Form the physical structure of the brain, maintain the neural network, provide a scaffold to support neuronal cells and synapses.

Supply neurons with nutrients such as lactate, derived from stored glycogen, which is crucial for high neuronal activity, where much more energy is needed.

The endfeet enwrap blood vessels, regulating the endothelial cells and ensuring only select substances can travel between the blood and the brain.

By releasing many different types of signaling molecules, astocytes keep the cells of blood vessel walls packed, preventing toxins from entering the brain.

With transporter proteins, astrocytes clean up leftover neurotransmitters (like glutamate and ATP) after an electrical signal passes through the synapse. This prevents overexcited neurons (which are bad) so the synapse works properly.

Astrocytes can also release neurotransmitters of their own into the synapse, which can drastically influence the receiving neuron's behaviour.

Reactive astrogliosis is a complex chain of actions that astrocytes undergo to form scars that isolate brain injuries. This includes changing which genes are expressed, cell swelling, and rapid astrocyte replication around the injury to form the scar.

Along with reactive astrogliosis, astrocytes release chemical signals called cytokines and chemokines that allow controlled inflammation. inflammation is good for healing but bad for function, so astrocytes also resolve inflammation once unnecessary.