Chapter: 3 Movement in & out of Cells

The iris

• In front of the lens is a circular piece of tissue called the iris.
• This is the colored part of your eye.
• The iris contains pigments, which absorb light and stop it passing through.
• In the middle of the iris is a gap called the pupil.
• The size of the pupil can be adjusted.
• The wider the pupil is the more light can get through to the retina .
• In high light intensity, the iris closes in, and makes the pupil small.
• This stops too much light getting in and damaging the retina.
• In low light intensity, the iris pulls back from the pupil, so that the pupil becomes larger.
• This allows more light to reach the retina.

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