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What Is Insulin And Its Function?

Type 2 Diabetes And Insulin

Type 2 Diabetes And Insulin

Getting Started When most people find out they have Type 2 diabetes, they are first instructed to make changes in their diet and lifestyle. These changes, which are likely to include routine exercise, more nutritious food choices, and often a lower calorie intake, are crucial to managing diabetes and may successfully lower blood glucose levels to an acceptable level. If they do not, a drug such as glyburide, glipizide, or metformin is often prescribed. But lifestyle changes and oral drugs for Type 2 diabetes are unlikely to be permanent solutions. This is because over time, the pancreas tends to produce less and less insulin until eventually it cannot meet the body’s needs. Ultimately, insulin (injected or infused) is the most effective treatment for Type 2 diabetes. There are many barriers to starting insulin therapy: Often they are psychological; sometimes they are physical or financial. But if insulin is begun early enough and is used appropriately, people who use it have a marked decrease in complications related to diabetes such as retinopathy (a diabetic eye disease), nephropathy (diabetic kidney disease), and neuropathy (nerve damage). The need for insulin should not be viewed as a personal failure, but rather as a largely inevitable part of the treatment of Type 2 diabetes. This article offers some practical guidance on starting insulin for people with Type 2 diabetes. When to start insulin Insulin is usually started when oral medicines (usually no more than two) and lifestyle changes (which should be maintained for life even if oral pills or insulin are later prescribed) have failed to lower a person’s HbA1c level to less than 7%. (HbA1c stands for glycosylated hemoglobin and is a measure of blood glucose control.) However, a recent consensus statement from Continue reading >>

Expression And Function Of The Insulin Receptor Substrate Proteins In Cancer

Expression And Function Of The Insulin Receptor Substrate Proteins In Cancer

Abstract The Insulin Receptor Substrate (IRS) proteins are cytoplasmic adaptor proteins that function as essential signaling intermediates downstream of activated cell surface receptors, many of which have been implicated in cancer. The IRS proteins do not contain any intrinsic kinase activity, but rather serve as scaffolds to organize signaling complexes and initiate intracellular signaling pathways. As common intermediates of multiple receptors that can influence tumor progression, the IRS proteins are positioned to play a pivotal role in regulating the response of tumor cells to many different microenvironmental stimuli. Limited studies on IRS expression in human tumors and studies on IRS function in human tumor cell lines and in mouse models have provided clues to the potential function of these adaptor proteins in human cancer. A general theme arises from these studies; IRS-1 and IRS-4 are most often associated with tumor growth and proliferation and IRS-2 is most often associated with tumor motility and invasion. In this review, we discuss the mechanisms by which IRS expression and function are regulated and how the IRS proteins contribute to tumor initiation and progression. Introduction The Insulin Receptor Substrate (IRS) proteins are a family of cytoplasmic adaptor proteins that were first identified for their role in insulin signaling. The first family member to be identified, IRS-1, was initially characterized as a 185 kD phosphoprotein that was detected in anti-phosphotyrosine immunoblots in response to insulin stimulation [1]. IRS-2 was discovered as an alternative insulin receptor substrate, initially named 4PS, in insulin-stimulated cells derived from Irs-1 -/- mice [2]. IRS-1 and IRS-2 are ubiquitously expressed and are the primary mediators of insulin- Continue reading >>

