Final answer:
Some drugs can act on all types of neurons by acting as agonists or antagonists that affect neurotransmitter activity, such as nicotine binding to nicotinic ACh receptors in autonomic ganglia.
Step-by-step explanation:
Some drugs may act on all types of neurons by affecting neurotransmitter systems as either agonists or antagonists. Agonists enhance the activity of neurotransmitters by promoting synthesis, reducing reuptake, or by mimicking their action at the receptors. Antagonists, on the other hand, block the normal activity of neurotransmitters at the receptor. For instance, drugs that affect both divisions of the autonomic system, such as nicotine, bind to nicotinic acetylcholine (ACh) receptors, which are activated by ACh released from preganglionic fibers in both sympathetic and parasympathetic ganglia. This results in depolarization of the ganglia.