diabetestalk.net

How Does Insulin Signal The Cell To Take In Glucose?

Blood Glucose Regulation

Blood Glucose Regulation

Blood glucose regulation involves maintaining blood glucose levels at constant levels in the face of dynamic glucose intake and energy use by the body. Glucose, shown in figure 1 is key in the energy intake of humans. On average this target range is 60-100 mg/dL for an adult although people can be asymptomatic at much more varied levels. In order to maintain this range there are two main hormones that control blood glucose levels: insulin and glucagon. Insulin is released when there are high amounts of glucose in the blood stream. Glucagon is released when there are low levels of glucose in the blood stream. There are other hormones that effect glucose regulation and are mainly controlled by the sympathetic nervous system. Blood glucose regulation is very important to the maintenance of the human body. The brain doesn’t have any energy storage of its own and as a result needs a constant flow of glucose, using about 120 grams of glucose daily or about 60% of total glucose used by the body at resting state. [1] With out proper blood glucose regulation the brain and other organs could starve leading to death. Insulin A key regulatory pathway to control blood glucose levels is the hormone insulin. Insulin is released from the beta cells in the islets of Langerhans found in the pancreas. Insulin is released when there is a high concentration of glucose in the blood stream. The beta cells know to release insulin through the fallowing pathway depicted in figure 2. [2,3]Glucose enters the cell and ATP is produce in the mitochondria through the Krebs cycle and electron transport chain. This increase in ATP causes channels to closes. These channels allow potassium cations to flow into the cell. [2,3,]With these channels closed the inside of the cell becomes more negative causin Continue reading >>

Insulin Signaling And The Regulation Of Glucose Transport

Insulin Signaling And The Regulation Of Glucose Transport

Go to: GLUT4 TRANSLOCATION OCCURS IN MULTIPLE STAGES In the absence of insulin, Glut4 slowly recycles between the plasma membrane and vesicular compartments within the cell, where most of the Glut4 resides. Insulin stimulates the translocation of a pool of Glut4 to the plasma membrane, through a process of targeted exocytosis (4,5) (Figure 1). At the same time, Glut4 endocytosis is attenuated (6,7). Thus, the rate of glucose transport into fat and muscle cells is governed by the concentration of Glut4 at the cell surface and the duration for which the protein is maintained at this site. There is substantial evidence that Glut4 exists in specialized vesicles sequestered within the cell, but the precise intracellular location and trafficking pathways of these vesicles are unclear. Following internalization, Glut4 is localized into tubulovesicular and vesicular structures that are biochemically distinct from but possibly interacting with the recycling endosomal network (8). In adipocytes, these vesicles are retained in a perinuclear region in the cell via an unknown mechanism that might involve a tethering protein (9) or continuous futile recycling (10). The Glut4 compartment is enriched in the v-SNARE (soluble N-ethylmaleimide sensitive factor attachment protein) protein VAMP2 (vesicle-associated membrane protein 2) but not the related VAMP3/cellubrevin isoform that is present in recycling endosome (11). Consistent with these data, ablation of transferrin receptor containing endosomes does not impair insulin-stimulated Glut4 translocation (12). The microtubule network and actin cytoskeleton play a role in Glut4 trafficking, either by linking signaling components or by directing movement of vesicles from the perinuclear region to the plasma membrane in response to insulin. Continue reading >>

Glucose Insulin And Diabetes

Glucose Insulin And Diabetes

Every cell in the human body needs energy to survive and do its different functions. If we're talking about a brain cell, it needs energy to keep stimulating other brain cells and sending on signals and messages. If it's a muscle cell, it needs energy to contract. They need energy just to do the basic functions of a cell. And the place that they get that energy from, or the primary source of that energy, is from glucose. Glucose is a simple sugar. If you were to actually taste glucose, it would taste sweet. And glucose gets delivered to cells through the bloodstream. So this right here, I'm drawing some blood that's passing by a cell. Maybe the blood is going in that direction over there. And inside the blood, let me draw some small glucose molecules passing by. And so in an ideal situation, when a cell needs energy, glucose will enter the cell. Unfortunately, it's not that simple for the great majority of cells in the human body. The glucose won't enter by itself. It needs the assistance of a hormone or a molecule called insulin. So let me label all of these. This right here is the glucose, and it needs insulin. So let me draw insulin as these magenta molecules right over here. That over there, that is insulin. And the surface of the cells, they have insulin receptors on them. And I'm just drawing very simplified versions of them, kind of a place where these magenta circles can attach, can bind. And what happens is, in order for the glucose to be taken up by the cell, insulin has to attach to these receptors, which unlocks the channels for glucose. In order for the glucose to go in, insulin has to bind to the insulin receptors. And then, once that happens, then the glucose can be taken up by the cell. Now, unfortunately, things don't always work as planned. So let me d Continue reading >>

