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The eye (DOC download)

VIEWS: 8 PAGES: 1

									                                              THE EYE

2 mins
http://www.youtube.com/watch?v=JunCyiGfreo&feature=related

evolution of the eye Attenborough - inutes
http://www.youtube.com/watch?v=Yj_lNQerUJ4

CORNEA                to converge and focus light… evolved from skin of head…merges with inner
                      layer of eyelid…continuous with skin
RETINA                to receive the image
LENS                  accommodation
RECEPTORS             RODS highly sensitive to intensity of light
                      CONES           for colour, 3 types R,G,B
YELLOW SPOT           most sensitive part of the retina
OPTIC NERVE
BLIND SPOT
SHAPE OF EYE          maintained due to pressure exerted by fluids
VITREOUS              almost permanent
HUMOUR
AQUEOUS               continuously drained and replaced, failure to drain…excess pressure…glaucoma
HUMOUR


n cornea =        1.376
n lens =          1.42
n vitreous humour =     1.336

RELAXED EYE…. From  to about 6 m objects can be seen clearly…below 6 m lens increases in
curvature…it accommodates to give clear image

								
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