Chemical synapse cells, known as a gap junction. At gap junctions, cells approach within about 3.5 nm of each other, rather than the 20 to 40 nm distance that separates cells at chemical synapses. As opposed to chemical synapses, the postsynaptic potential in electrical synapses is not caused by the opening of ion channels by chemical transmitters, but rather by direct electrical coupling between both neurons. Electrical synapses are faster than chemical synapses. Electrical synapses are found throughout the nervous system, including in the retina, the reticular nucleus of the thalamus, the neocortex, and in the hippocampus. While chemical synapses are found
Electrical conduction system of the heart well as to the endocardium at the apex of the heart, then finally to the ventricular epicardium; causing its contraction. These signals are generated rhytmically, which in turn results in the coordinated rhythmic contraction and relaxation of the heart. On the microscopic level, the wave of depolarization propagates to adjacent cells via gap junctions located on the intercalated disc. The heart is a "functional syncytium" (not to be confused with a true "syncytium" in which all the cells are fused together, sharing the same plasma membrane as in skeletal muscle). In a functional syncytium, electrical impulses propagate freely between cells