MODULE SUPPLEMENT: NEUROLOGICAL SYSTEM
Changes with Age: Definitions

Neuroglia or "nerve glue" function to support, nourish, and facilitate the function of the neurons. Neuroglia can proliferate and are not passive. There are three types of neuroglia, each with a unique function:

Astroglia are prominent in the gray matter that appear to link components of the nervous system and fill much of the intercellular space of the CNS. They provide contact between neurons and the circulatory system but also provide a barrier to the entrance of unwanted substances. Astrocytes can proliferate when neurons are destroyed, filling in the area.

Oligodendroglia cells deposit myelin within the central nervous system. Processes extend from these cells with each wrapping around several different axons forming multilayered myelin segments that function to increase the velocity of nerve conduction (Carroll & Curtis, 2002). Of note is that oligodendrocyte dysfunction has recently been implicated in neurodegenerative processes (Braak, et al, 1997).

Microglia are phagocytic macrophage cells of the central nervous system and serve an immune function and as 'garbage collectors'; that is, they clean up debris after cellular damage or death.