Gastrointestinal | Digestion & Absorption Of Lipids

iein engineers in this video we're gonna talk about the digestion and absorption of lipids if you guys haven't already we talked about this in a little bit of detail in the lipoprotein metabolism video we're gonna go into a lot more detail in this video on the chemical digestion and the absorption but we're not going to go into extreme detail on the packaging of these fats into structures called chylomicrons if you guys haven't go see our video on lipoprotein metabolism you'll get a little bit more information on that but in this video we're primarily going to focus on the chemical digestion the absorption and then we'll talk very briefly about the chylomicrons but if you guys want more information on that and lipoprotein metabolism in general like vldls IDL's HDL is LDLs go watch that video alright so cool when we talk about lipid metabolism it's an extremely interesting pathway what we need to first do is get down this basic understanding of what we're gonna do in this video so first thing we have to understand is we talked about lipids the big component that we are going to be you know consuming and certain types of foods is going to be triglycerides so we're gonna say here try glycerides other things that we're going to consume that are consistent of the lipid category are cholesterol but particularly the cholesterol that we ingest in the foods is what's called a cholesterol ester and we'll talk about that afterwards and the next thing i want to talk about after that is there's going to be one more substance that we can find abundant and within the lipids - and that's going to be phospholipids so certain types of sussan substances and food that contains phospholipids but of the most significant here in caps is going to be the triglycerides this is going to be the one that we contain tons of whenever we actually consume certain foods rich in fats imagine I don't know taking some butter or oil you know certain types of foods that are rich in fats now what we're gonna do is in this process we're gonna take these triglycerides these cholesterol esters these phospholipids which we're going to cat your eyes are a group as a polymer right we're gonna call these our polymers and remember polymers are the large unit of these actual macromolecules the lipids what we're gonna do is we're going to take these polymers and we are going to break them down through specific enzymatic steps into monomers what are some of those monomers well if you want to know the triglycerides we're actually gonna break those down into specific components let's like actually keep the color consistent here we're gonna break it down into triglycerides into fatty acids okay fatty acids and what's called ma G I'm gonna refer to it as and this stands for mono Aseel glycerol okay so that's one thing that we're gonna talk about the next thing is we're gonna take cholesterol esters and break down cholesterol esters into cholesterol you'll see how we do that afterwards as well and then the final thing is you'll see how we can break down phospholipids into their individual constituents and how we can break it down into like glycerol and fatty acids all right cool deal now again what is the whole purpose here we're taking polymers breaking them down into their individual units and these individual units are going to be monomers this process will we break down these big molecules into these small molecules is called catabolism right so this is a catabolic pathway now generally whenever we break down these substances we do it through a mechanism which is referred to as hydrolysis hydrolysis meaning that we add water into the actual reaction to break specific types of bonds and the bonds that you're going to see that we're gonna frequently break in this video is going to be what's called ester bonds a little bit of structure on the ester bond because I don't want us to go into super super detail here but the basic structure of an ester if some of you have taken biochemistry if you had organic chemistry the basic structure of an ester is you have what's called a carbonyl compound so it's a carbon doubly bonded to an oxygen singly bonded to another oxygen which is bound to some type of carbonyl I'm sorry carving groups so hydrocarbons and then coming off the other side there's this carbon whose W bonded to the oxygen is also bound to some hydrocarbons so this is the basic structure here of what we refer to as a ester okay so if you know a little bit about your organic chemistry or your biochemistry you'll understand this process what we're gonna do is is we're gonna take and go over these specific examples how we break down triglycerides cholesterol esters phospholipids into their individual monomers or basic building blocks utilizing specific enzymes within the gastrointestinal tract now remember we've used this diagram in the digestion of carbohydrates we've used this diagram in the digestion and absorption of proteins we're gonna do the same thing here this big big brown tube here is representing the lumen of your gastrointestinal tract now we're gonna assume that we're going from the oral cavity all the way down to the doodoo hole the anus right but along the way there's going to be specific points where we need enzymes to help in this chemical digestion some of those points are going to be represented by these little tubes here these little inlets now where are these going to be found one of the big ones is going to be found here in the oral cavity so at the oral cavity you're gonna find specific enzyme that's really important in the chemical digestion I shouldn't say significantly important he does play a role in the chemical digestion of lipids but