Major subdivisions of the nervous system. It is best to begin by thinking in very general terms about the function of the nervous system. The nervous system is a network of millions of cells which communicate with one another by means of nerve impulses transmitted along axons of nerve cells.he best functional definition of an axon is that it is a nerve process which is capable of transmitting a nerve impulse (action potential) over some distance. The nervous system also contains cells which are not neurons and which do not DIRECTLY participate in the task of sending and receiving electrical signals.