Insulin And Its Mechanism Of Action

Insulin And Its Mechanism Of Action

1. INSULIN AND ITS MECHANISM OF ACTION INSULIN AND ITS MECHANISM OF ACTION -Ashmita Chaudhuri B.Pharm, 4th year, 7th semester Roll- 27701910050 NSHM College Of Pharmaceutical Technology 2. INTRODUCTION: Insulin is a peptide hormone, produced by beta cells of the pancreas, and is central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, skeletal muscles, and fat tissue to absorb glucose from the blood. In the liver and skeletal muscles, glucose is stored as glycogen, and in fat cells (adipocytes) it is stored as triglycerides. When control of insulin levels fails, diabetes mellitus can result. As a consequence, insulin is used medically to treat some forms of diabetes mellitus. 3. STRUCTURE OF INSULIN  Human insulin consists of 51aa in two chains connected by 2 disulfide bridges (a single gene product cleaved into 2 chains during posttranslational modification).  T1/2~5-10 minutes, degraded by glutathione-insulin transhydrogenase (insulinase) which cleaves the disulfide links.  Bovine insulin differs by 3aa, pork insulin differs by 1aa.  Insulin is stored complex with Zn2+ions. in a 4. BIOSYNTHESIS OF INSULIN: Insulin is synthesized as preproinsulin in pancreatic β-cells. It contains a signal peptide which directs the nascent polypeptide chain to the rough endoplasmic reticulum. Then it is cleaved as the polypeptide is translocated into lumen of the RER, forming proinsulin. Proinsulin is transported to the trans-Golgi network (TGN) where immature granules are formed. Proinsulin undergoes maturation into active insulin through action of cellular endopeptidases known as prohormone convertases (PC1 and PC2), as well as the exoprotease carboxypeptidase E. The endopeptidases cleave at 2 positions, releasing a fragment c Continue reading >>

Pancreatic Hormones

Pancreatic Hormones

Pancreas is both exocrine and endocrine gland. The exocrinal part secretes pancreatic fluid into the duodenum after a meal. The endocrinal part secretes various types of hormones. These are produced by a specialized tissue in the pancreas and then released to the capillary system and reached the liver by the portal venous circulation. The specialized tissue is called islets of Langerhans. Islets of Langerhans represent approximately 1-2 % of the pancreas. Three types of cells are regonized in these islets. A cells – producing glucagon (25% of all islet cells). B cells – producing insulin (60% of all islet cells). D cells – producing somatostatin (10% of all islet cells). F cells – producing panceratic polypeptide (5% of all islet cells). Islets of Langerhans play a crucial role in carbohydrate metabolism and so in a plasma glucose concentration. It involves: Glycolysis – the anaerobic conversion of glucose to lactate. Occurs in the red blood cells, renal medulla and sceletal muscles. Glycogenesis – the synthesis of glycogen from glucose. Glucose is stored ( in liver, muscle) in the form of glycogen and this serves to maintain a constant plasma glucose concentration. Glycogenolysis – the breakdown of glycogen to glucose. Gluconeogenesis – the production of glucose from non-sugar molecules (amino acids, lactate, glycerol) Lipolysis – the breakdown of triacylglycerols into glycerol and free fatty acids. Lipogenesis – the synthesis of triacylglycerols. Pancreatic hormones are responsible for storage of fat and glucose, as glycogen, after meal. Enables the mobilisation of energy reserves as a result of food deprivation, stress, physical activity. Maintain the constant plasma glucose concentration. Promote growth. Pancreatic hormone Insulin is a peptide co Continue reading >>

All About Insulin

All About Insulin

What is insulin? Insulin is a peptide hormone secreted by the pancreas in response to increases in blood sugar, usually following a meal. However, you don’t have to eat a meal to secrete insulin. In fact, the pancreas always secretes a low level of insulin. After a meal, the amount of insulin secreted into the blood increases as blood sugar rises. Similarly, as blood sugar falls, insulin secretion by the pancreas decreases. Insulin thus acts as an “anabolic” or storage hormone. In fact, many have called insulin “the most anabolic hormone”. Once insulin is in the blood, it shuttles glucose (carbohydrates), amino acids, and blood fats into the cells of the body. If these nutrients are shuttled primarily into muscle cells, then the muscles grow and body fat is managed. If these nutrients are shuttled primarily into fat cells, then muscle mass is unchanged and body fat is increased. Insulin’s main actions Rapid (seconds) Increases transport of glucose, amino acids (among the amino acids most strongly transported are valine, leucine, isoleucine, tyrosine and phenylalanine), and potassium into insulin-sensitive cells Intermediate (minutes) Stimulates protein synthesis (insulin increases the formation of new proteins) Activates enzymes that store glycogen Inhibits protein degradation Delayed (hours) Increases proteins and other enzymes for fat storage Why is insulin so important? The pancreas releases insulin whenever we consume food. In response to insulin, cells take in sugar from the bloodstream. This ultimately lowers high blood sugar levels back to a normal range. Like all hormones, insulin has important functions, and an optimal level. Without enough insulin, you lose all of the anabolic effects, since there is not enough insulin to transport or store energy Continue reading >>

