Final answer:
Both cholinergic and adrenergic receptors are found in tissues innervated by the autonomic nervous system. Cholinergic receptors respond to acetylcholine, while adrenergic receptors respond to norepinephrine.
Step-by-step explanation:
All preganglionic fibers, both sympathetic and parasympathetic, release acetylcholine (ACh). The ganglionic neurons that receive these fibers have nicotinic receptors, which are ligand-gated cation channels. The postganglionic parasympathetic fibers also release ACh, but they act on muscarinic receptors, which are G protein-coupled receptors. On the other hand, postganglionic sympathetic fibers release norepinephrine, except for those that innervate sweat glands and blood vessels associated with skeletal muscles, which release ACh.