Emergency Medical Technician (EMT) Intermediate Practice Exam

What occurs in the pupil when a light is shone into it?

1. It dilates

2. It becomes smaller in size

3. It remains unchanged

4. It blinks rapidly

The correct answer is: It becomes smaller in size

When light is shone into the pupil, the correct response is that it becomes smaller in size, which is referred to as constriction. This process is part of the pupillary light reflex, a protective mechanism that helps regulate the amount of light entering the eye, thus avoiding damage to the retina from excessive brightness. The constriction occurs because of the contraction of the muscles in the iris. When bright light is detected, sensory information is transmitted to the brain, which sends signals to the iris muscles to constrict the pupil. This adjustment ensures that the correct amount of light enters the eye for optimal vision. Understanding this process is critical for emergency medical responders, as changes in pupil size and reactivity can indicate various clinical conditions. For instance, unresponsive pupils or pupils that do not react to light may suggest neurological impairment or drug effects. Thus, knowledge of normal pupil responses to light is essential in assessing a patient's condition.