Axon
Most axons carry messages in the form of action potentials which start in the cell body of a neuron and travel down the axon. Axon potentials are terminated at the point where axons make contact with synaptic vesicles. The axon's body has a negative charge because of charged potassium ions and a positive charge outside (sodium ions). The difference is called the resting membrane potential  about 70 millivolts in your body. When a neuron has a negative membrane potential it is said to be polarized. A protein in the nerve cell membrane adds to this difference in charge, since it pumps out three sodium ions for every two potassium ions it brings in. The difference in charge is called an electrochemical gradient, which the neuron wants to even  out. The cell membrane is also riddled with ion channels (examples are voltage gated channels, ligand gated channels, mechanically gated channels). When these gates open, the ions move down them to even out the differences in charges across the membrane; these actions are the key to all electrical events in neurons. If only a few channels open and only a few sodium ions pass through this is called a graded potential and only causes a small change in membrane potential in a localized part of the cell. Action potentials trigger release of voltage gated ion channels. Process: something stimulates you and causes the sodium channels to open causing the inner charge to increase. The stimuli has to be strong enough to trigger the action potential. At this level many voltage sodiums open causing a lot of sodium ions to enter the cell causing the cell to be massively depolarized, up to 40 mv. This causes a biological chain reaction causing the charges inside and outside the cell to swap. Repolarization is when voltage gated potassium ion channels cause the pot ions to go outside trying to rebalance the charges. This causes hyperpolarization which is when the membrane potential drops to -75mv before sodium potassium ;pumps take over and return everything to its resting level. Refractory period process during which the axon is not responsive to any other stimuli. The strength of an action potential is always the same, what changes is the frequency of the stimuli. The speed of conduction also varies, myelinated axons are faster than unmyelinated ones because impulses can jump from node to node in saltatory conduction.