An Overview

An Overview

Nearly 400 million people worldwide are living with diabetes, and that number is expected to jump to almost 600 million by 2035, according to the International Diabetes Federation. For many people, diabetes can be controlled with diet, exercise and, often, insulin or other drugs. However, complications from diabetes can be serious and include kidney failure, nerve damage, vision loss, heart disease and a host of other health issues. In this section: What is diabetes? How is diabetes treated? How are we using stem cells to understand diabetes? What is the potential for stem cells to treat diabetes? At its most basic, diabetes is a condition in which the body cannot regulate or properly use sugar (called glucose) in the blood. The pancreas, which helps the small intestine digest food, has hundreds of thousands of cell clusters called islets of Langerhans where beta cells live. Beta cells produce insulin, which is released into the bloodstream when blood sugar levels reach a certain threshold. The insulin signals other cells in the body to take up sugar, the primary energy source for all the body’s cells. Type 1, also known as juvenile diabetes. In type 1 diabetes, the body’s immune system attacks the beta cells in the pancreas. When the beta cells are damaged, they don’t produce insulin, or at least not enough insulin. Other cells never get the signal to take up sugar, so they don’t get the energy they need to function properly, and high sugar levels in the blood end up causing damage to the kidneys, eyes, nervous system and other organs. Type 2 diabetes, also called adult-onset diabetes. In type 2 diabetes, cells in the body become resistant to insulin. They don’t respond to the signals insulin sends out, so they don’t take up sugar from the blood. The beta c 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 >>

How Fat Cells Work

How Fat Cells Work

In the last section, we learned how fat in the body is broken down and rebuilt into chylomicrons, which enter the bloodstream by way of the lymphatic system. Chylomicrons do not last long in the bloodstream -- only about eight minutes -- because enzymes called lipoprotein lipases break the fats into fatty acids. Lipoprotein lipases are found in the walls of blood vessels in fat tissue, muscle tissue and heart muscle. Insulin When you eat a candy bar or a meal, the presence of glucose, amino acids or fatty acids in the intestine stimulates the pancreas to secrete a hormone called insulin. Insulin acts on many cells in your body, especially those in the liver, muscle and fat tissue. Insulin tells the cells to do the following: The activity of lipoprotein lipases depends upon the levels of insulin in the body. If insulin is high, then the lipases are highly active; if insulin is low, the lipases are inactive. The fatty acids are then absorbed from the blood into fat cells, muscle cells and liver cells. In these cells, under stimulation by insulin, fatty acids are made into fat molecules and stored as fat droplets. It is also possible for fat cells to take up glucose and amino acids, which have been absorbed into the bloodstream after a meal, and convert those into fat molecules. The conversion of carbohydrates or protein into fat is 10 times less efficient than simply storing fat in a fat cell, but the body can do it. If you have 100 extra calories in fat (about 11 grams) floating in your bloodstream, fat cells can store it using only 2.5 calories of energy. On the other hand, if you have 100 extra calories in glucose (about 25 grams) floating in your bloodstream, it takes 23 calories of energy to convert the glucose into fat and then store it. Given a choice, a fat cell w Continue reading >>

