve bundle?lSpinal cord?Cross sectionYou must know the position of:RetinaLensCorneaScleroticOptic nerveCilary musclesSuspensory ligamentsRetina receives the imagelFull of light receptors which are sensitive to:lCol
2、ourlLight levelslMassive blood supply is also neededFovea is the main focal point and has greatest density of light receptorsRetina receptorslLight receptors are called rods and coneFocusing on objectslThe lens and cornea focus the light on the retinaFocusinglThe lens job is to make the rays hit the
3、 same point The red rays will be out of focusBending lightlLight is refracted and bent to focus it as it passes through the lenslLens thickness can be changed so the amount of bending is changedNear visionl to bend the light more to focus itlFat lens neededDistance visionlRays enter the eye closer t
4、ogetherlNeed less bendinglThinner lens neededChanging lens thicknesslThe lens is slightly elastic, its relaxed state is short and fat.lCilary muscles are attached to the lens, when contracted they pull the lens thinControlling light levelslYour eye are very sensitive and can be damaged by harsh light. lYour iris controls light allowed into the eye by changing the size of the pupil
