Final answer:
The parasympathetic nervous system aids in the 'rest and digest' functions of the body, promoting relaxation and homeostasis by counteracting the effects of stress and preparing the body for conservation and recovery.
Step-by-step explanation:
The function of the parasympathetic nervous system is best characterized by its role in promoting a 'rest and digest' state in the body.
Unlike the sympathetic nervous system, which prepares the body for stress-related activities, the parasympathetic system is responsible for returning the body to a state of rest, maintaining homeostasis after stressful events have passed.
It slows down the heart rate, lowers blood pressure, constricts pupils, restores bladder control, and stimulates digestive processes.
Parasympathetic preganglionic neurons are located in the brainstem and the sacral region of the spinal cord, and they release acetylcholine or nitric oxide to affect target organs.