Bio - The Eye

Blind spot

no rods or cones

choroid

dark layer, prevents light bouncing around in the eye

ciliary muscles

adjusts the shape of the lens by pulling on suspensory ligaments

conjunctiva

transparent membrane, protects cornea

cornea

refracts light onto the lens

fovea

concentrated area of cones for a sharp image (in light)

iris

circular and radial muscles control how much light enters the eye

lens

focuses light to a point on the retina

optic nerve

carries nerve impulses to brain

pupil

allows light to enter the eye

retina

rods (night vision) and cones (colour vision) convert light into electrical impulses

sclera

protects the eye from injury

suspensory ligaments

allow ciliary muscles to change the shape of the lens to focus light

aqueous + vitreous humors

keep the eye's shape and absorb shocks

accommodation - near object

ciliary muscles contract, suspensory ligaments loosen, lens becomes more convex, light refracted more

accommodation - far object

ciliary muscles relax, suspensory ligaments tighten, lens becomes less convex, light refracted less

pupillary reflex - bright light

radial muscles relax, circular muscles contract, pupil gets smaller, less light enters eye

pupillary reflex - dim light

radial muscles contract, circular muscles relax, pupil gets larger, more light enters eye

constriction

pupil gets smaller

dilation

pupil gets larger

reason for pupillary reflex

prevents damage to retina in bright light, allows us to see in dim light