Editing Excitatory synapse (section)

==Chemical vs electrical synapses==
[[File:Synapse.theora.ogv|thumb|Animation showing the function of a chemical synapse.]]

:There are two different kinds of synapses present within the human brain: chemical and electrical. Chemical synapses are by far the most prevalent and are the main player involved in excitatory synapses. Electrical synapses, the minority, allow direct, passive flow of electric current through special intercellular connections called gap junctions.<ref name="Neuroscience, 4th ed.">{{cite book |title=Neuroscience, 4th ed |author=D. Purves |publisher=Sinauer Associates, Inc. |location=Sunderland, Massachusetts |year=2008 |display-authors=etal  }}</ref> These gap junctions allow for virtually instantaneous transmission of electrical signals through direct passive flow of ions between neurons (transmission can be bidirectional). The main goal of electrical synapses is to synchronize electrical activity among populations of neurons.<ref name="Neuroscience, 4th ed."/> The first electrical synapse was discovered in a [[caridoid escape reaction|crayfish]] nervous system.<ref name="Neuroscience, 4th ed."/>

:Chemical synaptic transmission is the transfer of neurotransmitters or [[neuropeptides]] from a presynaptic axon to a postsynaptic dendrite.<ref name="Neuroscience, 4th ed."/> Unlike an electrical synapse, the chemical synapses are separated by a space called the [[synaptic cleft]], typically measured between 15 and 25 nm. Transmission of an excitatory signal involves several steps outlined below.