Lecture 7 - Nutrition and Metabolism

hello everybody dr mike here in this video we're going to take a look at an introduction and overview of nutrition and metabolism now the first thing i think we should talk about is what we require for survival three major things oxygen water and nutrients now without oxygen we can only survive a few minutes without water we can only survive a few days and without nutrients depending on the nutritional status of the individual we will not survive likely more than 90 days without nutrients so this then brings us to what we define as a nutrient so let's write down a definition of what a nutrient is and what you'll find is that a nutrient is going to be a substance or a chemically defined component of food that we require for survival growth and reproduction this is a nutrient and there's many subcategories of nutrients we've got macro micro and essential nutrients and we'll go through all of those the first thing is what do we do generally with these nutrients well we can take a nutrient and we can bring it into a cell for example and in the cell we can use it to produce atp for survival or we can take nutrients that are stored in cells and we can use them to build this is just a very general overview of what we can do with nutrients now if we were to look at the main categories of nutrients what you're going to find is they will be made up of carbohydrates including fiber fats proteins minerals and vitamins when we take a look at carbohydrates first carbohydrates are one of our main energy sources carbohydrates and fats are our two main energy sources really important i say energy source i mean we use it to produce atp and we know that we can take glucose which is going to be a breakdown product of carbohydrates undergo glycolysis undergo the krebs cycle throw some components of the electron transport chain and produce a whole bunch of atp or energy now you've probably heard nutritionally of something called gi glycemic index not gastrointestinal but glycemic index glycemic index that's gi probably see this on food packets for example now the glycemic index is a measure it's a system of ranking basically of identifying carbohydrates in foods and when they're digested and absorbed how they can change our blood glucose levels that's what glycemic index is referring to so for example because it's a ranking or a scale it's zero to a hundred okay so what that means is if somebody if you have a gi ranking for example of zero to 55 that's a low gi ranking if you've got 56 to 69 that's going to be a medium or moderate gi and anything above 69 so 69 to 100 is going to be a high gi food product and like i said what it basically means is this if you ingest some food and it's a carbohydrate-containing food if you digest it and absorb it quickly it's going to quickly increase blood glucose levels that's going to be high gi if it's broken down or digested slowly and absorbed more slowly then it's going to be a low gi and this is referring to its ability to change the blood glucose levels and therefore alter the effects of insulin release which is important for diabetics for example so that's glycemic index and so that's one of the main reasons why we use carbohydrates fiber within carbohydrates so carbohydrates that we cannot digest so indigestible indigestible carbohydrates which include things like cellulose for example we don't ingest for its energy we actually ingest it because it bulks up our stool and it helps promote gut motility and it can help feed the microflora inside of our gut as well so for carbohydrates main energy source and as fiber to bulk up our stool and help feed that microflora within our gut what about fats well like i said fat is another main energy source but in addition to that we use fat for insulation we know that we can store a lot of our fat in adipose tissue fatty tissue it surrounds organs for example and that allows for structural support and protection and anchorage and insulation to maintain heat but in addition to that fat comprises of the membranes of our cells so really important for cell membranes now if we like we could include cholesterol here under fats and cholesterol is also important for cell membrane integrity but for steroids as well steroid synthesis what about proteins all right so proteins are important not so much as an energy source it can be used as a backup energy source because proteins can be breaking down to amino acids and they can be fed into those glycolytic pathways and krebs cycle as well but predominantly we use proteins for cell structure and function we know that right because for example muscle is made up predominantly of proteins enzymes provide function within the body now what about minerals many different types of minerals for example we can have just minerals generally which can often turn into ions within the body things such as sodium magnesium potassium chloride calcium and so forth but there's also trace minerals and these trace minerals are also called trace metals and this can include things like zinc for example iron fluoride they are trace minerals because they are required in such small amounts and then last but not least vitamins now with vitamins you can have water-soluble vitamins and fat-soluble vitamins i'll go through them in a sec but let's just write them down water soluble which means it's not stored in the body and fat soluble which means it is stored in the body because the cells of our body are made up of fats so we can bring them into the cells and store them now i want to talk about what we call essential nutrients because some of these we can produce and make us and synthesize ourselves some of these we cannot they're the essential nutrients we require them from our diet in order for us to survive so you can have essential fatty acids you can have essential amino acids and vitamins and minerals are also essential obviously because we can't synthesize them ourselves so let's focus on the essential nutrients now and first focus on our essential amino acids now the essential amino acids again we can produce amino acids or synthesize amino acids in our body some we can't we must get from our diet so let's write this up essential amino acids now there are nine for an adult or 10 if you are a child or young adult so look at these essential amino acids first one i want to talk about is phenylalanine phenylalanine now this is important because phenylalanine well tyrosine can be produced from phenylalanine and we need tyrosine for the production of certain neurotransmitters like noradrenaline and dopamine for example so phenylalanine valine leucine isoleucine threonine methionine lysine histidine and tryptophan these are the nine i hope that's nine one two three four five six seven eight nine these are the nine essential amino acids we must get them in our diet if we don't we cannot make them ourselves so they're the essential amino acids what about the essential fatty acids let's write these down here the essential fatty acids and again so you can make other amino acids from these amino acids in the same way that these essential fatty acids we can make other fatty acids from these now the two essential amino are fatty acids you need to know a linoleic acid and alpha linolenic acid and again other fatty acids can be made from these all right now i want to talk about the vitamins let's talk about the water soluble vitamins and the fat soluble vitamins what they are quick run through because again we can't make them ourselves we need to sin we need to ingest them from our diet or from supplements if we can't get it from our diet all right let's have a look at our vitamins when we look at vitamins let's do water soluble first now again with water soluble you ingest them and you use them firstly what are vitamins i should probably define that a vitamin we need in small quantities we can't synthesize them ourselves which i've already stated before because it's essential small quantities and usually are coenzymes so they help support enzymatic processes they help metabolism for example they help really important biological processes all right water soluble all right when we look at our water-soluble vitamins it's obviously going to be vitamin c really important but the b vitamins as well so vitamin b1 which is known as thiamine b2 which is known as riboflavin b3 which is niacin b5 which is pantothenic acid b6 which is peroxidine b7 which is biotin b10 which is sorry b7 is folic acid sorry about that folic acid b10 that's biotin and b12 the cabela means all right there are water-soluble vitamins you can ingest them and you'll pee them out if you don't utilize them you can overdose in them too so don't forget now if we're looking at our fat soluble vitamins for our fat soluble we can store these easier to overdose too because we can store them so don't forget so when we look at our fat soluble vitamins we've got vitamin d e k and a okay so vitamin d that's the calciferols vitamin e is the tocophenols vitamin k is