The Eye (WJEC GCSE Biology): Revision Note
Exam code: 3400
The Eye
The eye is a sense organ containing receptors sensitive to light intensity and colour
Receptors are groups of specialised cells that can generate an electrical impulse in a sensory neurone
The purpose of the eye is to receive light and focus it onto the retina at the back of the eye
The retina is where the light-sensitive cells are located that allow us to see images
Eye structure diagram
The eye is an organ made from several different types of tissue. All of the structures function together to allow light to hit the retina, which sends signals to the brain
Functions of the parts of the eye table
Structure | Function |
|---|---|
Sclera | Protective, tough white outer coat of the eye |
Cornea | Transparent part of the sclera that allows light to enter and refracts it as it enters the eye |
Pupil | Hole that allows light to enter the eye |
Iris | Muscles that control how much light enters the eye by changing the size of the pupil |
Lens | Transparent disc that can change shape to focus light onto the retina |
Choroid | A pigmented layer which absorbs light to prevent reflection Contains blood vessels |
Retina | A light-sensitive layer that contains light receptor cells Images are formed here and impulses are sent to the optic nerve |
Blind spot | The optic nerve leaves the eye here There are no light-sensitive cells here |
Optic nerve | Sensory neurone that carries impulses from the retina to the brain |
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