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How Does Glycogen Become Glucose?

How Our Bodies Turn Food Into Energy

How Our Bodies Turn Food Into Energy

All parts of the body (muscles, brain, heart, and liver) need energy to work. This energy comes from the food we eat. Our bodies digest the food we eat by mixing it with fluids (acids and enzymes) in the stomach. When the stomach digests food, the carbohydrate (sugars and starches) in the food breaks down into another type of sugar, called glucose. The stomach and small intestines absorb the glucose and then release it into the bloodstream. Once in the bloodstream, glucose can be used immediately for energy or stored in our bodies, to be used later. However, our bodies need insulin in order to use or store glucose for energy. Without insulin, glucose stays in the bloodstream, keeping blood sugar levels high. Insulin is a hormone made by beta cells in the pancreas. Beta cells are very sensitive to the amount of glucose in the bloodstream. Normally beta cells check the blood's glucose level every few seconds and sense when they need to speed up or slow down the amount of insulin they're making and releasing. When someone eats something high in carbohydrates, like a piece of bread, the glucose level in the blood rises and the beta cells trigger the pancreas to release more insulin into the bloodstream. When insulin is released from the pancreas, it travels through the bloodstream to the body's cells and tells the cell doors to open up to let the glucose in. Once inside, the cells convert glucose into energy to use right then or store it to use later. As glucose moves from the bloodstream into the cells, blood sugar levels start to drop. The beta cells in the pancreas can tell this is happening, so they slow down the amount of insulin they're making. At the same time, the pancreas slows down the amount of insulin that it's releasing into the bloodstream. When this happens, Continue reading >>

Glycogen Vs. Glucose

Glycogen Vs. Glucose

Lexa W. Lee is a New Orleans-based writer with more than 20 years of experience. She has contributed to "Central Nervous System News" and the "Journal of Naturopathic Medicine," as well as several online publications. Lee holds a Bachelor of Science in biology from Reed College, a naturopathic medical degree from the National College of Naturopathic Medicine and served as a postdoctoral researcher in immunology. A bowl of colored pasta.Photo Credit: AlexPro9500/iStock/Getty Images Glucose and glycogen are both carbohydrates, but glucose is classified as a monosaccharide and sugar. As a single unit, it is a much smaller molecule. According to Virtual Chembook at Elmhurst College, glycogen is classified as a complex carbohydrate and starch, and it's made up of several glucose molecules. Glucose can be rapidly metabolized to produce energy. It dissolves readily in water and can be readily transported throughout your body. It can be carried in your bloodstream as well as in the sap of plants. Glucose serves as a primary energy source for plants as well as animals. Joining different numbers of glucose units forms different types of carbohydrates, according to the Department of Chemistry at Imperial College in the U.K. Disaccharides like sucrose and lactose consist of two linked glucose units, while polysaccarides consist of many more. In animals, glycogen is a large storage molecule for extra glucose, just as starch is the storage form in plants. Your liver and muscles synthesize glycogen and act as your main storehouses. Your stores can be broken down again to glucose for energy if necessary, and they can also provide structural support in various tissues in your body. One glycogen molecule can consist of long chains of 1,700 to 600,000 glucose units. About 0.5 percent of Continue reading >>

