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What Happens To Glucose In The Liver?

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 >>

How Does The Liver Control Glucose In The Blood?

How Does The Liver Control Glucose In The Blood?

Your body needs a constant supply of glucose, or sugar, for cells to have energy, so it requires a readily available reservoir to keep blood glucose in balance. One of the liver’s main roles in the body is controlling the amount of glucose circulating in the blood. By storing excess glucose as glycogen and creating new glucose from proteins and fat byproducts, the liver is able to maintain balanced glucose levels in your body at all times. Video of the Day When you eat carbohydrates, the body releases glucose into the bloodstream immediately, triggering the production of insulin. The body cannot be in a state of constant consumption, so when insulin levels are high enough, the body links long chains of glucose together into a compound called glycogen, which is then stored in the liver and the muscles. The liver uses this stored glucose energy as its main reservoir for releasing glucose into the bloodstream when levels drop. Breakdown of Glycogen Blood glucose levels drop when you're not eating, such as during sleep or between meals. This low blood sugar signals the liver to produce glucose and release it back into the bloodstream. The liver favors glycogen as its primary source since it is efficiently broken down into glucose in a process known as glycogenolysis. In this process, the liver breaks the bonds that hold glucose molecules together as glycogen, degrading most but not all of the glycogen molecule. Effects of Insulin Resistance When your body is chronically subjected to high levels of blood sugar and insulin, such as after you've eaten an excessive amount of foods high in sugar, it develops a resistance to the hormone, and the liver cannot respond properly, eventually leading to type-2 diabetes if the resistance is not controlled. According to a study publish Continue reading >>

Controlling Blood Sugar Level

Controlling Blood Sugar Level

Diabetes Glucose is a sugar needed by cells for respiration. It is important that the concentration of glucose in the blood is maintained at a constant level. Insulin, a hormone secreted by the pancreas, controls blood sugar levels in the body. Diabetes is a disorder in which the blood glucose levels remain too high. It can be treated by carefully maintaining a certain diet or 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. Higher only What happens when glucose levels in the blood become too high or too low 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 Menstrual cycle The menstrual cycle in women is a recurring process in which the lining of the uterus is prepared for pregnancy. If pregnancy does not happen, the lining is shed at menstruation. Several hormones control this cycle: oestrogen, which causes the repair of the uterus wall progesterone, which maintains the uterus wall Both hormones are secreted by the ovaries. The image below shows how the levels of oestrogen and progesterone change during the menstrual cycle. If a woman becomes pregnant, the level of progesterone remains high. Controlling fertility Human fertility is controlled by hormones. This means that a knowledge of hormones can be used to decide to increase, or reduce, the chances of fe Continue reading >>

What Happens To Excess Protein?

What Happens To Excess Protein?

Li Z, Treyzon L, Chen S, Yan E, Thames G, Carpenter CL. Protein-enriched meal replacements do not adversely affect liver, kidney or bone density: an outpatient randomized controlled trial. Nutr J 2011;9(1):72. BACKGROUND: There is concern that recommending protein-enriched meal replacements as part of a weight management program could lead to changes in biomarkers of liver or renal function and reductions in bone density. This study was designed as a placebo-controlled clinical trial utilizing two isocaloric meal plans utilizing either a high protein-enriched (HP) or a standard protein (SP) meal replacement in an outpatient weight loss program. Subjects/methods: 100 obese men and women over 30 years of age with a body mass index (BMI) between 27 to 40 kg/m2 were randomized to one of two isocaloric weight loss meal plans 1). HP group: providing 2.2 g protein/kg of lean body mass (LBM)/day or 2). SP group: providing 1.1 g protein/kg LBM/day. Meal replacement (MR) was used twice daily (one meal, one snack) for 3 months and then once a day for 9 months. Body weight, lipid profiles, liver function, renal function and bone density were measured at baseline and 12 months. CONCLUSIONS: These studies demonstrate that protein-enriched meals replacements as compared to standard meal replacements recommended for weight management do not have adverse effects on routine measures of liver function, renal function or bone density at one year. Continue reading >>

How Does The Liver Work?

How Does The Liver Work?