About Diabetes

About Diabetes

How Diabetes Develops After eating a meal, the food is broken down by the digestive system and blood sugar (or glucose) rises. The pancreas is an organ near the stomach, which produces a hormone called insulin. With the help of insulin, the body's cells take up the glucose and use it for energy. When your body does not produce enough insulin and/or does not efficiently use the insulin it produces, sugar levels rise in the bloodstream. When this happens, it can cause two problems: Right away, the body's cells may be starved for energy. Over time, high blood glucose levels may damage the eyes, kidneys, nerves or heart. Types of Diabetes There are two main types of diabetes: type 1 diabetes and type 2 diabetes. A family history of diabetes can significantly increase a person's risk of developing the condition. Type 1 Diabetes Type 1 diabetes is a serious condition that occurs when the pancreas makes little or no insulin. Without insulin, the body is unable to take the glucose (blood sugar) it gets from food into cells to fuel the body. People with type 1 diabetes must take daily insulin or other medications daily. For that reason, this type of diabetes is also referred to as insulin-dependent diabetes. Type 1 diabetes was previously known as juvenile diabetes because it's usually diagnosed in children and young adults. However, this chronic, lifelong disease can strike at any age, and those with a family history of type 1 diabetes have a greater risk. Health Risks for Type 1 Diabetes During the development of type 1 diabetes, the body's immune system attacks certain cells (called beta cells) in the pancreas. Although the reasons this occurs are still unknown, the effects are clear. Once these cells are destroyed, the pancreas produces little or no insulin, so the glucose s Continue reading >>

Myth: Insulin Is Needed For Glucose Uptake

Myth: Insulin Is Needed For Glucose Uptake

Abstract: Despite evidence to the contrary, there is a widespread misconception that cells cannot take up glucose without insulin. It is believed that these starving cells, by their inability to absorb glucose, cause hyperglycemia (high blood sugar). This brief review of the available scientific literature intends simply to show that 1) considerable glucose uptake occurs independently of insulin, 2) that hyperglycemia is not caused by cells unable to import glucose, 3) AND lastly THAT CELLS ARE NOT STARVING DURING HYPERGLYCEMIA. Important: this text discusses the underlying mechanisms of glucose uptake. It has little clinical significance. Diabetics should continue to use insulin as prescribed by their doctor. As a medical student, i’ve been taught that cells need insulin to absorb glucose. Insulin causes a glucose transporter (glut) to rise to the cell surface. This transporter creates a channel for glucose to flow through. There are about 13 different gluts, and the one that needs insulin is glut4 (possibly 12, also). According to the misconception, glut4 is required for glucose uptake, and that is why insulin is necessary. Without insulin, there will be no glut4, and so we’re told that the cell cannot consume glucose, which causes glucose to build up in the blood – hyperglycemia. This is demonstrably false, as many experiments have shown. While insulin does impact absorption by doubling the glucose uptake speed, we’ll see that it is not required. 1 While it is true that glut4 is largely insulin dependent, it has almost a dozen brothers that function quite well without insulin. 2 take, for example, glut1. It’s nearly everywhere in the body, all the time, and it’s as powerful as the glut4. Glut1 is the day-to-day glucose transporter responsible for basal gl Continue reading >>

Glucose Transporters, Insulin, And Diabetes

Glucose Transporters, Insulin, And Diabetes

Sort Describe how insulin-dependent GLUT-4 transporters function (8 steps)? 1) insulin binds to insulin receptors 2) cytoplasmic side of the receptor phosphorylates itself 3) signal transduction pathway is activated 4) GLUT-4 transporters are lying in wait in cytoplasmic vesicles 5) signal transduction pathway leads to rapid fusion of GLUT-4 containing vesicles with the membrane 6) more GLUT-4 receptors allow glucose to be taken in more rapidly 7) glucose level drops in the bloodstream and interstitial fluid 8) Glut-4 transporters are brought back in to cell via endocytosis What is hyperglycemia and what are some of the major symptoms? Abnormally high blood glucose Symptoms: *excessive thirst *excessive urination *retina and kidney damage *capillaries get destroyed *nerve damage *diabetic shock, coma and death What is hypoglycemia and what are some of the major symptoms? abnormally low blood glucose *normally from insulin overdoes in type 2 diabetes *dizziness *disorientation *nausea *faintness *loss of consciousness *death Continue reading >>

Diabetes: What’s Insulin Resistance Got To Do With It?

Diabetes: What’s Insulin Resistance Got To Do With It?

