The functional cell type of the nervous system is the neuron. Neurons are cells whose function is to process and transmit information through specialized connections called synapses. Neurons are electrically excitable cells, which means they are capable of transmitting an electric current known as an action potential. Neurons communicate with each other and with muscle cells by means of action potentials. This chapter will introduce you to basic neuronal morphology as well as the electrochemical basis of neurotransmission.