vitamin k and vitamin a is the carotenoids or retinoids and these are our fat soluble vitamins now when we look at our minerals the trace minerals okay i've spoken about other minerals like sodium potassium chloride calcium and so forth the trace minerals that includes iron that includes zinc that includes fluoride for example but there's 15 of them and i'm not going to go through all of those now the last thing i want to talk about is calories and kilojoules for example so when we look at being able to utilize energy because we need to take energy from food right without the energy within food we're going to not survive so we need a way of being able to measure energy within food and this is where calories came from the term calories so calories refer to the ability of increasing the temperature well basically it's how much energy or heat is required to heat one gram of water by one degree celsius is the energy or heat required to heat one gram of water by one degree celsius you're probably sitting there going how is that even relevant what does that even mean basically a guy called atwood would take food he'd put that food into a container that had water he'd run electricity through that container until the food was fully burned when that food was fully burned he measured the temperature change in the water and that therefore was the calories how many calories that food contained it's just a way of measuring how much energy was contained within that food stuff now in australia we've moved on from using calories people still use it but we've moved on from using calories and we start referring to kilojoules so this is because obviously in australia we use the metric system right meters kilometers for example kilo and what's the difference here so one calorie for example is equivalent to 4.2 kilojoules all right and one kilojoule is equivalent to 0.2 calories so this is just again it's just another measure of the energy contained in food itself all right so i think that's a quick run-through introduction of metabolism and nutrition hi everybody dr mike here in this video i want to take a look at vitamin d so remember vitamin d is one of the four fat soluble vitamins d e k and a and a vitamin is a nutrient that we require in very small amounts that we cannot produce ourself but we need it for normal growth and development vitamin d being a fat soluble vitamin what that means is it can be stored within our body because the cells of our body are surrounded by fatty layers and it allows for the movement of this vitamin into those cells easily and therefore easy to be stored water-soluble vitamins however they often get excreted from the body quite quickly that's one of the major differences so when we look at vitamin d first thing you need to be aware of is that the main way that we get vitamin d is through uv exposure or our exposure to sunlight so this is going to be the first step in the synthesis of a precursor vitamin d to an active vitamin d we can get some from the food that we eat from animal and plant products but it's quite minimal but i'll get there in a second so our exposure to uv light is going to trigger the conversion of a cholesterol that's present in our skin in our epidermis called seven dehydrocholesterol what the uv light does is it turns seven dehydrated cholesterol into something called cholecalciferol so cholecalciferol will now be floating around in our bloodstream now when it's floating around in our bloodstream it's ultimately going to get to our liver and in our liver cholecalciferol which is also known as vitamin d3 still not active yet it's inactive once it gets to the liver it comes across an enzyme now this enzyme is called 25 hydroxylase and what it does is it gives a hydrogen to the 25th carbon of this colic calciferol molecule this cholesterol molecule and it turns chole calciferal into something called 25 hydroxy coli kelsey ferrell 25 hydroxycolic calcifera which is also known as calcifediol now interestingly when we ingest vitamin d so for example if we ingest it from animal products what we usually get it from is fish predominantly and liver this comes in the form of cholecalciferol or vitamin d3 and therefore it's just going to enter the bloodstream and go via this particular pathway in the liver if we ingest it through plant products one of the main ways is uv activated mushrooms we actually get ergo calciferol not coli calciferol ergo calciferol and this is actually vitamin d2 and this will travel to the liver and undergo this hydroxylation through 25 hydroxylase and then go via this calcifedial which means once this is produced it then moves to the kidneys so we've got calcifer deal also known as 25 hydroxycholic calciferol traveling to the kidneys it comes across another enzyme in the kidneys which is called one alpha hydroxylase and what one alpha hydroxylase does is it gives a hydrogen to the first carbon of this calcifidel so now we have a molecule which is 1 25 hydroxy coli kelsey ferrell which is a mouthful but it's also known as calcitriol now what we have is an active form of vitamin d important point these enzymes here really important because you're always going to go through this process and turn into kelsey fidel this 25 hydroxy coli calciferol we're always going to go to this point when you're exposed to sunlight but that means this enzyme is always going to be activated in the liver but this enzyme in the kidneys specifically it's produced by what's called the proximal convoluted tubule cells this one alpha hydroxylase that needs to be stimulated to be active right so what that means is when you get a blood test for vitamin d you are not actually testing often you're not testing kelsey triol or 125 hydroxy kelsey ferrell you're actually calcified hydroxycoli calciferol that's the one you're actually getting tested for because you're always going to be producing that at all times so that's a good indicator of your baseline vitamin d at least precursor if you've got a problem with calcium which i'm going to talk about in a sec then they may test this one down the track so this gets activated now the question is what activates this well we'll get there in a second because we need to now talk about what does the active form of vitamin d calcitriol do that will tell us here what it needs to do is it needs to increase calcium in the blood it needs to increase phosphate in the blood two really important points how does it do this well it's stimulated if calcium and phosphate levels are too low and that means the thing that stimulates one alpha hydroxylase is going to be low calcium low phosphate now think about like this what happens is low phosphate that's going to directly stimulate this enzyme to activate all right what indirectly stimulates this is calcium low calcium so when calcium levels are low it actually travels to the parathyroid gland so you've got your trachea and you've got your thyroid that hugs the front of your trachea behind your thyroid you've got the parathyroid gland so i'm going to draw the back of your trick here so here's the trachea there's the rings of your tricky this is at the back the parathyroid glands are these glands that are embedded in the larger thyroid gland and what the parathyroid gland does is it produces parathyroid hormone pth so low calcium triggered parathyroid hormone to be released and parathyroid hormone is going to trigger one alpha hydroxylase so that means we've now got active vitamin d it's whole job is to increase calcium because the stimulus was a drop increased phosphate its stimulus was a drop how does it do it it does it like this it increases absorption of both calcium and phosphate at the gastrointestinal tract it increases reabsorption of calcium and phosphate at the kidneys so throws it back from the tubes of the kidneys back into the blood really important increased absorption and also increases osteoclast activity osteo means bone class means to crush it breaks bone down to release calcium and phosphate into the bloodstream now you may be thinking wait a minute if this is breaking bone down and releasing calcium and phosphate into the bloodstream don't we need vitamin d for strong bones this seems like the opposite of what we want all right important point if we have vitamin d both calcium and phosphate will be released into the bloodstream calcium and phosphate love to be together they're partners for life they love to be together and when they're together they precipitate or mineralize into the bone so you're going to absorb it in the git it's going to be in the blood you're going to reabsorb it from the kidneys it's going to be in the blood sun's going to be taken out of the bone it's going to be in the blood it gets together and then goes back into the bone deposits into the bone strengthens the bone that's what we want now important point if we have no vitamin d and we only have parathyroid hormone something interesting happens calcium increases in the blood but phosphate gets peed out that means this connection