After a brief introduction of the morphology and classification of astrocytes (broadly protoplasmic - with short 30 micron processes and fibrous with 300 micron long processes), Abhilash went over the GFAP (expressed more during reactive astrogliosis) and S100Beta (Ca binding protein that gets expressed more during injury) expression and then came to the various functional roles of astrocytes.
Astrocytes have a significant role in the lifespan of synapse formation (from birth to death of synapes) and interestingly, under healthy conditions they maintain own territorial domains with less than 5% of overlap between astrocyte processes. Through the astrocytic gap junctions, K+ buffering and Ca+ wave propogation take place. In the tripartite synapse, only 20% of the glutamate released is taken up by the postsynaptic terminal with 80% of it being cleared up by astrocytes. Astrocytes are also involved in Glutathione synthesis and produce precursers that allow neurons to also manufacture Glutathione (as they can't take in Glutathione from extracellular space).
Astrocytes are implicated in neurodegenerative diseases such as ALS (can serve as an early marker for some SOD mutant mice models as reactive astrogliosis is observed at 5 weeks while motor neuron loss is seen only at 15 weeks),Alzheimers and Parkinsons Disease(astrocytes can secrete MPTP like toxins. Microglia could be causative for astrogliosis).