THE ACTION POTENTIAL

Neurons have 3 different kinds of potentials – resting, graded, and the action potential. The neuron maintains a resting potential of -70 mV due to differences in permeability of ions on either side of its cell membrane, as well as the sodium potassium pump. The ions contributing to the charges on either side of the membrane are proteins, chloride, sodium, and potassium. Several kinds of channels found in cell membranes, allowing for the transport of substances from one side to the other. Two kinds are important for action potentials – leaky channels and voltage-gated channels. Leaky channels allow the free flow of substances through them. Voltage-gated channels only open at certain voltages. Back to the ions – chloride and the proteins stay put. However, the neuron has leaky sodium and potassium channels. These are always open and allow flux of these ions. There’s a lot more potassium in the cell than outside the cell. The potassium wants to rush out because of the chemical gradient but wants to s