Final answer:
The autonomic nervous system uses acetylcholine and norepinephrine as neurotransmitters, which bind to either nicotinic or adrenergic receptors for sympathetic responses, and muscarinic receptors for parasympathetic responses.
Step-by-step explanation:
The neurotransmitters (NTs) and receptors of the autonomic nervous system play a pivotal role in regulating involuntary physiological functions. In the autonomic nervous system, the preganglionic fibers of both the sympathetic and parasympathetic divisions release acetylcholine (ACh), which binds to nicotinic receptors on ganglionic neurons. Postganglionic sympathetic fibers typically release norepinephrine, which binds to adrenergic receptors. A notable exception to this are postganglionic sympathetic fibers that innervate sweat glands and certain blood vessels associated with skeletal muscles; these release ACh which binds to muscarinic receptors. On the other side, postganglionic parasympathetic fibers release ACh, which binds to muscarinic receptors on the target cells. Muscarinic receptors are G protein-coupled receptors, which means their activation may result in a variety of cellular responses, not just depolarization.