Insulin Resistance Speeds Up Cognitive Decline

Insulin Resistance Speeds Up Cognitive Decline

Mounting research suggests Alzheimer’s disease is intricately connected to insulin resistance; even mild elevation of blood sugar is associated with an elevated risk for dementia A study that followed seniors with heart disease over 20 years found those with the highest levels of insulin resistance had the worst cognitive performance and scored lowest on memory and executive function tests Insulin resistance appears to promote cognitive decline by adversely impacting the blood vessels in your brain, promoting the formation of plaques and hindering memory formation By Dr. Mercola We are facing a tsunami of Alzheimer's disease. It's often said that the underlying causes of Alzheimer's disease are unknown, but there are numerous theories. For example, research suggesting that an infectious component is at play is becoming increasingly difficult to ignore. In addition to viruses, bacteria and fungi, an infectious protein called TDP-43, which behaves like infectious proteins known as prions — responsible for the brain destruction that occurs in Mad Cow and Chronic Wasting Diseases — has been linked to the disease. Research presented at the 2014 Alzheimer's Association International Conference revealed Alzheimer's patients with TDP-43 were 10 times more likely to have been cognitively impaired at death than those without.1 Due to its similarities with Mad Cow Disease, investigators have raised the possibility that Alzheimer's disease may be linked to eating meat from animals raised in concentrated animal feeding operations (CAFOs). Mounting research also suggests Alzheimer's disease is intricately connected to insulin resistance; even mild elevation of blood sugar is associated with an elevated risk for dementia.2 Diabetes and heart disease3 are also known to elevate yo Continue reading >>

Arginine Boosts Insulin Sensitivity And Cardiovascular Function

Arginine Boosts Insulin Sensitivity And Cardiovascular Function

Arginine Improves Energy Efficiency Major age-related health problems can benefit from this amino acid nsulin is as vital a molecule as there is. We can't live without it. The older we get, though, the harder it is for our bodies to make efficient use of our precious insulin. The problem is called insulin resistance. It's a common feature of aging, but one we can combat through the enlightened application of our scientific knowledge. We have learned that there are many ways to resist insulin resistance. Number one is regular exercise, which, not at all coincidentally, is also the number one way to prevent, and often cure, a host of other ills associated with aging. Exercise is king. Number two is a healthy diet, with plenty of fresh fruits and vegetables. And number three (we don't mind being third after those two) is savvy supplementation with natural nutrients that we just don't get enough of even with a healthy diet. One such nutrient is arginine, the champion of amino acids when it comes to biochemical versatility: no other amino acid can match its broad spectrum of benefits. Now we have learned that arginine can help improve our insulin sensitivity, which is the same as diminishing our insulin resistance. We'll look at the evidence, but first, a primer on what insulin actually does. Let's start with a homely analogy. EVERYONE NEEDS HEAT ENERGY Imagine that you live in the snowy north, in a sturdy but aging house that's showing some signs of wear and tear - not everything works quite as well as it used to, and some things are in need of repair. The house is heated by a coal-fired furnace, and you've laid in a generous supply of coal, piled high for the winter. Now the fire is burning low, and the house feels a bit chilly. You need more heat. You go to the furnace, g Continue reading >>

