Metabolism | Mobilization of Triglycerides

all right n nerds in this video we're going to specifically focus on the mobilization of fats now generally where are these fats and what are we what do we categorize as fats we technically categorize them as triglycerides okay so now these fats are going to be stored within tissue cells in our body and this is going to be one of the main storages of this actual fat this is actually going to be the adapost tissue but we're just zooming in on one cell or you can also refer to this as an adipo site which is

just a fat cell so this right here is a adipo site so this is an adipo site an adipo site is a fat cell right what we're going to do is we're going to look at how we're actually going to break this triglyceride down into its constituent units what are the constituent units of a triglyceride one is glycerol and the other one is Three fatty acid chains so that's the goal of this video is to go over exactly what mechanisms are triggering the breakdown of this triglyceride and how is that happening okay so the first

question to ask is when is this happening okay so this usually is happening in our body whenever we're in the fasting State okay so this is usually occurring when we're in the fasting State what is the fasting State the fasting state is the state in which we haven't eaten in a while right so we haven't either we we're starving ourselves or we're actually not taking in food we're in the postabsorptive state so what does that mean for our blood glucose levels what does that mean if you haven't eaten for a while then you're not going

to really have high blood glucose levels so your blood glucose levels as a result are going to be low is going to be low when blood glucose levels are low what hormones or molecules are going to be released to be able to bring those blood glucose levels back up there is many many many many molecules but we're going to focus on just a select few okay the main main one that you guys need to remember is within the pancreas in the pancreas there's actually these things called eyelets of langerhan they're clusters of clusters of endocrine

tissue and there's two different types of significant cells in this area Alpha and beta cells the beta cells are releasing insulin but that's when the blood glucose levels are high glucagon is releasing sorry alpha cells are releasing glucagon whenever the blood glucose levels are low easy way to remember that is glucagon is being released whenever the glucose is gone or look okay so now the pancreatic alpha cells will release a hormone referred to as glucagon okay so one hormone that we're going to release this is going to be a very significant one is glucagon and

this is going to be triggered based upon low blood glucose levels another hormone that can get released you know whenever we're uh in stressful situations our body is trying to be able to accomplish this way of being able to deal with certain situations in which our blood glucose levels are low maybe we have to be able to increase them in some type of flight ORF flight situation or stressful situation sometimes our body can activate the sympathetic nervous system and you know the sympathetic nervous system has these uh preganglionic motor neurons within the lateral gry Horn

of the spinal cord from about T1 to L2 and those fibers can come out here into the Adrenal medulla and you know the Adrenal medulla has specific types of uh postganglionic motor neurons of the sympathetic nervous system they're consist of things called chromin cells and what they do is they secrete a chemical into the blood who's going to help us with this actual blood glucose levels this molecule is going to be epi nephrine so epinephrine is going to be released and he's released in very very significant amounts from the adrenal Med about 80% of it

is epinephrine very very very tiny amounts of it about 20% of it is going to be in the form of norepinephrine so noro epi nephrine okay so these are the main chemicals but there is other molecules being released like cortisol like thyroid hormone many many other different types of hormones growth hormone we're going to focus on the three significant ones the more important ones okay so glucagon epinephrine and orrine what are they going to do they're going to come to this adepoy this atopos tissue cell you know they have receptors on the extracellular membrane a

g protein coupled receptor what they can do is let's say that I show here in just in green this is representing these hormones okay so this is I'll put H4 these hormones and what could these hormones be it could be norepinephrine could be epinephrine or could be glucagon when these hormones are binding onto this G protein coupled receptor you know that when it activates it it B activates a g stimulatory protein and then G stimulatory proteins bind onto GTP which make them active when they become active they go and activate a specific type of of

eector enzyme that's present or embedded with inside of the cell membrane this affector enzyme is called a denate cyclas and a denate cyclas does what it takes ATP and converts it into cyclicamp and then cyclicamp goes and activates another enzyme and this enzyme is called protein kyes a okay why is all of this important okay you see this protein CA you know he loves to phosphorate specific types of proteins within the body so in this cell there's special proteins you know this there's kind of like a little surrounding structure around this triglyceride because you know

there's many many triglycerides within this this uh deposite tons and tons and tons this protein CA you know there's molecules kind of surrounding this triglyceride you see that maroon colored molecule that molecule right there is called Peril lipin so again what is this molecule right here called it's called per Li lipin Peril lippin is normally bound to another molecule right adjacent to it you see this green molecule right there that green molecule is called a CGI molecule CGI molecule so these two are literally connected to one another okay so you have Peril lippin with CGI

bound together but what happens is this protein kyese a comes over here and puts phosphate groups on to this Peril lippin so he phosphates this Peril lippin when he phosphorites this Peril lippin the CGI so look we're going to put phosphates on this Peril lippin when we put phosphates on this Peril lippin the CGI dissociates when the CGI disassociates where does he go so look here is our CGI he's going to go somewhere else where is he going to go you see this enzyme right here this brown scissor enzyme that brown scissor enzyme is really

