AAMC FL Practice Exam

What happens to neurotransmitters after their release?

1. They accumulate in the vesicles

2. They bind to their ligands

3. They are reabsorbed by the neuron

4. They diffuse into the surrounding blood

The correct answer is: They bind to their ligands

The correct response indicates that after neurotransmitters are released into the synaptic cleft, they engage with receptors on the postsynaptic neuron, effectively binding to their respective ligands. This binding process is crucial as it leads to the activation of the receptor, which can then trigger various responses within the postsynaptic neuron, such as initiating an excitatory or inhibitory signal. This interaction is essential for neurotransmission and ultimately facilitates communication between neurons. The binding to receptors is a transient process, after which neurotransmitters must be cleared from the synaptic cleft to ensure that signals are properly modulated and do not persist indefinitely, which could lead to disruptions in neural communication. Other options can clarify the broader context: accumulation in vesicles would not occur after release, as neurotransmitters are designed to be released into the synapse during signaling. Reabsorption by the neuron, typically through reuptake mechanisms, does occur but following the binding and subsequent action of neurotransmitters. Diffusing into the surrounding blood is not a typical process for neurotransmitters in a synaptic context; they are generally meant to act locally at the synapse rather than enter systemic circulation.