Exam 3 Review:  Chapter 11:  Types of Glial Cells  

neuroglia = glia = glial cells - The sustentactular tissue that surrounds, provides mechanical and physical support for, helps convey nourishment to, and provides electrical insulation for, neurons in the CNS; glial and neural cells (neurons) together compose the tissue of the CNS.

glioma - A tumor of the brain consisting of neuroglia; three types are recognized, indicating their cell of origin:  astrocytoma, oligodendroglioma, and ependymoma; all such tumors infiltrate adjacent brain tissue but they do not metastasize.

astrocyte - A glial cell named for its characteristic star-like shape with long cytoplasmic processes which bridge neurons and capillary endothelial cells; these cells provide both mechanical and metabolic support for neurons, regulating the environment where they function; they contribute to the blood-brain barrier and control transport of substances from the blood to neural tissue; they also help coordinate nerve pathway development.

oligodendrocyte - A glial cell named for its characteristic limited number of dendritic processes; those processes provide electrical insulation for a few adjacent neurons by forming a part of the myelin sheath for their axons, and, thereby, increasing the speed of transmission of action potentials along that axon (saltatory conduction).

microglia cell - A glial cell named for its characteristic small size; these cells are derived from mesoderm and provide a protective function to nervous tissue in that they can become phagocytic.

ependymal cell - The simple squamous cells forming the linings of the ventricles of the brain and the central canal of the spinal cord; any ependymal cell is capable of contributing to the production of cerebrospinal fluid (CSF) but the vast majority of CSF is produced in the several specialized regions, the choroid plexuses, within the ventricles by a combination of plasma filtration and secretion.

Schwann cell = neurolemmocyte - A glial cell of the peripheral nervous system which provides a small region of electrical insulation for one or a few neurons by forming a part of the myelin sheath for their axons, and, thereby, increasing the speed of transmission of action potentials along that axon (saltatory conduction).

satellite cell - Any of the glial cells that encapsulate and provide protection and support for the cell bodies of peripheral neurons in the many peripheral ganglia.  [Note:  there is also a different "satellite cell" identified in muscle tissue.  satellite cell - a low frequency (<1%) striated muscle tissue cell (discovered in 1961) which is an undifferentiated stem cell (myoblast) which is dormant in healthy muscle tissue but can help repair damage by dividing and migrating to an injured area of the muscle; satellite cells are decreased in number with increased age or with certain diseases such as Duchenne muscular dystrophy.]

List:

3. The types of glial cells found in the central and peripheral nervous system and describe the function of each.

4. The cells that myelinate axons in the CNS and PNS.

          oligodendrocyte in CNS and Schwann cell = neurolemmocyte in PNS