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Membrane Potential: all living cells have membrane potential; means polarized electrically; membrane potential; is the separation of opposite electrical charges across the plasma membrane. membrane potential is due to the difference in concentraction and permeability of key ions such as Na, K, Cl and proteins. action potential: are brief, rapid, large changes in membrane potential once initiated are conducted through out nerve fibers. action potential starts by change in permeability of cell membrane to ions by trigger event result in decrease membrane potential (depolarization) until reaching threshold potential then rapid large increase in permeability of cell membrane along with NA influx then after reaching peak there will be increase in membrane potential "re-polarization" along k efflux. In neurons: input zones (cell body & dendrities): part where incoming signals from other neurons are received  trigger zones (axon hillock): part where action potentials...