| A | B |
|---|
| lens | curved transparent material through which light travels |
| convex lens | lens which is thicker in the middle and focuses light inward |
| concave lens | lens which is thinner in the middle and focuses light outward |
| retina | light-sensitive layer of eye packed with photoreceptors |
| pupil | opening in the eye |
| iris | colored ring of muscle fibers in eye |
| cones | photoreceptors in the retina which detect colors |
| rods | photoreceptors in the eye which detect very dim light |
| optic nerve | transport nerve impulses from the eye's photoreceptors to the brain |
| cochlea | snail shaped organ in middle ear which conduct sound vibrations and contain neurons |
| eardrum | vibrate bones of the middle ear when struck by sound waves |
| auditory nerve | neurons which send signals from the ear to the brain |
