Health and medicine
This video describes the structure and function of Schwann cells. By Matt Jensen. Created by Matthew Barry Jensen.
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- These are really great videos. I was just sort of thrown off because in class we were told that what you call "Schwann cells" are called neurolemmocyes. Are "nodes of ranvier" the same thing as gap junctions? I feel like that's what I was told in class but I'm not sure that makes sense now that I've watched and mostly understood this video.(8 votes)
- Neurolemmocytes are the same as Schwann cells. They're called oligodendrocytes in the CNS. Gap junctions usually refer to connections between cells. Nodes of Ranvier are gaps in myelination where saltatory conduction can take place.(37 votes)
- What does myelinating mean?(3 votes)
- myelinating means covering the axons of the neurons with the layer of myelin sheath. It is a process done in order to prevent the loss of potential inside the neuronal membrane.(11 votes)
- Are there any structural differences between the myelin sheath created by oligodendrocytes and the ones created by Schwann cells? Or are they identical in chemical composition and configuration?(8 votes)
- What is the difference between Schwann Cells and Oligodendrocytes since they work closely together in the spinal cord?(2 votes)
- At1:33he mentions that Schwann cells only produce myelin sheath for one segment for one axon. That means there are three Schwann cells for the axon he drew right?(2 votes)
- Is Schwann cells present in central nervous system(2 votes)
- The cells that cover axons with myelin in the cns are called oligodenricytes.(1 vote)
- I thought that cell membrane was only there to surround a cell. In the case of mylenating schwann cells and oligodendrocytes, does its membrane surround any other part of its cell when it acts as a myelin sheath?(1 vote)
- Yes, These cells wrap around the axons of neurons.(2 votes)
- What is the role of schwann cells in an unmyelinated nerve? Is it metabolic support?(2 votes)
- Does cells cover the nerves of the peripheral nervous system by producing a myelin sheath; which helps to increase the speed of nervous electrical signals.(0 votes)
- Hi, since Scwann cell transplant can repair the mylelination in Perpheral Nervous System, what kind of stemcell would be for repairing myelination in Central Nervous System (CNS) such VLPO neurons or Spinal Cord neuron apoptosis? And with which method?(1 vote)
- These ideas are still being researched and are not in clinical use.
- Between1:42and1:45you mentioned how a schwann cell differs from an oligodendrocyte. Why is it that a schwann cell can only produces the myelin sheath for one segment of one axon?(1 vote)
In this video, I want to talk about Schwann cells. Schwann cells are glia of the peripheral nervous system derived from neural crest cells and named after a person who described them. Schwann cells come in a couple of shapes. Some are fairly shapeless cells that have little troughs on their surface. And the axons of neurons that have small diameter axons often just sit inside these troughs. So these are neurons with a soma. And I'm leaving off the dendrites. And these have small axons, small diameter axons. And they'll just kind of sit in these little troughs on the surface of these Schwann cells. And these are called nonmyelinating Schwann cells. They do provide some support to these peripheral neuron axons that are small diameter. But they don't myelinate them. So they're nonmyelinating Schwann cells. Now, peripheral neurons that have a larger axon-- and let me just draw this one with a little larger axon-- usually have a myelin sheath. And just like in the central nervous system, there will be a sheath going all the way down the axon, that's regularly interrupted by these little gaps called the nodes of Ranvier. And these little segments of myelin in the myelin sheath of peripheral neurons have the same structure and function as the myelin sheath in central neurons. However, the Schwann cells create the myelin sheath in the peripheral nervous system, as opposed to the oligodendrocytes of the central nervous system. Now while the structure and the function of the little myelin segments is the same, a big difference between the Schwann cells in the peripheral nervous system and the oligodendrocytes in the central nervous system is that a Schwann cell only produces the myelin sheath for one segment of only one axon. It's not myelinating multiple neurons, like oligodendrocytes do. Now, let's take a little closer look at one of these areas of myelin sheath. And let's cut through this segment of myelin, just like this. And we'll look at it this way, like we're looking down from the end of the axon. And this is going to look just like the myelin sheath for a central axon. Here's the axon. And we're looking at it end-on. And the cell membrane of the Schwann cell, which is this material we call myelin, that's very rich in lipid, is just going to be wrapped again and again and again, very thinly and very tightly, like a role of tape, around the axon. Now for a Schwann cell, this is almost the entirety of its cell membrane. And then it's just going to have this little lump on the outside that's going to be sort of like a soma because it's going to have a nucleus and it's going to have most of the cytoplasm of a Schwann cell. But most of its membrane is actually wrapped around the axon as the myelin sheath. In addition to these functions, Schwann cells also appear to influence neurons, and vice versa, through exchange of a variety of substances.