Final answer:
Acetylcholine induces an excitatory response in skeletal muscle cells by binding to nicotinic receptors, leading to depolarization and initiating muscle contraction.
Step-by-step explanation:
The effect of acetylcholine (ACh) on nicotinic receptors on skeletal muscle cells is excitatory. Nicotinic receptors are ligand-gated cation channels and upon binding with ACh, these channels open, allowing positively charged sodium ions (Na+) to depolarize the muscle cell. This depolarization initiates an action potential leading to muscle contraction. Unlike nicotinic receptors, muscarinic receptors, which ACh also binds to, can cause either depolarization or hyperpolarization, depending on their subtype.