What Every Weightlifter Should Know About Glycogen

What Every Weightlifter Should Know About Glycogen

If you want to know what glycogen is and how it affects your ability to build muscle and gain strength, then you want to read this article. Key Takeaways Muscle glycogen is a form of carbohydrate that’s stored in your muscles and liver. Glycogen is the primary source of fuel during exercise, and low glycogen levels decreases your ability to gain strength and muscle. The best way to maintain high levels of muscle glycogen is to eat a high-carb diet, with around 1 to 3 grams of carbs per pound of body weight. After decades of research, you can bet on a few “nutritional truths” when it comes to losing fat and building muscle: You need maintain an energy deficit to lose weight. You need to maintain an energy surplus to gain weight. Ask people “in the know,” about those ideas, and they’ll all more or less agree. Ask them about how many carbs you should eat, though, and you’ll get a more polarized response. Many will tell you that you need to eat plenty of carbs to build muscle and strength. Poke your head around some corners of the Internet, and it’s easy to think that you should be subsisting almost entirely on bread, pasta, and cereal if you want to get bigger, leaner, and stronger. If you’re more interested in sports than throwing around weights, then you’ve also likely heard that most of your calories should come from carbs. Why, though? Well, their argument brings us to the topic at hand–muscle glycogen. Higher carb diets increase your muscle glycogen levels, which improves your performance in every sport, they say. Not everyone agrees, though. Others say that high glycogen levels have no effect on muscle growth or strength gains, and can actually get in the way of fat loss. When it comes to other sports, another group says that you can train your Continue reading >>

Glycogen And Glucagon: Managing Your Self-storage Unit

Glycogen And Glucagon: Managing Your Self-storage Unit

There’s an element of type 2 diabetes we don’t talk about much. We do talk a lot about carbohydrates, how digesting carbohydrate food makes blood glucose levels go up. We talk a lot about insulin too, how insulin normally stimulates certain cells to “absorb” glucose, bringing blood glucose levels back down, and how those cells become resistant to insulin in type 2 diabetes. We don’t often talk about what happens to the glucose that does get absorbed into cells, and how that story is an important part of diabetes too. And, it’s a story about your brain. Having some glucose available in your blood is essential to keep your brain operating – that’s why there is a “normal” blood glucose level. Your brain must have glucose to fuel its constant activity, and your brain uses a lot of glucose. So, you might wonder why your brain doesn’t run out of fuel unless you keep eating a steady stream of carbohydrate foods. That’s a story about your glucose self-storage unit – your liver. Much of the glucose that is absorbed into cells with the help of insulin is stored away. In liver cells, glucose is packed away in starch molecules called glycogen, and that makes your liver an extremely important storage unit. When blood glucose levels begin to drop, as your brain and muscles use the glucose fuel, a hormone called glucagon causes your liver to unpack glycogen and release glucose into your bloodstream. Glucagon causes blood glucose levels to rise, an opposite effect of insulin. In normal metabolism, insulin and glucagon work to keep blood glucose levels constant. With type 2 diabetes the glucagon system can lose its precision too, signaling for a release of glucose from your liver even when blood glucose levels are normal or already high. That premature release Continue reading >>

Glycogenolysis And Glycogenesis

Glycogenolysis And Glycogenesis

Structure of glycogen Figure 1. Glycogen structure (Click for enlarged view). Panel A. Schematic two-dimensional cross-sectional view of glycogen: A core protein of glycogenin is surrounded by branches of glucose units. The entire globular granule may contain around 30,000 glucose units. [Source: Mikael Häggström[2], . Panel B. Schematic of glycogen structure showing the glucose units in each chain linked together linearly by α(1→4 glycosidic bonds. Branches are linked to the chains from which they are branching off by α(1→6) glycosidic bonds between the first glucose of the new branch and a glucose on the stem chain.Glycogen is a multi-branched polysaccharide of glucose that serves as an energy store primarily in muscle and liver. It is stored in the form of granules in the cytoplasm of the cell and is the main storage form of glucose in the body. The concentration of glycogen in muscle is low (1-2% fresh weight) compared to the levels stored in the liver (up to 8% fresh weight)[1]. Glycogen is an energy reserve that can be quickly mobilized to meet a sudden need for glucose. The significance of the multi-branched structure is that multiple glucose units, rather than a single glucose can be mobilized from any glycogen molecule when glycogenolysis is initiated. The structure of glycogen is summarized in Figure 1[2]. Enzymes involved in glycogenolysis The process of glycogenolysis involves the sequential removal of glucose monomers by phosphorolysis, a reaction catalysed by the phosphorylated (active) ‘a’ form of the enzyme glycogen phosphorylase[3]. This enzyme cleaves the glycosidic bond linking a terminal glucose to a glycogen branch by substituting a phosphoryl group for the α[1→4] linkage producing glucose-1-phosphate and glycogen that contains one le Continue reading >>

