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Nonneuronal Cells of the Nervous System. Melissa Metzler. Glial Cells. Make up about 90% of the cells in the nervous system but only 50% of the volume. Cannot generate or transmit nerve signals. They are responsible for the physical and metabolic support of the neurons.
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Nonneuronal Cells of the Nervous System Melissa Metzler
Glial Cells • Make up about 90% of the cells in the nervous system but only 50% of the volume. • Cannot generate or transmit nerve signals. • They are responsible for the physical and metabolic support of the neurons.
Types of Nonneuronal Cells • Four types associated with the central nervous system. • Astrocytes, oligodendrocytes, microglia, and ependymal cells • Two types associated with the peripheral nervous system • Satellite cells and Schwann cells.
Astocytes • Star-shaped cell that provides glucose and removes ammonia from the neurons. • Also regulates potassium and neurotransmitters around synapses. http://fig.cox.miami.edu/~cmallery/150/neuro/neurophysiology.htm
Astrocytes Continued… • Form a barrier around the blood vessels in the brain (blood-brain barrier). • Keeps certain substances from moving into the brain. • Helps to direct neurons during embryo development and supplies the neurons with growth factors. www.rit.edu/~umagwww/ winter2002/gallery.html
Oligodendrocytes and Microglia • Oligodendrocytes wrap extension of their cell membranes around sections of the axon (myelin sheaths). • Myelin sheaths help to transmit nerve impulses. • Microglia remove pathogens and cell debris from the brain.
Ependymal Cells • Lines the ventricles or hollow spaces of the central nervous system and secretes cerebrospinal fluid • Cerebrospinal fluid acts as a shock absorber and helps to carry nutrients to the cells. http://faculty.southwest.tn.edu/rburkett/A&P1_nervous_system_lab.htm
Nonneuronal Cells of the Peripheral Nervous System • Satellite cells protect the cells of the ganglia • Schwann cells form a myelin sheath around a segment of an axon. www.steve.gb.com/science/ nervous_system.html
References • Pasternak, Jack J. An Introduction to Human Molecular Genetics: Mechanisms of Inherited Diseases. Second Edition. John Wiley & Sons, Inc. 2005. • Widmaier, Eric P.; Hershel, Raff; Strang, Kevin T. Vander’s Human Physiology: The Mechanisms of Body Functions. Tenth Edition. Mcgraw-Hill. 2006.