and the reason why that brown scissor enzyme is important because he's going to make the first cut into this triglyceride and who's going to help him you see this green molecule here this green molecule here this CGI is going to come over here and it's going to bind with this enzyme and stimulate this enzyme this enzyme is going to make the first cut on the triglyceride what he's going to do is he's going to cut you know the uh bonds here are specifically Ester bonds you have Esters here because you have the carboxy end of

the fatty acid and then you have the alcohol you have an alcohol in from the glycerol what's going to happen here is that you're going to specifically cut that Ester Bond when you cut that Ester Bond guess what I'm going to release from this first point here what what am I going to release out of this first step this first step is specifically going to release out a fatty acid so from this reaction the first thing that I'm going to do is I'm going to release out a fatty acid so let's show that one fatty

acid let's put one here to simplify and to signify that this is the first fatty acid so now coming out of that is going to be specifically the first fatty acid molecule we're just now going to put F free fatty acid and let's denote this one one okay so this is the first free fatty acid that we released and this was from that point right there so we're going to call this one let's put a one right here on this one okay what does this en this enzyme here is called adose triglyceride lipase so again

what is this enzyme here called atgl is the abbreviation and this enzyme is stimulating this step again right what is he doing he's breaking the specifically this Esther bond between this free fatty acid and that glycerol molecule when he breaks that Bond he releases out a free fatty acid and this enzyme is called atopos triglyceride lipase and he is activated whenever CGI who is this molecule here again CGI dissociates from the Peril lippin and activates this enzyme then you know protein K say he's not picky he's not going to be like Oh I'm going to

phosphorate this guy but not any of these other guys he comes over here and phosphorites these enzymes too you know these enzymes are also important too so look let's show this phosphates right here there's phosphates added on to this enzyme and this enzyme is going to make the next cut but again what's going to be released let's actually show what's going to be released as a process from this so we cut away that fatty acid as a result let's show The Next Step of this reaction what we're left with because this is what we refer

to as a t a g a tri AAL glycerol or a triglyceride it's synonymous okay but from the breakdown what am I going to have left over guys well I should still have the glycerol so I'm still going to have the glycerol here but all I'm going to have left now is going to be two fatty acid chains because I released a free fatty acid in that first step then what's going to happen is this enzyme is going to cut this next one so look what this enzyme's going to do he's going to come over

here and he's going to cut that part he's going to cut this Bond when he cuts this Bond he's going to release another fatty acid so look I'm going to release out of this step I'm going to release a another and the second one I'm going to release another free fatty acid what is this enzyme called that's doing this this enzyme is called this is again free fatty acid we're going to denote it two this enzyme right here is called hormone sensitive lipase okay which you're going to denote hsl so hormone sensitive lipase is doing

what it's cutting this this molecule here what do you call this molecule when you have a glycerol in two AAL groups or fatty AAL groups you call this D AAL glycerol or just dag so this is a d AAL glycerol or we call it a dag who's breaking down this dag and releasing a free fatty acid hormone sensitive lipase when he's phosphorated by protein kisee a then what are we going to have left over so again this was the first step this was the first step which was acted on by adapost triglyceride lipase and then

he released a free fatty acid in the second step going to this next enzyme because we have one more enzyme left in the second step what did we do we released a another free fratty acid which was accomplished by hormone sensitive lipase we have one last enzyme left what do you think he's going to do guys what do we have left we have this glycerol and one fatty acid so now what is this guy going to do he's going to see this last Point here he's like that Ester Bond look good I'm going to come

in there and break that Ester Bond so he comes in breaks that Ester Bond when he breaks that Ester Bond he's going to release two molecules out of this so what are the molecules that are going to be released from the product of this reaction so look at this this would be the third step from the third step this enzyme and we'll mention him in just a second is going to release what it's going to release the third free fatty acid this was the third one and what else is going to come out as a

product glycerol and you're also going to release out of this glycerol this is accomplished in that third step so now what is this enzyme who's doing this it's not even that bad it's called monoglyceride lipase not that bad right because this is a monoglyceride this is a dial glycerol this is a trial glycerol or a triglyceride diglyceride monoglyceride it's that simple or we can call it mono AAL glycerol so this is a mono AAL glycerol lip or a monoglyceride lipase they're synonymous okay let's recap on what happened in this again when is the mobilization of

fats going to be occurring it's going to be occurring in the fasting State and the fasting state is when we haven't eaten in a while right so we're not taking in food we're not ingesting food so our blood glucose levels are going to be low our body needs to have glucose supplying our muscles our brain and vital tissues in order for them to operate and function and produce ATP in order for that to happen our body has these pets of langeron was specifically the pancreatic alpha cells that are releasing glucagon and sometimes in stressful situations

whether more specifically acute stress our sympathetic nervous system can get activated and what will it do it'll activate the Adrenal medulla to release 80% of epinephrine and 20% norepinephrine and these molecules will come to the A and like I said in very very chronic stress or in certain situations like severe hypoglycemia the Zona facula can also release cortisol and our anti pituitary can relow growth hormone and our thyroid gland is also able to produce thyroid hormone that can also facilitate these functions too but like I said we're only focusing on these three but do recognize

