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/neuroph ysiology.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.s outhwest.tn.e du/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 1. Pasternak, Jack J. An Introduction to Human Molecular Genetics: Mechanisms of Inherited Diseases. Second Edition. John Wiley & Sons, Inc. 2005. 2. Widmaier, Eric P.; Hershel, Raff; Strang, Kevin T. Vander’s Human Physiology: The Mechanisms of Body Functions. Tenth Edition. Mcgraw-Hill. 2006.