Glial cells and neurons are the cells that form the nervous system. Neurons are cells that have the function of receiving and transmitting the neural impulses and glial cells (astrocytes, microgliacytes, ependymal cells and oligodendrocytes) are the cells that support, feed and insulate (electrically) the neurons. The Schwann cells that produce the myelin sheath of the peripheral nervous system can also be considered glial cells.