nowhere near is the the amount played by the pancreas so that's one the next place is going to be the actual stomach okay the stomach has gastric glands and one of them is going to be having a special cell they're called a chief cell and they also secrete an important chemical that's going to help with this digestion and the last one is going to be the pancreas so the last point here will be the pancreas and you'll see that the pancreas is also connected with the liver we'll have a mini diagram in the video afterwards but there's gonna be a lot of different digesting enzymes coming from the pancreas and there's going to be a really important component coming from the liver or the gallbladder called bile and we'll talk about that when we get to that point all right so let's go ahead and say first that we've digested some type of food substance that is rich in fat okay so here's this big fat molecule here's our little fat substance that we've ingested so this is the fat okay we're going to ingest this fat here and we're gonna bring it in to our GI tract the first point that it's going to come into contact with is the oral cavity we already said that there's special types of salivary glands let's denote this in pink they're primarily in high concentration these glands the ones that make this enzyme underneath the tongue you know there's the the sublingual salivary gland there and then there's another one here on the side of the face right and this is going to be anterior to the ear and around the masseter muscle this is going to be the parotid salivary gland so you have two important glands here one is the parotid salivary gland and the other one is the sublingual salivary gland what these guys do is they secrete a chemical into the actual oral cavity and this chemical is called lingual lipase how convenient right so this chemical is called lingual lipase now I'm gonna come back to this because we're also gonna have another one here in the stomach which is going to be acting very very similar and then tandem with this enzyme because you have to remember when we talk about ingesting food food isn't in our twirled cavity that law okay for me it is that when I'm eating food I'm swallowing pretty quick right so the enzymatic activity that's enzyme isn't going to be very long inside of the oral cavity so whenever we swallow the food via deglutition it goes down through the pharynx the esophagus and into the stomach in the stomach you have specific cells here called chief cells and the chief cells are secreting a chemical and that chemical that they're releasing out into this area is going to have similar similar function to this enzyme and this is called gastric lipase okay so again just as a side note here up here in the top this is coming from the sublingual and the parotid the extrinsic salivary glands and then from the stomach it's going to be coming particularly from the chief cells okay sweet deal if you remember the chief cells were also responsible for secreting of protein digesting enzyme called pepsin again which got converted into pepsin cool these guys are primarily going to be focusing on breaking down triglycerides so now we have to do is I have to give you a basic structure of the triglycerides so now the first thing that this is going to digest we said is the triglyceride so now let's go ahead and look at a triglyceride here so first off we have to have a molecule here called glycerol and glycerol is really important because it's going to be one of the structures of the triglyceride okay so here we have this and then coming off of glycerol generally has these h groups but we get rid of the H and we combine on to this a fatty acid so now what I need to have here is I'm going to have a carbon double bonded to an oxygen and then we're just going to have some hydrocarbons coming off of this point here and then same thing right here and then same thing right here okay remember I told you before there was a particular bond with inside of these structures here that was really really specific that we wanted to know what was that bond an ester bond it was an ester bond that is the bond that these enzymes are going to be particularly looking to digest so lingual lipase and gastric lipase what they're gonna do is is these guys are gonna come in here and focus on breaking these bonds so what it's going to do is it's going to come in here and try to digest these bonds so now when these enzymes lingual lipase and gastric lipase come over here and they break the ester bonds right they're breaking these ester bonds and lipids they're not doing all of them because these guys are do are playing a very significant role in the chemical digestion but not enough to break down all of the fat okay you got to think about it whenever we are ingesting food that's coming the lingual lipase is coming from the oral cavity the gastric lipase is coming from the stomach these enzyme aren't gonna have a lot of time to be able to focus on these triglycerides and break them down completely but what they will do is when they break down the triglycerides they can give off some free fatty acids let's assume here that the lingual lipase and the gastric lipase are able to cleave off a couple fatty acid let's say let's just say - maybe they break down to two fatty acids they give off two fatty acids so now if that's the case then I'm gonna take here my glycerol which is kind of like that backbone structure here let me get him drilling up here and let's assume that the top two was the one that we lost so if we lost this we're gonna cleave that off here what's gonna happen is this is gonna get an OHA from the water reacting and that's gonna get an O age but this part here we're gonna say we left it alone