Editing Action potential (section)

===Anatomy of a neuron===
{{Neuron map}}
Several types of cells support an action potential, such as plant cells, muscle cells, and the specialized cells of the heart (in which occurs the [[cardiac action potential]]). However, the main excitable cell is the [[neuron]], which also has the simplest mechanism for the action potential.{{cn|date=May 2024}}

Neurons are electrically excitable cells composed, in general, of one or more dendrites, a single [[soma (biology)|soma]], a single axon and one or more [[axon terminal]]s. Dendrites are cellular projections whose primary function is to receive synaptic signals. Their protrusions, known as [[dendritic spine]]s, are designed to capture the neurotransmitters released by the presynaptic neuron. They have a high concentration of [[ligand-gated ion channel]]s. These spines have a thin neck connecting a bulbous protrusion to the dendrite. This ensures that changes occurring inside the spine are less likely to affect the neighboring spines. The dendritic spine can, with rare exception (see [[Long-term potentiation#Properties|LTP]]), act as an independent unit. The dendrites extend from the soma, which houses the [[Cell nucleus|nucleus]], and many of the "normal" [[eukaryote|eukaryotic]] organelles. Unlike the spines, the surface of the soma is populated by voltage activated ion channels. These channels help transmit the signals generated by the dendrites. Emerging out from the soma is the [[axon hillock]]. This region is characterized by having a very high concentration of voltage-activated sodium channels. In general, it is considered to be the spike initiation zone for action potentials,{{sfn|Bullock|Orkand|Grinnell|1977|p=11}} i.e. the [[trigger zone]]. Multiple signals generated at the spines, and transmitted by the soma all converge here. Immediately after the axon hillock is the axon. This is a thin tubular protrusion traveling away from the soma. The axon is insulated by a [[myelin]] sheath. Myelin is composed of either [[Schwann cells]] (in the peripheral nervous system) or [[oligodendrocytes]] (in the central nervous system), both of which are types of [[glial cells]]. Although glial cells are not involved with the transmission of electrical signals, they communicate and provide important biochemical support to neurons.{{sfn|Silverthorn|2010|p=253}} To be specific, myelin wraps multiple times around the axonal segment, forming a thick fatty layer that prevents ions from entering or escaping the axon. This insulation prevents significant signal decay as well as ensuring faster signal speed. This insulation, however, has the restriction that no channels can be present on the surface of the axon. There are, therefore, regularly spaced patches of membrane, which have no insulation. These [[nodes of Ranvier]] can be considered to be "mini axon hillocks", as their purpose is to boost the signal in order to prevent significant signal decay. At the furthest end, the axon loses its insulation and begins to branch into several [[axon terminal]]s. These presynaptic terminals, or synaptic boutons, are a specialized area within the axon of the presynaptic cell that contains [[neurotransmitters]] enclosed in small membrane-bound spheres called [[synaptic vesicle]]s.{{cn|date=May 2024}}