Which physiological change occurs when the parasympathetic system is activated?

When the parasympathetic nervous system is activated, one of the key physiological changes that occur is an increase in gastric motility. This is part of the body's "rest and digest" response, which aims to promote digestive processes and enhance the efficiency of nutrient absorption. The activation of the parasympathetic system stimulates various digestive functions, including increased peristalsis and the secretion of digestive enzymes, which collectively contribute to improved gastrointestinal activity.

In contrast, the other physiological changes described are consistent with activation of the sympathetic nervous system rather than the parasympathetic system. The sympathetic system prepares the body for "fight or flight" responses, which typically include an increase in heart rate, inhibition of activities such as lacrimation, and dilation of the pupils (mydriasis) to enhance vision in preparation for perceived threats. Therefore, recognizing the specific functions of the parasympathetic nervous system is key to understanding why the increase in gastric motility is the correct answer.