NeuronGlia

Neuroglia, also sometimes spelled neuronglia, are the non-neuronal cells of the nervous system that provide support, protection, and metabolic assistance to neurons. They accompany neurons throughout the central and peripheral nervous system and are essential for development, homeostasis, and response to injury. Glial cells vastly outnumber neurons in many regions of the brain and spinal cord.

In the central nervous system, the major glial types are astrocytes, oligodendrocytes, microglia, and ependymal cells. Astrocytes help maintain the blood-brain barrier, regulate the extracellular ion and neurotransmitter environment, and supply metabolic support to neurons. Oligodendrocytes form myelin sheaths around axons, increasing the speed of electrical signaling. Microglia act as resident immune cells, surveilling for pathogens and debris. Ependymal cells line the ventricles and contribute to the production and circulation of cerebrospinal fluid.

In the peripheral nervous system, Schwann cells perform a similar myelinating role for peripheral axons, with each cell wrapping a single axon segment. Satellite cells surround neuron cell bodies in ganglia, regulating the chemical milieu and providing structural support.

Functions of neuroglia extend beyond structural support and myelination. They participate in synaptic modulation, clearance of neurotransmitters, ion balance, tissue repair, and immune defense. Glial pathology is implicated in several disorders, including gliomas (glial tumors) and demyelinating diseases such as multiple sclerosis, which reflect disruptions in glial function and myelin integrity.