Parasympathetic nerves innervate most blood vessels in the body and mediate vasodilatation.

The pre-ganglionic vagal neurones arise in the rostral ventrolateral medulla.

The major neurotransmitter in parasympathetic ganglia is the excitatory amino acid glutamate.

Relative to the sympathetic nervous system, the pre-ganglionic neurones of parasympathetic nerves are long and the post-ganglionic nerves are short.