Understanding Our Bodies: Insulin
Almost everyone has heard of Insulin. You probably know that people with type 1 diabetes need to inject themselves with insulin to survive, and must constantly monitor the amount of sugar they eat. But what do you really know about insulin? What is its purpose in the body, and why do we need it? How does it relate to our diets? What happens when things go wrong with it? And why should anyone who doesn’t have diabetes give a hoot? Insulin is one of the most important hormones in the human body, and yet most people don’t really understand why our bodies make it or how what we eat affects the levels of insulin we produce. More so than any other hormone, our diet is key in regulating insulin levels, and thus a number of biological processes. As you’ll soon see, everyone should think about how what they eat impacts their body’s insulin release to be at their happiest and healthiest. Why We Need Insulin Every living thing requires energy to survive. In cells, energy is stored and shuttled around using a molecule called Adenosine Tri-Phosphate, or ATP. Whenever the cell then has an energy-requiring reaction, enzymes can use the energy stored in ATP’s phosphate bonds to fuel it. Cells rely on ATP to survive, and to create ATP, they rely on glucose. All cells, from bacteria and fungi to us, take glucose and use it to generate ATP by a process called Oxidative Phosphorylation. First, glucose is converted to an intermediate molecule called pyruvate via a process called glycolosis. As long as there is oxygen around, this pyruvate is further converted to Acetyl CoA, which enters a cycle of reactions called the Citric Acid Cycle. This takes the carbon to carbon bonds and uses them to create high energy electrons, which are then passed down a chain of enzymes which use the e Continue reading >>
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 >>
- American Diabetes Association® Releases 2018 Standards of Medical Care in Diabetes, with Notable New Recommendations for People with Cardiovascular Disease and Diabetes
- Leeds diabetes clinical champion raises awareness of gestational diabetes for World Diabetes Day
- Diabetes doctors: Which specialists treat diabetes?
Facts About Diabetes And Insulin
Diabetes is a very common disease, which, if not treated, can be very dangerous. There are two types of diabetes. They were once called juvenile-onset diabetes and adult diabetes. However, today we know that all ages can get both types so they are simply called type 1 and type 2 diabetes. Type 1, which occurs in approximately 10 percent of all cases, is an autoimmune disease in which the immune system, by mistake, attacks its own insulin-producing cells so that insufficient amounts of insulin are produced - or no insulin at all. Type 1 affects predominantly young people and usually makes its debut before the age of 30, and most frequently between the ages of 10 and 14. Type 2, which makes up the remaining 90 percent of diabetes cases, commonly affects patients during the second half of their lives. The cells of the body no longer react to insulin as they should. This is called insulin resistance. In the early 1920s, Frederick Banting, John Macleod, George Best and Bertram Collip isolated the hormone insulin and purified it so that it could be administered to humans. This was a major breakthrough in the treatment of diabetes type 1. Insulin Insulin is a hormone. Hormones are chemical substances that regulate the cells of the body and are produced by special glands. The hormone insulin is a main regulator of the glucose (sugar) levels in the blood. Insulin is produced in the pancreas. To be more specific, it's produced by the beta cells in the islets of Langerhans in the pancreas. When we eat, glucose levels rise, and insulin is released into the bloodstream. The insulin acts like a key, opening up cells so they can take in the sugar and use it as an energy source. Sugar is one of the top energy sources for the body. The body gets it in many forms, but mainly as carbohydr Continue reading >>
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 >>
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 >>
- Effects of resveratrol on glucose control and insulin sensitivity in subjects with type 2 diabetes: systematic review and meta-analysis
- Effects of resveratrol on glucose control and insulin sensitivity in subjects with type 2 diabetes: systematic review and meta-analysis
- Postprandial Blood Glucose Is a Stronger Predictor of Cardiovascular Events Than Fasting Blood Glucose in Type 2 Diabetes Mellitus, Particularly in Women: Lessons from the San Luigi Gonzaga Diabetes Study
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 >>
- Postprandial Blood Glucose Is a Stronger Predictor of Cardiovascular Events Than Fasting Blood Glucose in Type 2 Diabetes Mellitus, Particularly in Women: Lessons from the San Luigi Gonzaga Diabetes Study
- Antidepressant Medication as a Risk Factor for Type 2 Diabetes and Impaired Glucose Regulation
- Body temperature regulation in diabetes
G-protein-coupled Receptors, Pancreatic Islets, And Diabetes
