(3) Types, Locations, and Functions of Glial Cells Neuroglia of CNS/PNS

Astrocytes (CNS)

• Most abundant

• Regulate availability of NT

• Connect to capillaries and neurons

• Modulate chemical environment

• Nervous tissue repair

• Maintain the blood brain barrier

• Guide neuronal development

Microglia (CNS)

• Smallest and least abundant

• Macrophages of the CNS (immune)

• Originate from monocytes

• Non-nervous tissue

Ependymal Cells (CNS)

• Line the ventricles

• Modified epithelial cells (columnar)

• Forms and circulate CSF

Oligodendrocytes (CNS)

• Produce myelin that wraps around axons to insulate and speed up the electrical signals

• Can coil over several axons

• Spaced nodes of Ranvier

Satellite Cells (PNS)

• Amphicytes

• Surround neurons cell bodies

• Regulate the exchange of nutrients and waste products between the cell body and the extracellular fluid

• Help in insulate the cell body

Schwann Cells (PNS)

• Form myelin around axons

• The external layer of the axons where

the schwann cell is located is called

neurilemma

• Wraps around one axon

• It wraps around unmyelinated axons

(~15) without forming myelin