neurog or simply Gia makes up about half the volume of the central nervous system Gia refers to glue and is derived from the idea that neurog are the glue that holds a nervous system together neurog are typically smaller than neurons although they're 5 to 25 times more numerous they don't generate or propag action potentials but they have several other functions of the six different types of neuroglia four are found only in the central nervous system while the remaining two are present only in the peripheral nervous system so starting with neurog found in the central nervous system and our first type of neurog are asites and our asites are these blue starshaped cells here here and here asites have many processes and are the largest and most numerous of the neuroglia the processes make contact with blood capillaries with neurons and with Pat which is the deepest membrane that surrounds the brain and the spinal cord and their functions include providing structural support to a neuron forming part of the blood brain barrier which keeps potentially harmful substances in the blood and away from brain tissue in an embryo asites secrete chemicals that appear to regulate the growth migration and interconnection of neurons among the brain asites help maintain the appropriate chemical environment for the generation of an action potential they also serve as a passageway for nutrients and other substances between capillaries and neurons so for example asites are the site of storage for glycogen or carbohydrate within the brain and it's also believed that asites may play a role in learning and memory by influencing the formation of a neural sinapse so the connection of a neuron with another neuron the second type of neuroglia found within the central nervous system are our alod dendrites alod dendrites I think look somewhat like an octopus so their processes are reaching out from the body and they wrap around the axons of neurons so lioden sites are these cells here and here the processes of these cells are responsible for forming and maintaining the m and sheath the m and sheath which we will talk about more in an upcoming module helps protect the axon and assist in the propagation of an action potential potential one alod dendrite can wrap around the axons of multiple neurons the next type of neurog found within the central nervous system are our microG these are the small green cells here and here they have thin slender processors which have little spines or projections coming out of those processors micral or micral cells function as fites so like fites outside of the central nervous system our microG Gia remove cellular debris which is formed during the normal development of the nervous system as well as any microbes or damaged nervous tissue that is present in these regions epid demal cells which are these cells which are lining the bottom of the IM here are the final type of neuroglial cell found within the central nervous system these cells are cuboidal to columna cells arranged in a single layer and containing microvilli or Celia so microvilli and Celia are these little fingers that you can see coming out from each border of those cells these cells tightly line the ventricles of the brain and the central Canal of the spinal cord again these are spaces which we will learn more about in upcoming modules but are spaces within the brain and spinal cord that are filled with cerebros spinal fluid which helps protect and nourish brain tissue our epid demal cells help produce and assist in the circulation of this cerebros spinal fluid and they also form the blood cerebros spinal fluid barrier moving across to the peripheral nervous system and the first type of neurog glal cell we find in the peripheral nervous system is a Schwan cell so a swan cell acts a little bit like an algo dendrite in the central nervous system but it wraps around the axons of neurons in the peripheral nervous system so a swan cell is this cell here this cell here this cell here like an alod dendri side they form and they maintain the M and sheath this yellow structure here is our M and sheath however unlike an Alo dendrite each Schwan cell melinates only a single axon Schwan cells are also involved in axon regeneration so this is the repair of an axon following an injury which is more easily accomplished and more common in the peripheral nervous system than it is in the central nervous system finally satellite cells are the other type of neuroglial cell that we find in the peripheral nervous system our satellite cells are these flat cells here they surround the bodies of neurons in the peripheral nervous system so a cluster of cell bodies in the peripheral nervous system is called a gangion these cells provide structural support as well as the exchange of material so nutrients and wastes between the cell body of a neuron and the surrounding interstitial fluid