Blood Glucose Regulation

Blood Glucose Regulation

Glucose is needed by cells for respiration. It is important that the concentration of glucose in the blood is maintained at a constant level. Insulin is a hormone produced by the pancreas that regulates glucose levels in the blood. How glucose is regulated Glucose level Effect on pancreas Effect on liver Effect on glucose level too high insulin secreted into the blood liver converts glucose into glycogen goes down too low insulin not secreted into the blood liver does not convert glucose into glycogen goes up Use the animation to make sure you understand how this works. You have an old or no version of flash - you need to upgrade to view this funky content! Go to the WebWise Flash install guide Glucagon – Higher tier The pancreas releases another hormone, glucagon, when the blood sugar levels fall. This causes the cells in the liver to turn glycogen back into glucose which can then be released into the blood. The blood sugar levels will then rise. Now try a Test Bite- Higher tier. Diabetes is a disorder in which the blood glucose levels remain too high. It can be treated by injecting insulin. The extra insulin allows the glucose to be taken up by the liver and other tissues, so cells get the glucose they need and blood-sugar levels stay normal. There are two types of diabetes. Type 1 diabetes Type 1 diabetes is caused by a lack of insulin. It can be controlled by: monitoring the diet injecting insulin People with type 1 diabetes have to monitor their blood sugar levels throughout the day as the level of physical activity and diet affect the amount of insulin required. Type 2 diabetes Type 2 diabetes is caused by a person becoming resistant to insulin. It can be controlled by diet and exercise. There is a link between rising levels of obesity (chronic overweight) and i Continue reading >>

Does Carbohydrate Become Body Fat?

Does Carbohydrate Become Body Fat?

Dear Reader, Ah, poor carbohydrates, maligned by diets such as Atkins’ and the ketogenic diet. However, carbohydrates are your body’s main source of energy — in fact your muscles and brain cells prefer carbs more than other sources of energy (triglycerides and fat, for example). To answer your question: research completed over the last several decades suggests that if you are eating a diet that is appropriate for your levels of daily activity, little to no carbohydrate is converted to fat in your body. For most people (unless you have a metabolic disorder) when you eat carbs they are digested, broken down to glucose, and then transported to all the cells in your body. They are then metabolized and used to support cellular processes. If you’re active and eating appropriately for your activity level, most of the carbs you consume are more or less burned immediately. There are two caveats here: first, if you’re eating a lot more calories per day than you are burning, then yes, your liver will convert excess calories from carbohydrate into fats; second, not all carbs are created equal. If you consume too many calories from simple sugars like sucrose and fructose (think sugary sodas sweetened by sugar and high fructose corn syrup) then your body will more readily take some of those sugars and turn them into triglycerides (fat) in your liver. What happens to excess calories that come from carbs? The answer depends on several things: what kind of carbs you consumed, your genetics, as well as how many extra calories we’re talking about. For those who eat a well-balanced diet and have no metabolic disorders, excess dietary carbohydrates are converted by the liver into complex chains of glucose called glycogen. Glycogen is stored in liver and muscle cells and is a sec Continue reading >>

Glycogen And Diabetes - Role, Storage, Release & Exercise

Glycogen And Diabetes - Role, Storage, Release & Exercise

Glycogen is a stored form of glucose. It is a large multi-branched polymer of glucose which is accumulated in response to insulin and broken down into glucose in response to glucagon . Glycogen is mainly stored in the liver and the muscles and provides the body with a readily available source of energy if blood glucose levels decrease. Energy can be stored by the body in different forms. One form of stored energy is fat and glycogen is another. Fatty acids are more energy rich but glucose is the preferred energy source for the brain and glucose also can provide energy for cells in the absence of oxygen, for instance during anaerobic exercise. Glycogen is therefore useful for providing a readily available source of glucose for the body. In a healthy body, the pancreas will respond to higher levels of blood glucose , such as in response to eating, by releasing insulin which will lower blood glucose levels by prompting the liver and muscles to take up glucose from the blood and store it as glycogen. People with diabetes either do not make enough of their own insulin and/or their insulin does not work effectively enough. As a result, the pancreas may not be able to respond effectively enough to rises in blood glucose. In these situations, when the body feels extra glucose is needed in the blood, the pancreas will release the hormone glucagon which triggers the conversion of glycogen into glucose for release into the bloodstream. Glycogen plays an important role in keeping our muscles fuelled for exercise. When we exercise, our muscles will take advantage of their stored glycogen. Glucose in our blood and glycogen stored in the liver can also be used to keep our muscles fuelled. Once we complete our exercise session, our muscles will replenish their glycogen stores. The tim Continue reading >>