this bond of the two is not present and bones actually get broken down so without vitamin d and only parathyroid hormone bones will start to become brittle all right now i want to talk about deficiencies what happens if we don't have enough what happens if we have too much all right let's have a look deficiencies are important let me tell you why firstly because 50 percent of the world's population is deficient in vitamin d and that's because of their lack of exposure to sunlight the color of your skin actually changes how much vitamin d you produce if you have lighter skin you'll produce five times more vitamin d than somebody with darker skin and this has to do with where the individual is in the world and they're exposed to that sunlight so let's first talk about deficiencies so a deficiency what can cause it well lack of sunlight obviously lack of uv light it can be caused if you've got a problem with fat absorption why what does this mean vitamin d is a fat soluble vitamin it needs fat in order to be absorbed from the intestines into the lymphatic system then to go from the lymphatic system into the bloodstream and into the tissues of the body if you've got a problem with fat absorption so what could that be an issue with your bile for example or maybe it's a problem with your intestinal tract it doesn't lay to absorb fats this can have a problem and lead to diminished vitamin d and maybe you're not getting enough vitamin d from the diet now the main issue here with the deficiency is going to be the exposure to uv light so the question then is how much vitamin d should we be having so somebody under one year of age around about 400 international units 600 international units if you're between 1 to 70 years and 800 international units if you're above 70 years of age so what happens if you don't have enough vitamin d well you can have something called rickets if you're a child or you can have something called osteomalacia if you're an adult it's basically the same thing right both are vitamin d deficiencies that result in issues with bone now here's the thing if it happens in a child their bone has not matured yet so there's a lot of collagen and not a lot of the hard stuff the solidified mineralized bone tissue from the calcium of phosphate so if somebody doesn't have enough vitamin d and the calcium of phosphate is leaving it's still collagenous so it's bendy so somebody with rickets gets bendy bones because they're a child and the bone hasn't matured somebody with osteomalacia this is an adult so ricketts happens in children osteomalacia as an adult the bone has mineralized and has hardened so what's now happening is you're pulling calcium and phosphate out of already hardened bones so it doesn't become bendy it just becomes brittle and this is what happens in osteomalacia brittle bones all right so the best way to get vitamin d especially if one of these disorders is through supplementation obviously uv exposure but supplementation as well now what this also means is anytime you're exposed or start to ingest supplements you have the risk of overdosing overdosing vitamin d very bad very toxic it's one of the worst types of toxicities you can get from having too much vitamins so let's have a look at what happens when you have too much vitamin d so overexposure now you're not going to get over exposure vitamin d from sunlight you will get overexposed your vitamin d from supplementation so what happens is this you get stones bones abdominal moans and psychic groans this is an old-school way of remembering what happens if you have too much vitamin d stones bones abdominal moans and psychic groins let's have a look so stones increased amount of calcium increases the likelihood of calcium-based kidney stones they're the stones bones we spoke about osteomalacia right if you're an adult which i assume this is going to be abdominal moans calcium remember you're going to have too much calcium floating through the bloodstream this is the problem with an over amount of overabundance of vitamin d abdominal moans calcium we need to tell muscle to contract so it contracts the smooth muscle of the abdomen contracts the smooth muscle and anytime you have abdominal pain it's because the muscle is contracting over something so contraction and psychic groans now what's this referring to too much calcium blocks your neurons ability to fire properly so you get a depression of the nervous system now not depression in the classical sense but just a depression in the firing of the nervous system so nervous depression leading to the psychic groans so what we've had to look at here is vitamin d how it's synthesized what happens if you don't have enough or if you have too much hi everybody dr mike here in this video we're going to go through three of the four fat soluble vitamins vitamin a k and e i've already recorded a video on vitamin d which i suggest you watch let's take a look so let's first start with vitamin a vitamin a which is the retinoids now when we look at vitamin a we can take vitamin a in through plant material or animal material and predominantly it comes as retinol retinol and retinoic acid now interestingly in the body retinol can turn into retinal retinal can turn into retinoic acid and retinol can reversibly turn into retinol but once it is retinoic acid it stays as retinoic acid we'll talk more about that in a sec like i said we can get vitamin a from our food stuff so we can get it from plant material for example in plant material beta carotene is a good example of it and beta carotene is just two retinols glued together animal products that we can get it in include things like liver and kidneys for example and it can come as retinol retinal or retinoic acid but it's a sterified with a long chain fatty acid which is important because we need to play around with its esterifications of long chain fatty acid either pull it off or put it back on depending on what we want to do with the retinal so vitamin a because it's fat soluble it can be stored and when we store it we usually store it esterified with long chain fatty acid which is palmitate as the long chain fatty acid okay what does retinol do in the body so you've probably heard of retinol being really important when we look at the functions really important for night vision that's true specifically what we're referring to is low or dim light its ability to respond to lower dim light and allow for you to be able to see something it's also really important for maturation and development so early on it's important for maintaining healthy skin and mucosa so mucous lining and it's important for reproductive health so for example for males it's important for sperm production and for females maintaining a healthy placenta so that means it's important throughout one's pregnancy all right let's talk about how all this happens let's first start off in a cell of the eye so let's just say this is a cell of the eye what is going to happen is we'll take in retinol it will get turned into retinal specifically it gets turned into 11 cis retinal and what 11 cyst retinal does is it's like gollum off lord of the rings trying to find its ring it really wants the ring and once it gets it it doesn't want to let go of it but it's really paranoid of somebody stealing it so it's very anxious it's always looking around now the ring in this case is going to be something called opsin so i like to think of the o as the ring opsin binding to this 11 cyst retinal and actually produces something called rhodopsin now rhodopsin is golem with the ring it's having a look it's waiting around seeing what's happening if a little bit of light comes into the eye it stimulates it scares it it throws the ring away it removes the ops and it throws it away and when it gets scared it stimulates the optic nerve to send a signal to the brain now this is happening at low light we need rhodopsin to see at night time in low light it's all because of vitamin a if we have no vitamin a in our diet we have no night vision really important in actual fact if we have no vitamin a for long periods we can ultimately go blind and sadly half a million children around the world half a million children around the world are blind because of vitamin a deficiency luckily we've begun to fortify foods with vitamins like vitamin a so golden rice vitamin a fortified rice to try and prevent because it's all preventative prevent this blindness that's occurring now too much or too little can be damaging too little can obviously result in reproductive issues sterility for example and blindness damage to the skin because we know that obviously when we look at vitamin a it's really important for maintaining healthy skin and so one of the treatment options for acne is retinoic acid right all right importantly a pregnant woman they don't want their vitamin a levels too low or too high both can be a threat to the pregnancy which is extremely important all right the next thing is talking about what's happening so this is just happening