The liver is one of the largest organs in the body. It has many important metabolic functions. It converts the nutrients in our diets into substances that the body can use, stores these substances, and supplies cells with them when needed. It also takes up toxic substances and converts them into harmless substances or makes sure they are released from the body. The human adult liver weighs about 1.4 kg (3.1 pounds) and is found in the right upper abdomen, below the diaphragm. It takes up most of the space under the ribs and some space in the left upper abdomen, too. Viewed from the outside, a larger right lobe and smaller left lobe can be distinguished. The two lobes are separated by a band of connective tissue that anchors the liver to the abdominal cavity. The gallbladder, where bile is stored, is found in a small hollow on the underside of the liver. Liver tissue is made up of lots of smaller units of liver cells called lobules. Many canals carrying blood and bile run between the liver cells. Blood coming from the digestive organs flows through the portal vein to the liver, carrying nutrients, medication and also toxic substances. Once they reach the liver, these substances are processed, stored, altered, detoxified, and passed back into the blood or released in the bowel to be eliminated. In this way the liver can, for example, remove alcohol from your blood and get rid of by-products from the breakdown of medications. With the help of vitamin K, the liver produces proteins that are important in blood clotting. It is also one of the organs that break down old or damaged blood cells. The liver plays a central role in all metabolic processes in the body. In fat metabolism the liver cells break down fats and produce energy. They also produce about 800 to 1,000 ml of bi Continue reading >>

Glycogen

Glycogen

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.[1] A view of the atomic structure of a single branched strand of glucose units in a glycogen molecule. Glycogen (black granules) in spermatozoa of a flatworm; transmission electron microscopy, scale: 0.3 µm Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in humans,[2] animals,[3] fungi, and bacteria. The polysaccharide structure represents the main storage form of glucose in the body. Glycogen functions as one of two forms of long-term energy reserves, with the other form being triglyceride stores in adipose tissue (i.e., body fat). In humans, glycogen is made and stored primarily in the cells of the liver and skeletal muscle.[2][4] In the liver, glycogen can make up from 5–6% of the organ's fresh weight and the liver of an adult weighing 70 kg can store roughly 100–120 grams of glycogen.[2][5] In skeletal muscle, Glycogen is found in a low concentration (1–2% of the muscle mass) and the skeletal muscle of an adult weighing 70 kg can store roughly 400 grams of glycogen.[2] The amount of glycogen stored in the body—particularly within the muscles and liver—mostly depends on physical training, basal metabolic rate, and eating habits. Small amounts of glycogen are also found in other tissues and cells, including the kidneys, red blood cells,[6][7][8] white blood cells,[medical citation needed] and glial cells in the brain.[9] The uterus also stores glycogen during pregnancy to nourish the embryo.[10] Approximately 4 grams of glucose are present in the blood of humans at all times;[2] in fasted individuals, blood glucos Continue reading >>

What Is Glucagon?

What Is Glucagon?

Blood sugar levels are an important part of overall health. When blood sugar levels drop, an individual may feel lethargic. If they drop too low, the individual may become disoriented, dizzy or even pass out. Blood sugar control involves a complex system of hormones, and one of those hormones is glucagon. Glucagon is a hormone that works with other hormones and bodily functions to control glucose levels in the blood. It comes from alpha cells found in the pancreas and is closely related to insulin-secreting beta cells, making it a crucial component that keeps the body’s blood glucose levels stable. What does glucagon do? Although secreted by the pancreas, glucagon directly impacts the liver as it works to control blood sugar levels. Specifically, glucagon prevents blood glucose levels from dropping to a dangerous point by stimulating the conversion of stored glycogen to glucose in the liver. This glucose can be released into the bloodstream, a process known as glycogenolysis. Secondly, glucagon stops the liver from consuming some glucose. This helps more glucose to enter the bloodstream, rather than being consumed by the liver, to keep levels stable. Finally, glucagon works in a process known as gluconeogenesis, which is the production of glucose in the amino acid molecules. In each of these processes, glucagon and insulin work together. Insulin will prevent glucose levels from increasing to a point that is too high, while glucagon prevents it from dropping too low. Glucagon production is stimulated when an individual eats a protein-rich meal, experiences a surge in adrenaline, or has a low blood sugar event. Potential problems with glucagon function Glucagon function is crucial to proper blood glucose levels, so problems with glucagon production will lead to problems Continue reading >>

What Happens To Food In Your Body?

What Happens To Food In Your Body?

