Illustration of a neuronal network in the central nervous system, composed of neurons, blood vessels and glial cells : the neurons, yellow star-shaped cells, are interconnected at the synapses, which ensure the propagation of the nerve impulse from one neuron to the next. The blood vessels irrigate the brain. The oligodendrocytes, small purple cells, surround the axons, forming a protective sheath which facilitates faster propagation of the electric signal from one neuron to the other. The astrocytes are small green star-shaped cells connected to the synapses and surrounding the blood vesels. These cells are believed to protect the brain from dangerous elements circulating in the blood. The pink cells are microglia. Here, the neuronal network is emphasized by a white halo symbolizing the path taken by nerve impulses.
