Week 2

This week we continued to talk about the Nervous system. I want to discuss the different neuroglia of the nervous system and their functions. Astrocytes are star shaped cells. They create the blood brain barrier and also help to regulate Ca++ ions in the extra cellular fluid. Astrocytes are capable of mitosis. Oligodendrocytes form the myelin sheath of the CNS. They are able to wrap multiple axons for insulation. Although these cells are capable of mitosis, they are unable to assist in regeneration of cell. An injury to the CNS is often permanent because of this. Ependymal cells are the producers/regulators (via the cilia) of CSF. They appear cuboidal, and also are capable of mitosis. Microglia are the macrophages of the CNS. They have phagocytic/mitotic capabilities. Schwann cells are the producers of the myelin sheath in the PNS. Unlike Oligodendrocytes, Schwann cells are only able to wrap one axon. Schwann cells are capable of mitosis and use a process called Wallerian regeneration to assist in repair of an injury to the PNS. These cells form a "fatty tunnel" towards the intended targeted neurons. The axon then grows and is guided through this tunnel of schwann cells.
In my line of work I am able to see injury to both the CNS and the PNS. I never really understood why some injuries healed and some did not. Now that we have studied these different cells and how they function it is more clear. An injury to a limb is more easily repaired than recovering from a cva b/c a limb is part of the PNS and the brain is part of the CNS.