Dictionary

Dictionary

Definition noun A polypeptide hormone secreted by the beta cells of the islets of Langerhans of the pancreas to regulate the concentration of carbohydrates in blood by promoting metabolism of glucose Supplement Insulin is released when glucose concentration in blood is high (e.g. following an intake of carbohydrate-rich diet). Insulin regulates the concentration of glucose and other sugars circulating in blood by stimulating the uptake of glucose by cells in liver, skeletal muscles and fat tissues. The lack of or inadequate insulin production results in diabetes mellitus. Thus, insulin has also been prepared pharmacologically for use in managing diabetes. In humans and other vertebrates, the pancreas is a glandular structure that has exocrine and endocrine functions. The exocrine function of the pancreas is basically the production of pancreatic juice that aids in the digestion of complex biomolecules whereas the endocrine function of the pancreas is the production of hormones such as insulin and glucagon. Its production of such hormones makes the pancreas a part of the endocrine system. The cells in the pancreas that carry out endocrine functions are the islets of Langerhans. The two major cells of the islets are the alpha cells and the beta cells. The alpha cells produce glucagon whereas the beta cells make insulin. These hormones are essential in regulating carbohydrate and fat metabolism. Insulin, in particular, regulates the metabolism of carbohydrates and fats by promoting the uptake of glucose from the bloodstream into the skeletal muscles and fat tissues to be stored as glycogen for later use in glycogenolysis. In type 1 diabetic individuals, the beta cells have become non-functional resulting in the insufficiency of insulin that regulates blood sugar levels. In Continue reading >>

Insulin And The Brain

Insulin And The Brain

In the Paleo world, we talk a lot about insulin and insulin resistance, and how diet affects metabolic health, diabetes, and other related diseases. But all that talk tends to be really focused on insulin in the bloodstream, and it ignores insulin in the brain. Insulin is one of the few chemicals that can cross the blood-brain barrier, and it’s important for appetite regulation, learning, and memory. Your brain can get insulin resistant just like your muscles or fat tissue, and insulin resistance in the brain is associated with weight gain and also degenerative brain diseases (like Alzheimer’s Disease). Insulin and the Brain Insulin is best-known as a carbohydrate storage hormone. If you eat something containing digestible carbohydrates, you’ll end up with higher blood sugar: more carbohydrates (glucose) in your bloodstream. In the long term, high blood sugar is dangerous. That glucose needs to get out of the bloodstream and preferably sooner rather than later. Enter insulin, which shuttles it off to muscle and/or fat cells as needed. It shouldn’t be surprising that insulin is important for your brain – the brain is the biggest glucose hog in your whole body. It’s the only organ that actually requires glucose. Everything else can run on fat if it has to, but for the brain, it’s glucose or bust. Even if you don’t eat any carbohydrate, your liver will turn protein into glucose (through a process called gluconeogenesis) to make sure your brain gets enough. Even if you don’t eat anything at all, your liver will break down your own muscle tissue to get protein to make glucose for your brain. This review goes over some of the major points about insulin and the brain. Unlike most substances, insulin can pass fairly easily between the bloodstream and the brain Continue reading >>

Types Of Insulin

Types Of Insulin

Insulin analogs are now replacing human insulin in the US. Insulins are categorized by differences in onset, peak, duration, concentration, and route of delivery. Human Insulin and Insulin Analogs are available for insulin replacement therapy. Insulins also are classified by the timing of their action in your body – specifically, how quickly they start to act, when they have a maximal effect and how long they act.Insulin analogs have been developed because human insulins have limitations when injected under the skin. In high concentrations, such as in a vial or cartridge, human (and also animal insulin) clumps together. This clumping causes slow and unpredictable absorption from the subcutaneous tissue and a dose-dependent duration of action (i.e. the larger dose, the longer the effect or duration). In contrast, insulin analogs have a more predictable duration of action. The rapid acting insulin analogs work more quickly, and the long acting insulin analogs last longer and have a more even, “peakless” effect. Background Insulin has been available since 1925. It was initially extracted from beef and pork pancreases. In the early 1980’s, technology became available to produce human insulin synthetically. Synthetic human insulin has replaced beef and pork insulin in the US. And now, insulin analogs are replacing human insulin. Characteristics of Insulin Insulins are categorized by differences in: Onset (how quickly they act) Peak (how long it takes to achieve maximum impact) Duration (how long they last before they wear off) Concentration (Insulins sold in the U.S. have a concentration of 100 units per ml or U100. In other countries, additional concentrations are available. Note: If you purchase insulin abroad, be sure it is U100.) Route of delivery (whether they a Continue reading >>

