Parasympathetic nervous system

The parasympathetic nervous system (main nerve: vagus nerve, 10th cranial nerve) is one of the two important nerve structures of the vegetative nervous system.

It is also known as the "resting nerve" because it is mainly active during the regenerative phases and during digestion. It provides peace, relaxation and protection. Its centers are in the brain stem, upper spinal cord and sacral marrow.

The neurotransmitter is acetylcholine. The main nerve is the predominantly cholinergic Nervus vagus, which supplies the organs of the thoracic and abdominal cavity with many branches.

Smaller parasympathetic parts also show other cranial nerves. The functional effect of the PNS is mostly opposite to that of the sympathetic and primarily serves nutrition, energy saving and recovery (trophotropic effect).

New findings show that the vagus nerve (also) provides information from the belly brain to the (head) brain.

https://en.wikipedia.org/wiki/Parasympathetic_nervous_system _([1])