Stand on a streetcorner and ask people if they know what insulin is, and many will reply, "Doesn't it have something to do with blood sugar?" Indeed, that is correct, but such a response is a bit like saying "Mozart? Wasn't he some kind of a musician?"
Insulin is a key player in the control of intermediary metabolism. It has profound effects on both carbohydrate and lipid metabolism, and significant influences on protein and mineral metabolism. Consequently, derangements in insulin signalling have widespread and devastating effects on many organs and tissues.
The Insulin Receptor and Mechanism of Action
Like the receptors for other protein hormones, the receptor for insulin is embedded in the plasma membrane. The insulin receptor is composed of two alpha subunits and two beta subunits linked by disulfide bonds. The alpha chains are entirely extracellular and house insulin binding domains, while the linked beta chains penetrate through the plasma membrane.
The insulin receptor is a tyrosine kinase. In other words, it functions as an enzyme that transfers phosphate groups from ATP to tyrosine residues on intracellular target proteins. Binding of insulin to the alpha subunits causes the beta subunits to phosphorylate themselves (autophosphorylation), thus activating the catalytic activity of the receptor. The activated receptor then phosphorylates a number of intracellular proteins, which in turn alters their activity, thereby generating a biological response.
Several intracellular proteins have been identified as phosphorylation substrates for the insulin receptor, the best-studied of which is insulin receptor substrate 1 or IRS-1. When IRS-1 is activated by phosphorylation, a lot of things happen. Among other things, IRS-1 serves as a type of docking center for recruitment and activation of other enzymes that ultimately mediate insulin's effects. A more detailed look at these processes is presented in the section on Insulin Signal Transduction.
Insulin and Carbohydrate Metabolism
Glucose is liberated from dietary carbohydrate such as starch or sucrose by hydrolysis within the small intestine, and is then absorbed into the blood. Elevated concentrations of glucose in blood stimulate release of insulin, and insulin acts on cells thoughout the body to stimulate uptake, utilization and storage of glucose. The effects of insulin on glucose metabolism vary depending on the target tissue. Two important effects are:
Insulin facilitates entry of glucose into muscle, adipose and several other tissues.
The only mechanism by which cells can take up glucose is by facilitated diffusion through a family of hexose transporters. In many tissues - muscle being a prime example - the major transporter used for uptake of glucose (called GLUT4) is made available in the plasma membrane through the action of insulin.
...s a component monomer of starch. As a monomer as opposed to a polymer, it is much smaller and would thus be able to cross the plasma membrane. However, glucose is a larger solute than the component ions of salt, thus meaning that simple diffusion would not be sufficient. Instead, facilitated diffusion would be needed to transport the glucose. However, in the dialysis tubing, there is no facilitated transport like there is for the plasma membrane. Thus, the glucose may pass through the dialysis tubing, but it would not be due to transport, but the artificial enlargement of the passages in the dialysis tubing. Water would move freely inside and outside of the cell, however, because there is a greater solute concentration inside the cell, the water would diffuse through osmosis into the cell model, increasing the final mass of the dialysis tubing and causing cytolysis.
The pathophysiology of diabetes mellitus in is related to the insulin hormone. Insulin is secreted by cells in the pancreas and is responsible for regulating the level of glucose in the bloodstream. It also aids the body in breaking down the glucose to be used as energy. When someone suffers from diabetes, however, the body does not break down the glucose in the blood as a result of abnormal insulin metabolism. When there are elevated levels of glucose in the blood, it is known as hyperglycemia. If the levels continue to remain high over an extended period of time, damage can be done to the kidneys, cardiovascular systems; you can get eye disorders, or even cause nerve damage. When the glucose levels are low in one’s body, it is called hypoglycemia. A person begins to feel very jittery, and possibly dizzy. If that occurs over a period of time, the person can possibly faint. Diabetes mellitus occurs in three different forms - type 1, type 2, and gestational.
II. The American Diabetes association, containing health care professionals and staff members from all over the world, wrote an article published in September 14, 2014 describing two conditions when the body’s respond to insulin is crucial.
This occurs when special carrier proteins carry solutes dissolved in the water across the membrane by using active transport. When the concentration gradient can not allow travel from one side of the membrane to the other fast enough for the cell’s nutritional needs, then facilitated diffusion is used. The transport protein is specialized for the solute it is carrying, just as enzymes are specialized for their substrate. The transport protein can be
Diabetes is a chronic disorder of metabolism characterized by a partial or complete deficiency of the hormone insulin. With this, there are metabolic adjustments that occur everywhere in the body. Specific to this child is Type One Diabetes. This is characterized by demolition of the pancreatic beta cells, which produce insulin. Because of this, it leads to complete insulin deficiency. Within Type One diabetes, there are two different forms. First there is immune-mediated deficiency, which typically results from an autoimmune destruction of the beta cells. The second type is called idiopathic type one, in which the cause is unknown. (Wong, Hockenberry, Wilson, 2015)
Throughout the whole of the United Kingdom, between 2 and 3 of every 100 people have a known form of diabetes (DTC, 2004). What is diabetes? Explained simply, it is a disease in which the body does not produce or properly use insulin. In the normal state of glucose function, there is a stable release and uptake of glucose, regulated by two hormones produced in the pancreas, glucagon and insulin. There are two distinct mechanisms which give rise to the abnormal blood glucose levels seen in patients with type I and type II diabetes. In type I diabetes, a deficiency in insulin production at the pancreas results in elevated blood glucose levels due to the lack of hormonal regulation. In type II diabetes, although the pancreas produces regular levels of insulin, the body resists the effect of insulin, inhibiting the ability of insulin to break down glucose in the blood. Because of the inherent differences in the biochemical mechanisms of these two diseases, the characteristics associated with type I and type II diabetes are very different. The typical onset of type I diabetes is usually ...
