EYE STRUCTURE – HOW COLOUR IS SEENDescribe how colour is able to be seen by the human eye.

EYE

The eye is an extension of the brain

EYE BRAIN PROXOMITY

Can you see :

the optic nerve bundle?

spinal cord?

CROSS SECTION

You must know the position of:

Retina

Lens

Cornea

Sclerotic

Optic nerve

Cilary muscles

Suspensory ligaments

RETINA – 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 RECEPTORS

Light receptors are called rods and cones

FOCUSING ON OBJECTS

The lens and cornea focus the light on the retina

FOCUSING The lens job is

to make the rays hit the same point

The red rays will be out of focus

BENDING 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

LONG SIGHTED

A fat lens is needed to bend the light more to focus it.

SHORT SIGHTED

Rays enter the eye closer together

Need less bending

Thinner lens needed

CHANGING 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 LIGHT 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

SEEING COLOURS

The retina has receptors that are sensitive to colours and give you your colour vision.

There are others that are sensitive to shades of light and give you your black and white vision.

EYE ACTIVITIES

https://www.youtube.com/watch?v=VxTFGVp2R-8

https://www.youtube.com/watch?v=5oZtx8vVnA0

https://www.youtube.com/watch?v=HhvOP_q33Hw

COLOUR BLINDNESS

https://www.youtube.com/watch?v=EOlmjHLO388

NEXT LESSON

Eye Dissection