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What Is The Target Tissue Of Insulin?

Tissue Specificity On Insulin Action And Resistance: Past To Recent Mechanisms.

Tissue Specificity On Insulin Action And Resistance: Past To Recent Mechanisms.

Tissue specificity on insulin action and resistance: past to recent mechanisms. Departamento de Bioqumica y Biologa Molecular II, Facultad de Farmacia, Universidad Complutense, Madrid, Spain. [email protected] Acta Physiol (Oxf). 2011 Mar;201(3):297-312. doi: 10.1111/j.1748-1716.2010.02201.x. Insulin resistance is the most important pathophysiological feature in many pre-diabetic states. Type 2 diabetes mellitus is a complex metabolic disease and its pathogenesis involves abnormalities in both peripheral insulin action and insulin secretion by pancreatic -cells. The creation of monogenic or polygenic genetically manipulated mice models in a tissue-specific manner was of great help to elucidate the tissue specificity of insulin action and its contribution to the overall insulin resistance. However, a complete understanding of the molecular bases of insulin action and resistance requires the identification of intracellular pathways that regulate insulin-stimulated proliferation, differentiation and metabolism. Accordingly, cell lines derived from insulin target tissues such as brown adipose tissue, liver and beta islets lacking insulin resistance or sensitive candidate genes such as IRS-1, IRS-2, IRS-3, IR and PTP1B have been developed. Indeed, these cell lines have also been very useful to understand the tissue specificity of insulin action and inaction. Obesity is a risk factor for several components of the metabolic syndromes such as type 2 diabetes, dyslipidaemia and systolic hypertension, because white and brown adipose tissues as endocrine organs express and secrete a variety of adipocytokines that can act at both local and systemic levels, modulating the insulin sensitivity. Recent studies revealed that the subjects with the highest transcription rates of genes e Continue reading >>

Insulin

Insulin

Insulin is a hormone, that means it is a chemical secreted into the blood by an endocrine organ and carried around the body to a target organ. Insulin helps to control the amount of glucose dissolved in the blood. Insulin prevents the blood sugar level from rising too high. It is also necessary to have insulin in your blood for respiration to take place. Without insulin cells can only get energy from fat and this causes serious problems. The control of blood sugar level is a homeostatic mechanism. How Insulin Works: Insulin is secreted by the Islets of Langerhans which are special groups of cells in the pancreas. The Islets (little islands) are endocrine organs. If you have a large carbohydrate meal, the level of glucose in the blood will start to rise as your digestive system turns all the starch and sugars in your food into glucose. If you have not had a meal for several hours your blood sugar level will fall because your cells use up the glucose in aerobic respiration. When your blood sugar level rises, the Islets of Langerhans secrete MORE insulin. When your blood sugar level falls, the Islets of Langerhans secrete LESS insulin. The main target organ for insulin is the liver. It is the liver which removes glucose from the blood by turning it into glycogen. All other tissues in your body need insulin to help then respire glucose, so in a way they are also target organs. If you eat, and eat, and eat, and eat, never mind how little exercise; there will come a time when there is no more room for glycogen in your liver. High levels of insulin will make you start to turn the excess glucose into FAT. Please balance your diet!!!!! When you fast for more than two days, your liver will run out of glycogen, so you will have to use fat and protein to get energy. When your blood Continue reading >>

Insulin Target Tissues And Cells

Insulin Target Tissues And Cells

Rodent adipose tissue and cells represent the targets exhibiting the most prominent insulin sensitivity (i.e., lowest EC/IC50) and responsiveness (i.e., highest fold stimulation/inhibition above basal) of the relevant insulin signaling cascades (e.g., insulin receptor activation) and metabolic end effector systems (e.g., lipolysis) in comparison to liver (e.g., gluconeogenesis) and muscle cells (e.g., glucose transport). This might be based in part on technical advantages of the adipose tissue/adipocyte preparation in comparison to that of muscle/myocytes. But more likely, it reflects the exquisite physiological role of the adipose tissue in the regulation and coordination of glucose and lipid metabolism, i.e., insulin stimulation of lipid synthesis (lipogenesis) and insulin inhibition of lipolysis. On the basis of their relatively easy technical preparation, functional adipose tissue fragments (epididymal fat pads) and primary adipocytes (isolated epididymal adipocytes) from rats as well as adipocyte cell lines derived from mice (3T3-L1, F442A) are the first choice for the development of robust and reliable cell-/tissue-based assay systems for insulin-like activity. Do you want to read the rest of this chapter? Continue reading >>

Jakes Human Physiology 2

Jakes Human Physiology 2

A B When you haven't eaten for a couple of hours and your blood glucose levels drop (low), what happens within your body? If we haven't eaten for several hours, our blood glucose levels decline. This decrease in blood glucose stimulates the alpha cells of the pancreas to release the hormone glucagon. Glucagon stimulates glycogenolysis within the LIVER, the breakdown of glycogen, to yield glucose. The glucose is released from the LIVER into the bloodstream, raising the levels of glucose back to normal. What happens to glucose when it is not being used for energy? Glucose gets stored in muscle cells and the liver. When these storages are full, glucose then gets stored as fat. What is a special paracrine that is secreted by a neuron? A Neurotransmitter. Give an example of an Antagonistic Effect that occurs within the CNS? NE and ACh binding on the heart. What is Catabolism? The breaking down of larger molecules into smaller ones, with the aid of enzymes. What is Anabolism? (Give an example) The building of smaller molecules by enzymes into larger molecules./ (Amino acids-into- Proteins.) What branches does Metabolism consist of? Catabolism and Anabolism. Name the most important hormone associated with maintaining metabolism and body heat./ What organ Secretes it? And what is its "Target Tissue"? Thyroxine./ The Thyroid Gland/ Target= All body cells. Explain the process in which the body regulates metabolic rate... The Thyroid gland secretes Thyroxine, which increases metabolic rate. Also the Pituitary Gland secretes (TSH) Thyroid Stimulating Hormone which enters the blood stream to the Thyroid gland and stimulates it to "produce" more Thyroxine! What is the target tissue for Estrogen?/ What is its specific action? The Uterus./ It stimulates the endometrium of the Uterus to Continue reading >>