we didn't brig this bond let's assume that we did not break this bond and if that is the case we're still going to have this ester bond here that wasn't completely digested now what we see here as a structure is you have a fatty acid bound to a glycerol so we call that a mono Aseel glycerol we can kind of denote it here as AM a G but what else did it really release off of this technically we actually relief don't released off two fatty acids so what else should I have over here I should also have two free fatty acids let me draw all these guys here so boom-boom there's my carbon eel and here's one fatty acid and let's say another one here and there is my other fatty acid so these are my free fatty acids so when this enzyme gastric lipase a lingual lipase function the actually are designed to break down the ester bonds and triglycerides and when they do it they're not going to have a large large function here because the fats are you have to think about it if you take fats and water what happens they don't really mix that well so because of that these enzymes lingual lipase and gastro like gastric lipase don't have a large surface area that they have to work on that's where bile is going to come into play okay these enzymes are breaking down lipids but not a large amount of them and so this is something that will get as a result of the lingual lipase and the gastric lipase maybe some mono so glycerol and some free fatty acids but in reality it's not going to break down a large amount of these triglycerides a lot of these triglycerides are going to continue to go down the gut tube eventually till we get to the small intestine so now let's go to the small intestine so we already talked about the stomach we talked about the oral cavity structures now we're gonna get to this next level the next level we're gonna hit is we're going to be in this portion of the GI tract which is going to be the duodenum now if you have watched our videos you realize that we know that the duodenum is important because what happens is you have a structure here you know you have a structure here called the gallbladder and the gallbladder is storing and concentrating the bile there's one structure here this green tube right here which is actually getting bile from the liver via the right and left to patek ducts then the common hepatic ducts fuses with the cystic duct here and then what happens is it comes down to the level of the pancreas and if you know the pancreas has a special duct here and let's draw all this stuff like this this is the main pancreatic duct but what happens is is the main pancreatic duct in this green tube here which is the cystic duct to use together when they fuse together they make this area called the apado pancreatic ampulla or the ampulla of Vater and what happens is that area right there is actually surrounded by a ring of smooth muscle and that ring of smooth muscle is called the sphincter of Oddi okay or the paddle of pancreatic sphincter why is this important because the gallbladder is storing and concentrating the bile the liver is secreting the bile the bile is going to be extremely important because whenever the bio comes out into the duodenum let's assume that it actually opens up and releases out the bile the bile is extremely and crucial because the bile is actually going to be what's called an emulsification agent so what is it called it's called an emulsification agent what that means is it's able to take a big big big fat globule and break it down into smaller fatty droplets let me show you what I mean here okay so let's assume that the duodenum we're here the duodenum let's assume that this is the pancreas and then remember that the common of patek duct and the Cystic doctor fusing and bringing down that common bile duct here's our common bile duct okay and what are they releasing out into this area whenever that muscle relaxes it's going to secrete out what chemicals - specific chemicals one is it's going to seek read out the bile and the other one is going to secrete out pancreatic lipase pancreatic lipase all right sweet so before we can actually talk about pancreatic lipase we have to talk about the bile first so remember the whole purpose of the bile is to act as an emulsification agent if you guys have ever washed dishes before you've ever had like certain foods that are rich in fat and let's say that it's on the plate and you mix it with water the water isn't enough to get all that grease off right are all that fat off then what do you have to add you have to add some dish detergent the dish detergent is actually going to be an emulsification agent in beyal there's a lot of different substances but crucial to this video is going to be two substances one is what's called phospholipids particularly one called lecithin okay that's one the other component of the bile here that we're gonna want to know about is what's called your bile salts and these are gonna be like Kolak acid and Chino deoxy Kolok acid these are actually derivatives these two Kolok acid and Chino deoxycholic acid are derivatives of cholesterol now what these two molecules are is they're kind of like amphipathic molecules what does that mean let's imagine here that I have that big fat globulin so here is going to be the big fat globule that we're gonna refer to here here's my big fat globule and in that big fat globulin I glow sir IDEs okay I might even have some cholesterol esters which I'm gonna represent a CH II I might even have a little bit of phospholipids in this too what happens is this fat globule imagine it kind of just like floating on top of this con this is going to be the intestinal kind so all this right here is the intestinal kind it's the fluid secretion okay all