The neurons form long chains along which the impulses are conducted in different directions. Each junction between the neurons is called a synapse. It is important to know that the contact between the neurons is by contiguity and not by continuity. The impulse is transmitted across a synapse by specific neurotransmitters, like acetylcholine, catecholamines (noradrenalin and dopamine), serotonin, histamine, glycine, GABA and certain polypeptides.
Types of synapses:
The most common types of the synapse are axo-dendritic, somato-somatic and somato-dendritic.
In synaptic glomeruli, groups of axons make contact with the dendrites of one or more neurons for complex interactions. Functionally, a synapse may either be inhibitory or excitatory.