Just thinking about eating causes your body to start secreting insulin, a hormone that helps keep blood sugar (glucose) under control. Insulin is made by the pancreas. As you eat, more insulin is released, in response to the carbohydrates in the meal. Insulin is released when you eat protein-rich foods, but at a slower rate. If your pancreas is functioning properly, the amount of carbohydrates in what you’re eating usually determines how much insulin is released. As you digest carbohydrates, they go into the blood stream as glucose. To keep blood sugar levels under control, insulin signals the cells in your body to take in glucose from the blood stream. The cells use some of glucose for energy and store some for later use. The way glucose is stored depends on the type of cell doing the storing. Muscle cells store glucose as glycogen. Liver cells store some glucose as glycogen and convert some to fat. Fat cells store glucose as fat. As glucose is removed from the blood stream, insulin levels go down and your cells start using fat for fuel instead of glucose. This is why you can go for long stretches – overnight, for example, when you’re sleeping, without eating. Your cells rely on fat for fuel. There are two types of body fat: fatty acids and triglycerides. Fatty acids are small enough to move in and out of cells and be used as fuel for cells. Fat is stored inside fat cells as triglycerides, three fatty acids bound together. Triglycerides are too big to flow through cell membranes and so are stored for future use. Insulin also plays a major role in telling your body when to store and use fat and protein. It does this by affecting the actions of two enzymes, lipoprotein lipase (LPL) and hormone-sensitive lipase (HSL). LPL sits on the surface of cells and pulls fat o Continue reading >>

Blood Sugar Or Blood Glucose: What Does It Do?

Blood Sugar Or Blood Glucose: What Does It Do?

Blood sugar, or blood glucose, is sugar that the bloodstream carries to all the cells in the body to supply energy. Blood sugar or blood glucose measurements represent the amount of sugar being transported in the blood during one instant. The sugar comes from the food we eat. The human body regulates blood glucose levels so that they are neither too high nor too low. The blood's internal environment must remain stable for the body to function. This balance is known as homeostasis. The sugar in the blood is not the same as sucrose, the sugar in the sugar bowl. There are different kinds of sugar. Sugar in the blood is known as glucose. Blood glucose levels change throughout the day. After eating, levels rise and then settle down after about an hour. They are at their lowest point before the first meal of the day, which is normally breakfast. How does sugar get into the body's cells? When we eat carbohydrates, such as sugar, or sucrose, our body digests it into glucose, a simple sugar that can easily convert to energy. The human digestive system breaks down carbohydrates from food into various sugar molecules. One of these sugars is glucose, the body's main source of energy. The glucose goes straight from the digestive system into the bloodstream after food is consumed and digested. But glucose can only enter cells if there is insulin in the bloodstream too. Without insulin, the cells would starve. After we eat, blood sugar concentrations rise. The pancreas releases insulin automatically so that the glucose enters cells. As more and more cells receive glucose, blood sugar levels return to normal again. Excess glucose is stored as glycogen, or stored glucose, in the liver and the muscles. Glycogen plays an important role in homeostasis, because it helps our body function du Continue reading >>

Metabolic Functions Of The Liver

Metabolic Functions Of The Liver

Hepatocytes are metabolic overachievers in the body. They play critical roles in synthesizing molecules that are utilized elsewhere to support homeostasis, in converting molecules of one type to another, and in regulating energy balances. If you have taken a course in biochemistry, you probably spent most of that class studying metabolic pathways of the liver. At the risk of damning by faint praise, the major metabolic functions of the liver can be summarized into several major categories: Carbohydrate Metabolism It is critical for all animals to maintain concentrations of glucose in blood within a narrow, normal range. Maintainance of normal blood glucose levels over both short (hours) and long (days to weeks) periods of time is one particularly important function of the liver. Hepatocytes house many different metabolic pathways and employ dozens of enzymes that are alternatively turned on or off depending on whether blood levels of glucose are rising or falling out of the normal range. Two important examples of these abilities are: Excess glucose entering the blood after a meal is rapidly taken up by the liver and sequestered as the large polymer, glycogen (a process called glycogenesis). Later, when blood concentrations of glucose begin to decline, the liver activates other pathways which lead to depolymerization of glycogen (glycogenolysis) and export of glucose back into the blood for transport to all other tissues. When hepatic glycogen reserves become exhaused, as occurs when an animal has not eaten for several hours, do the hepatocytes give up? No! They recognize the problem and activate additional groups of enzymes that begin synthesizing glucose out of such things as amino acids and non-hexose carbohydrates (gluconeogenesis). The ability of the liver to synthe Continue reading >>