the intestinal kind intestinal kind now when we talk about this intestinal con what I'm really really referring to here is I'm referring to the watery secretions from the intestinal con so I'm talking about a lot of the watery secretions this fat globule is just going to kind of sit on top of it and the problem with that is is we have some special enzymes that were actually secreted remember we talked about the pancreatic lipase the pancreatic lipase is just sitting down here and he's like man I want me some fat globules problem is though he doesn't have enough surface area to work on so here's where these emulsification agents come into play the first thing that we want is we're gonna want phospholipids so this is gonna come first the phospholipids will be first and the bile salts will come second okay and you'll see what I mean of this what these molecules do is is if you take a bile salt or you take a phospholipid on one side let's imagine that it's just like this circle here one side of it has a lot of negative charges okay one side of it has a lot of negative charges and this side of it which is like the ionic side or the hydrophilic side is the part that can interact with the actual intestinal kind here the watery secretions and get that fat globule to kind of get distributed into this intestinal watery clime the other part of it is actually going to be this top part here and this part is really really good at being able to interact with lipids this part up here is the hydro phobic portion that is such an interesting thing this kind of molecule we refer to this as an amphipathic molecule this is a an fie Pathak molecule so what happens is is these bile salts and these phospholipids they're amphipathic molecules and they come and interact with this - this factor lobule so let's imagine first as the phospholipids so the phospholipids are gonna represent here in blue they're going to have one portion interacting with the actual fat globules this side these residues on this side interacting with the fact lobule should be the hydrophobic side okay that's the first part the other side of it should be the portion which can interact with the water so it should be this portion here so now look at this so now I'm going to have all of these guys are gonna come over and they're just going to kind of surround this fat globule and if you look at it one portion here the inner side this is going to be the part that's really good at interacting with the fat globule these pink little parts here okay the other part is the hydrophilic portion which is ionizable right it actually has charged points on it and what allows it to do is to actually allow it for it to interact with the watery secretions now if it can interact with the watery secretions guess what it can do it's soluble it can mix with this intestinal kind so now let me bring the intestinal calm down a little bit like a little bit deeper so now look what's gonna happen here it's gonna be a little bit deeper and now that actual fact lobule is really a Beloit it into this intestinal kind so now from here I'm gonna bring this puppy down into this area here because now I have the things to surround it which is hydrophilic interacting with the water and keeping it bound there I'm gonna have these hydrophobic portions such a cool thing now once we bring it into this area into the actual fluid it starts actually dispersing into smaller fat globules are smaller fatty droplets let's say so the first thing we have to do is get the phospholipids on here cause it to become distributed into the intestinal calm once it becomes to distribute into the intestinal Clym it starts dispersing out into small fatty droplets let's represent here a couple of them so now here I'm going to have a small fatty droplet here and now these small fatty droplets should still have what's surrounding them they should still have my phospholipids or that lecithin surrounding them but here's where it gets even better now the next molecules come in remember I told you first would be the phospholipids the second thing is we would need the bile salts to come along let's do the bile salts in this red color here okay now the bile salts are going to come into play so here we're going to have one of these structures right here this is our fat droplets which are gonna be smaller this right here is our fat globule which is pretty friggin big okay and it's not able to be dissolved into this intestinal kind now we're gonna do is we're gonna make these fat droplets even smaller next we're gonna bring in the bile salts and the bile salts are gonna be just like this okay so imagine here I have this red structure here on one side of it I'm gonna have the negative charges on the other side of it I'm gonna have the hydrophobic portions okay we're gonna represent the red as the bile salts which is going to be like the cola Cassatt of the Chino di-oxygen Kolak acid these are actually bile acids but what will happen is they'll get reacted with certain types of things like taurine so these guys this Kolak acid and this Chino deoxycholic acid they'll actually react with two different types of molecules called taurine and glycine and when they do that it'll actually help them to become even more hydrophilic on one side and then they still have that hydrophobic portion on the other side now once these bile salts come over here and attach on so going to come over here and they're going to attach on to these little fat droplets here's what's really cool okay so here I'm gonna have my bile salts surrounding this bile salts surrounding this and my bile salts surrounding this there's gonna be another protein that's going to come over here and it's gonna bind okay it's going to come over