The term "pupila" refers to the pupil, which is the opening in the center of the iris of the eye. It allows light to enter the eye and reach the retina, where images are formed. The size of the pupil can change in response to light conditions; it constricts in bright light and dilates in dim light to help regulate the amount of light that enters. The pupil's size is controlled by the muscles of the iris, which respond to various stimuli, including light intensity and emotional states. This adjustment helps protect the retina from excessive light and enhances vision in different environments.