Acetylcholine is the primary neurotransmitter in the parasympathetic nervous system, while norepinephrine is released in the sympathetic system during fight or flight responses.
Acetylcholine (ACh) is the primary neurotransmitter in both the pre- and postganglionic fibers of the parasympathetic nervous system and in the preganglionic neurons in the sympathetic system. In the sympathetic nervous system, the postganglionic neurons release norepinephrine. When faced with the threat of a physical attack, the activation of the sympathetic nervous system leads to the release of norepinephrine, which helps prepare the body for 'fight or flight' responses.
https://brainly.com/question/40200275