Glycogenesis, Glycogenolysis,

Glycogenesis, Glycogenolysis,

Biosynthesis of Glycogen: The goal of glycolysis, glycogenolysis, and the citric acid cycle is to conserve energy as ATP from the catabolism of carbohydrates. If the cells have sufficient supplies of ATP, then these pathways and cycles are inhibited. Under these conditions of excess ATP, the liver will attempt to convert a variety of excess molecules into glucose and/or glycogen. Glycogenesis: Glycogenesis is the formation of glycogen from glucose. Glycogen is synthesized depending on the demand for glucose and ATP (energy). If both are present in relatively high amounts, then the excess of insulin promotes the glucose conversion into glycogen for storage in liver and muscle cells. In the synthesis of glycogen, one ATP is required per glucose incorporated into the polymeric branched structure of glycogen. actually, glucose-6-phosphate is the cross-roads compound. Glucose-6-phosphate is synthesized directly from glucose or as the end product of gluconeogenesis. Link to: Interactive Glycogenesis (move cursor over arrows) Jim Hardy, Professor of Chemistry, The University of Akron. Glycogenolysis: In glycogenolysis, glycogen stored in the liver and muscles, is converted first to glucose-1- phosphate and then into glucose-6-phosphate. Two hormones which control glycogenolysis are a peptide, glucagon from the pancreas and epinephrine from the adrenal glands. Glucagon is released from the pancreas in response to low blood glucose and epinephrine is released in response to a threat or stress. Both hormones act upon enzymes to stimulate glycogen phosphorylase to begin glycogenolysis and inhibit glycogen synthetase (to stop glycogenesis). Glycogen is a highly branched polymeric structure containing glucose as the basic monomer. First individual glucose molecules are hydrolyzed fr Continue reading >>

Do All Sugars Transported To The Liver Convert To Glucose?

Do All Sugars Transported To The Liver Convert To Glucose?

Sugar can come from natural sources, such as fruits, honey and maple syrup, or added sugars, such as table sugar or high-fructose corn syrup. The way sugar is processed by your body does not depend on what food it is found in but rather on the nature of the sugar molecules. Some sugars need to be transported directly to the liver in order to be metabolized or processed by your body, while others can also be used directly by your muscles and brain. Fructose is transported to your liver to be converted to glucose or fat, while glucose can be burned for energy as is anywhere in your body. Types of Sugars Glucose is one of the main sugar molecules found in various types of sugar. The sucrose found in table sugar and maple sugar is actually half glucose. Dextrose is 100 percent glucose. Although fructose is usually thought to be the main sugar in fruits, all fruits also contain varying proportion of glucose and sucrose. Both fructose and glucose are also found in high-fructose corn syrup, agave syrup and other sweeteners. Glucose Metabolism Once absorbed into your bloodstream, glucose does not necessarily have to be transported to your liver. Almost all of your cells, including the cells of your liver, muscles, brain and fat, can take some of the glucose circulating in your blood. Glucose can be used as a form of energy by most of your cells and converted to glycogen by your liver or muscles or converted to fat in your fat cells. Fructose Metabolism Fructose can only be processed by your liver. After absorbing fructose from fruits or a food sweetened with sugar, agave syrup or high-fructose corn syrup, fructose enters your bloodstream to be transported right to your liver. Part of this fructose can be converted into glucose by the liver to be stored as glycogen, and the rema Continue reading >>

How Are Carbohydrates Converted Into Fat Deposits?

