Which system is responsible for conserving energy and promoting resting functions?

The autonomic nervous system is indeed responsible for conserving energy and promoting resting functions. It operates largely unconsciously to manage bodily functions that occur without voluntary control, such as heart rate, digestion, respiratory rate, and pupillary response.

Within the autonomic nervous system, there are two main branches: the sympathetic and parasympathetic systems. The sympathetic system prepares the body for 'fight or flight' situations, increasing heart rate and energy expenditure. In contrast, the parasympathetic system is more aligned with energy conservation; it facilitates 'rest and digest' processes. This includes stimulating digestive activities, lowering heart rate, and promoting relaxation throughout the body.

Concisely, the autonomic nervous system's primary role is to maintain homeostasis by balancing the activities of these two branches, particularly under varied environmental conditions. By managing these functions effectively, it ensures that the body can conserve energy and maintain essential resting functions even during stressful situations.