and it's gonna by and let's do this one in black there's gonna be a protein that will come over here and bind on to this portion this protein molecule this black protein here is called Co lipase okay so that's one first thing first thing that we're gonna do is we're gonna have the bile salts bind which is gonna actually help them become even smaller in turn on next structures we'll call me cells the next thing is it'll facilitate the binding of this protein molecule called coli pace then once this coli paste binds this little Pacman dude what does this pac-man do that we refer to as this pac-man dude here is called our pancreatic lipase pancreatic lipase has a hard time being able to act on these fatty droplets because of the its interactions so what happens is coli paste kind of gives it a little help for the pac-man do the pancreatic lipase to come over and bind to the actual coli paste and then helping facilitate in the chemical digestion of these fat droplets so now what's going to happen is this pancreatic lipase is gonna come over and it's gonna bind with this coli pace when it binds with the coli paste it's now going to have the perfect ability to start breaking down all these triglycerides inside of these fat droplets now if we break down the triglycerides what are we gonna get out of this so here come over here for a second we're gonna have here a small little fat droplet and it's fat droplet here is gonna have triglycerides it's gonna have some cholesterol esters and it might even have a tiny bit of phospholipids and we're gonna have this lecithin in this left lecithin was actually kind of forming this little coating around it to help but to become mole safai then after that we have what else we had our bile salts which came from the Kola Kassadin Chino deoxycholic acid which reacted with the taurine and the glycine is helped to pack it up even more and then we had this next structure which is bound to it called E coli pace when the pac-man dude comes over here our pancreatic lipase here we'll put here a little hat pancreatic lipase it starts breaking down the fat droplet particularly the triglycerides if I break down the triglycerides what am I going to get out of this I'm gonna get two substances what was the substances that I actually had well here was just try glyceride the pet lingual lipase and the gastric lipase exert the same functions as the pancreatic lipase except the pancreatic lipase is going to be even more active so when it breaks down these triglycerides it can break it down into a mono seal glycerol into free fatty acids a lot of it so it's able it's going to be able to work on a lot of triglycerides break a lot of triglycerides down into mono is so glycerol and free fatty acids so we're gonna write that as M a G and F a mono is still glycerol and free fatty acids what we're going to get out of this now you guys are probably wondering we've broken down the triglycerides but Zach you say that we were also gonna break down cholesterol esters and phospholipids we do another thing that I didn't talk about here yet is because it's not it's not as large as the paint critic lipase but still important is from this dye pancreatic juice there's going to be two other chemicals that are released one is called phospholipase a2 okay PLA 2 and the other one is called cholesterol ester hydrolase okay cholesterol ester hydrolysis the phospholipase a2 guess what its gonna do it's gonna come over and break down phospho lipids phospholipids are kind of just like these uh triglycerides if you want to know a little bit about it here I'll show you a very tiny little quick thing here imagine here I have my glycerol and let's say here I'm gonna have a phosphate group coming off here that phosphate group it allows for it to be nice and polar and then coming off here I'm going to have a two hydrogens i have total of two hydrogens here and then coming off of this point here I'm gonna have my fatty acids and let's say here again I'll have a fatty acid and usually one of these has a double bond in there where its causes to be a little kinked and it caused the phospholipid to take on like this little bench structure okay but this is our phospholipids so what happens is is this phospholipase a2 is going to be really good at breaking down these actual phospholipids and it breaks it down into the free fatty acids and even some of that actual glycerol so that's one thing okay the other one is the cholesterol ester hydroxylase same thing you don't have to know too much like all the different things like this but if you remember cholesterol has this basic structure here like this is a bunch of rings and what's important here is that it has this Oh H group over here and usually what happens is if I take this o age group and I bond it with a fatty acid I have this structure here which we refer to as a cholesterol ester usually you have something like this okay and then BOOM and then usually a boom here all right but this is the basic structure of our cholesterol ester what this actual cholesterol ester hydroxylase is going to do is is it's going to come over here and it's going to break this bond and release off that actual fatty acid structure so it'll actually come over break off the bond by adding water into it and give off a fatty acid structure okay so what have we seen so far we've seen lingual lipase gastric lipase we've seen the bile via the phospholipids with the which act first to help to make the actual fat globules soluble and make it into fat droplets then the bile salts they come over bind on to these small fat droplets make them even smaller which we're gonna talk about here in one second and it also helps to allow for coli paste to bind which facilitates the