Parasympathetic nerves are part of the autonomic nervous system, which controls involuntary bodily functions. They primarily promote a state of rest and relaxation, helping to conserve energy. When activated, these nerves slow the heart rate, increase digestive activity, and stimulate glandular secretions. These nerves originate in the brain and spinal cord, specifically from the cranial nerves and the sacral region. They release neurotransmitters like acetylcholine, which bind to receptors in target organs, facilitating various bodily functions. Overall, the parasympathetic system plays a crucial role in maintaining homeostasis and supporting recovery after stress.