When activated, which system makes the heart beat slower, constricts pupils, and increases mucus production?

The chosen answer, which is the Parasympathetic Nervous System, is correct because it is responsible for promoting a state of rest and relaxation in the body. When activated, this system performs various functions that counteract the "fight or flight" response of the Sympathetic Nervous System. Specifically, it slows down the heart rate, allows for constriction of pupils, and stimulates increased mucus production, particularly in the respiratory system.

This mode of operation is often referred to as the "rest and digest" system, emphasizing its role in conserving energy and promoting bodily functions that occur during restful states. It ensures that functions related to digestion and maintenance of body systems predominate when the body is not under stress. This physiological modulation is crucial for maintaining homeostasis and allowing the body to recover from heightened states of arousal.

Thus, the Parasympathetic Nervous System is essential for managing involuntary functions that promote recovery and replenishment, aligning perfectly with the listed effects of a slower heartbeat, pupil constriction, and increased mucus production.