What is the function of the iris and of the pupil, Biology

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What is the function of the iris and of the pupil?

The iris works like the diaphragm of a photographic camera as it has muscles that contract or relax varying the pupil diameter. When the luminous intensity heightens the parasympathetic nervous system commands the contraction of the pupil; when there is shortage of light the sympathetic nervous system stimulates the dilation of the pupils. These movements depend upon the muscles of the iris.

 


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