The Human Eye: Structure (Edexcel IGCSE Science (Double Award)): Revision Note

The Human Eye: Structure

• The eye is a highly specialised sense organ containing receptor cells that allow us to detect the stimulus of light

• The retina of the eye contains receptor cells sensitive to light

The eye is a sense organ that contains light receptor cells

The structures of the eye 

• Conjunctiva - a clear membrane that covers the white of the eye and the inside of the eyelids; it lubricates the eye and provides protection from external irritants

• Cornea - transparent, curved layer at the front of the eye that refracts light as it enters the eye

• Sclera - the strong outer wall of the eyeball that helps to keep the eye in shape and provides a place of attachment for the muscles that move the eye

• Pupil - circular opening in the centre of the iris that allows light to enter the eye

• Iris - controls how much light enters the pupil

• Lens - transparent disc that can change shape to focus light onto the retina

• Ciliary muscle - a ring of muscle that contracts and relaxes to change the shape of the lens

• Suspensory ligaments - ligaments that connect the ciliary muscle to the lens

• Retina - contains receptor cells sensitive to light

• Optic nerve - carries impulses between the eye and the brain

• Blind spot - the point at which the optic nerve leaves the eye, where there are no light receptor cells