2.86 Eyes

2.86 Describe the structure and function of the eyes as receptor

Eye is the receptor that detects light.

Stimulus : Light

Sense: Sight

Ciliary Muscles - contract or relax to alter shape of the lens (for focusing)

Cornea - allows light in and bends light

Iris - (colored part of the eyes) change pupil size to control the amount of light entering the eyes

Pupil - hole in the centre of the eye in which light enters

Lens - change shape to focus light (of near and far objects)

Vitreous Humour - (transparent, jellylike substance) supports the back of the eyes

Retina - contains receptor cells (nerves) which is concentrated on one part of the eye. It change light into electrical impulse

- Rods - sensitive in dim light (but can't see colors as cones does not work well in dark) 

- Cones - detect colors, work best in bright light

Sclera - Protect the eyes

Suspensory ligaments - hold lens in place as it changes shape (pulls or contract lens in response to ciliary muscle)

Optic nerve - carries electrical impulse to the brain (not receptor!)

The eyes contain three pairs of eye muscles which helps it move.

Circular & Radial - located in the iris, controls pupil size  

Ciliary - controls lens shape