Nutrient Intake And Hormonal Control Of Insulin Action

Nutrient Intake And Hormonal Control Of Insulin Action

Insulin and Metabolism Insulin is a major metabolism regulating hormone secreted by β-cells of the islets of Langerhans of the pancreas. The major function of insulin is to counter the concerted actions of a number of hyperglycemia-generating hormones and to maintain low blood glucose levels. In addition to its role in regulating glucose metabolism, insulin stimulates lipogenesis, diminishes lipolysis, and increases amino acid transport into cells. Because there are numerous hyperglycemic hormones, untreated disorders associated with insulin generally lead to severe hyperglycemia and shortened life span. Insulin as Growth Factor Insulin also exerts activities typically associated with growth factors. Insulin is a member of a family of structurally and functionally similar molecules that includes the insulin-like growth factors (IGF-1 and IGF-2), and relaxin. The tertiary structure of all four molecules is similar, and all have growth-promoting activities. Insulin modulates transcription and stimulates protein translocation, cell growth, DNA synthesis, and cell replication, effects that it holds in common with the insulin-like growth factors and relaxin. back to the top Insulin is synthesized, from the INS gene, as a preprohormone in the β-cells of the islets of Langerhans. The INS gene is located on chromosome 11p15.5 and is composed of 3 exons that generate four alternatively spliced mRNAs, all of which encode the same 110 amino acid preproprotein. The signal peptide of preproinsulin is removed in the cisternae of the endoplasmic reticulum. The insulin proprotein is packaged into secretory vesicles in the Golgi, folded into its native structure, and locked in this conformation by the formation of two disulfide bonds. Specific protease activity cleaves the center thir Continue reading >>

What Is Insulin?

What Is Insulin?

Insulin is a hormone; a chemical messenger produced in one part of the body to have an action on another. It is a protein responsible for regulating blood glucose levels as part of metabolism.1 The body manufactures insulin in the pancreas, and the hormone is secreted by its beta cells, primarily in response to glucose.1 The beta cells of the pancreas are perfectly designed "fuel sensors" stimulated by glucose.2 As glucose levels rise in the plasma of the blood, uptake and metabolism by the pancreas beta cells are enhanced, leading to insulin secretion.1 Insulin has two modes of action on the body - an excitatory one and an inhibitory one:3 Insulin stimulates glucose uptake and lipid synthesis It inhibits the breakdown of lipids, proteins and glycogen, and inhibits the glucose pathway (gluconeogenesis) and production of ketone bodies (ketogenesis). What is the pancreas? The pancreas is the organ responsible for controlling sugar levels. It is part of the digestive system and located in the abdomen, behind the stomach and next to the duodenum - the first part of the small intestine.4 The pancreas has two main functional components:4,5 Exocrine cells - cells that release digestive enzymes into the gut via the pancreatic duct The endocrine pancreas - islands of cells known as the islets of Langerhans within the "sea" of exocrine tissue; islets release hormones such as insulin and glucagon into the blood to control blood sugar levels. Islets are highly vascularized (supplied by blood vessels) and specialized to monitor nutrients in the blood.2 The alpha cells of the islets secrete glucagon while the beta cells - the most abundant of the islet cells - release insulin.5 The release of insulin in response to elevated glucose has two phases - a first around 5-10 minutes after g Continue reading >>

