Which autonomic division is associated with 'rest and digest' responses?

• A. Sympathetic nervous system
• B. Parasympathetic nervous system
• C. Somatic nervous system
• D. Enteric nervous system

Answer: (B)

Rest and digest describes the parasympathetic division of the autonomic nervous system. This branch promotes energy conservation and activities needed after eating, such as digestion and nutrient storage. When it dominates, heart rate slows, GI activity and secretions increase, and pupils constrict. The parasympathetic system uses acetylcholine at both preganglionic and postganglionic synapses, with ganglia situated near the target organs to produce localized effects.

In contrast, the sympathetic division is tied to fight-or-flight responses, prepping the body for rapid action by increasing heart rate, dilating pupils, redirecting blood to muscles, and inhibiting digestion. The somatic nervous system controls voluntary skeletal muscle movement and is not involved in autonomic rest-digest regulation. The enteric nervous system governs GI function and can operate independently, but the label rest and digest specifically reflects parasympathetic influence on digestion and energy management.