© 2010 Nature Education All rights reserved. Figure Detail Following a meal, glucose levels in the blood circulation increase. Multiple factors regulate the level of glucose in the blood, and central among these are insulin and glucagon. Glucose is taken up into pancreatic beta cells through a glucose transporter called GLUT2 (Figure 1). As glucose is taken up into beta cells, it is metabolized, which leads to an increased production of ATP. This, in turn, increases the ATP/ADP ratio, which results in closing of potassium channels in the cell membrane and subsequent depolarization of the cell. As potassium channels close and cell depolarization increases, this causes calcium channels in the cell membrane to open and allow the flow of calcium into the cell. This accumulation of calcium causes the secretion of insulin into the blood by particular cells in the islet called beta cells. Subsequently, insulin circulates and acts on cells in a variety of tissues. Important among these are fat, muscle, and liver. Insulin binds to a receptor for insulin in the plasma membrane of the cells in these tissues, and stimulates intracellular signaling pathways that ultimately cause the translocation of glucose transporters (GLUT4 in the case of fat and muscle cells) to the cell membrane. These transporters increase glucose uptake into the cell. In fat and muscle cells, glucose normally serves as an important source of energy which can be converted into fat or glycogen (as a form of stored energy) if necessary. In liver cells, an important function is to produce glucose (either by the breakdown of glycogen or de novo synthesis of glucose). The binding of insulin to its receptor on liver cells leads to increased synthesis of glycogen and inhibition of glucose production by liver cells. Continue reading >>
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 >>
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 >>
Problems With Sugars
(See related pages) View the animation below, then complete the quiz to test your knowledge of the concept. A) breaks down glucose in the blood. B) releases glucose from cells. C) allows cells to take in glucose. D) prevents cells from taking in glucose. 2 Individuals with type I diabetes A) are allergic to insulin. B) do not produce insulin. C) overproduce insulin. D) do not respond to insulin. 3 Individuals with type II diabetes C) overproduce insulin. 4 Type I diabetes in obese patients can be treated with metformin. 5 Type II diabetes can be treated with injection of insulin. Continue reading >>
What Is Glucose?
Glucose comes from the Greek word for "sweet." It's a type of sugar you get from foods you eat, and your body uses it for energy. As it travels through your bloodstream to your cells, it's called blood glucose or blood sugar. Insulin is a hormone that moves glucose from your blood into the cells for energy and storage. People with diabetes have higher-than-normal levels in their blood. Either they don't have enough insulin to move it through or their cells don't respond to insulin as well as they should. High blood glucose for a long period of time can damage your kidneys, eyes, and other organs. How Your Body Makes Glucose It mainly comes from foods rich in carbohydrates, like bread, potatoes, and fruit. As you eat, food travels down your esophagus to your stomach. There, acids and enzymes break it down into tiny pieces. During that process, glucose is released. It goes into your intestines where it's absorbed. From there, it passes into your bloodstream. Once in the blood, insulin helps glucose get to your cells. Energy and Storage Your body is designed to keep the level of glucose in your blood constant. Beta cells in your pancreas monitor your blood sugar level every few seconds. When your blood glucose rises after you eat, the beta cells release insulin into your bloodstream. Insulin acts like a key, unlocking muscle, fat, and liver cells so glucose can get inside them. Most of the cells in your body use glucose along with amino acids (the building blocks of protein) and fats for energy. But it's the main source of fuel for your brain. Nerve cells and chemical messengers there need it to help them process information. Without it, your brain wouldn't be able to work well. After your body has used the energy it needs, the leftover glucose is stored in little bundles Continue reading >>
- Exercise and Glucose Metabolism in Persons with Diabetes Mellitus: Perspectives on the Role for Continuous Glucose Monitoring
- Postprandial Blood Glucose Is a Stronger Predictor of Cardiovascular Events Than Fasting Blood Glucose in Type 2 Diabetes Mellitus, Particularly in Women: Lessons from the San Luigi Gonzaga Diabetes Study
- Exercise and Blood Glucose Levels
When Cell Communication Goes Wrong
The cells in our bodies are constantly sending out and receiving signals. But what if a cell fails to send out a signal at the proper time? Or what if a signal doesn't reach its target? What if a target cell does not respond to a signal, or a cell responds even though it has not received a signal? These are just a few ways in which cell communication can go wrong, resulting in disease. In fact, most diseases involve at least one breakdown in cell communication. Normal blood sugar regulation. After food enters the body (1), it is broken down and sugar enters the bloodstream (2). Sugar stimulates cells in the pancreas to release insulin (3). Insulin travels through the blood to other cells in the body and signals them to take up sugar (4). The food that you eat is broken down into sugar, which enters the blood stream. Normally, cells in the pancreas release a signal, called insulin, that tells your liver, muscle and fat cells to store this sugar for later use. In type I diabetes, the pancreatic cells that produce insulin are lost. Consequently, the insulin signal is also lost. As a result, sugar accumulates to toxic levels in the blood. Without treatment, diabetes can lead to kidney failure, blindness and heart disease in later life. Multiple sclerosis is a disease in which the protective wrappings around nerve cells in the brain and spinal cord are destroyed. The affected nerve cells can no longer transmit signals from one area of the brain to another. The nerve damage caused by multiple sclerosis leads to many problems, including muscle weakness, blurred or double vision, difficulty with balance, uncontrolled movements, and depression. Type I and type II diabetes have very similar symptoms, but they have different causes. While people who have type I diabetes are unable Continue reading >>
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 >>
How Does Blood Glucose Control With Insulin Save Lives In Intensive Care?
