eye

only part of the body with clear structures

sclera

white of the eye

very tough, fibrous

made of same proteins as cornea but arranged in a different way

cornea

anterior (front) covering of the eye

no blood supply (would block light)

transparent

sphincter muscle that controls the amount of light the comes into the eye (size of the pupil)

colored part of the eye: brown - a lot of melanin

blue - little melanin

hole in iris

important for focusing/refraction (bending light)

never stops growing, adds new layers every year and loses flexibility

flat lens used for distant objects

lens round used for near objects

absorbs high frequency light before it can damage retina

cataracts

loss in clarity of lens

risks: smoking, UV light exposure

makes aqueous humor; continuously made and drained out

attached to lens via zonules

controls lens shape

retina

area of photosensitivity located in fundus (back) of eye

2 layers:

outer pigmented layer that absorbs light and prevents it from scattering in eye

neural layer (inner transparent) that contains rods and cones (photoreceptors)

rods

more sensitive than cones

black and white

night time

3 different kinds (sensitive to different waves of light)

less sensitive than rods

color

day time

support cells for rods and cones

barrier between blood supply and neurons

eats tips off rods and cones every day -- if it loses this ability, rods and cones degenerate

choroid

blood supply for rods and cones at back of retina

blind spot

blind spot where optic nerve enters the eye

gustation

taste

bumps on the tonge; taste buds found on top of some of these

specific receptors for the sense of taste located on top of some papillae