that there is other hormones what are these hormones doing they're binding onto a g protein coupled receptor of the adapost tissue when they do that they activate eventually throughout all this second messenger system protein kyes a protein KY a phosphates what molecule Peril lippin Peril lipins are kind of surrounding this whole triglyceride right but they're bound to a CGI protein whenever this Peril lippin is phosphorated by protein kyes a the CGI molecule disassociates when he disassociates he comes over here and binds onto adapost triglyceride lipase when this atopos triglyceride lipas is activated he'll make the

first cut on this triglyceride or Tri AOG glycerol when he does that he'll break this Ester Bond and release a free fatty acid that's the first one then what are we left with after this trial glycerol we're left with a dial glycerol two fatty acids in this glycerol there's also going to be phosphorilation of this enzyme the hormone sensitive lipase the hormone sensitive lipase will then cut the DI glycerol and release a second free fatty acid what's left over I should denote what this one is called this one is called a mono AAL glycerol okay

or monoglyceride and what happens here here this monoglyceride lice we should show that he's also getting phosphorated so you know he's also getting phosphorated and when he gets phosphorated he becomes stimulated and when he is therefore stimulated he breaks the monoglycerol at the esteron and releases two things the third free fatty acid and a glycerol and that glycerol and free fatty acids are going to go where that's what we're going to lead into next but we're not going to finish here we're going to do that in another video where we talk about how they're being

oxidized but specifically those free fatty acids they're going to get pushed out here so let's say I draw here free fatty acids and this is representing how many of them so far three and then what else will we have we'll also have glycerol these molecules are going to get pushed in the blood now glycerol is slightly soluble right he's kind of a water soluble molecule because he has he has some nice um alcohol groups on him whereas free fatty acids are not very soluble at all so we can't just transport these in the blood on

their own so glycerol can be transported in the blood kind of on his own a little bit of it might be bound to transport proteins but not very much this free fatty acids though they have to be B to a transport protein so sitting over here waiting for those free fatty acids is a special molecule this molecule is is waiting and he's circulating throughout our blood plasma he accounts for about 60% of our plasma proteins inside of the blood this molecule is called albumin and albumin will bind these free fatty acids and then what will

he do with them he'll take these free fatty acids to different tissues in the body like where he could take these free fatty acids to the muscles he could take it to the heart muscle so this could be skeletal muscles could be heart muscle or he could even take it into the liver or other tissues that are going to oxidize it for what you making ATP and we'll talk about all of this process now the next question is what about that glycerol we didn't talk about that glycerol this glycerol is going to be special because

the glycerol can actually be taken up by muscle cells too or different types of tissues and utilize for energy but there's also something special about this one I'm going to show it in a different color it can actually be taken up by the liver and through a process called glucon neogenesis I can convert that glycerol into glucose and again what is this process here called gluco neo genesis okay okay and so again this could be glycerol so glycerol can be utilized for energy because you can get funneled into dihydroxy acetone phosphate and we'll see that

in a second but specifically one of the special things about this if our blood glucose levels are low we're going to want to be able to raise those blood glucose levels so how does our body do that it can take this glycerol and do what take it into the liver or even your kidneys proximal convoluted tubular cells and convert that into glucose if we get if we make more glucose what was the original stimulus what was the problem our blood glucose levels were low if we could take this glucose and contribute it into the bloodstream

what will happen to our glucose levels they'll eventually come back up so that's one way but also another thing is the whole reason this is happening is because our body needs energy when you're in the fasting State you don't have a lot of glucose so you don't have a lot of fuel sources and so what your body's going to do is is whenever your blood glucose levels are low maybe you're not actually taking in carbohydrates maybe you're on a keto ketogenic diet whatever it might be your body needs to energy wherever it possibly can and

so what it's going to do whenever your blood glucose levels are low if it doesn't have that glucose as a source of fuel it's going to start breaking down fat tissue to utilize that for energy because fat is actually going to produce more energy than carbohydrates you know carbohydrates only produce about four kilo calories per gram whereas fats is almost nine kilo calories per gram so these produce they're very very concentrated sources of energy and we'll see that why we'll see why but the whole point here was that was the blood glucose levels were low

we can do two things with breaking down these fatty acids and this glycerol one thing is that if you don't have those carbohydrates in your diet whether because you're fasting or you're having you have diabetes or you're on a ketogenic diet whatever it is your body is going to use these free fatty acids to produce ATP because your body needs energy to function the second thing is is that we can take a small amount of this glycerol into the liver or the kidneys proximal convoluted tubular cells and make glucose via gluconeogenesis to increase the blood

glucose levels all right Engineers that prettyy much covers everything in this video for the mobilization of fats in the next video we're going to see exactly how these free fatty acids are getting broken down to produce ATP all right Engineers I hope you guys enjoyed this video hope you liked it if you did hit that like button subscribe put a comment down that comment section all right Engineers until next time