The eye
Introduced| English | Meaning |
|---|---|
| cornea/ˈkɔːnɪə/ | cornea |
| pupil/ˈpjuːpl/ | The hole in the iris that lets light into the eye. |
| iris/ˈaɪrɪs/ | The coloured structure of the eye whose muscles change pupil size to regulate the amount of light entering. |
| lens/lenz/ | lens |
| retina/ˈretɪnə/ | The light-sensitive layer at the back of the eye that converts light into nerve signals. |
| optic nerve/ˈɒptɪk nɜːv/ | The bundle of nerve fibres that carries visual signals from the retina toward the brain. |
A living camera
- The eye is a remarkable organ that focuses light to form a clear image.
- Each part has a specific job in capturing and focusing light.
The part that controls the size of the pupil is the:
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The iris adjusts the pupil size.
Light first enters the eye through the transparent ______.
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The cornea does most of the focusing.
Letting light in
- Light enters through the clear cornea 角膜, then the pupil 瞳孔 (the hole in the middle).
- The coloured iris 虹膜 controls how big the pupil is.
Light is focused by the cornea and lens 晶状体 onto the retina 视网膜; impulses leave by the optic nerve 视神经
Explore the eye
Tap each part to follow light through the eye — from the cornea and lens that focus it to the retina that detects it.
Light is focused onto the:
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The lens focuses light onto the retina.
Focusing the light
- The lens focuses light onto the retina at the back.
- The cornea does most of the focusing; the lens fine-tunes it.
Impulses travel from the retina to the brain along the:
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The optic nerve carries impulses to the brain.
The image formed on the retina is upside down.
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The brain interprets it the right way up.
Sending the signal
- The retina has light-sensitive cells that turn light into nerve impulses.
- The optic nerve carries these impulses to the brain.
The image on the retina is upside down. The lens flips the image, so it lands inverted on the retina. Your brain turns it the right way up — you never notice.
You've got it
- light enters through the cornea and pupil (size set by the iris)
- the lens focuses light onto the retina
- the retina makes nerve impulses; the optic nerve carries them to the brain