Final answer:
When agonists bind to nAChRs post-synaptically, it causes ligand-gated ion channels on the postsynaptic membrane to open, leading to depolarization and an excitatory postsynaptic potential (EPSP).
Step-by-step explanation:
When agonists bind to nAChRs (nicotinic acetylcholine receptors) post-synaptically, it causes ligand-gated ion channels on the postsynaptic membrane to open. This allows positive ions (such as Na+) to flow into the postsynaptic cell, leading to depolarization. The depolarization is known as an excitatory postsynaptic potential (EPSP) and makes the postsynaptic neuron more likely to fire an action potential.