During synaptic transmission, what happens when neurotransmitters bind to receptors on the postsynaptic neuron?

During synaptic transmission, what happens when neurotransmitters bind to receptors on the postsynaptic neuron?

• A. They always trigger an action potential.
• B. They produce either excitatory or inhibitory effects, influencing whether the postsynaptic neuron fires.
• C. They are destroyed immediately by enzymes and have no effect.
• D. They convert the postsynaptic neuron into a presynaptic neuron.

Answer: (B)

Neurotransmitter binding to receptors on the postsynaptic membrane can produce either excitation or inhibition. When a receptor opens ion channels that let positive ions in, the postsynaptic membrane depolarizes, creating an excitatory postsynaptic potential that brings the neuron closer to firing. If the receptor causes ions to leave or negative charge to enter, the membrane hyperpolarizes, producing an inhibitory postsynaptic potential that moves the neuron away from firing. The overall likelihood of the postsynaptic neuron firing depends on the sum of all these excitatory and inhibitory inputs arriving at the axon hillock. Some receptors work through second messenger systems and have longer-lasting effects, but the key idea is that binding can increase or decrease the chance of an action potential, not automatically trigger one.

Neurotransmitter binding to receptors on the postsynaptic membrane can produce either excitation or inhibition. When a receptor opens ion channels that let positive ions in, the postsynaptic membrane depolarizes, creating an excitatory postsynaptic potential that brings the neuron closer to firing. If the receptor causes ions to leave or negative charge to enter, the membrane hyperpolarizes, producing an inhibitory postsynaptic potential that moves the neuron away from firing. The overall likelihood of the postsynaptic neuron firing depends on the sum of all these excitatory and inhibitory inputs arriving at the axon hillock. Some receptors work through second messenger systems and have longer-lasting effects, but the key idea is that binding can increase or decrease the chance of an action potential, not automatically trigger one.