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What Hormone Promotes Storage Of Glucose By The Liver

Role Of Insulin And Other Hormones In Diabetes

Role Of Insulin And Other Hormones In Diabetes

SHARE RATE★★★★★ Insulin and glucose Our bodies require energy to function properly and we get that energy from three food groups: protein, fat, and carbohydrates (sugars, starches, and fibers). When the body digests carbohydrates, they are transformed through digestion into a very important source of instant energy, a form of sugar called glucose.1,2 Three forms of simple sugars (also called monosaccharides) are able to enter the bloodstream directly after digestion. These are often broken down from more complex sugars (polysaccharides and disaccharides). These simple sugars include glucose (found in most carbohydrates, including grains and starches), fructose (found in fruits and vegetables), and galactose (found in dairy products and in certain vegetables). The word glucose comes from the Greek word for sweet, and it is the key source of energy for cells in the body. Upon digestion, glucose can be used for instant energy or stored in the form of glycogen when the body’s energy needs are being met.1,2 Hormones and glucose control Our bodies depend on the action of a number of different hormones, working together in conjunction, to control how we use glucose. We depend on insulin, a hormone produced in the beta cells of the pancreas (an organ located behind the stomach) to use glucose. Insulin serves as sort of a “gate keeper,” allowing glucose to enter cells where it can be transformed into energy and used to support vital cell functions. Insulin also has other important functions related to the way our body uses glucose.3,4 In addition to insulin, another hormone produced by beta cells called amylin controls how quickly glucose is released into the blood stream after a meal. It does this by slowing emptying of the stomach and increasing the feeling tha Continue reading >>

The Liver & Blood Sugar

The Liver & Blood Sugar

During a meal, your liver stores sugar for later. When you’re not eating, the liver supplies sugar by turning glycogen into glucose in a process called glycogenolysis. The liver both stores and produces sugar… The liver acts as the body’s glucose (or fuel) reservoir, and helps to keep your circulating blood sugar levels and other body fuels steady and constant. The liver both stores and manufactures glucose depending upon the body’s need. The need to store or release glucose is primarily signaled by the hormones insulin and glucagon. During a meal, your liver will store sugar, or glucose, as glycogen for a later time when your body needs it. The high levels of insulin and suppressed levels of glucagon during a meal promote the storage of glucose as glycogen. The liver makes sugar when you need it…. When you’re not eating – especially overnight or between meals, the body has to make its own sugar. The liver supplies sugar or glucose by turning glycogen into glucose in a process called glycogenolysis. The liver also can manufacture necessary sugar or glucose by harvesting amino acids, waste products and fat byproducts. This process is called gluconeogenesis. When your body’s glycogen storage is running low, the body starts to conserve the sugar supplies for the organs that always require sugar. These include: the brain, red blood cells and parts of the kidney. To supplement the limited sugar supply, the liver makes alternative fuels called ketones from fats. This process is called ketogenesis. The hormone signal for ketogenesis to begin is a low level of insulin. Ketones are burned as fuel by muscle and other body organs. And the sugar is saved for the organs that need it. The terms “gluconeogenesis, glycogenolysis and ketogenesis” may seem like compli Continue reading >>

