Final answer:
A neurotransmitter binding can open ligand-gated ion channels, causing either an excitatory or inhibitory postsynaptic potential in the membrane. These changes, which can be prolonged by indirect receptor activation, may affect the membrane potential for minutes.
Step-by-step explanation:
When a neurotransmitter binds to its receptor on the postsynaptic cell, it can lead to the opening of ligand-gated ion channels, causing a change in the electrical potential known as a postsynaptic potential (PSP). This PSP can either be excitatory, as in the case of acetylcholine at the neuromuscular junction where Na+ enters the cell leading to depolarization, or inhibitory, as with GABA causing Cl- to enter the cell and hyperpolarize the membrane. The response to neurotransmitter binding can also be prolonged through indirect activation where, for example, a metabotropic receptor leads to metabolic changes and the generation of second messengers like cAMP. These changes can last minutes and may result in lasting membrane potential changes or alterations in cell function.