• sclera - white part of the eye. tough outer layer to prevent bacteria/etc getting in and protect from attacks.
• conjuctiva - covers the sclera, a thin membrane. runs to the edge of the cornea. keeps the front surface of the eye moist & lubricated. lubricates inside of the eyelid so they can close w/o friction or . protects the eye from bacteria and dust.
• cornea - clear dome on front of eye, lets light in. protects eye and focuses light on the retina.
• iris - circular, coloured area of eye. controls how much light gets into the eye by making the pupil bigger/smaller.
• pupil - black area in the middle of the eye. becomes bigger in dark environments to let more light in, or smaller in light areas to reduce the light intake.
• lens - sits behind the iris. changes shape to focus light onto the retina.
• ciliary muscles - muscles that contract to cause the lens to become thicker, to allow the lens to focus on nearer objects. they relax to allow the lens to focus on things far away.
• retina - contains the cells that sense light photoreceptors. there are rods which activate in low light situations (hence lack of colour), and cones which are for high light situations, and have better colour reception. they translate light waves into electrical impulses.
• retinal blood vessels - provide nourishment to the inner layers of the retina.
• macula or fovea - a part of the retina that is packed with millions of cone cells - this is where the clearest image is produced.

each retinal cell is connected to a nerve fiber. these combine together to form the optic nerve.

• optic nerve - carries the impulses from the photoreceptors to the brain.
• aqueous humour - the fluid in the posterior (front) part of the eye. this nourishes the eye and gives it the nutrients it needs. it is produced at the back of the eye, travels through the pupil, then drains out where the iris meets the cornea.
• vitreous humour - this is a jelly like substance in the back of the eye. this along with the aqueous humour ensures the eye is filled and retains its structure, or it would deflate.
• choroid - a thin membrane between the retina and sclera. is composed of layers of blood vessels which provide nourishment to the outer layers of the retina.
• ciliary body - the part that produces the aqueous humour.