Pancreatic Regulation Of Glucose Homeostasis

Pancreatic Regulation Of Glucose Homeostasis

Go to: The pancreas is an exocrine and endocrine organ The pancreas has key roles in the regulation of macronutrient digestion and hence metabolism/energy homeostasis by releasing various digestive enzymes and pancreatic hormones. It is located behind the stomach within the left upper abdominal cavity and is partitioned into head, body and tail. The majority of this secretory organ consists of acinar—or exocrine—cells that secrete the pancreatic juice containing digestive enzymes, such as amylase, pancreatic lipase and trypsinogen, into the ducts, that is, the main pancreatic and the accessory pancreatic duct. In contrast, pancreatic hormones are released in an endocrine manner, that is, direct secretion into the blood stream. The endocrine cells are clustered together, thereby forming the so-called islets of Langerhans, which are small, island-like structures within the exocrine pancreatic tissue that account for only 1–2% of the entire organ (Figure 1).1 There are five different cell types releasing various hormones from the endocrine system: glucagon-producing α-cells,2 which represent 15–20% of the total islet cells; amylin-, C-peptide- and insulin-producing β-cells,2 which account for 65–80% of the total cells; pancreatic polypeptide (PP)-producing γ-cells,3 which comprise 3–5% of the total islet cells; somatostatin-producing δ-cells,2 which constitute 3–10% of the total cells; and ghrelin-producing ɛ-cells,4 which comprise <1% of the total islet cells. Each of the hormones has distinct functions. Glucagon increases blood glucose levels, whereas insulin decreases them.5 Somatostatin inhibits both, glucagon and insulin release,6 whereas PP regulates the exocrine and endocrine secretion activity of the pancreas.3, 7 Altogether, these hormones regul Continue reading >>

Blood Proteins - Albumen, Clotting Proteins

Blood Proteins - Albumen, Clotting Proteins

Liver Pathology Functions of the liver: Manufacture - blood proteins - albumen, clotting proteins urea - nitrogenous waste from amino acid metabolism bile - excretory for the bile pigments, emulsification of fats by bile salts Storage - glycogen - carbohydrate fuel iron - as hemosiderin and ferritin fat soluble vitamins A, D, E, K Detoxification - alcohol drugs and medicines environmental toxins Protein metabolism - (See Figure 25.15) transamination - removing the amine from one amino acid and using it to produce a different amino acid. The body can produce all but the essential amino acids; these must be included in the diet. (See Figure 25.3) deamination - removal of the amine group in order to catabolize the remaining keto acid. The amine group enters the blood as urea which is excreted through the kidneys. Glycemic Regulation - the management of blood glucose. glycogenesis - the conversion of glucose into glycogen. glycogenolysis - the breakdown of glycogen into glucose. gluconeogenesis - the manufacture of glucose from non carbohydrate sources, mostly protein. See Disorders below. See [Liver Pathology] Structure of the liver - (See Figure 24.24) The liver is composed mostly of cells known as hepatocytes which perform the functions listed above. They have the ability to shift functions so their efforts can be directed at what is most needed. They can also divide to repair and replace tissue. Cirrhosis is a condition which can occur in the liver and other organs in which the cells are damaged as a result of toxins, pathogenic organisms, etc. Cirrhosis causes thickening and fibrosis and can progressively damage the liver to the point it can no longer recover by replacing its cells. Other functions also suffer as more hepatocytes become committed to detoxification. The Continue reading >>

Role Of Insulin And Other Related Hormones In Energy Metabolism—a Review

Role Of Insulin And Other Related Hormones In Energy Metabolism—a Review

This review aims to review hormones mechanisms that affect fuel metabolism and are involved in regulation of blood glucose, dealing insulin and glucagon hormones, and includes other related hormones, which increase the blood glucose level: growth hormone, thyroxine, cortisol and adrenaline. However, this review focuses on insulin and glucagon hormones as widely, and on other related hormones as briefly. Insulin plays an important role in a decrease blood glucose concentration in hyperglycemic response to emergencies or stress by an increasing rate of glucose transport into the muscle cell of animals and facilitating glucose utilization and by maintaining normal blood glucose concentrations. Insulin is a hypoglycemic hormone, promoting the storage of metabolites in peripheral stores. While, glucagon is a hyperglycemic hormone, stimulates gluconeogenesis—at the expense of peripheral stores by enhancing the hepatic removal of certain glucose precursors and stimulates lipolysis; however, it has not influence on peripheral protein stores directly. Insulin, glucagon and other related hormones regulate blood glucose concentrations and act on movement of glucose, amino acids and possibly volatile fatty acids between the liver and peripheral tissues directly. In another way, glucagon may be considered catabolic and insulin anabolic. In conclusion, insulin promotes body gain by stimulating protein and fat synthesis, growth hormone increases protein retention and decrease fat deposition. Growth hormone can alter the sensitivity of tissues to insulin. In contrast, catabolic hormones such as glucagon, epinephrine and glucocorticoids are provided for mobilization of energy reserves to allow the animal to deal with adverse situations. Continue reading >>