How Are Carbohydrates Converted Into Fat Deposits?

How are carbohydrates converted into fat deposits? There are two ways that carbohydrates and body fat interact. One is directly by turning into body fat, and the other is via insulin. Turning into body fat is like adding fat into the fat cells, whereas carbohydrates spiking insulin does not add anything to fat cells per se, but hinders the release. The former is like a + equation, where the latter is a double negative which results in something that seems positive. There is a process called de novo lipogenesis (literally: Creation of fat from non-fat sources) that can occur in the body. This process turns glucose into lipids, which are then stored as body fat. This process is normally quite inefficient in the body [1] , which suggests that carbohydrates cannot be stored as fat to a high degree. The process can be upregulated (enhanced) if dietary fat comprised almost none of the diet (lesser than 10%, as a rough estimate), if carbohydrate intake is excessively high for a period of a few days, or if one follows an obesogenic diet (diet that is likely to make you fat) for a prolonged period of time. [1] [2] [3] Carbohydrates spike insulin , which is a hormone that mediates glucose metabolism. Insulin is not good or bad, insulin is insulin. It can be thought of as a lever that switches the body from fat burning mode into carbohydrate burning mode. This allows carbohydrates (and glycogen) to be burnt at a greater rate, but directly reduces the ability of fat to be lost. Overall metabolic rate (calories burnt over the course of a day) does not change significantly, just where the calories come from. When insulin is spiked in presence of ingested dietary fat, the dietary fat can go into body fat stores and not be released since glucose from glycogen is being used in place of Continue reading >>

Glycogen And Glucose

Glycogen And Glucose

Glycogen and Glucose are the two forms of sugar that your body employs to store and use as energy . Glucose is the sugar your body converts into energy. Glycogen is the sugar your body stores in both your liver and muscle cells. Your body can't use glycogen directly as a source of energy, and cannot store glucose. When you eat a well-balanced meal with both carbohydrates and protein, your body converts and absorbs the carbohydrates and part of the protein into glucose. It then attempts to maintain an even blood glucose level. When your blood glucose is too high, your pancreas produces insulin to convert some of that glucose into glycogen and then stores it for later use. When it is running low, it produces glucagon, a hormone secreted by the pancreas which stimulates your liver to convert some glycogen into glucose. Once converted, the glucose can be released into your blood stream. (The glycogen stored in your muscles can't be converted back into sugar, so it can only be used by your muscles.) Your liver can only store 90 to 110 grams of glycogen (the equivalent of about three to four hours of normal activity). When your glycogen reserves are full, and you still have glucose in your blood or glucose being absorbed into your bloodstream from a meal, your liver then starts to convert glucose into fat. That is actually a normal process because with a regular size meal, you will invariably fill up your glycogen reserves. Therefore it is customary to store some fat when you eat. If you don't eat between meals, after around three hours your liver glycogen will be running low and your body will start converting that fat into energy until you eat your next meal. Overall, this is a healthy, natural process of filling up your glycogen supply, storing some fat, and then accessing Continue reading >>

Difference Between Glucose And Glycogen

Difference Between Glucose And Glycogen

Categorized under Science | Difference Between Glucose and Glycogen Whats the difference between glucose and glycogen? To secondary school students, this question may come as easy as it is one of the most discussed topics in biology. There are many types of sugars namely: monosaccharide, disaccharide and polysaccharide. Glucose is a monosaccharide while glycogen is a polysaccharide. It is therefore a more complex sugar than glucose. When many glucose molecules bind altogether along with oxygen, glycogen can most likely be formed as an end result. The other difference between the two can be best explained by knowing the process of glucose metabolism. When a person eats food, the food components will be broken down by the body into simpler sugars termed glucose. If there is an excess of glucose in the system then it will be converted and then stored as glycogen in the liver. Similarly, if the liver (an organ that can normally hold as much as 100g of glycogen) is deficient in such, then the body will most likely tend to store the glucose as glycogen. If the true is correct (theres an excess of glycogen in the liver) then glycogen will be released to the muscle cells by first being broken down into glucose. The rate and extent of release will also be dependent on the bodys energy needs. During workouts, the energy source primarily used is glucose. But the muscles would rely more on glycogen most especially when glucose level are starting to get low. Hence, it is better to have sufficient amounts of glucose in the body so that the glucose can be used for other more vital functions like for brain function and not for the provision of energy for your muscles. This can be done by taking in some simple carbohydrates after you engage in strenuous physical exertions (the time whe Continue reading >>