at the eye how do we do all these other functions well let's just take another cell of the body for example and we know that in the cell of the body we have a nucleus and in that nucleus we have dna which needs to be transcribed and then translated into proteins so again what happens is retinol enters the cell turns into retinal turns into retinoic acid retinoic acid enters i'll just write it as ra and it promotes transcription of the dna into an mrna that mrna transcribes itself translates i should say into proteins and it's these proteins depending on what tissue is doing this role it's these proteins that may play a role in maturation development they may play a role in maintaining healthy skin and mucosa they may play a role in protecting and enforcing the placenta and also that for sperm maturation so this is how vitamin a works let's now take a look at vitamin k vitamin k is really important when it comes to coagulation so if you cut yourself the thing that stops you from bleeding all over the place is we have platelets which plug up the area very quickly and then we have coagulation factors which are proteins that are expressed and they stick to those platelets to form this nice mesh work that stop any further bleeding and also promote regeneration of the damaged tissue vitamin k is extremely important in this process so vitamin k is important for coagulation now this is what happens again there is the dna within our cells and we can transcribe that into mrna and this mrna is going to be an mrna for a coagulation factor now there's heaps right coagulation factor 4 5 9 there's a whole bunch of coagulation factors that then gets translated into a protein the here are amino acids and we know that proteins have side chains for example so there's a side chain so this is a coagulation factor protein that's been expressed it's been translated here it is there's the side chain something needs to happen to it what needs to happen to this protein is it needs to be carboxylated carboxylated let's write that down simply we've got to add carbon dioxides to it now if we add carbon dioxides to it we're adding carbon dioxides to that side chain and what we end up getting something that looks like that and something that looks like that firstly how does this happen vitamin k vitamin k comes along and it promotes this carboxylation that's what vitamin k does it promotes carboxylation helps add those two carbon dioxides you're probably thinking who cares all right now that they're added there and you can see they're negative they can now bind to platelets to help mesh up right create a mesh work around the the damaged area and promote regeneration this is how it works you've got damaged site there's a cut all right to stop you from bleeding luckily our platelets have come along and they've plugged up the area there's our platelets when they do this they become negatively charged so there's a negative charge associated with them all right then we've got this i'm going to draw this more simply like this like that like that like that that is a coagulation factor we have these coagulation factors here now but the thing is they're negatively negatively charged as well they can't bind negative and negative can't bind together we need something that facilitates this binding calcium calcium comes along calcium has two positive charges associated with it it binds to the platelets it binds to the coagulation factors and brings them all in calcium so calcium is allowing for this clotting to occur but vitamin k allowed for the activation of coagulation factors do we still make coagulation factors without vitamin k yes you can see that they just don't become carboxylated and they don't promote clotting this is important here because if you donate your blood to a blood bank they give a collating agent something that binds to calcium and stops it from doing this to stop your blood clotting in the bag all right all right so that's vitamin k last one we need to look at is vitamin e now vitamin e is an antioxidant also known as tocopherol vitamin a also known as alpha tocopherol and what you'll find is that it is a potent antioxidant now it's a potent antioxidant for peroxyl free radicals so now we need to talk about what is an antioxidant what is a proxy of free radicals okay antioxidant it goes against oxidants things that oxidize so things that oxidize like to pull electrons off things loss loss of electrons is oxidation leo loss of electrons is oxidation so an oxidant pulls electrons off things we don't want to pull electrons off things we've got cell membranes that are remember you've got a cell cell membranes filled with fatty acids fatty acids have negative charges associated with them so what's going to happen is these free radicals love to come along and steal electrons it makes the membrane unstable we don't want this this is damaging so we need antioxidants to stop it vitamin e does this now peroxidation is when this happens to specifically fatty acids perfect and so what happens is if a peroxil which may look like that comes along tries to steal an electron it damages the fatty acid it then is missing electron it wants to go find the electron itself and it results in this chain reaction of issues of free radicals being produced and so forth we need to stop it so vitamin e actually sits in the membranes of cells and when peroxial free radicals come along it comes out and binds to it and stops it from doing this but now the vitamin e is bound up with a free radical and is unable to do its job it needs to be freed itself in order to do this vitamin c comes along which will be the focus of another lecture and freeze that vitamin e and neutralizes the free radical perfect that's what vitamin e does now how do we get vitamin e vitamin e is really abundant in nuts for example and it's highly abundant in seeds for example but also liver liver is going to be a good source of many vitamins probably too much vitamins in all honesty so this is vitamin e it's really difficult to od it's really difficult to be deficient because it's stored but it can happen so here is a quick run through of the fat soluble vitamins excluding vitamin d hi everybody dr mike here it's time to talk metabolism so you know the three major macronutrients proteins fats carbohydrates what happens when you ingest them let's have a look so you take in a burger take a bite you chew it up you break it down you get those proteins fats and carbs in your stomach which then further digested once they get into your intestines so now we have proteins we've got fats being triglycerides we have carbs being sugars here now your intestines are going to further break these components down into their micronutrients so that means proteins will break down into amino acids sugars will break down predominantly into glucose and triglycerides will break down into glycerol and fatty acids from the intestines they will then get absorbed into what's called the portal vein the portal vein is a blood system that takes all these nutrients from the intestines directly to the liver for processing okay now what you can find is that the amino acids glucose glycerol and fatty acids all get taken via the portal vein to the liver so this is the liver cell here but triglycerides as glycerol and fatty acids actually get absorbed into the lymphatic system now the lymphatic system will then send glycerol and fatty acids as triglycerides into the systemic circulation this is the bloodstream that actually goes to the entire body so that means unlike proteins and carbs fats will actually be delivered to the entire body prior before them go into the liver not all of them but a lot of them okay now let's just say the amino acids have now been absorbed or taken from the portal vein into the liver glucose into liver glycerol and fatty acids into the liver what happens well if we've just eaten a meal the idea is that the body wants to store these products so we can store amino acids as proteins we can store glucose or something called glycogen remember if you read a biological term and it ends in ogen it means stored and inactive and it can store glycerol and fatty acids as triglycerides or fat all right easy now what if we want to use these substances well mainly we want to do it to produce energy energy being atp how does this work well okay let's first look at glucose because this is our primary energy source in the body glucose will be turned into something called pyruvate pyruvate will jump into the mitochondria and turn into something called acetyl-coa acetyl-coa goes through this cycle called the krebs cycle or the citric acid cycle and as it goes through this cycle and turns into a number of products it releases carbon dioxide as a waste product but also releases atp bang we've created some energy we also create a small amount of atp when we turn glucose into pyruvate but not too much now as we turn this acetyl coa into energy it releases some hydrogen now hydrogen remember hydrogen helium lithium beryllium of