You And Your Hormones

You And Your Hormones

What is glucagon? Glucagon is a hormone that is involved in controlling blood sugar (glucose) levels. It is secreted into the bloodstream by the alpha cells, found in the islets of langerhans, in the pancreas. The glucagon-secreting alpha cells surround a core of insulin-secreting beta cells, which reflects the close relationship between the two hormones. Glucagon’s role in the body is to prevent blood glucose levels dropping too low. To do this, it acts on the liver in several ways: It stimulates the conversion of stored glycogen (stored in the liver) to glucose, which can be released into the bloodstream. This process is called glycogenolysis. It promotes the production of glucose from amino acid molecules. This process is called gluconeogenesis. It reduces glucose consumption by the liver so that as much glucose as possible can be secreted into the bloodstream to maintain blood glucose levels. Glucagon also acts on adipose tissue to stimulate the breakdown of fat stores into the bloodstream. How is glucagon controlled? Glucagon works along with the hormone insulin to control blood sugar levels and keep them within set levels. Glucagon is released to stop blood sugar levels dropping too low, while insulin is released to stop blood sugar levels rising too high. Release of glucagon is stimulated by low blood glucose (hypoglycaemia), protein-rich meals and adrenaline (another important hormone for combating low glucose). Release of glucagon is prevented by raised blood glucose and carbohydrate in meals, detected by cells in the pancreas. In the longer-term, glucagon is crucial to the body’s response to lack of food. For example, it encourages the use of stored fat for energy in order to preserve the limited supply of glucose. What happens if I have too much glucagon? Continue reading >>

Exam 4

Exam 4

1. Which of the following is true for ACTH? A. it is formed from cholesterol B. is the major mineralocorticoid C. it has glucocorticoid activity D. all of the above * E. none of the above 2. Which of the following has the greatest affect on glucocorticoid activity in the body? A. insulin B. glucagon * C. cortisol D. aldosterone E. testosterone 3. Which of the following is the major regulator of the rate of cortisol secretion? A. potassium B. angiotensin II * C. cortisol D. sodium E. ionized calcium 4. If both adrenal glands of a person are severely damaged by disease, which of the following hormones will increase in the blood? A. aldosterone * B. ACTH C. corticosterone D. cortisol E. all of the above 5. Which of the following is not a result of excessive aldosterone secretion? A. Na retention, but only for a period of time B. K excretion C. blood pressure elevation * D. production of adrenal androgens E. weight gain 6. Problems concentrating, overeating, smoking, and disorganization would be considered what type of response to stress? A. emotional * B. behavioral C. physiological D. social E. personal 7. What is the primary physiological stimulator of CRH? A. plasma osmolarity * B. low cortisol C. ACTH D. aldosterone E. MSH 8. During the fasting state, which one of the following is an action of cortisol to promote hepatic gluconeogenesis? * A. increase breakdown of muscle protein B. decreased release of glycerol from adipose tissue C. suppression of gluconeogenic enzymes in other tissues D. increase hepatic production of beta-hydroxybutyrate E. decrease hepatic production of beta-hydroxybutyrate 9. Which of the following is NOT linked to an increase in cortisol release? A. increase in sensitivity to norepinephrine in the vascular smooth muscle B. increase in aldosterone 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 >>

