Neuroglia
a class of cells in the nervous system
Overview
Along with neurons, neuroglia makes up the cells of the nervous system. Commonly called glial cells, they make up about half the mass of the brain. Their main function is to support neurons, including maintaining homeostasis to create safe conditions for neuron function, forming the myelin sheath, and playing an important role in synapse formation. The types of neuroglia are described below.
Neuroglia in the Central Nervous System
astrocytes
Overview:
Astrocytes are delicate, star shaped branching glial cells. Being the most numerous glial cells, they cling to neurons and their synapses and cover capillaries.
Functions:
- help make exchanges between capillaries and neurons
- anchor neurons to their blood supply
- regulate the chemical environment of neurons by removing excess ions and recycling neurotransmitters
- Maintains blood brain barrier
oligodendrocytes
Overview:
Oligodendrocytes are cells located along nerve fibers.
Functions:
- Line up along nerve fibers and wrap their processes around the fibers that produce the myelin sheath, like an electrical insulation
- Called myelination
microglial
Overview:
Microglial cells are small with thorny processes.
Functions:
- Can transform into macrophages that can clean up neuronal debris and other pathogens
- Monitor health of neurons by detecting any injuries
ependymal
Overview:
Ependymal cells line the ventricles (cavities in the brain that produce cerebrospinal fluid) of the brain and central canal of the spinal cord.
Functions:
- Form barrier between CSF (cerebrospinal fluid) and underlying cells
- Aid in circulation of CSF
Neuroglia in the Peripheral Nervous System
Schwann cells
Overview:
Schwann cells are the major cell type in the PNS.
Functions:
- Wrap around axons to form myelin that provides electrical insulation and speeds up neuronal transmission
- Clears cellular debris like a phagocyte
satellite cells
Overview:
Satellite cells are very similar to astrocytes except they are in the PNS. They surround neurons sensory ganglia in the autonomic nervous system.
Functions:
- Helps regulate external environment
- Very sensitive to injury and inflammation
- appears as pathological pain (chronic pain)