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The iris reflex

Biology

QuestionAnswer
Describe what happens to the iris (circular muscle fibres & radial muscles) in bright light. The circular muscle fibres contract whilst the radial muscles relax.
What does this ensure? That less light reaches the retina so the eye isn't damaged. (Pupil constricts).
Describe what happens to the iris (circular muscle fibres & radial muscles) in dim light. The circular muscle fibres relax whilst the radial muscles contract.
What does this ensure? That more light reaches the retina so we can see! (Pupil dilates).
Created by: eloiseis
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