Answer
Acetylcholine is released by all preganglionic neurons , all postganglionic parasympathetic neurons and by sympathetic post ganglionic neurons that go to sweat glands
Norepinephrine or epinephrine are the neurotransmitters released by sympathetic post ganglionic neurons (fibers)
Work Step by Step
Cholinergic neurons release acetylcholine . Acetylcholine is mostly but not always stimulator. its effect depends on the kind of receptor in the target cell(s). There are two kid of cholinergic receptors -- nicotinic and muscarinic receptors. Nicotinic receptors are found on skeletal muscle cells, on post-ganglionic neurons, and on hormone producing cells of the adrenal medulla. Muscarinic receptors mainly but not only on parasympathetic postsynaptic receptors .
Acetylcholine stimulation slows heart rate but also stimulates muscles of GI viscera and increases GI motility This difference in effect of the stimulation by the same neurotransmitter is mediated by the difference in the muscarinic receptor.
There are also different classes and sublalsses of Adrenergic receptors. The two main classes are alpha and beta receptors . The subclasses are alpha 1, and alpha 2. The betat class is subdivided int beta1, beta2 and beta 3 sub casse. Whether adrenergic stimulation is excitatory or inhibitory depends on the type adrenergic receptor.
