Final answer:
Ions that flow into the postsynaptic cell can have either a positive or negative charge, depending on the specific ion. For example, acetylcholine opens ligand-gated Na+ channels, allowing Na+ ions to enter and cause depolarization. GABA opens Cl- channels, allowing Cl- ions to enter and hyperpolarize the membrane.
Step-by-step explanation:
The ions that flow into the postsynaptic cell can have different types of charge depending on the specific ion. They can have either a positive charge or a negative charge. For example, the neurotransmitter acetylcholine opens ligand-gated Na+ channels on the postsynaptic membrane, allowing Na+ ions to enter the cell and causing depolarization, which is an excitatory postsynaptic potential (EPSP). On the other hand, the neurotransmitter GABA opens Cl- channels, allowing Cl- ions to enter the cell and hyperpolarize the membrane, resulting in an inhibitory postsynaptic potential (IPSP).