... to the outside; the potential is normally -70mV across the membrane. This is called the resting potential i.e. when the cell is not firing. The resting potential exists because ions are concentrated on different sides of the membrane; sodium (Na+) cations and chloride (Cl-) anions ions on the outside and potassium (K+) cations and organic anions on the inside. The electrical voltages and concentration gradients across the membrane exert forces on the ions. Overall, the outside of the membrane is positively charged and the inside is negatively charged at resting potential. An action potential is a brief, rapid and large change in potential, in which the inside of the cell (which is said to be excitable) rapidly becomes more positive than the outside (1). When a presynaptic neuron is active, an action potential is propagated down the length of the axon, from the axon hillock. The action potential causes rapid ...

See this essay or coursework document in full right now