What is the main function of Astrocytes?

Astrocytes play a critical role in maintaining the blood-brain barrier, which is essential for protecting the brain from harmful substances while allowing necessary nutrients to pass through. They are star-shaped glial cells in the central nervous system that not only provide structural support to neurons but also regulate the transport of ions and nutrients, ensuring that the environment surrounding neurons is stable and conducive to their functioning.

The maintenance of the blood-brain barrier involves the regulation of blood flow and the composition of the extracellular environment. Astrocytes interact with endothelial cells that form the barrier, secrete signaling molecules, and help to regulate the permeability of the barrier, thus protecting neural tissue from fluctuations in the systemic circulation and potential neurotoxic substances.

In contrast, the other options represent functions associated with different types of cells. For example, the myelin sheath is primarily produced by oligodendrocytes in the central nervous system. Pathogen engulfment is typically the role of microglia, the immune cells of the central nervous system. The transmission of impulses is the function of neurons, rather than glial cells like astrocytes. Thus, the primary function of astrocytes indeed revolves around supporting and maintaining the integrity of the blood-brain barrier.