An illustration of the key component of the nervous system, the neuron; human brain in the background. Neurons have a large number of extensions called dendrites; branches of the neuron cell body that can be long, or very short to act as chemical message receivers from other neurons. The main extension here is the axon, the purpose of which is to transmit electro-chemical signals from one neuron to another neuron. Long axons are covered by a myelin sheath, a fatty substance that covers the axon and insulates it. Shown here is the connection between one neuron (center) and a foreground neuron body. At the end of the axon ending, the bouton, a synapse with the dendrite of the foreground cell is taking place. Across this synapse, very small neurotransmitters (red) cross this gap into the next neuron, creating the nervous system message transferral system.