Insulin

Insulin

Insulin is a small peptide (protein) consisting of fifty-one amino acids synthesized and stored within the pancreas, an organ situated behind the stomach. The protein itself consists of two chains, denoted A and B, linked by disulfide (sulfur-sulfur) bridges between cysteine residues (see Figure 1). Insulin is a hormone, a chemical transported in the blood that controls and regulates the activity of certain cells or organs in the body. When blood sugar levels rise following a meal, the pancreas is stimulated to release insulin into the bloodstream. In order for tissues to absorb glucose from the blood, they must first bind insulin. Glucose metabolism is necessary for cell growth and energy needs associated with cell function. When insulin binds to receptors on cell membranes, glucose transporter proteins are released from within the cell to the surface of the cell membrane. Once on the exterior surface of cells, glucose transporters can carry sugar from the blood into the tissue where it is metabolized. Without insulin, cells cannot absorb glucose and effectively starve. A deficiency in insulin production results in a condition called diabetes mellitus. Approximately 6.2 percent of the population in the United States is affected with diabetes. Type 1 diabetics account for 10 percent of those individuals suffering from diabetes mellitus. It is also known as juvenile diabetes and generally develops in young people, typically between the ages of ten and fifteen years, as a result of an autoimmune disorder. Why the body's immune system turns on itself, attacking and destroying beta cells, the pancreatic cells in which insulin is synthesized, is not clear. The unfortunate consequence is insulin deficiency. The majority of individuals afflicted with diabetes mellitus suffer f Continue reading >>

Diabetes And Insulin

Diabetes And Insulin

On this page: Diabetes mellitus (diabetes) is a chronic and potentially life-threatening condition where the body loses its ability to produce insulin, or begins to produce or use insulin less efficiently, resulting in blood glucose levels that are too high (hyperglycaemia). Blood glucose levels above the normal range , over time, can damage your eyes, kidneys and nerves, and can also cause heart disease and stroke. An estimated 280 Australians develop diabetes every day. Diabetes is Australia's fastest-growing chronic disease. The main types of diabetes are type 1, type 2, and gestational diabetes. Type 1 diabetes Type 1 diabetes develops when the cells of the pancreas stop producing insulin. Without insulin, glucose cannot enter the cells of the muscles for energy. Instead the glucose rises in the blood causing a person to become extremely unwell. Type 1 diabetes is life threatening if insulin is not replaced, and people need to inject insulin for the rest of their lives. Type 1 diabetes often occurs in children and people under 30 years of age, but it can occur at any age. This condition is not caused by lifestyle factors. Its exact cause is not known but research shows that something in the environment such as the rubella virus can trigger it in a person that has a genetic risk. The body’s immune system attacks and destroys the beta cells of the pancreas after the person gets a virus because it sees the cells as foreign. Most people diagnosed with type 1 diabetes do not have family members with this condition. For more information about symptoms, visit the Diabetes type 1 fact sheet. Type 2 diabetes Type 2 diabetes develops when the pancreas does not make enough insulin and the insulin that is made does not work as well as it should (also known as insulin resistan Continue reading >>

114 17.9 The Endocrine Pancreas

114 17.9 The Endocrine Pancreas

Learning Objectives By the end of this section, you will be able to: Describe the location and structure of the pancreas, and the morphology and function of the pancreatic islets Compare and contrast the functions of insulin and glucagon The pancreas is a long, slender organ, most of which is located posterior to the bottom half of the stomach (Figure 1). Although it is primarily an exocrine gland, secreting a variety of digestive enzymes, the pancreas has an endocrine function. Its pancreatic islets—clusters of cells formerly known as the islets of Langerhans—secrete the hormones glucagon, insulin, somatostatin, and pancreatic polypeptide (PP). Figure 1. Pancreas. The pancreatic exocrine function involves the acinar cells secreting digestive enzymes that are transported into the small intestine by the pancreatic duct. Its endocrine function involves the secretion of insulin (produced by beta cells) and glucagon (produced by alpha cells) within the pancreatic islets. These two hormones regulate the rate of glucose metabolism in the body. The micrograph reveals pancreatic islets. LM × 760. (Micrograph provided by the Regents of University of Michigan Medical School © 2012) View the University of Michigan WebScope at to explore the tissue sample in greater detail. View the University of Michigan WebScope at to explore the tissue sample in greater detail. Cells and Secretions of the Pancreatic Islets The pancreatic islets each contain four varieties of cells: The alpha cell produces the hormone glucagon and makes up approximately 20 percent of each islet. Glucagon plays an important role in blood glucose regulation; low blood glucose levels stimulate its release. The beta cell produces the hormone insulin and makes up approximately 75 percent of each islet. Elevated Continue reading >>

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