the periodic table hydrogen will travel to the membrane of the mitochondria remember the mitochondria being the powerhouse why because of this whole process here the hydrogen jumps into the membrane where it starts talking with a number of proteins embedded in the membrane now with oxygen so you need hydrogen and oxygen coming together with these transmembrane proteins and it produces atp this is called oxidative phosphorylation this is the electron transport chain okay so with this process here we create huge amounts of atp around about 30 to 30 to 32 to 36 atp molecules okay what if we don't have any oxygen for example so if we're going for a jog this process is fine but let's just say we're doing a 100 meter sprint okay where we need more atp than oxygen we can get in that means this process is going crazy producing all these hydrogen but we don't have enough oxygen oxygen is the rate limiting step here so this starts to backlog so what ends up happening is that the pyruvate turns into something called lactic acid lactic acid doesn't need oxygen to be produced and lactic acid can form atp that's why after intensive bouts of usually anaerobic exercise not requiring oxygen you get that lactic acid all right okay what else can happen well the triglycerides that are broken up into glycerol and fatty acids glycerol can jump into this glucose chain here at the level of pyruvate this is perfect fatty acids can jump into this glucose metabolism down at acetyl coa important point is that once it hits pyruvate it can turn back into glucose if need be but once it's gone past pyruvate into acetyl coa it cannot go backwards now this is important because if we don't have any glucose in the system we start to break down triglycerides for energy the glycerol jumps in here the level of pyruvate wonderful fatty acids jump in here level of acetylchola wonderful we start producing atp but what happens is because we don't have any glucose we want to replenish those stores and oxaloacetate here jumps back and turns into glucose pyruvate jumps back and turns into glucose but all these fatty acids are coming down at the level of acetyl coa so we start to produce too much acetyl coa so the acetyl-coa starts to back up back up back up and produce something called ketones ketones are the beta-hydroxybutyrate right acetoacetate these are the ketones they can turn into atp perfect okay this is basically the entire system when it comes to metabolism now obviously i've missed out on a couple of processes but this is the metabolic processes of proteins fats and carbohydrates hi everyone dr mike here in this video we're going to take a look at glycogenesis now the word glycogenesis has the prefix glyco which means glycogen and the suffix genesis which means the beginning of so it's the beginning of glycogen what is glycogen it's the stored form of glucose and what is glucose well it's that monosaccharide that simple sugar that we use to create atp and we know from previous videos that one molecule of glucose can produce around about 34 to 36 atp molecules so it's a really efficient way of creating energy now we know that we can take glucose and we can absorb it into the body and it can go into a number of different cell types to use to make energy but in what situations do we want to take glucose and store it in the form of glycogen well these are going to be fed states so just after eating also known as the absorptive state 0 to 4 hours we're going to be taking the glucose we've just ingested and we're going to store it as this glycogen all right so we've got glucose you can see that there's 6 carbon 12 hydrogen 6 oxygen and i'm going to simplify this ring shaped structure of glucose into this structure and you can also see that i've labeled the six carbons that's where the first carbon is second third fourth carbon fifth carbon and six carbon this is going to be important because when we create glycogen all we do is snap together glucose we have to change it a little bit but basically we're snapping them together to create this molecule that we can compactly store within the liver or the muscle or the kidney so here's glucose first step is we need to turn this glucose into something called glucose 6-phosphate and you're probably aware that glucose 6-phosphate is the first step in the glycolytic pathway it's also the first step in creating glycogen how do we do it we take some atp give that glucose one of those phosphates we now have adp diphosphate adenosine triphosphate to adenosine diphosphate and we snap that atp here now which carbon is that one two three four five six it's on the sixth carbon so it's called glucose six phosphate perfect now what we need to do is take that phosphate and put it in another position we do this with another enzyme called phosphoglucomutase take it off the sixth position put it on the first position so there's the first position now we've got the phosphate there now the next step is different what we get is something called uridine triphosphate now this uridine is telling you that there's a nucleotide what's a nucleotide remember nucleotides are really important components of dna and we've got nucleotides they can turn into amino acids and proteins we've got the nucleotide uracil here and we've got uridine triphosphate so there's three phosphates as well we take the uridine and one phosphate pop them off connect it to that phosphate so now we've got two phosphates and the uridine so it's uridine diphosphate attached to the first carbon there's the uridine diphosphate and what we're simply left if we take that off is two phosphates okay so the uridine triphosphate just turns into diphosphates okay and now we've got this uridine diphosphate attached to the first carbon of the glucose we can now snap these together to create glycogen and what we do is we take an enzyme called glycogen synthase makes sense snaps things together we take a glycogen a glucose molecule and we pull off the udp and it facilitates the linking together at which carbons at the fourth carbon and the first carbon fourth carbon first carbon fourth carbon first carbon and we put this process on repeat now you can see that at some points you have different branching and you can see that the sixth carbon can also bind to the first carbon and then here we've got fourth and first so what type of binding do we have we've got one to four binding and we've got one to six binding and what we end up getting over time over this period is this very branched molecule that we call glycogen now here's an important point when we store glucose in the form of glycogen this is how animals store glucose so animals store glucose in the form of glycogen plants store glucose in the form of starch and cellulose and they are really really similar to this structure in actual fact what you'll find is that starch is nearly identical it's just not as branched so it's the same bonds what you're going to find with cellulose is it's the same one to four bonds however what you're going to find is that nearly every second glucose is flipped upside down so what that means is this is down here and this bond like this is up like that for every second one and this is important because the enzyme that we use when we are now in a fasting state a post-absorptive state and we need to break this glycogen down back into glucose to use for energy we need to chop these one to four bonds and one to six bonds and we use an enzyme called amylase to do this right so when we have glycogen or starch we can easily chop it up with this amylase but if we're ingesting cellulose certain plant material we don't actually have the enzymes to break these every second bonds where it's flipped upside down and this is the reason why we can't break down grass for example in the form of cellulose but cows can they do have the enzyme that can chop this up so what we now have is an indigestible carbohydrate because glycogen is a carbohydrate just a complex sugar molecule and that ends up becoming fiber so this is the quick process of glycogen hi everybody dr mike here let's talk about the amazing process of gluconeogenesis what's gluconeogenesis well let's break the word up gluco means glucose neo means new genesis means the beginning of let's read it backwards the beginning of new glucose basically this is producing glucose from non-carbohydrate-based sources now you know that there's three macronutrients proteins fats and carbs and we make glucose primarily from carbs so if we were to make glucose from non-carbohydrate-based sources that's basically making it from the proteins and the fats so we've got the fats over here as triglycerides got the proteins over here and we're going to talk about how they can come in to produce glucose now why do we want to produce glucose couple of reasons one the brain's only energy source is that of glucose now you may say to me what about ketones i know ketones can fuel the brain that's true but it's a backup energy source and i'll talk about that very shortly so why do