EYE The eye is an extension of the brain Visit For 100’s of free powerpoints.
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Transcript of EYE The eye is an extension of the brain Visit For 100’s of free powerpoints.
EYEEYE
The eye is an extension of the brain
Visit www.teacherpowerpoints.comFor 100’s of free powerpoints
Eye brain Eye brain proxomityproxomity
Can you see :
the optic nerve bundle?
Spinal cord?
Cross Cross sectionsection
You must know the position of:
Retina
Lens
Cornea
Sclerotic
Optic nerve
Cilary muscles
Suspensory ligaments
Retina – receives the imageRetina – receives the image
Full of light receptors which are sensitive to:
Colour Light levels
Massive blood supply is also needed
Fovea is the main focal point and has greatest density of light receptors
Retina receptorsRetina receptors
Light receptors are called rods and cone
Focusing Focusing on objectson objects
The lens and cornea focus the light on the retina
FocusingFocusing The lens job is
to make the rays hit the same point
The red rays will be out of focus
Bending lightBending light
Light is refracted and bent to focus it as it passes through the lens
Lens thickness can be changed so the amount of bending is changed
Near visionNear vision
to bend the light more to focus it
Fat lens needed
Distance visionDistance vision
Rays enter the eye closer together
Need less bending
Thinner lens needed
Changing lens thicknessChanging lens thickness The lens is slightly
elastic, its relaxed state is short and fat.
Cilary muscles are attached to the lens, when contracted they pull the lens thin
Controlling Controlling light levelslight levels
Your eye are very sensitive and can be damaged by harsh light.
Your iris controls light allowed into the eye by changing the size of the pupil