pancreatic lipase to come and bind and break down the triglycerides into mono so glycerol free fatty acids and also phospholipase a2 breaks down phospholipids into the free fatty acids and even the cholesterol ester Hydrox we'll break down the cholesterol esters into free cholesterol now what is this molecule because what the bile salts do is when they actually bind on there they're gonna help to make them the actual fact droplet even smaller so when they make it smaller after these actual mono so glycerol and free fatty acids start getting broken down this little guy here this fat droplet we're gonna make it even smaller so it was first pretty big with the fact lobule then smaller with the fat droplets then we're gonna break it on to mono so glycerol into free fatty acids this sucker is gonna be so tiny what is this structure here call so look here I'm gonna have a tiny little circle there with now containing my mono so glycerol and free fatty acids and even some false some actual phospholipid surrounding it's still a little bit right and now I've broken down my cholesterol esters into cholesterol breaking down the phospholipids to fatty acids I breaking down the triglycerides to fatty acids and mono so blister all whoa and I have my bile salts here surrounding it and guess what else some other guys say hey can I hop on for a ride you know who these guys are so other guys come on which are gonna be vitamin A vitamin D vitamin E and vitamin okay they say hey can we hop in here because we're fat soluble vitamins and we can just hop on and hitch a ride with you so we've broken down the fats the cholesterol esters and the phospholipids and we've actually how loud for the fat soluble vitamins A D and K to even get on to these little molecules what are these little molecules here called these little molecules here that are super super tiny are called me cells okay they're called me cells now me cells are so cool because what they do is they help to make the actual little fat droplets that we formed kind of go down even further in this intestinal chyme watery like secretions so far that it actually gets to this cell what does this cell here called this is going to be a cell that you can find with them pretty much all the intestine so we're gonna say prime this cell will be in the small intestine well we're gonna refer to this as a in Tarot site okay what happens is as we get close to the cell membrane of this entero site the bile salts say I'm out the bile salts will say all right I'm out of here so we'll get rid of the bile salts here and what's really cool is we'll learn in later on we talked about the liver ninety-four percent of these bile salts get recycled and go to the liver so 94 percent of them they'll go via the paddock portal system and they'll go back to the liver so this circulation here that we're gonna call for right now it's called the entero hepatic circulation so these by also actually get recycled which is pretty cool but then after that we're gonna release in so what happens is the free fatty acids in the monomyth so glycerol and all those different substances they're gonna get released right in here so what kind of substances will release into the cell that can diffuse right into it by passive diffusion will release some cholesterol will release some fat soluble vitamins vitamin A D e K will also release what else some free fatty acids and will release some mono a seal dallisa Rawls now what these guys are going to do is is we're gonna take a lot of these substances particularly the free fatty acids and even some of the cholesterol and we're gonna take it to a specific area which is going to be what's called the smooth endoplasmic reticulum okay so this red structure here is going to be our smooth endoplasmic reticulum once they go to the smooth endoplasmic reticulum there are special types of enzymes that are going to convert the free fatty acids and the mono so glycerol back into triglycerides so that's pretty interesting so it's going to actually resynthesize that and convert it right back into again this structure here which is going to be the triglycerides and the cholesterol okay so now look here we do that we reconvert it we're gonna put here this Brown that's going to be the triglycerides that we resynthesized we're also going to put some of these vitamins in there too so the vitamins will actually get incorporated into this in the cholesterol that we had we're gonna actually take some of that cholesterol some of it we might keep in the actual free cholesterol form he'll represent and Ballou but some of the cholesterol we're actually going to reconvert back into cholesterol esters okay so so far the smooth endoplasmic reticulum takes these structures up as it takes these structures up it's going to synthesize triglycerides which again represent in the brown it might keep some of the collector on the free cholesterol form it might turn some of the cholesterol into this baby blue form which is gonna be the cholesterol esters and some of these fats like vitamins are still going to be packaged in there now from the smooth endoplasmic reticulum we can take these structures here and we can have it combined with some other things what is this other thing let's say we take it to the next or organelle and this organelle is going to be what's called the rough endoplasmic reticulum the rough endoplasmic reticulum will take the structures all these different things that we just decided to resynthesize okay and when it does that it's going to put like a protein coat on it so it's going to undergo some modifications and then from this modifications we're gonna bud this thing off here so now it's actually like a little budding thing here and from this we're going