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 >>

Absorbing And Storing Energy: How The Body Controls Glucose

Absorbing And Storing Energy: How The Body Controls Glucose

Editor’s note: Physicians have a special place among the thinkers who have elaborated the argument for intelligent design. Perhaps that’s because, more than evolutionary biologists, they are familiar with the challenges of maintaining a functioning complex system, the human body. With that in mind, Evolution News is delighted to offer this series, “The Designed Body.” For the complete series, see here. Dr. Glicksman practices palliative medicine for a hospice organization. Just like a car needs the energy, in the form of gasoline, to run properly, the body needs the energy in glucose to survive. When we haven’t eaten for a while, our blood glucose level drops and our stomach is empty, causing the hunger center in our brain to tell us to eat or drink something with calories. As I have explained in my last couple of articles, the complex molecules that are in what we eat and drink enter the gastrointestinal system, where digestive enzymes break them down into simpler molecules so the body can absorb them. Carbohydrates are broken down into simple sugars, like glucose, which are then absorbed into the blood. Tissues, such as the brain and other organs, rapidly absorb some of this glucose, to be used for their immediate energy needs. However, the amount of glucose absorbed after a meal is usually much more than what the tissues can use right away, causing excess. The body is able to chemically link these excess glucose molecules together to form a carbohydrate called glycogen. Most of the glycogen in the body is made and stored in the liver, with smaller amounts in the muscles, kidneys, and other tissues. Once the liver and other tissues have filled up their glycogen stores, any excess glucose is stored as fat, apparently without limit. These tissues can use this Continue reading >>

Shared Flashcard Set

Shared Flashcard Set

Details Title Chapter 21 Description Endocrine System Total Cards 60 Subject Physiology Level Undergraduate 1 Created 04/28/2010 Click here to study/print these flashcards. Create your own flash cards! Sign up here. Additional Physiology Flashcards Cards Term Anabolism Definition or biosynthesis, is the process by which living organisms synthesize complex molecules of life from simpler ones together with catabolism, are the two series of chemical processes in cells that are, together, called metabolism requires input of energy "uphill process" Term Catabolism Definition produce smaller molecules used by the cell to synthesize larger molecules "downhill" process during which energy is released Term Describe Glucose Tranporters in the blood Definition Inside cells, glucose can be oxidized for energy which generates carbon dioxide as a waste product; provides substrates for other metabolic reactions or be converted to glycogen for storage if glucose levels in the cell decrease, glycogen can be broken down to glucose by glycogenolysis Term Describe amino acids in the blood Definition amino acids are used for the synthesis of proteins or catabolized for energy by proteolysis the proteins function as amino acid stores that can subsequently be broken down to amino acids which can then be catabolized for energy or released into the bloodstream for use by other cells Term What three metabolic pathways ar necessary for the handling of glucose Definition Glycolysis Krebs cycle Electron transport chain Term Triglycerides are transported in the bloodstream in Definition lipoproteins, small protein- and lipid- containing particles Term To facilitate entry into cells, triglycerides at the outer surface of lipoproteins are broken down by the enzyme Definition lipoprotein lipase which i Continue reading >>

Regulation Of Glycolysis And Gluconeogenesis

Regulation Of Glycolysis And Gluconeogenesis

- [Instructor] At its most simplistic level, regulation of metabolic pathways inside of the body is really just a fancy word for a balancing act that's occurring in the body. So, to illustrate this, I have a seesaw and we've been learning about two metabolic pathways: glycolysis, which is the process of breaking down glucose into pyruvate; and gluconeogenesis, which is essentially the opposite in which we start out with pyruvate and through a little bit of a different route we end up back at glucose. And when we're talking about the regulation of these particular pathways, we're essentially asking ourself, "When is glycolysis the predominant pathway and when is gluconeogenesis the predominant pathway?" The body wants to make sure that we either have a net breakdown of glucose, in the case of glycolysis, or that we have a net production of glucose, in the case of gluconeogenesis. So now the next question is, "How does the body "accomplish this balancing act?" And to answer this question, the way I like to think about it is to think about it along a spectrum. There are very fast-acting forms of regulation that take place on the order of seconds, and there are very very slow forms of regulation that can take up to hours or even days to occur. So let's talk about each of these in a little bit more detail. The major principle that helps me understand fast-acting forms of regulation is a good old principle from general chemistry: Le Chatelier's Principle. So if you remember, Le Chatelier's Principle talks about anything that's in equilibrium and it says that if there's any change to this equilibrium, let's say more products are added or reactants are taken away, the equilibrium will adjust to essentially counter that change and return the system back to equilibrium. So what d Continue reading >>

