Nervous System

The nervous system has three levels of organization:

Level	Overview
Neuron	At the most simple level is the neuron. A neuron is a large, complex cell designed to propagate and transmit chemical and electrical signals to other cells such as muscle fibers or fellow neurons.
Local Circuit	Within local circuits, interconnected nerve cells elaborate incoming signals and send the output to other centers or circuits.
System	At a higher level, connections among systems (aka pathways) make possible complex behaviors such as reading and speaking.