2.86

2.86 describe the structure and function of the eye as a receptor

- The eye is the receptor that detects light.

- The ciliary muscles contract or relax to alter the shape of the lens.

- The cornea bends light rays and let them focus on the retina. It does most of the bending of the light.

- The iris controls the amount of light entering by controlling the size of the pupil. It contains of circular and radial muscles.

- The lens provides fine focus to sharpen the image.

- The humour is a clear jelly that fills the inside of the eye to provide shape. 
- The retina contains light-sensitive receptor cells of rods and cones.

They change the light à electrical impulses.

- Rods are sensitive in dim light, but can only sense black and white.

- Cones are sensitive in bright light and they detect colour.

- Sclera is a protective, tough outer layer.

- Suspensory ligaments hold the lens in position.

- Optic nerve carries electrical impulses to the brain.