in this video I'll be talking about the neurog gal cells sometimes just called gal cells that are the supporting cells that help to support the functions of the neurons neurog gal cells are found in the peripheral nervous system that's outside of the brain and spinal cord and in the central nervous system supporting the brain and the spinal cord the gal cells of the peripheral nervous system are called the Schwan cells the Schwan cells are cells that wrap around axons in the peripheral nervous system they're responsible for performing this myelination this electrical insulation around peripheral axons and they can participate in the repair process after injury the neuroglia of the central nervous system are more diverse the first type are similar to The Schwan cells they're the oligodendrocytes they myelinate axons within the central nervous system they do the same thing as the Schwan cells but in a different location and they help to provide structural framework for the central nervous system by tying axons together in a sheath of myelin astrocytes are cells that maintain the bloodb brain barrier they provide structural support they regulate ion nutrient and dissolved gas concentrations they absorb and recycle transmitters and they form Scar Tissue after injury asites have a large number of cytoplasmic processes projections out of the cell so they look sort of like stars and that's how they get their name Astros sites they control the chemical content of the interstitial environment within the central nervous system they isolate the neurons from the general circulation of the blood the microglia are fosic cells they crawl around in the nervous system like the longer Han cells do in the skin they protect the neuron by removing cell debris removing wastes and removing pathogens by a phagocytosis the endal cells are cells that line the ventricles they line the central Canal these are spaces within the brain and the spinal cord where cerebros spinal fluid travels the endal cells assist in producing circulating and monitoring the cerebros spinal fluid cerebros spinal fluid is a distillate of blood it contains a lot of the products that are present in blood but not red blood cells so it's somewhat similar to blood plasma some endal cells are responsible for secreting that cerebros spinal fluid here's an illustration of these neurog gal cells in action and I'll make a brief aside before I dive into these neurog gal cells nervous tissue is divided up into gray m and into white matter gray matter is mostly cell bodies it has the Soma of the neurons it has the dendrites and it has the nissle bodies inside of the Soma so this is a spot that appears gray because of all of those inclusions this is the site of integration up here at the top in this gray matter that's where messages are being received at the dendrites and processed at the Soma white matter is just axons of cells no cell bodies those axons are transmitting information it appears white because we don't have all of those inclusions and organel that would be present in the Soma of the cell and because often these axons are wrapped in myin this lipidlike layer that causes it to appear lighter white matter is just an area of information transmission gray matter is an area of information reception now I'll get back into the neurons and the neurog gal cells in this illustration the neurons are Illustrated in blue and the neurog gal cells are Illustrated in yellow and in pink what we can see are the oligodendrocytes and those oligodendrocytes are responsible for making that myelin that electrical insulation the wrapping around axons and an alod dendrite can insulate multiple neurons or can group neurons together by function they would only be found in the white matter because they only wrap around axons and axons are found in the white matter we can see astrocytes those star-like branches reaching out to multiple neurons they're wrapping around blood vessels here's a capillary and therefore they're connecting neurons to the nutrient Supply and you can think of them as the the gatekeeper cells they would for instance let sugar in from the capillary but not alcohol these would be found in both the White and the gray matter there are also micral cells those would be found in both the gray and the white matter roving around playing roles in repair and defense the endal cells which I guess I'm in the way here the endal cells are these cells that are forming the lining of hollow cavities in the brain and in the spinal cord they're epithelial like cells and together with the capillaries they produce the cerebros spinal fluid that would be traveling in this Central canal and that the brain and the spinal cord float in cerebral spinal fluid is a distillate of blood you think about it like plasma blood without the blood cells and the proteins but its content is tightly regulated by these neurog gal cells that help produce it we've been talking a lot about myelination without getting into the details of it neurons have those long axons myelin is a compound that forms a sheath around the axons in what's often called the myelin sheath you can think about axons as wires that send electrical signals to various parts of the body those axons connect neurons to other cells at synapses myelin is comprised of gal support cells that protect the axons so you can think about it like the insulation on electrical wires although not all axons have a Molin cating myelin lets nerve cells transmit information more quickly and allows for more complex brain processes myelination occurs in the central nervous system and in the peripheral nervous system myelination is really important for um for healthy central nervous system functioning as well as peripheral nervous system functioning what is being Illustrated here is on the left we have a neuron it's in the peripheral nervous system I know that it's in the peripheral nervous system because it's being myelinated with Schwan cells that are only found in the peripheral nervous system what Schwan cells will do is it's a single cell that will wrap its cell membrane around the axon of a a neuron so we'll start with the formation of the myelin sheath and then you can imagine it like squeezing a tube of toothpaste like rolling a tube of toothpaste around that Central axon and what we end up with is a Schwan cell that's now completely flattened and completely wrapped around that axon and up here would be the nucleus and other organel of that Schwan cell that's wrapped around the neuron axon not all axons are myelinated um first off there's just not enough space in the body to have every neuron axon wrapped up in insulation that insulation does take up space so you don't have enough room that's one reason why not all axons are myelinated another reason is that myelination helps impulses travel more quickly sometimes we need nerve impulses to travel more slowly if you hit your finger with a hammer then you feel a sharp pain right away that's those myelinated neurons that help you respond quickly to that stimulus and to pull your hand away but then you'll feel a dull thuing pain that continues that's unmyelinated neurons that are telling you to protect your damaged hand and if you are taking a test then you might face a question like this matching each neurog gal cell with its function on the left there I have the five types that we just talked about oligodendrocytes asites micral cells Schwan cells and endal cells you could try to match them to their description a Liga dendrites I know are found only in the central nervous system and this description down here at e seems about right they form the myelin sheath in the central nervous system astrocytes they're those starshaped cells and they're helping with making multiple connections they anchor neurons and blood vessels they maintain the extracellular environment around neurons they're important in the formation of that blood brain barrier preventing some things that are traveling in the blood from uh entering into the interstitial space around the neurons micral cells I remember that those are important in defense and that they're the fosic cells of the central nervous system Schwan cells are the only one that we talked about in the peripheral nervous system they create a myelin sheath in the peripheral nervous system and that leaves endal cells to be those ciliated cells in the central nervous system that form and circulate cerebros spinal fluid