How neurons carry impulses

During the 1800's, scientists discovered that nerve impulses involve electrical charges. They assumed a nerve impulse was simply an electric current flowing through nerves. By the 1900's, researchers had learned that different concentrations of certain ions in neurons and in their surrounding fluids create a potential electrical charge. It was also learned that nerve cell membranes have pores that allow only certain substances to pass through. Scientists then theorized that a nerve impulse was an electrochemical process controlled by the nerve cell membrane. In the 1930's, researchers developed techniques to test the membrane theory of nerve conduction, which is the theory discussed in this section. This theory is the accepted explanation of how neurons carry impulses.

Begining of an impulse

Conduction along an axon

Transmission across synapses