Cells and Components of the Nervous System Quiz

See Oligodendrocytes. Option C is correct. Glia are the supporting cells of the nervous system, and the oligodendrocyte is the glial cell that makes myelin in the brain and spinal cord (the central nervous system). Myelin is a fatty insulating layer wrapped around an axon (the long, thin cable of a neurone that carries electrical signals away from the cell body). It forces the electrical impulse to jump along the axon rather than creep along it, which makes conduction much faster. A single oligodendrocyte puts out a few branches (its name means 'cell of a few branches') and each branch wraps myelin around a segment of a different axon. In the peripheral nervous system (the nerves outside the brain and spinal cord) the same job is done by Schwann cells, but there each cell wraps only one segment of one axon. Loss of CNS myelin is the basis of multiple sclerosis. Memory aid: oligodendrocytes work in the central nervous system, while Schwann cells work out in the peripheral nerves.

• Cell: The oligodendrocyte makes myelin in the brain and spinal cord.
• Myelin: A fatty insulating layer that makes impulses jump along the axon, so conduction is much faster.
• Contrast: In the peripheral nervous system Schwann cells do the same job, but each wraps only one segment of one axon.