Invisible changes in the body begin long before a person is diagnosed with type 2 diabetes. That’s both bad news (no symptoms mean you won’t know you have it) and good news (you can prevent or delay it if you’re at risk). One of the most important unseen changes? Insulin resistance. Insulin in a Nutshell Insulin is a key player in developing type 2 diabetes. This vital hormone—you can’t survive without it—regulates blood sugar (glucose) in the body, a very complicated process. Here are the high points: The food you eat is broken down into glucose. Glucose enters your bloodstream, which signals the pancreas to release insulin. Insulin helps glucose enter the body’s cells so it can be used for energy. Insulin also signals the liver to store glucose for later use. Glucose enters cells, and glucose levels in the bloodstream decrease, signaling insulin to decrease too. Lower insulin levels alert the liver to release stored glucose so energy is always available, even if you haven’t eaten for a while. That’s when everything works smoothly. But this finely tuned system can quickly get out of whack, as follows: A lot of glucose enters the bloodstream. The pancreas pumps out more insulin to get glucose into cells. Over time, cells stop responding to all that insulin—they’ve become insulin resistant. The pancreas keeps making more insulin to try to make cells respond. Eventually, the pancreas can’t keep up, and glucose keeps rising. Now What? Lots of glucose in the bloodstream is very damaging to the body and needs to be moved into cells as soon as possible. There’s lots of insulin, too, telling the liver and muscles to store glucose. When they’re full, the liver sends the excess glucose to fat cells to be stored as body fat. Yep, weight gain. And what Continue reading >>

The Role Of Insulin In The Body

The Role Of Insulin In The Body

Tweet Insulin is a hormone which plays a key role in the regulation of blood glucose levels. A lack of insulin, or an inability to adequately respond to insulin, can each lead to the development of the symptoms of diabetes. In addition to its role in controlling blood sugar levels, insulin is also involved in the storage of fat. Insulin is a hormone which plays a number of roles in the body’s metabolism. Insulin regulates how the body uses and stores glucose and fat. Many of the body’s cells rely on insulin to take glucose from the blood for energy. Insulin and blood glucose levels Insulin helps control blood glucose levels by signaling the liver and muscle and fat cells to take in glucose from the blood. Insulin therefore helps cells to take in glucose to be used for energy. If the body has sufficient energy, insulin signals the liver to take up glucose and store it as glycogen. The liver can store up to around 5% of its mass as glycogen. Some cells in the body can take glucose from the blood without insulin, but most cells do require insulin to be present. Insulin and type 1 diabetes In type 1 diabetes, the body produces insufficient insulin to regulate blood glucose levels. Without the presence of insulin, many of the body’s cells cannot take glucose from the blood and therefore the body uses other sources of energy. Ketones are produced by the liver as an alternative source of energy, however, high levels of the ketones can lead to a dangerous condition called ketoacidosis. People with type 1 diabetes will need to inject insulin to compensate for their body’s lack of insulin. Insulin and type 2 diabetes Type 2 diabetes is characterised by the body not responding effectively to insulin. This is termed insulin resistance. As a result the body is less able to t Continue reading >>

Insulin And Student Response Sheet

Insulin And Student Response Sheet

1. In the space below, properly document each of the three sources you found that show how insulin signals a cell to take in glucose from the blood. Under each documented source, write an explanation of why it is a legitimate and reliable source of information about insulin and its effects on cells. R, Bowen. (2009, August). Physiological Effect of Insulin. Colostate. Retrieved from This source is legitimate because the information is up to date until 2009 and has an author. Also there are very few ads and the sponsor is popular for their knowledge. There is also a contact information, if you have any comments or anything to correct. Insulin and Glucose Regulation (n.d.). In bcs.whfreeman. from This source is legitimate because the sponsor is popular for their tutorials. The site is knowledgeable and has no errors, a lot of info, and there’s also a quiz to see if you learned what you read. Jagoda, Robin. (2011, March). How Does Insulin Signal a Cell to Take in Glucose From the Blood?. Livestrong Foundation. Retrieved from This source is legitimate because it has an author and also citations on where they got the information from. Very few ads, but no errors and there’s also a comment box, where you can comment the mistakes they made if there was any. 2. Take notes on the relationship between insulin and glucose. Draw sketches or diagrams if necessary. Glucose is the main source of energy and insulin is the key to body cells. Both work together to give energy to the body cells. The insulin opens the door of the body cells for the glucose to enter the body. If the body does not produce insulin then the body cells won’t be able to get any glucose and it means that they have type 1 diabetes. If the insulin cannot unlock the body cells door then that means that they ha Continue reading >>

