in the last video we saw some of the glial cells associated with the central nervous system and in this video we're going to take a look at some of those glial cells associated with the peripheral nervous system well each glia cell that we find in the CNS we essentially have an equivalent in the p NS so I'm going to pick up with the equivalent of the Astro siding and that's going to be a satellite cell a satellite so now the place where we find cell bodies in the peripheral nervous system are in what we call ganglia and we have ganglia associated with each spinal nerve it's called a dorsal root ganglia for the autonomic nervous system we find the ganglia in what's called the sympathetic chain it's like a spinal cord alongside the spinal cord bilateral structure actually and that has to do with autonomic nervous system and then we also find what one of my professors used to refer to as the Stardust these scattered ganglia or cell bodies in the pns near the target organs okay the Stardust so we do have cell bodies in the peripheral nervous system and many of those cell bodies are associated with pseudo unipolar or unipolar neurons these are the type that we would find in the peripheral or in the dorsal root ganglia now even if it's a different one somewhere else we may find a by itself and just like a satellite does around the earth this cells going to kind of orbit and hover around the outside of the neuron cell body and it's going to do a lot of similar things as the Astro site it's going to help maintain a stable environment it's going to take up excess neurotransmitters it's going to take up waste products and toxins maintain a good eye on balance basically help guide and support this neuron cell body what it doesn't do is it doesn't signal using calcium waves because these aren't syncytium zuv cells the way that astrocytes are these are single isolated cells support cells for that neuron it also doesn't form a blood-brain barrier we have our own capital our own capillaries out here in the P NS and they're not covered in photo site or these cells with foot processes that are limiting the movement of material through not the way that pastro sites do for the for the central nervous system we're gonna let those nutrients come right out of the blood and bathe these cells these are a little less fragile than ground zero or the command center okay and they still do provide some some degree of scaffolding and structure and glue okay pretty straightforward there now the next one I'm not going to write in the equivalent of the microglia because that would just be your run of the I mean so the run-of-the-mill macrophage okay these would just be blood cells that can clean up any other tissue whatever the resident macrophage for where this neuron is okay if it's in the skin it would be a dendritic cell is the right resident macrophage if it's outside the vascular system it might be a mast cell within the blood we would call it a monocyte neutrophils eosinophils any of your granulocytes and those are white blood cells these white blood cells that are all Union nucleate one has a multi lo2 nucleus one has a by lobed nucleus kind of looks like a telephone receiver sometimes and then once nucleus is out actually obscured by all the cytoplasmic granules this is the big bad basil film with its irregular border this is the yo sena fella tends to take up more yes and die with its distinct distinct red granules and then this is a neutrophil it looks neutral color because it takes up basic dyes and acid dyes equally these are blood cells so it's called a neutrophil cuz it can have this neutral color between these two we also have those are the granulocytes all granulocytes are phagocytic to some degree we also have the monocyte which usually has a kidney-shaped or u shaped nucleus okay and these don't have visible cytoplasmic granules this would be an a granulocyte the agranulocytes no granules also include the lymphocytes which become plasma cells and producing antibodies of these two only this one is phagocytic all granulocytes are phagocytic to some degree these regular immune cells we don't have the specialized microglia the way that the brain does all these immune cells flow freely throughout our peripheral nervous system and may become vagus erik like the microglia do in the CNS so we have an equivalent for those microglia they're just off the run-of-the-mill blood cells that have the potential of leaving the blood and become active as immune cells so I'm not gonna worry too much about the but then we would have our lasso and these ones are very important like all these cells shworvels Schwann cells are the myelin eating cells of the pianist they produce Milan in the pianist now usually how you see these questions on standardized exams is you get this long elaborate question and you immediately think to yourself oh my god I studied all the wrong stuff but somewhere within that question it's talking about the likud enterocytes and in the last sentence of the question it says what body organ does this pathology or this disease of fact and basically it's asking you if you know the fundamental principle that oligodendrocytes are common CNS or that Schwann cells are found in the pianist it's a very simple question written in a very convoluted way so make sure that you remember oligodendrocytes make the myelin in the CNS Schwann cells make it in the pianos and the way that i draw this in my in-person classes is I represent the axon of a neuron as a hot dog and the Schwann cell is going to be that dough I don't know if you've ever taken that dough from the grocery store they usually come in rolls like Pillsbury Dough to roll croissants and you them against the counter and they they pop little kids love them [Music] adults love them too because you can take it and you can wrap it around this hot dog and you can start to roll it tighter and tighter so what we start to end up with when we start wrapping this lipid rich buttery dough around that hot dog what we start to get is these concentric rings [Music] of Milan now as we wrap this tighter and tighter as we wrap this tighter and tighter it's going to squeeze the cytosol out of this Schwann cell and the cytosol is going to collect out here in this area yeah that's where we would find the nucleus different organelles could be found out there now we call this part the outer collar sorry this part here an outer collar of Perry nuclear cytoplasm around the nucleus cytoplasm and we call this area here the myelin sheath these concentric rings of myelin that basically act as an insulator within this axon there's little pores or little holes for sodium that entered into this axon to escape sodium can escape back out after it entered but when we wrap concentric layers of myelin or more plasma membrane we cover those sodium pores and now when sodium enters into this part of the neuron the only place for it to move to is along that neuron and because neurons are normally negatively charged under their membranes this positive charge is going to move along getting away from other positive charges and be propagated down the axon this is the race of those positive charges down sections of axon this is what saltatory conduction is now we periodically have a gap between adjacent Schwann cells there's gonna be another Schwann cell over here and that gap provides a spot let me put another Schwann cell here and add to the length of this axon can extend this axon a bit further in both directions now what we've created are these small gaps where sodium channels are exposed in charge can re-enter or escape to regenerate an action potential it's often been described as this jumping from node to node of the signal this jumping from node to node but that's not the case at all it gets regenerated here and then it raced down it gets regenerated and then raced down and we'll see that in at another time but for now we know that the gaps between the Schwann cells that are made up of the perinuclear cytoplasm and the myelin sheath we have these gaps called the nodes of ranvier i'm going to talk about those when we talk about the neuron in the next video