[Music] welcome back friends welcome to another video lecture from Shomus Biology we've been talking about carbohydrate metabolism and in this video I'm going to talk about Kore i already posted video on Koreycle couple of years earlier but this time with some animated material now the thing about Kore cycle if you want to hear the first question that what is it and why Kodi cycle is important now normally to understand Kore cycle you need to know a simple idea in our body about metabolism and that idea is uh the process of cellular respiration or cellular metabolism both in terms of in presence of oxygen and absence of oxygen so if there is plenty of oxygen in our body our body will undergo the oxygen or aerobic mode of cellular respiration so let me write it in terms of oxygen so if there is oxygen present and let's say oxygen absent so if oxygen is present uh the body under goes the aerobic aerobic aerobic mode of respiration in oxygenic is absent an arerobic mode of respiration so when the oxygen is present through aerobic mode of respiration our body usually take let's say glucose molecules at the beginning and glucose is converted to pyate in glycolysis then this pyrovate is further converted through TCA cycle and then pyroate dehydrogenous complex it will make acetal coa then it enters the TCA cycle and then it will ultimately produce NADH FADH2 at the end of TCA cycle which will be useful for production of ATP which is the energy source of our body this is the aerobic mode of respiration but if you look the anorobic mode of respiration that means when we need energy but we don't have oxygen around and this thing happens if we do intense exercises or let's say somebody is running for a while for long distances what happens is that normally there are two locations in our body which are very much involved with the process of energy production and metabolic processes especially the carbohydrate metabolism and two such tissue one is the liver and second one is our muscles now the thing is while we're doing extensive exercise our muscle cells they're utilizing the glucose they try to make energy out of it but the problem is let's say due to some reasons we are not getting enough oxygen if you're running for a long time or uh put lifting a lot of weight for for a long time what will happen or let's say you are going in a staircases for a long time you're you're climbing something in those situation what happens in the muscle the cells don't get the amount of oxygen it needs they lack oxygen so as a result of lacking oxygen what happens our muscle cells they are not wellfed so the first step of the reaction is well carried out because that process does not need any oxygen to do so they convert glucose into pyrovate without a issue pyrovate is made in the muscle cell so let me think of this whole process that we are looking is in muscle cell okay so glucose is converted to pyrovate but the problem is pyrovate is not being converted to acetyl or cannot be converted tca cycle is prevented because there is no oxygen uh the terminal electro acceptor is the oxygen so there is no terminal electron acceptor so as a result TCSI as a result the electron transport chain will not uh occur so as a result pyrovate is produced in the body and not only pyrovate but as there is no oxygen there is an enzyme start working on pyrovate that is known as lactate dehydrogenase lactate dehydrogenous enzyme converts pyrovate into lactic acid or lactate lactic acid once start to build up in the muscle cell is very very bad for our health because two things one is that we are not producing any energy that is the biggest thing actually because from glucose to pyrovate we have net gain of two ATP molecules two ATP molecules are produced but while the same uh single molecule of glucose undergoing all the process of glycolyis cre cycle and electron transport chain it can give us up to 32 to 38 ATP molecules so you see we are already running at least 30 molecules of ATP lagging in the muscle cells but you are doing exercise so muscle cells will need energy that is the problem that's the physiological problem that we have at that point of time now how to solve this because the muscle cells are filled with lactic acid and this is a dead end we can't do anything about that or is it to solve this our body has a has a secret process another process to bypass the production of lactic acid and not exactly to bypass the production of lactic acid but uh there is liver for rescuing our body once again in the metabolic pathway so now let me draw the liver here let's say this is the liver we have liver and the problem with liver here is that liver can liver has enzyme and liver can convert this lactic acid into pyrovate again convert lactic acid into pyrovate back and then pyrovate into glucose and once it produce glucose it can take the glucose into the bloodstream let's say this is the blood vessel and let's drag glucose into the bloodstream so we know liver can convert lactic acid to pyroate and then pyroate to finally glucose so what we can do here is simply one simple job of taking this lactic acid into the blood and then through the bloodstream taking it into the liver so once we supply the lactic acid which is produced in the muscle to the liver liver converts lactic acid to the pyroate with the help of the same enzyme lactate dehydrogenase but a reverse step and then the sequential stages that converts pyroate into glucose known as gluco neoenesis or neogluccogenesis and if you want to know details about neogluccogenesis and steps of how converting pyrovate into glucose I'll recommend you to watch my video on neoglyucenesis in the same series you probably find that in the in the description as well as you can see it in the playlist now here that is the whole idea so whenever lactic acid start building up in the muscle it's taken by the into the blood and then blood circulates and provide it to the liver and then liver converts lactic acid into pyrovate pyrovate is like going back with gluconneioenesis in the backward reaction produce glucose and then glucose is further transported into the bloodstream then glucose is supplied to the muscle cell and now muscle can utilize glucose and it can utilize normal process of glycolyis script cycle and electron transport chain then finally produce the desired amount of ATP now this is the process this whole cycle of taking lactic acid converting into the glucose provide it back to the muscle this whole cycle it is known as ki cycle now remember one important thing here for the process of production of glucose to pyrovate that's a simple process it takes only 2 ATP but growing from pyrovate to glucose it consumes like say normally from one glucose there are two pyroate molecules produced so if you go from two pyroate to one glucose molecule production it actually consumes six ATP molecules so it's a energy consuming process but still body will do that because except for the glucose which is the food for muscle the muscle will fail to work and that will be bad for our body that's the idea of Kore cycle okay uh I hope you understand this video and also the second part of the video I also have I'll tell you the sequential stages of this process as well uh I'll recommend you to watch the second part of this video lecture where you'll see the actual sequential stages of the Kore cycle in details lactate is produced in muscle when ATP demand exceeds the capacity of the oxidative phosphorilation and anorobic production of ATP through glycolysis or glycogenolyis generates the end product which is lactic acid the process of conversion of glucose into lactic acid is known as lactic acid fermentation now in cori cycle the lactate is transported from the muscle through the bloodstream to the liver where it can be converted back to the glucose in the liver the lactate is converted first to the pyrovate by lactate dehydrogenase then pyrovate is converted to glucose through the glycogenesis or gluconneogenesis process which requires hydraysis of ATP and GTP in two different stages back to back which requires a lot of energy for the process to complete now the glucose is produced in the liver is transported through the bloodstream to the muscle tissue where it can be used or stored as glycogen it can be used for the process of glycolysis or we can convert the glucose into glycogen with the help of the glycogen synthes enzyme