Module 7: Figure astrocyte structure
Relationship between astrocytes, neurons and blood vessels.
Astrocytes are stellate cells with numerous branches. Only a few of the branches are shown, and the two circles illustrate astrocyte domains that show very little overlap. In the regions of overlap, the astrocytes are connected to each other by gap junctions. Some of the branches also have endfoot processes that spread out over the blood vessels (arterioles). Many of the branches make intimate connections with neuronal synapses to form a tripartite synapse. Here only two such synapses are shown, but in reality each astrocyte can form 150 000 such synapses. The elaborate branching pattern is shown in Module 7: Figure astrocyte organization and the function of the tripartite synapse is described in more detail in Module 7: Figure astrocyte tripartite synapse. The red arrows represent the spatial buffering of K+. The K+ released during neuronal activity is taken up by the astrocytes and flows down towards the blood vessels where it is released at the end feet.