At chemical synapses, primarily dictates the postsynaptic response.

At chemical synapses, neurotransmitter primarily dictates the postsynaptic response. Chemical synapses are biological junctions between neurons (or neuron and effector cell) which help them communicate and control other functions in the body.   At a chemical synapse, the presynaptic neuron releases neurotransmitter from its the synaptic vesicles (by exocytosis) into the synaptic cleft. Neurotransmitter binds to its receptors on the postsynaptic cell and achieves its effect. After this event, neurotransmitters must be cleared from the synapse via enzymatic degradation or re-uptake by specific transporters (to terminate the action of the transmitter).