Final answer:
Glia are support cells in the nervous system, with several types providing functions such as myelination, neurotransmitter regulation, and immunity in both the CNS and PNS.
Step-by-step explanation:
Glia, also known as glial cells, are non-neuronal cells in the central nervous system (CNS) and the peripheral nervous system (PNS) that provide various support functions to neurons. Astrocytes are star-shaped glial cells abundant in the CNS that regulate ion concentration, uptake of neurotransmitters, and help form the blood-brain barrier. Oligodendrocytes produce myelin in the CNS, with a single cell capable of myelinating multiple neurons, distinguishing them from Schwann cells in the PNS, which myelinate only a single axon.
Additionally, microglia serve as the brain's immune cells, scavenging dead cells and protecting against microorganisms. Other glial types include satellite glia, which provide nutrients and support in the PNS, and ependymal cells, which are involved in the production of cerebrospinal fluid.