You And Your Hormones

You And Your Hormones

Where is the pancreas? The pancreas is a large gland that lies alongside the stomach and the small bowel. It is about six inches (approximately 15 cm) long and is divided into the head, body and tail. What does the pancreas do? The pancreas carries out two important roles: It makes digestive juices, which consist of powerful enzymes. These are released into the small bowel after meals to break down and digest food. It makes hormones that control blood glucose levels. The pancreas produces hormones in its 'endocrine' cells. These cells are gathered in clusters known as islets of langerhans and monitor what is happening in the blood. They then can release hormones directly into the blood when necessary. In particular, they sense when sugar (glucose) levels in the blood rise, and as soon as this happens the cells produce hormones, particularly insulin. Insulin then helps the body to lower blood glucose levels and 'store' the sugar away in fat, muscle, liver and other body tissues where it can be used for energy when required. The pancreas is very close to the stomach. As soon as food is eaten, the pancreas releases digestive enzymes into the bowel to break food down. As the food is digested, and nutrient levels in the blood rise, the pancreas produces insulin to help the body store the glucose (energy) away. Between meals, the pancreas does not produce insulin and this allows the body to gradually release stores of energy back into the blood as they are needed. Glucose levels remain very stable in the blood at all times to ensure that the body has a steady supply of energy. This energy is needed for metabolism, exercise and, in particular, to fuel the parts of the brain that 'run' on glucose. This makes sure that the body doesn't starve between meals. What hormones does th 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 >>

Glucagon - Regulation Of Blood Glucose

Glucagon - Regulation Of Blood Glucose

1. DR NILESH KATE MBBS,MD ASSOCIATE PROF DEPT. OF PHYSIOLOGY GLUCAGON 2. OBJECTIVES.  Source  Chemistry  Synthesis.  Mechanism of action  Actions of glucagon.  Applied aspects.  Blood glucose control Friday, April 8, 2016 3. WHERE IS THE PANCREAS? 4. INTRODUCTION  They constitute endocrine part of pancreas.  1-2 million islets , more in tail 5. ISLETS OF LANGERHANS  Four types of cells are present in islets. They are  A or alpha cells – secrete Glucogon  B or beta cells – secrete Insulin  D or delta cells – secrete Somatostatin  F or PP cells -- secrete Pancreatic Polypeptide 6. ENDOCRINE PANCREAS 7. ISLETS OF LANGERHANS 8. Pancreatic Hormones, Insulin & Glucagon Regulate Metabolism Beta cells produce insulin – cellular uptake of blood glucose Alpha cells produce glucagon – ↑ blood glucose (from cells) D cells produce somatostatin – ↓ gastric secretion 9. HISTOLOGICAL ORGANIZATION  B CELLS, AT THE CORE  A/D CELLS, AT THE PERIPHERY 10. GLUCAGON  Source of secretion : A cells or Alpha cells of pancreas.  Chemistry : Glucagon is a polypeptide with a molecular weight of 3500.  It has 29 amino acid. 11. SYNTHESIS  From Preproglucagon precursor by islets α cells.  Proglucagon  GLUCAGON. 12. SECRETION.  Stored in dense granules  Released by Exocytosis.  Ca is needed for exocytosis. Friday, April 8, 2016 13. PLASMA LEVELS  Circulating Glucagon – Unbound.  Basal level in Fasting – 100-150 pg/ml.  Half life – 6 min(5-9 min)  Secretion Rate 100 -150 μg/day.  Degradation – in liver & kidney Friday, April 8, 2016 14. MECHANISM OF ACTION Friday, April 8, 2016 15. ACTIONS OF GLUCAGON  Mobilization of stored nutrients  Glucose, fatty acids, ketoacids.  A Continue reading >>

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