Final answer:
Muscarinic agonists or parasympathomimetic drugs increase gastrointestinal motility by mimicking the action of acetylcholine on muscarinic receptors.
Step-by-step explanation:
The class of drugs that exhibit a parasympathomimetic effect on gastrointestinal motility are muscarinic agonists, also known as parasympathomimetic drugs. These drugs act similarly to the neurotransmitter acetylcholine (ACh), which is released by parasympathetic postganglionic fibers, binding to muscarinic receptors and enhancing the cholinergic activity of the digestive system. By doing so, they increase the motility of the gastrointestinal tract, thus supporting the digestive process. It's important to note that these drugs can influence other organs controlled by the parasympathetic nervous system, not just the gastrointestinal system.