Answer: It is used for the "rest and digest" part of the autonomic system.
Explanation:
Parasympathetic branch consist of nerve fibres that extends from the top to the bottom of the spinal cord, the cranial and sacral segments. It is activated when the body is in the state of rest during digestion, defecation and sexual arousals. Hormone acetylcholine is mostly released during these state so as to slow the heart rate.