to get a structure here and this structure is still going to have the fat soluble vitamins it's still going to have these triglycerides it's still going to have some cholesterol and it's still going to have some cholesterol esters and if we did have any fatty acid that we have free fatty acids and some other structures here we can I even do one more straw you're here not super super careful about it on the sensitive about it but other things that could be phospholipids okay so what are these some of these things here let's write them down here the pink we're gonna represent as phospholipids the orange we're gonna represent is the fat soluble vitamins so I'll put here a d e okay the brown is going to represent the triglycerides I'm going to put PT AG for the triacylglycerols the blue is going to represent the cholesterol free cholesterol and the baby blue is going to represent D cholesterol esters now once we have all that we start throwing in another protein so the rough endoplasmic reticulum actually puts a protein on the outer part of it let's do this one here and black it puts an outer protein on this one so here I'm gonna have this protein here and this protein that it's gonna put on the outer part of it is going to be what's called a bo b48 so it is gonna have some actual proteins here they're going to be dispersed around it once you're gonna be the april-b 48 which if you watch our lipoprotein metabolism video it'll make more sense now after that this guy it'll go to the Golgi apparatus and get even a little bit more packaged and then what happens is it gets excreted out so it's going to get exocytosed out of this cell so now once it gets released out here so let's say that we actually have this sucker get exocytosis l there's inteiro site the next thing that happens is he's a pretty decent size structure so because he's pretty decent-sized he's not going to be able to really just fit into our circulation our blood right so because of that we have to take him a different route what is that different route well there's these highly specialized lymphatic capillaries and these highly specialized and fatty capillaries found in the intestines are called lacteals okay these lacteals are going to be really important because we'll talk about the lymphatic system later they have these little structures called mini valves which is formed by the endothelial cells lining it and they have these valves that only open up one way and when the pressure inside of the interstitial fluid is high it opens up those actual valves those flap like mini valves and allows for the fluid here in the actual interstitial fluid to leak in so now this structure that we just made in the intestines is going to get released into our lacteals what is this structure here called this structure is called a Kyllo micron what what happens is is the chylomicron will get pushed into our lymphatic capillaries the lacteals it'll go up via different types of you know lymphatic vessels and then to lymphatic trunks and then to lymphatic ducts or particularly lymphatic duct that it actually does go to is called the thoracic duct which is on the left side and it actually dumps in right where the the left subclavian vein and the left internal jugular vein meet where they become the brachiocephalic it empties that lymph into that structure then from there the lymph can then go to particular I'm sorry the chylomicrons can then go to particular organs some of those organs that it goes to is it can go to your skeletal muscles so I can go to your skeletal muscles or it can go to your adipose tissue the reason why I'm saying this is a special enzyme located in the capillary endothelium of this area and this special enzyme is called lipoprotein lipase so let's here let's represent him and like this maroon color here there's a special enzyme here and this special enzyme here is called lipoprotein lipase lipo protein lipase and what the lipoprotein lipase does is any of the triglycerides that we've repackaged into the chylomicrons which is represented here in brown we cleave it and then we cleave that we release into the muscle cells and the adipose tissue free fatty acids into these guys and then this free fatty acids they can actually metabolize that for energy or for ATP purposes so for this they can actually make ATP for this guy or they can take these free fatty acids and then the adipose tissue re synthesize it into triglycerides okay Sophia what's called lipo Genesis after that that chylomicron will then take the remaining substances that it has in it and goes to the liver and then the liver will actually take up that chylomicron via what's called a poly LDL receptors or proteoglycan containing heparin sulfate molecules take it up and then eventually use that substances to make what's called another molecule called VL DL all right and VLDL we actually can push back into the circulation and go and distribute it to other tissues I ninja nurse so that pretty much covers the actual lipid digestion and absorption I really do hope this made sense I hope you guys did like it if you guys did please hit that like button comment down the comments section please subscribe also if you guys get a chance go check out our patreon account if you guys have the opportunity to donate we would truly appreciate it helps us to be able to make the most highest quality videos for you guys as enjoyment so please if you guys can go check that out alright as always an engineer its until next time [Music] you

Channel: Ninja Nerd

Views: 209,962

Keywords: Gastrointestinal physiology, Digestion and absorption of Lipids, Digestion of Lipids, Absorption of Lipids

Id: ja-MWkFNvDg

Length: 46min 1sec (2761 seconds)

Published: Tue May 08 2018