B10//2 Flashcards
what are the structures of the eye designed to do
focus light onto the retina
what is the sclera
tough white outer layer that prevents damage to the eye
what is the cornea
transparent area at the front of the sclera which lets light into the eye .
what does the curved surface of the cornea do
changes the direction of the light rays so they are refracted towards the retina
what does the iris do
contract and relax to control the size of the pupil
what does the iris do if the light is too bright or dim
relaxes if light is to bright
contracts if light is too dim
what is the pupil
the hole in which light enters the eye
what is the lens
clear disc which changes the direction of the light so that its image is focused on the retina
what do the suspensory ligaments and ciliary muscles do
hold the lens in place
how is light entering the eye focused
by refraction
light changes direction when as it passes the cornea and the lens
how and why does the shape of the lens change
by contraction or relaxation of the ciliary muscles and the change in shape alters the amount of refraction depending how far the light is coming from
what does the optic nerve do
carries light impulses from retina to brain
what are the light rays like from nearer objects
spreading out or diverging
what are the light rays like from a distant object
travelling in almost parallel
how does the eye focus on a distant object
ciliary muscles relax so the lens is pulled flat and thin.