we want to produce glucose well sometimes glucose is low in the body this can happen in fasting states so in what we call the post-absorptive state when we need to increase our blood glucose levels back to that four to six millimoles per liter blood glucose levels that it should be at all right so you already know of glycolysis where we take glucose turn it into pyruvate and that pyruvate then jumps into the mitochondria turns into acetyl coa and then undergoes the krebs cycle to produce a whole bunch of atp also produces carbon dioxide also produces hydrogen which can go to the membrane and undergo electron transport a lot of this happens under aerobic conditions so there's oxygen we also know that under anaerobic conditions pyruvate can turn into lactate right now this is reversible so when the oxygen is back again lactate turns back to pyruvate but what you probably didn't know is that lactate seems to be a normal end product of this glycolysis anyway so we know that lactate is the preferred end product in the liver and in the muscle even at rest in the muscle and significantly more so in active muscle all right so what we're saying now is we have a stimulus in our body and our stimulus is we've got low blood glucose levels this travels to the pancreas the pancreas has certain cells called alpha cells they pick up this change or this drop in blood glucose and they release a hormone called glucagon now it also or the body also releases cortisol and also releases noradrenaline so glucagon cortisol noradrenaline also known as norepinephrine are three stimulators of gluconeogenesis this process we're just about to talk about and again what's the end goal stimulus dropping glucose what's the outcome and increasing glucose that's what we want all right so let's have a look and see what happens so the first thing the first non-carbohydrate based source that we're going to look at that turns into glucose is going to be lactate let's say that our muscles have produced huge amounts of lactate and now we're bringing it into the hepatocyte so the liver cell this lactate jumps in and reversibly turns into pyruvate now we want ultimately to get glucose but pyruvate can't go backwards in actual fact there's 10 steps in this glycolysis pathway to go from glucose to pyruvate and you can see i've only written a couple these are the non-reversible which means all the other steps can go backwards but here they get caught up so specific or special things need to happen in order for that to go to that that to go to that that to go to that we'll talk about it so pyruvate lactates turns to pyruvate pyruvate goes into the mitochondria turns into acetyl coa usually but in this case pyruvate is going to turn into oxaloacetate now oxaloacetate is needed to bind with acetyl coa in order for the krebs cycle to happen produce carbon dioxide produce atp produce hydrogen all right but in this case oxaloacetate needs to turn to glucose and it does it by turning into malate first and then malate leaves the cell now when malate leaves the cell it turns back into oxaloacetate so oxalyl acetate couldn't leave the mitochondria that's what i meant the mitochondria not the cell once it's oxaloacetate oxaloacetate jumps into this cycle here and i'll go through a couple of backward steps going back back back until it gets caught up at fructose 1 6 bisphosphate it can't go backwards to glucose 6-phosphate so we need an enzyme and this enzyme is called fructose 1 6 bis phosphotase and what it does is it can turn that fructose 1 6 bisphosphate to one step back and it's going to keep going back until boom it gets caught up again at glucose 6-phosphate glucose 6-phosphate will travel into the smooth endoplasmic reticulum here in the smooth endoplasmic reticulum it's going to come across an enzyme called glucose 6 phosphate and what it does is it turns glucose 6-phosphate into glucose and what this glucose can now do is it can exit the hepatocyte and what do we get we get an increase in blood glucose levels that's exactly what we wanted so this is just from lactate coming in from the muscle turns the pyruvate turns into well jumps into the mitochondrion turns into oxaloacetate which turns into malate which jumps back out of the mitochondria turns back into oxaloacetate jumps into this glycolytic pathway tries to go backwards but gets caught at fructose 1 6 bisphosphate fructose 1 6 bisphosphatase comes along helps it go backwards keeps going backwards till it gets caught again at glucose 6-phosphate which then jumps into the smooth endoplasmic reticulum hits this enzyme called glucose 6-phosphatase which then turns it to glucose and it can leave the cell that's lactate what happens with fats well we know that triglycerides are made up of glycerol and fatty acids now here we've got a glycerol backbone with three fatty acids that's what a triglyceride is so you relieve one glycerol and you got three fatty acids now glycerol will jump into this process here as well and again the same thing happens as what happened with lactate it goes back all through that this process until we create glucose and it's back out of the system perfect so that means the glycerol from triglycerides will turn into glucose if needed under gluconeogenesis what happens to the fatty acids well the fatty acids they can jump into the mitochondria and they can turn into acetyl coa now acetyl coa cannot turn into glucose but it can turn into something else we'll talk about that in a second what about proteins well we've got these amino acids and amino acids such as alanine and glutamate for example what they can do is they can jump into this pathway at different phases they can jump in here and that's going to go through that same pathway before it can jump here it can jump down here as well so we know that proteins and amino acids can ultimately turn into glucose as well now what happens if somebody's a diabetic well if somebody's a diabetic what can happen is this process of breaking down triglycerides into glycerol and fatty acids occur over and over and over and over and over and over and over again because there's very low levels of glucose and more specifically very low levels of insulin almost absent insulin absent insulin is a trigger to stimulate this breakdown process now the fatty acids are turning into acetyl coa that's been pumped out glycerol is going into this process here right so as pyruvate comes down to turn into acetyl-coa we've got heaps of acetyl-coa being made and in order for that to turn into energy atp needs to bind to oxaloacetate but you know that when glucose is low oxaloacetate leaves the mitochondria to turn into glucose so there's actually not much oxaloacetate for this acetyl-coa to bind to so acetyl-coa just builds up builds up builds up and actually stack on top of each other when they stack on top of each other they produce something called ketones two major types beta-hydroxybutyrate and acetoacetate and what these ketones do is they can leave the hepatocyte they can go to the brain and the brain can turn it into glucose for energy wonderful but what can also happen is when you produce ketones you also produce acid and a individual with type 1 diabetes who is not being managed with insulin so the insulin is zero means they get ketones and acid that's called ketoacidosis that's not very good so what do we have we've got the process of gluconeogenesis what triggered it low glucose what was the outcome high glucose what else was playing a role the hormones glucagon cortisol and noradrenaline and what were the substrates for it lactate amino acids and triglycerides specifically glycerol hi everybody dr mike here in this video i want to take a look at the fed state also known as the absorptive state which is what's happening metabolically after we've eaten a meal so first thing i want to talk about is the fact that the fed state is characterized by high blood glucose levels and subsequently high insulin levels and the whole point of it is to bring the blood glucose levels back down and it tells the body to do a couple of really important things so we've just eaten a meal and that meal is going to contain proteins fats and carbohydrates which are macronutrients they end up getting broken down through our digestive system predominantly in the mouth stomach and first part of the small intestines known as the duodenum into glucose primarily fatty acids glycerol and amino acids now the fatty acids and glycerol which were fats triglycerides actually get absorbed into our lymphatic system so we'll talk about that lastly firstly i want to talk about glucose and then we'll look at amino acids so if we have a look at glucose first of all we've got glucose that's been absorbed from our duodenum or our small intestines into our bloodstream all right now blood glucose levels are going to be high now now if blood glucose levels are high and it's floating through the bloodstream it's ultimately going to go to the pancreas and trigger a certain type of cell in the pancreas known