Introduction

Introduction

INTRODUCTION Glucose in the blood provides a source of fuel for all tissues of the body. Blood glucose levels are highest during the absorptive period after a meal, during which the stomach and small intestine are breaking down food and circulating glucose to the bloodstream. Blood glucose levels are the lowest during the postabsorptive period, when the stomach and small intestines are empty. Despite having food only periodically in the digestive tract, the body works to maintain relatively stable levels of circulatory glucose throughout the day. The body maintains blood glucose homeostasis mainly through the action of two hormones secreted by the pancreas. These hormones are insulin, which is released when glucose levels are high, and glucagon, which is released when glucose levels are low. The accompanying animation depicts the functions of these hormones in blood glucose regulation. CONCLUSION Throughout the day, the release of insulin and glucagon by the pancreas maintains relatively stable levels of glucose in the blood. During the absorptive period blood glucose levels tend to increase, and this increase stimulates the pancreas to release insulin into the bloodstream. Insulin promotes the uptake and utilization of glucose by most cells of the body. Thus, as long as the circulating glucose supply is high, cells preferentially use glucose as fuel and also use glucose to build energy storage molecules glycogen and fats. In the liver, insulin promotes conversion of glucose into glycogen and into fat. In muscle insulin promotes the use of glucose as fuel and its storage as glycogen. In fat cells insulin promotes the uptake of glucose and its conversion into fats. The nervous system does not require insulin to enable its cells to take up and utilize glucose. If glucose 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 >>

You And Your Hormones

You And Your Hormones

What is insulin? Insulin is a hormone made by an organ located behind the stomach called the pancreas. Here, insulin is released into the bloodstream by specialised cells called beta cells found in areas of the pancreas called islets of langerhans (the term insulin comes from the Latin insula meaning island). Insulin can also be given as a medicine for patients with diabetes because they do not make enough of their own. It is usually given in the form of an injection. Insulin is released from the pancreas into the bloodstream. It is a hormone essential for us to live and has many effects on the whole body, mainly in controlling how the body uses carbohydrate and fat found in food. Insulin allows cells in the muscles, liver and fat (adipose tissue) to take up sugar (glucose) that has been absorbed into the bloodstream from food. This provides energy to the cells. This glucose can also be converted into fat to provide energy when glucose levels are too low. In addition, insulin has several other metabolic effects (such as stopping the breakdown of protein and fat). How is insulin controlled? When we eat food, glucose is absorbed from our gut into the bloodstream. This rise in blood glucose causes insulin to be released from the pancreas. Proteins in food and other hormones produced by the gut in response to food also stimulate insulin release. However, once the blood glucose levels return to normal, insulin release slows down. In addition, hormones released in times of acute stress, such as adrenaline, stop the release of insulin, leading to higher blood glucose levels. The release of insulin is tightly regulated in healthy people in order to balance food intake and the metabolic needs of the body. Insulin works in tandem with glucagon, another hormone produced by the pan 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 >>

Glycogenolysis

Glycogenolysis

Glycogenolysis, process by which glycogen, the primary carbohydrate stored in the liver and muscle cells of animals, is broken down into glucose to provide immediate energy and to maintain blood glucose levels during fasting. Glycogenolysis occurs primarily in the liver and is stimulated by the hormones glucagon and epinephrine (adrenaline). When blood glucose levels fall, as during fasting, there is an increase in glucagon secretion from the pancreas. That increase is accompanied by a concomitant decrease in insulin secretion, because the actions of insulin, which are aimed at increasing the storage of glucose in the form of glycogen in cells, oppose the actions of glucagon. Following secretion, glucagon travels to the liver, where it stimulates glycogenolysis. The vast majority of glucose that is released from glycogen comes from glucose-1-phosphate, which is formed when the enzyme glycogen phosphorylase catalyzes the breakdown of the glycogen polymer. In the liver, kidneys, and intestines, glucose-1-phosphate is converted (reversibly) to glucose-6-phosphate by the enzyme phosphoglucomutase. Those tissues also house the enzyme glucose-6-phosphatase, which converts glucose-6-phosphate into free glucose that is secreted into the blood, thereby restoring blood glucose levels to normal. Glucose-6-phosphate is also taken up by muscle cells, where it enters glycolysis (the set of reactions that breaks down glucose to capture and store energy in the form of adenosine triphosphate, or ATP). Small amounts of free glucose also are produced during glycogenolysis through the activity of glycogen debranching enzyme, which completes the breakdown of glycogen by accessing branching points in the polymer. Epinephrine, similar to glucagon, stimulates glycogenolysis in the liver, resul Continue reading >>

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