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How do our eyes work?
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Light enters a small opening in the centre of the eye, called the pupil, which is covered by a clear, protective shield. Muscles in the coloured iris around the pupil change its size and control the amount of light that enters the eye. The light passes through a lens, which focuses an image on the retina at the back of the eye. The retina contains nerve cells that send messages to the brain through the optic nerve. | | The image of what we see is upside down on the retina. The brain turns the image the right way up. |
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Previous:
Back
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Book:
1001
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Section:
Human World
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Chapter:
Human Body: Organs
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