Glucose Transport | Metabolism

[Music] hi everybody dr. Mikey in this video we're talking about glucose transport so you're taking a big bite of some sort of carbohydrate and that carbohydrate is made up of multiple sugars these sugars if we look at their basic form what we call the mono saccharide it's going to be either glucose fructose or galactose now the thing is that fructose and galactose will turn into glucose and it's glucose that we want that makes all this ATP energy so it means that when we get this sugar into our mouth it needs to go from the mouth at some point into the bloodstream so it can be distributed around the body to all the different cells of the body but it needs to also go from the bloodstream into those cells so there's multiple different cells that glucose needs to move through to go from point A to point B to Point C so think about it like this from the mouth into the small intestines it needs to go through the cells of the small intestines to get into the blood for distribution then the bloodstream at the capillaries the glucose will leak out and needs to go from the interstitial which is the area just outside the cells into the cells are the specific tissues for them to be used so there's multiple different membranes that glucose needs to move through this is so important because this is the rate limiting step for glucose metabolism so you need to understand all these transport molecules now predominantly at the tissues the transport molecules are called glutes and I'm going to go through glut once and glut4 but there's around about 13 different glut molecules or transporters that you should be aware of but before we do that we need to talk about some other glucose transporters called SGL t1 and sglt2 so think about it like this you take a big bite of a cheeseburger which has that delicious carbohydrate feel bun you use the amylase which is an enzyme in the saliva of your mouth to break down that complex carbohydrate into its simple sugars let's just say the glucose you then swallow it goes down the esophagus into the stomach from the stomach into the small intestines now we're here in the hollow inside of the small intestines we call that the hollow lumen the hollow inside so needs to go from the small intestines into the bloodstream for distribution so it needs to move through cells that line the walls of the small intestines these are called antara sites there's two membranes that glucose needs to move through the membrane closest to the hollow inside and the membrane closest to the bloodstream there the membrane closest to the hollow inside is called the apical membrane and then the one closest to the blood is called the basolateral membrane so the first membrane that the glucose needs to move through the apical side it uses sglt2 an sporters okay so I'm zoomed in on this cell here what you can see is in order to get glucose from the hollow lumen into the intera site cell it uses sodium as a co transporter so glucose and sodium move at the same time that's actually what SG LT stands for stands for sodium glucose linked transporter now if this is happening in the intestines it's using the SG lt1 transporter now once the glucose is inside that cell it needs to go from inside the cell into the blood and it moves through another transporter this is a glut transporter specifically for the small intestines its glut - but I'll get to that now there's another hollow tube that glucose moves through and needs to go through two membranes as well to go back into the bloodstream this is going to be that of the kidneys so when again you take that glucose into the bloodstream and it moves around it's ultimately going to go to the kidneys and get filtered now glucose does get filtered into the kidneys but the thing is you shouldn't be paying out any of that glucose that glucose should be reabsorbed back into the body which means if we now imagine that this is the hollow tube of our kidneys which we call a renal tubule it also needs to move from the hollow inside to the blood and go through two membranes the SGL t or s GL transporter in the kidneys is actually sglt2 okay and the glut transporters that it uses to go back into the bloodstream of the body is going to be that of glut 3 or glut 2 depending on where we refer to Spurs predominately glut 2 if it's happening at the proximal convoluted tubules but that may be too much for this video okay so I'm spoken about the SG LTS let's now talk about the glutes so this is how we get glucose into specific tissues of body now there's four glutes you need to know and different tissues that these got to locate it to how do you remember it through my wonderful mnemonic minor Monica is big fat boys kills small little pansies producing nervous kids and mad fathers so what do they stand for okay the be big here this is standing for blood so this is referring to red blood cells so in order for red blood cells to pick up glucose it needs a glut one transporter the F here is for fetus so as a developing fetus in your mother's womb you only have glut one transporters for glucose metabolism okay the B here is blood-brain barrier so in order for glucose to go from our bloodstream into our brain it needs a glut one transporter in actual fact we need the blood-brain barrier there's actually a blood retinol barrier as well that also uses glut1 okay for glut two ki in kill stands for kidneys SM or even the whole small stands for small intestines li here stands for liver and PA stands for pancreas so all these tissues in order to get glucose it uses a glucose to transporter and it's kidneys small intestines liver and pancreas and the pancreas you should probably be aware of it needs to pick up glucose to release insulin right so at the beta cells of the pancreas is where we have glut to transporters and these are the glucose sensing areas okay so glucose transporter 3 we've got P here so it's not going to be pancreas it's going to be plus center and II neurons and ki kidneys again then down here for glut 4 we've got m4 muscles and F for fat so here we referring to adipose tissue so again for muscles and fat to get glucose we need glut for transporters now some more important points here is this glucose one does it need insulin the answer is no glucose two does it need insulin the answer is no glucose 3 does it need insulin the answer is no glucose 4 yes glucose 4 is insulin-dependent so that means that when somebody has diabetes which is a problem with producing insulin or that insulin binding to receptors it's happening at glut 4 which means it's a problem with muscles taking up glucose and fats taking up glucose in actual fact all these other different areas can take the glucose up without insulin no problem and the way that it takes all this take up glucose without any problem the way that it takes it up is diffusion so that means it goes down a concentration gradient all of them diffusion diffusion diffusion so it only goes from a high concentration gradient to a low concentration gradient of glucose so means it doesn't go against its concentration gradient it doesn't need ATP none of them use ATP to be able to take glucose in these ones are facilitated diffusion so these are transported but no energy going down a concentration gradient and glute 4 needs insulin to stimulate the transporter glut 4 to diffuse glucose in an actual fat forgot for this transport is sits inside the cell for all these others it goes through across the entire membrane of the cell so you can take glucose from the outside throw it on the inside glut 4 isn't in the mitt is it in the membrane it's inside the cell and when insulin comes along it triggers glut 4 to move its way to the membrane to then pick up glucose but another so this is why when people don't produce insulin due to type 1 diabetes for example that no glut 4 comes to the surface so you have reduced numbers of glut 4 and therefore the muscles can't take up the energy you get very tired you can't work alright so another important thing here specially for diabetes is exercise induces glut 4 to move to the surface so two things can actually bring glut 4 receptors to the surface of your muscle cells and fat cells one insulin to exercise and this is one important reason why diabetics should exercise is because it's stimuli the amount of glut4 receptors they have on the surface increasing the amount of glucose they can get into the cells of their body so that they can function animal studies have shown that if you reduce the amount of glut4 not get rid of it just reduce it these animals mice for example become diabetics okay so exercise increases glut for transportation or translocation to the surface to be able to bring more glucose into the muscles and the fat now these receptors don't just take a look I see and they can take in other things so for example glut one can take in mannose galactose and glucose Amin glut 2 can take in fructose and glucose Amin and glut 3 can take in manners and galactose so as you can see these glut transporters don't just transport glucose but they can transport a whole bunch of other types of sugars alright so this is a quick run-through of glucose transportation

Channel: Dr Matt & Dr Mike

Views: 63,269

Keywords: glucose transport, glucose transporters, glucose transportation, glucose metabolism, glut1, glut2, glut3, glut4, sglt1, sglt2, sglt, glut, insulin, glucose and insulin, glucose and muscle, muscle metabolism, sugar metabolism

Id: 4ScyFDY1cjA

Length: 10min 9sec (609 seconds)

Published: Tue Aug 20 2019