Storage Of Glucose As Glycogen

Storage Of Glucose As Glycogen

The liver secretes glucose into the bloodstream as an essential mechanism to keep blood glucose levels constant. Liver, muscle, and other tissues also store glucose as glycogen, a high‐molecular‐weight, branched polymer of glucose. Glycogen synthesis begins with glucose‐1‐phosphate, which can be synthesized from glucose‐6‐ phosphate by the action of phosphoglucomutase (an isomerase). Glucose‐1‐phosphate is also the product of glycogen breakdown by phosphorylase: The K eq of the phosphorylase reaction lies in the direction of breakdown. In general, a biochemical pathway can't be used efficiently in both the synthetic and the catabolic direction. This limitation implies that there must be another step in glycogen synthesis that involves the input of extra energy to the reaction. The extra energy is supplied by the formation of the intermediate UDP‐glucose. This is the same compound found in galactose metabolism. It is formed along with inorganic pyrophosphate from glucose‐1‐phosphate and UTP. The inorganic pyrophosphate is then hydrolyzed to two phosphate ions; this step pulls the equilibrium of the reaction in the direction of UDP‐glucose synthesis (see Figure 1). Figure 1 Glycogen synthase transfers the glucose of UDP‐glucose to the nonreducing end (the one with a free Carbon‐4 of glucose) of a preexisting glycogen molecule (another enzyme starts the glycogen molecule), making an A, 1‐4 linkage and releasing UDP (see Figure 2 ). This reaction is exergonic, though not as much as the synthesis of UDP‐ glucose is. Figure 2 Summing up, the synthesis of glycogen from glucose‐1‐phosphate requires the consumption of a single high‐energy phosphate bond and releases pyrophosphate (converted to phosphates) and UDP. Overall, the reaction is: G Continue reading >>

Glycogen Biosynthesis; Glycogen Breakdown

Glycogen Biosynthesis; Glycogen Breakdown

Glycogen is a polymer of glucose (up to 120,000 glucose residues) and is a primary carbohydrate storage form in animals. The polymer is composed of units of glucose linked alpha(1-4) with branches occurring alpha(1-6) approximately every 8-12 residues. The end of the molecule containing a free carbon number one on glucose is called a reducing end. The other ends are all called non-reducing ends. Related polymers in plants include starch (alpha(1-4) polymers only) and amylopectin (alpha (1-6) branches every 24-30 residues). Glycogen provides an additional source of glucose besides that produced via gluconeogenesis. Because glycogen contains so many glucoses, it acts like a battery backup for the body, providing a quick source of glucose when needed and providing a place to store excess glucose when glucose concentrations in the blood rise. The branching of glycogen is an important feature of the molecule metabolically as well. Since glycogen is broken down from the "ends" of the molecule, more branches translate to more ends, and more glucose that can be released at once. Liver and skeletal muscle are primary sites in the body where glycogen is found. The primary advantagesof storage carbohydrates in animals are that 1) energy is not released from fat (other majorenergy storage form in animals) as fast as from glycogen; 2) glycolysis provides a mechanism of anaerobic metabolism (importantin muscle cells that cannot get oxygen as fast as needed); and 3) glycogen provides a means of maintaining glucose levels thatcannot be provided by fat. Breakdown of glycogen involves 1) release of glucose-1-phosphate (G1P), 2) rearranging the remaining glycogen (as necessary) to permit continued breakdown, and 3) conversion of G1P to G6P for further metabolism. Remember that G6P can be Continue reading >>

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