Final answer:
When a neurotransmitter binds to a postsynaptic receptor, it can either cause depolarization or hyperpolarization of the postsynaptic neuron. Depolarization leads to an excitatory postsynaptic potential (EPSP), which makes the neuron more likely to fire an action potential. Hyperpolarization leads to an inhibitory postsynaptic potential (IPSP), which makes the neuron less likely to fire an action potential.
Step-by-step explanation:
When a neurotransmitter binds to a postsynaptic receptor, it can either cause depolarization or hyperpolarization of the postsynaptic neuron. Depolarization leads to an excitatory postsynaptic potential (EPSP), which makes the neuron more likely to fire an action potential. Hyperpolarization leads to an inhibitory postsynaptic potential (IPSP), which makes the neuron less likely to fire an action potential.
For example, when acetylcholine (a neurotransmitter) is released at the neuromuscular junction, it opens Na+ channels, causing depolarization and an EPSP. On the other hand, when GABA is released in a synapse, it opens Cl- channels, causing hyperpolarization and an IPSP.