Patients requiring prolonged intensive care are at high risk for multiple organ failure and death. Insulin resistance and hyperglycemia accompany critical illness, and the severity of this “diabetes of stress” reflects the risk of death. Recently it was shown that preventing hyperglycemia with insulin substantially improves outcome of critical illness. This article examines some potential mechanisms underlying prevention of glucose toxicity as well as the effects of insulin independent of glucose control. Unraveling the molecular mechanisms will provide new insights into the pathogenesis of multiple organ failure and open avenues for novel therapeutic strategies. The 1952 Scandinavian epidemic of poliomyelitis necessitated mechanical ventilation of a large number of patients with respiratory failure, an intervention that reduced mortality from 80% to 40% (1). Since then, development of sophisticated mechanical devices to support all vital organ functions, a wide array of powerful drugs, and high-tech monitoring systems have revolutionized modern intensive-care medicine. This evolution improved short-term survival of previously lethal conditions such as multiple trauma, extensive burns, major surgery, and severe sepsis. Many patients nowadays indeed survive the initial shock phase of such conditions but often subsequently enter a chronic phase of critical illness. Mortality among such patients requiring intensive care for more than a few days has remained around 20% worldwide, to a large extent irrespective of the initial disease or trauma for which they were admitted to the intensive care unit (ICU). Most deaths in the ICU occurring beyond the first few days of critical illness are attributable to nonresolving failure of multiple organ systems, either due to or coin Continue reading >>
- Type 2 diabetes IS reversible: Eating just 600 calories a day for 8 weeks can save the lives of millions of sufferers
- Type 2 diabetes IS reversible: Eating 600 calories a day for 8 weeks can save lives of millions
- Diabetes... or the first sign of killer pancreatic cancer? How screening people with the disease could save thousands of lives
How Does Insulin Signal A Cell To Take In Glucose From The Blood?
Just as we receive and act on signals from our environment, our cells also receive and act on signals from their environment, our bodies. This is a necessary biological occurrence that keeps cells alive and functioning. Insulin is a hormone released by our pancreas that signals cells in a specific way in order to stimulate them to take in, use and store glucose. Function of Insulin After ingesting food, your meal is broken down and digested. As a result, glucose is released into your bloodstream. High concentrations of glucose in the blood are a signal for the beta cells of the pancreas to release insulin. This hormone works like a key to unlock the protective cell membranes and allow the passage of glucose into the cell to be used for energy. Mechanism of Insulin Insulin works to decrease the concentration of glucose in the blood and facilitate transport into the cells by binding to special receptors embedded in their membranes. Although there are some tissues such as the brain and the liver that do not require insulin for glucose uptake, most of our cells would not be able to access blood glucose without it. Glucose is the energy source for all cells and is required for their, and ultimately our, survival. The insulin signaling pathway includes an insulin receptor that is made up of two receptor subunits that are located on the outside of the cell membrane and two subunits that penetrate through the membrane. These subunits are chemically bonded together. The extracellular (outside the cell) subunits contain a binding site for insulin. When insulin binds to the extracellular subunits, it activates a chemical reaction that travels through the linked subunits into the cell. This mechanism sends chemical signals to proteins within the cell and causes them to alter their Continue reading >>
- Cell-Centered: Scientists Embrace Cell-Replacement Therapy for Type 1 Diabetes
- NIHR Signal Insulin pumps not much better than multiple injections for intensive control of type 1 diabetes
- International Textbook of Diabetes Mellitus, 4th Ed., Excerpt #59: Mechanisms of insulin signal transduction Part 3 of 8
