Flashcards · Biology · The Nervous System
The Eye
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What is the function of the cornea?
To refract (bend) light as it enters the eye.
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What is the function of the lens?
To focus light onto the retina.
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What does the iris do?
It controls the size of the pupil, and so the amount of light entering the eye.
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What is the pupil?
The hole in the middle of the iris through which light enters.
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What is the retina?
The layer at the back of the eye that contains the light receptors.
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What does the optic nerve do?
Carries impulses from the retina to the brain.
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What happens to the pupil in bright light?
It gets smaller.
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What happens to the pupil in dim light?
It gets larger.
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Which iris muscles contract in bright light?
The circular muscles.
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Why does the pupil get smaller in bright light?
To stop too much light damaging the retina.
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Which cells work in dim light?
Rod cells.
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Which cells detect colour?
Cone cells.
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Where are most cone cells found?
In the fovea, at the centre of the retina.
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How many types of cone cell are there and what colours do they detect?
Three: red, green and blue.
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What happens to the lens when looking at a near object?
It becomes thicker and more curved.
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Why can you not see colours well at night?
Only the rod cells work in very dim light, and they cannot detect colour.