as a beta cell to release insulin and what insulin does is something really important insulin decreases blood glucose levels by telling certain tissues of the body to open up their transport membranes and let glucose in that's first thing second thing is insulin inhibits certain functions or metabolic functions of the body like lipolysis which is the breakdown of fats to produce energy and proteolysis or proteolysis which is the breakdown of proteins ultimately to produce energy it inhibits this the reason why is because insulin is here to primarily promote storage so we've just eaten we want to store all of these micronutrients and maybe use a little bit for energy once it's inside the cell because we want to drop this blood glucose level down so insulin's been released now the certain tissues of the body that are insulin dependent they need insulin to let glucose in these tissues include muscle and fat but tissues like the liver for example in the brain and the kidneys and red blood cells in the intestines they do not require insulin in order to get glucose into their cells their glucose or their insulin independent and that's important because when our blood glucose levels are high in insulin is released our brains are always going to take that glucose in our liver is always going to take that glucose in but our muscle and our fat will not so blood glucose levels have gone up insulin's been released this high glucose level let's look first at what's happening at the liver glucose like i said will always enter the liver and once that glucose is in the liver it can do a couple of things primarily it's going to be stored and glucose is mainly stored in the form of glycogen now remember if in biology you see a word that ends in ogen it means stored and inactive glycogen is the stored form of glucose i like to think about glucose as lego blocks glycogen when you click all those lego blocks together that's how it's stored this is how most of our glucose is stored in the fed state some of this glucose a little bit less than 10 of it may turn through a process of glycolysis going from glucose ultimately into something called pyruvate and pyruvate ultimately into something called acetyl coa acetyl coa enters something called the krebs cycle and in the krebs cycle it spits out some atp so spits out some energy really important another important point here however is the fact that acetyl coa can also produce fatty acids and the process of glycolysis going from glucose to pyruvate if we need to it can produce glycerol and if we bring fatty acids and glycerol together what do we get trisylglycerides so trisy glycerides but we can also get so we can get triglycerides which is the stored form of fat and we can also get very low density lipoproteins very low density lipoproteins have lots of fatty acids and glycerol can travel throughout the body and deliver these substances to the adipose tissue to the muscle tissue two different tissues of the body all right another thing that can happen is that's glucose amino acids that we've got can be absorbed in the liver as well and they can actually just enter the krebs cycle this cycle that produces the atp from acetyl coa all right what happens to glucose at the muscle tissue well remember muscle tissue needs insulin so we've got a right insulin up here because it won't let that glucose in without the insulin but now the insulin is here so let's get that glucose in and similar to what's happening in the liver glucose can be stored as glycogen otherwise that glucose can undergo glycolysis turn into pyruvate go from pyruvate into acetyl-coa and that acetyl-coa can undergo the krebs cycle again and produce some atp the amino acids that are coming in for muscle tissue are predominantly going to be stored as proteins so you've got protein storage at muscle glycogen storage at muscle as well in the liver you're going to have glucose storage's glycogen fat storage as well and amino acids jumping into the acetyl coa system what's happening at adipose tissue well glucose can enter adipose tissue as well it's insulin dependent so we need to put insulin here again like we did for muscle and then once the glucose enters the adipose tissue glucose will not be stored as glycogen what glucose will do is undergo glycolysis pyruvate acetyl coa undergo the krebs cycle and what's going to happen is that it can spit out some atp if need be but we'll also spit out let's go this way glycerol and acetyl-coa again can turn into fatty acids we can store those two as triglycerides but also from the meal that we've eaten the fatty acid so we've eaten that meal the fatty acids and glycerol got absorbed into the lymphatic system not the bloodstream right not the portal vein which most of these do right glucose and amino acids for example but what happens is fatty acids and glycerol into the portal vein get put together into something called a kylo micron fatty acids glycerol into something called micron and that carla micron can deliver fatty acids and glycerol to the adipose tissue which again can be stored as triglycerides okay and so what we've got here is a run through what's happening in the fed state it's all mediated by this insulin and mediated by high nutrient levels predominantly high glucose levels but also high levels of amino acids and high levels of broken down triglycerides in the form of fatty acids and glycerol hi everybody dr mike here in this video i want to talk to you about the post-absorptive or fasting state this is characterized by a decrease in blood glucose levels and how the body responds to increased blood glucose levels now you may be thinking why do we focus on glucose why aren't we focusing on fats and proteins and the answer to that question is because glucose is the most important energy substrate for organs such as our brain for example our brain only wants carbs for energy now if you think about other energy sources like proteins and fats and their derivatives like amino acids fatty acids glycerol they all feed into the processes that can turn into glucose or a glucose substrate for energy so we need to look at glucose itself firstly normal glucose levels so i'm going to write glucose like this normal glucose levels sit between four to six millimoles per liter this is where we want it to sit if it goes too low blood glucose levels dropping too low we need to increase it if it goes too high we need to bring it back down what we're going to talk about today is what happens after extended periods of time of not eating what we call fasting or the post absorptive state this can be between meals so between four to eight hours or it could even be longer for example when we wake up in the morning after not eating for about 10 to 12 hours what's happening in our body to maintain our blood glucose levels between four to six all right so first thing is this i wake up in the morning i'm the i'm a 70 kilogram male i have my liver for example and in my liver we have cells called hepatocytes which do all the metabolic processing and a whole bunch of other things and there's the mitochondria as well which plays a really important role of producing energy from our micronutrient substrates we've got our pancreas which we need to talk about here and we've also got muscle tissue and adipose tissue as well all of these organs and structures are playing a role in maintaining blood glucose levels so i've just woken up as a 70 kilogram male i have around about 80 grams of glycogen stored in my liver now firstly glycogen is the stored form of glucose so glucose being a simple sugar if we don't want to use it to make energy or atp we click it together like lego blocks to produce glycogen and our liver is our primary storage site for glycogen our kidney also stores some glycogen that we can use and i may talk about that in a little bit so i've got about 80 grams of glycogen stored in my liver and i start to break it down again i'm not eating it's been 10 to 12 hours and i haven't eaten a thing this glycogen what can happen is it can break down into something called glucose 6 phosphate and glucose 6-phosphate can reversibly turn into glucose via an enzyme called glucose 6 phosphatase and that turns into glucose glucose can then leave the bloodstream and increase our blood glucose levels but how does this happen how do we take stored glycogen break it down into glucose to be released in the bloodstream this is where the pancreas comes into play because if our blood glucose levels begin to drop the blood supply that feeds the pancreas stimulates a certain type of pancreatic cell called an alpha cell and these alpha cells they produce a hormone called glucagon now what glucagon does is it stimulates this process glucagon can stimulate glycogen so if it ends in ogen remember it means stored in an active that's how you remember glycogen as being the stored and active version of glucose glucagon when the blood glucose levels are low so that's its stimulus it's stimulus is when there's a drop in blood glucose