Presynaptic and postsynaptic neurons

 Presynaptic neuron

A presynaptic neuron is aneuron (nerve cell) that fires the neurotransmitter as a result of an action potential entering its axon terminal.

In both the central and peripheral nervous systems in mammals, presynaptic terminals mostly operate in the same way. Vesicles in the synapse form a ‘synaptic pool’ when they are ready for exocytosis-meaning they are readily releasable. When an action potential arrives at the nerve terminal the electrical signal induces opening of voltage gated Ca2+ channels.

Postsynaptic neuron

A postsynaptic neuron in a neuron (nerve cell) that receives the neurotransmitter after it has crossed the synapse and may experience an action potential if the neurotransmitter is strong enough.

Postsynaptic neurons work through temporal summation and spatial summation.

Through neurotransmission there can also be divergence or convergence.

Sumiko Mochida (2015 Presynaptic Terminals, Tokyo Japan : Springer

Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Walkter P (2008) Molecular Biology Of The Cell, 5th edition, New York: Garland Science. 676, 683.