A girl has her eyes shut and is standing inside a brightly lit room. What happens to her pupils when she opens her eyes? Why?
Her pupils grow because the muscles contract.
Her pupils grow because the muscles relax.
Her pupils shrink because the muscles contract.
Her pupils shrink because the muscles relax.
Her pupils shrink because the muscles contract.
Her pupils shrink because the muscles contract.
When a person opens their eyes, the muscles in their iris (specifically the radial muscles) contract, causing the pupil to become smaller. This contraction reduces the size of the pupil and decreases the amount of light entering the eye. The contraction of these muscles is controlled by the autonomic nervous system, specifically the sympathetic nervous system.
When a girl with her eyes shut opens them inside a brightly lit room, her pupils shrink because the muscles contract.
To understand why this happens, we need to know a little bit about how the eye works. The pupil is the black circular opening in the center of the iris, which is the colored part of the eye. The size of the pupil can change in response to the amount of light entering the eye.
In bright light, the muscles in the iris contract, causing the pupil to shrink. This is known as pupillary constriction. The purpose of this contraction is to limit the amount of light that enters the eye and protects the retina from being overloaded with excessive light. By reducing the size of the pupil, less light can reach the sensitive parts of the eye, preventing potential damage.
On the other hand, in dim light, the muscles in the iris relax, causing the pupil to dilate or expand. This is known as pupillary dilation. The purpose of this dilation is to allow more light to enter the eye and improve visibility in low-light conditions.
In the scenario described, the brightly lit room triggers the contraction of the muscles in the girl's iris, causing her pupils to shrink.