Type 1 diabetes has a genetic onset that often occurs in adolescence (Porth, 2005). It is an autoimmune disease in which the insulin-producing beta cells within the liver are destroyed (Dorman, 1993). This causes a deficiency in insulin secretion, which ultimately leads to high blood glucose levels, also referred to as hyperglycemia (Guthrie & Guthrie, 2004). The mechanism for insulin deficiency leading to hyperglycemia is described in more detail in the following section and in Figure 1.
Diabetes is a disease in which a person’s body in unable to make or utilize insulin properly which affects blood sugar levels. Insulin is a hormone that is produced in the pancreas, which helps to regulate glucose (sugar) levels, break down carbohydrates and fats, and is essential to produce the body’s energy. The CDC (2013) offers reliable insight, summarized here, into the different types of diabetes, some causes, and health complications that may arise from the disease.
Glucose is the primary source of energy for the cells and consequently is necessary for all cellular functions that require energy. Facilitated diffusion plays a significant role in the management of concentrations of glucose, both intracellular and extracellular, providing a balance of glucose in the cells that when poorly utilized upsets the body’s homeostasis.
The many effects that insulin has on metabolism and cellular growth begin when insulin binds to its receptor at the cell membrane. The insulin signals from the insulin receptor is transmitted through the insulin receptor substrate (IRS)-1. The phosphorylation (creation of a phosphate derivative of an organic molecule) of IRS-1 has been linked to signal transduction from the insulin receptor to PI 3-kinase. This leads to GLUT-4 translocation and subsequent glucose uptake. Preliminary studies have shown that the enzyme PI 3-kinase is correlated with glucose being absorbed by the entire body. This suggests that the enzyme is important in regulating insulin-mediated glucose uptake in skeletal muscle. PKB (AKT)has been proposed as a key step linking the activation of PI 3-kinase to glucose uptake.
Glucose is an organic molecule will provide an energy source towards the metabolic activities of the human body. It is also a key source of carbon skeletons for biosynthesis. The energy stored with the glucose molecule is released via a process called glycolysis. Glycolysis occurs during respiration. When it is fully broken down, glucose is converted into adenosine triphosphate (ATP). This allows manageable amount of energy to be released to power the various biochemical reactions which occurs.
Glucose is one of important source in the body because it is the primary source of energy for all body functions and is indeed the only form of energy which can used by the brain and central nervous systems. It is necessary for blood glucose levels to be regulated and this is achieved through homeostasis; however, low blood glucose or high blood glucose can lead to serious problems overtime. Thus, maintaining normal blood glucose is greatly decreases the risk of further complications due to diabetes. In this paper, I will explain how the glucoses move across the cell membrane including the difference between simple and facilitated diffusion.
When we eat, the body works to break down our food to this simplest form of organic molecule. Once the glucose is obtained, it is released into the bloodstream to be delivered to the cells, which is then absorbed into the cell and undergoes the process of respiration to get ATP. Most excess glucose is then stored as glycogen, mostly in the liver, so that the body tissues which need a constant glucose supply are able to get it without us having to be constantly eating.
Glucose is a simple sugar that is an important source of energy and is needed by all living organisms. As glucose increases in the blood, insulin releases which then allows insulin to act on cells throughout the body to stimulate uptake, usage, and storage of glucose. Blood glucose level rise in the blood when carbohydrate rich food are consumed. The change in blood glucose levels is a result of the intestinal absorption of glucose from starch and sugars by amylase and disaccharides. The function of insulin plays an important part as well once it is released. Insulin is used in order to lower the body’s blood glucose levels by regulating the metabolism of carbohydrates and fats (Bowen et al., 2006). Insulin is secreted by beta cells in the islets of Langerhans in response to elevated blood glucose levels and also aids in glucose transport. As an important part of the body, insulin is plays two major roles which include increase of glucose transport in the liver, muscles, and fat cells and polymerization of glucose to glycogen (Randall et al., 2002). The
Insulin is a hormone that is produced within the pancreas. The pancreas contains three types of cells: α, β, and σ (Striegel, Hara, and Periwal 1). Alpha cells (α) produce a hormone called glucagon. Glucagon is the antidote of insulin, which means its function is not to decrease blood sugar levels, but to bring blood sugar levels back to normal. Beta Cells (β) secrete insulin. The delta cells (σ), which produce somatostatin, regulate both insulin and glucagon to stabilize the body’s energy amounts. According to Striegel, Hara and Periwal (2015), researchers from the Laboratory of Biological Modeling at the National Institute of Health in Bethesda, Maryland, and the Department of Medicine at the University of Chicago, these types...