Neurons or neurones are the core constituents of the nervous system (this was discovered by the Spanish anatomist Santiago Ramón y Cajal in the 20th century). They are formed by a body (soma), dendrites and an axon. Neurons are electrically excitable cells and its main functions are to process and to transmit information. They do it in two ways: by chemical signals (synapses) and by electrical signals. There are many different kinds of neurons depending on which aspect you use to classify them.