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