levels glycogen breaks down glucose 6-phosphate glucose 6-phosphatase turns it to glucose it can then be shuttled out of the hepatocyte into the bloodstream and be delivered to the tissues of the body but now think about this now the glucose released into the bloodstream what happens to the blood glucose levels it starts to go up a little bit we don't want to just continually break down that stored glycogen right because our blood glucose levels will go too high so the increase in blood glucose will travel again to the pancreas and this time trigger another cell type called a beta cell and the beta cells produce something called insulin and like i said this is now triggered by an increase in blood glucose what does insulin do in this process insulin again travels to the hepatocyte of the liver and it's a negative regulator glucagon was a positive regulator glucagon stimulated this process insulin inhibited so now that insulin's been released it stops this from happening blood glucose levels start to drop if it drops glucagon stimulates goes too high insulin inhibits can you see that this is maintaining a happy healthy balance this whole process here that we've just spoken about for the breakdown of glycogen into glucose ultimately this is called glycogenolysis glyco genome which basically means glycogen there's glycogen lysis meaning splitting apart or breaking apart this is the breaking part of glycogen into glucose to make energy so this is how we first begin to increase our blood glucose levels however i only have 80 grams of stored glycogen over time if i don't eat i will use eight percent of my stored glycogen from my liver every hour now the kidneys also contribute the kidneys contribute around about 10 percent in this process so don't forget the kidneys don't discount them kidneys contribute 10 of glycogen storage to the utilization to produce glucose in this process but after 10 to 12 hours of doing this and not eating my glycogen stores are gone so how do i maintain blood glucose levels all right this is where another process comes into play which is called gluconeogenesis once i've used up my glycogen the blood glucose levels start to drop again glucagon is stimulated insulin is inhibited it's low glucagon is high and what glucagon can do is it can travel to distant tissues so glucagon now can travel via the bloodstream to the muscle glucagon can travel via the bloodstream to the fat and what it does is it's a positive regulator of two important processes the first process here is proteolysis or proteolysis in muscle what this does is it takes protein and breaks it down into amino acids one really important amino acid in this process which i'll talk about is alanine but there are other amino acids what we call gluconeogenic amino acids that contribute to this so glucagon stimulates this now think about this if insulin is released into the bloodstream doesn't matter how much even if it's a little bit this is significantly inhibited so we need to have low blood glucose levels and low blood insulin levels in order for glucagon to stimulate muscle to break down protein into amino acids and to stimulate fat or lipids or triglycerides to be broken down into fatty acids and glycerol because as we know triglyceride three fatty acids one glycerol so now what we've done is we've used up our glycogen insulin levels are low glycogen levels glucagon levels are high proteolysis has been stimulated amino acids are released like alanine what we've got here i didn't talk about it is called lipolysis i should probably say liposis which is the splitting apart of triglycerides into fatty acids and glycerol have been released and now what happens again what's the whole point increased blood glucose levels so what happens here glycerol can jump into this process and it can reversibly turn into glucose it can jump into this process here now this process which i haven't yet spoken about is called glycolysis glycolysis is taking glucose to produce atp the opposite of what we're talking about here right glucose turning into atp glucose goes to glucose 6-phosphate glucose 6-phosphate turns into pyruvate through a number of steps which i haven't mentioned pyruvate can jump into the mitochondria turn into acetyl coa and through the krebs cycle also known as the citric acid cycle can produce a whole number of products it produces nadh it produces carbon dioxide these products go specifically the nadh go to the electron transport chain to produce a whole bunch of atp for energy but we can hijack this system and make it go backwards to produce glucose to increase blood glucose levels so glycerol can jump into the glycolytic pathway go backwards because that's what's happening ultimately turn into glucose 6-phosphate turn into glucose jump out so glycerol from triglycerides can increase blood glucose levels all right that's the first point alanine what can alanine do alanine let's write it in red it can turn into pyruvate now pyruvate is irreversible it can't go back to glucose 6-phosphate so how do we use alanine to produce glucose if we can't go backwards well pyruvate can turn into oxaloacetate and if pyruvate turns into oxaloacetate oxaloacetate can leave the system ultimately turn into glucose 6-phosphate which is turning into glucose brilliant so through this process amino acids such as alanine not all amino acids but alanine specifically turn into pyruvate pyruvate turns into oxaloacetate leaves the krebs cycle can jump back into this glycolytic pathway but go backwards turn to glucose 6-phosphate and increase blood glucose levels fatty acids fatty acids can jump into the system and turn into acetyl coa now i want you to think about this if this process of proteolysis or proteolysis and lipolysis have been stimulated what will happen is these amino acids that have been utilized diminish the amount of oxaloacetate because they're turning into pyruvate which is turning into oxaloacetate and that's leaving the system now oxaloacetate is a substrate that needs to bind to acetyl coa to produce atp but what's happening here is fatty acids are turning into acetyl acetyl coa so acetyl coa levels are going up oxaloacetate levels are going down because they're leaving to turn into glucose so there's a mismatch oxaloacetate just starts to increase increase increase increase it can't bind to oxaloacetate so what happens when all this acetyl coa increases too much well they turn into ketones and so acetyl coa there's not much room here will turn into ketones and ketones can leave the system to again be utilized as an energy substrate how because it jumps back into this process and it can be used to produce atp ketones all right something else lactate we can use lactate as a substrate in this process and so lactate can come in and turn into pyruvate and again pyruvate oxaloacetate turn into glucose so this process called gluconeogenesis now there's no room to really write it up here but let's put it down here gluconeogenesis gluco neo genesis takes all of these non-carbohydrate-based sources so what were they so it's amino acids like alanine it's fatty acids it's glycerol it's lactate and takes them and utilizes them to produce glucose increase in blood glucose levels insulin like i said is a strong negative regulator of gluconeogenesis and after 10 to 12 hours gluconeogenesis is contributing to 50 of all the glucose that's been released into our bloodstream because like i said every hour eight percent of my glycogen is being utilized until there's hardly any or none left at all so what we're talking about here is gluconeogenesis glycogenolysis to ultimately increase blood glucose now the final point i need to make here is that it's not just glucagon that stimulates this there are other hormones or chemicals that are released in the body that can contribute to increasing blood glucose levels in times of fasting what are these hormones and chemicals noradrenaline adrenaline cortisol growth hormone and thyroid hormones they are also strong strong agonists to promote this process of gluconeogenesis specifically glucagon and adrenaline so adrenaline is the sympathetic nervous system fight or flight right so glucagon and adrenaline they're fast acting they do this immediately but cortisol growth hormone thyroid hormones they're more slow acting they take time and they can have their effects over a longer period so this is a quick run through what happens metabolically to your body in the post-absorptive or fasting state

Channel: Dr Matt & Dr Mike

Views: 17,492

Rating: 4.8829789 out of 5

Keywords: lecture, university, nclex, nursing, medicine, health, biology, nutrition, metabolism, dietetics, diet, introduction, carbohydrates, carbs, fats, proteins, amino, acids, lipids, vitamins, minerals, glycolysis, calorie, kilojoule, catablism, anabolism, gluconeogenesis, glycogenolysis, glycogenesis, fed, fasting, absorptive, post-absorptive, post, state, insulin, storage, food

Id: HLzB3miHWM8

Length: 89min 24sec (5364 seconds)

Published: Thu Aug 20 2020