GCSE AQA Biology- The Eye

Tough supporting wall of the eye - Sclera Transparent outer layer found at the front of the eye. Refracts (bends) light into the eye - Cornea Contains muscles that allow it to control the diameter of the Pupil (hole in the middle) and therefore how much light enters the eye - Iris Focuses light onto the retina - Lens Contains receptor cells sensitive to light intensity and colour - Retina Controls the shape of the lens - Ciliary Muscles and Suspensory Ligaments Carries impulses from the receptors on the Retina to the Brain - Optic Nerve Pupil decreases in size as the circular muscles in the Iris contract and radial muscles relax - Adjusting To Bright Light Pupil widens as the radial muscles in the Iris contract and the circular muscles relax - Adjusting To Dim Light Ciliary muscles contract, meaning the suspensory ligaments slacken, causing the lens to fatten (curve) increasing the amount by which it refracts light - Focusing On Near Objects