Nerve impulses begin with a change in the charge of voltages found in axon walls, which are stimulated by ions moving in and out of the neuron walls. Nerve impulses are formed from a change in voltage, which then creates waves of electrical energy that move from one end of the surrounding cell body to the other. These waves travel across the long and narrow passageway of the axon, and ultimately terminate in the synapse.
Nerve impulses ultimately create a difference in the electrical charge of the surrounding cell. Nerves are sensitive to slight changes in intracellular electrical activity, and the smallest change can produce a series of nerve impulses. Once generated, nerve impulses carry tremendous amounts of energy, and may reach high speeds when traveling across cells. Some nerve impulses can reach speeds of 250 miles per hour, although there is a considerable amount of variation in top speeds of nerve impulses among the different types of cells. Nerve impulses transport energy across cells, and also act as messengers by carrying coded information throughout cells as well. These impulses disseminate coded information rapidly, and at various rates of speed. Nerve impulses are formed and carried out throughout the body, and may occur in the heart, brain and limbs.