Astrocytes regulate the CNS environment by controlling the levels of ions like potassium and calcium. They uptake excess extracellular potassium, preventing neuronal hyperexcitability. Moreover, they modulate the concentration of glutamate and other neurotransmitters, ensuring proper synaptic signaling. Through their extensive end-foot processes, astrocytes form a crucial component of the blood-brain barrier, thus protecting the brain from harmful substances in the bloodstream.
