Module 10: Figure synaptic organization
Structural organization of a tripartite synaptic ending.
The synapse, which is the microprocessor of the brain, connects one neuron (the synaptic ending) to the spine of another neuron. The presynaptic ending has the synaptic vesicles that are released into the synaptic cleft to activate receptors on the spine. The bulbous head of the latter is connected to the dendrite by a shaft. At the base of the shaft, where it connects to the dendrite, there usually is a single polyribosome, which may play a role in the neuronal protein synthesis necessary for memory acquisition and consolidation. Many spines, but by no means all, contain extensions of the dendritic endoplasmic reticulum (red). Such synaptic endings are usually enclosed within an astrocytic process, and the three components thus constitute a tripartite synapse (Module 7: Figure astrocyte tripartite synapse).