structure of eye + what happens in bright/dim light conditions

sclera

outer protective layer of eye

cornea

translucent layer in front of eye which refracts light into eye

pupil

hole where light goes in

iris

contains muscles that control pupil diameter and how much light goes in

lens

focusing light on retina

retina

contains light receptors sensitive to light intensity and colour

optic nerve

carries impulses to brain

suspensory ligaments and cilarly muscles

control lens shape

radial and circular muscles in iris

control pupil diameter

radial and circular muscles are antagonistic muscles that means

when one relaxs the other contracts

the circular will… in bright light and radial will… in bright light

circular will constrict and radial relax

in bright light this is so

the pupil gets smaller to limit amount of light entering and prevent damage

in dim light the opposite happens circular relax this is so

the pupil is larger there’s more surface area for light to enter maximising vision

image of eye