Supporting Cells of the Nervous System There are several types of supporting cells that occur in both the CNS and the PNS. • None of them conduct impulses, instead they “assist” neurons. • As a group they are called neuroglia or “glial” cells, (means “nerve glue”) found in between neurons. Different cells do different jobs. • In the CNS the cell is called the oligodendrocyte • In the PNS the cell is the Schwann cell. Supporting Cells of the Nervous System Functions of neuroglia: 1)support, protect and separate neurons 2) act as phagocytes to clean up worn-out neuron organelles. 3) Electrically insulate neurons by forming a myelin sheath. 4) increase the speed of the action potential (electrochemical message) in those cells that have a myelin sheath. Supporting Cells of the Nervous System Schwann cells• Additional functions- they make it possible for some peripheral nerves that are damaged to regenerate their axons. Peripheral neurons will not regenerate if the cell body is damaged. • NOTE: This only occurs in the PNS. CNS neurons do not regenerate their axons at all. Supporting Cells of the Nervous System Schwann cell structure: Schwann cells can also surround other unmyelinated neurons in clusters to give them insulation. Supporting Cells of the Nervous System Schwann cells structure: • They do all this by making a myelin sheath around many of the neuron processes in the PNS. They wrap themselves very tightly around the process of a neuron. • The cytoplasm and nucleus is squeezed to the surface of the wrapping called the neurolemma. • The layer that lies against the axon is just many layers of the fatty plasma membrane- called the myelin sheath. Supporting Cells of the Nervous System Schwann cells structure: • The myelin sheath is many Schwann cells, wrapped up, side-by-side along a neuron axon. This type of neuron is said to be “myelinated”. • The Schwann cells don’t touch each other, so there are spaces between, called Nodes of Ranvier. These allow for faster impulse conduction.