Insulin Signal Transduction Pathway

Insulin Signal Transduction Pathway

The insulin transduction pathway is a biochemical pathway by which insulin increases the uptake of glucose into fat and muscle cells and reduces the synthesis of glucose in the liver and hence is involved in maintaining glucose homeostasis. This pathway is also influenced by fed versus fasting states, stress levels, and a variety of other hormones. When carbohydrates are consumed, digested, and absorbed the pancreas senses the subsequent rise in blood glucose concentration and releases insulin to promote an uptake of glucose from the blood stream. When insulin binds to the insulin receptor, it leads to a cascade of cellular processes that promote the usage or, in some cases, the storage of glucose in the cell. The effects of insulin vary depending on the tissue involved, e.g., insulin is most important in the uptake of glucose by muscle and adipose tissue. This insulin signal transduction pathway is composed of trigger mechanisms (e.g., autophosphorylation mechanisms) that serve as signals throughout the cell. There is also a counter mechanism in the body to stop the secretion of insulin beyond a certain limit. Namely, those counter-regulatory mechanisms are glucagon and epinephrine. The process of the regulation of blood glucose (also known as glucose homeostasis) also exhibits oscillatory behavior. On a pathological basis, this topic is crucial to understanding certain disorders in the body such as diabetes, hyperglycemia and hypoglycemia. Transduction pathway[edit] The functioning of a signal transduction pathway is based on extra-cellular signaling that in turn creates a response which causes other subsequent responses, hence creating a chain reaction, or cascade. During the course of signaling, the cell uses each response for accomplishing some kind of a purpose al Continue reading >>

Save Time And Improve Your Marks With Cite This For Me

Save Time And Improve Your Marks With Cite This For Me

10,587 students joined last month! ✔ Save your bibliographies for longer ✔ Super fast and accurate citation program ✔ Save time when referencing ✔ Make your student life easy and fun ✔ Pay only once with our Forever plan ✔ Use our extensive Premium features (Plagiarism checks, Word Add On...) ✔ Create and edit multiple bibliographies Continue reading >>

Insulin Signaling Pathways

Insulin Signaling Pathways

Cellular responses to insulin include the regulation of blood sugar levels by increased glucose uptake in muscle and fat; increased storage of energy reserves in fat, liver and muscle through the stimulation of lipogenesis, glycogen synthesis and protein synthesis; decreased glucose production by the liver and inhibition of the mobilization of stored energy reserves via lipolysis, glycogenolysis or protein breakdown. Insulin also acts as a growth factor and stimulates cell growth, differentiation and survival. Aberrant signaling by the insulin receptor exon 11 minus isoform (IR-A), which binds IGF-II with high affinity, is associated with some cancers. The 1992 Nobel Prize in Physiology or Medicine was awarded to Edwin Krebs and Edmond Fischer for their discovery that reversible phosphorylation of proteins is the key regulatory process in the transmission of signals that impinge on cells[1][2]. That signaling pathways involve cascades of phosphorylation (by kinases) and dephosphorylation (by phosphatases) has been shown to be true not only for signaling by insulin and other growth factors, but for other types of stimuli as well. Insulin receptor signaling starts with the autophosphorylation of key tyrosine residues in the intracellular region of the IR, generating phosphotyrosine docking sites for various proteins containing SH2 (Src-homology-2) domains or PTB (phosphotyrosine binding) domains. These docked substrates include enzymes and adaptors such as IRS proteins and Shc. Insulin signaling is downregulated by internalization of the insulin/IR complex leading to dissociation and degradation of insulin in the intracellular endosome/lysosome system, inactivation of the autophosphorylated IR by the phosphatase PTP1B and recycling of the inactivated IR back to the plasma Continue reading >>

More in insulin