Bbc Bitesize - National 5 Biology - Control And Communication - Revision 4

Bbc Bitesize - National 5 Biology - Control And Communication - Revision 4

Communication between cells in a multicellular organism occurs by use of nerve impulses or hormones. The central nervous system produces electrical impulses for rapid response. Hormones are chemical messengers. Hormones are released into the bloodstream by groups of cells called endocrine glands . Hormones are transported in the blood plasma to target body tissues where they bind to cells to produce a response. A specific hormone can only affect cells if the cells have a receptor for it. The diagram below shows two cells targeted by two different hormones. Hormone one cannot affect the cell on the right because the cell does not have a receptor for it. The concentration of glucose in the blood must be kept at a set point. If the blood glucose concentration rises too high then the water concentration of the blood will fall and water will diffuse out of cells by osmosis. This may interfere with cell reactions. If the blood glucose concentration falls too much, then body cells will not receive as much glucose and so will not be able to release as much energy in respiration. The concentration of glucose in the blood is regulated by the action of the hormones insulin Continue reading >>

Insulin Receptors

Insulin Receptors

Insulin Receptors are areas on the outer part of a cell that allow the cell to join or bind with insulin that is in the blood. When the cell and insulin bind together, the cell can take glucose (sugar) from the blood and use it for energy. Phe 25B is the active site of insulin. Insulin makes contact with the insulin receptor in a hydrophobic pocket. This causes the C-terminus of the B chain to separate from the N-terminus of the A chain. This allows for more binding and reactions to occur. Although insulin stimulates a vast array of responses in its target tissues skeletal muscle, adipose tissue and the liver, they all appear to be initiated by an interaction between insulin and a protein receptor located on the cell membranes of these tissues. The insulin receptor protein can only be found on these tissues, which explains the specificity of the action. When insulin binds it induces a conformational change within the receptor, known as oligomerization, which leads to autophosphorylation of specific tyrosine residues in the cytoplasmic domains of the receptors. Insulin Receptor To view the insulin receptor in cartoon form Continue reading >>

Target Tissues Of Insulin? Watch

Target Tissues Of Insulin? Watch

Q: What are the major target tissues/organs of insulin? Summarize briefly the PROCESSES controlled by insulin action on: liver, skeletal muscle, adipose (fat) tissue I know that insulin targets the liver to store glucose as glycogen (so the process is glycogenesis), but Im stuck on the muscle/fat tissue. I know that GLUT4 remains in vesicles until insulin causes them to fuse with the plasma membrane and allow glucose into the cell, but what would the answer to the processes question be? Thanks in advance the process is a negative feedback loop, so when blood glucose levels increase insulin lowers blood glucose levels. i have no idea if this is the correct answer~~ The PROCESSES mentioned by OP are correct - other processes affected by insulin include:- 1. It slows down the process of gluconeogenesis [Greek neo = new; genesis = production] - gluconeogenesis is the production of new glucose from amino acids (mainly) - slowing of this process obviously tends to lower blood glucose. 2. Insulin slows down glycogenolysis [opposite of glycogenesis: Greek lyse = breakdown as in lysosome, which is the organelle where acid hydrolases break down internal [e.g. dead mitochondria] or external [e.g. phagocytosed bacteria] waste]. Less decomposition of glycogen into glucose, once again, reduces blood glucose. 3. Increases protein synthesis in ribosomes 4. Increases ketone uptake (this explains the classical diagnostic smell of hyperglycaemic coma patient due to increased levels of e.g. alphaketobutyrate) 5. (In adipose tissue): - a) Activates lipoprotein lipase 6. Increases K+ uptake in muscle and adipose tissue An additional fact to remember is that the opposite(s) of these actions are brought about by the hormones that are called insulin antagonists, namely adrenaline, corticostero Continue reading >>

Sulfonylurea Effects On Target Tissues For Insulin.

Sulfonylurea Effects On Target Tissues For Insulin.

Diabetes Care. 1984 May-Jun;7 Suppl 1:42-6. Sulfonylurea effects on target tissues for insulin. McCaleb ML , Maloff BL , Nowak SM , Lockwood DH . We have examined the nonpancreatic actions of sulfonylureas on multiple aspects of insulin responsiveness in two target tissues for insulin, liver and fat. In vivo administration of tolazamide and glipizide reduced significantly the postabsorptive serum glucose levels in rats without altering the levels of insulin. This was consistent with extrapancreatic sites of drug action. The number and affinity of hepatic insulin receptors was not different from those of control rats. Using a tissue culture system for rat adipose tissue, a 20-h treatment with sulfonylureas markedly potentiated insulin action in fat cells. The primary augmentation was at the level of insulin-stimulated glucose transport. Again, there was no alteration of the insulin receptors located on the adipose tissue. Furthermore, consistent with the lack of an influence on insulin-induced receptor loss after in vitro treatment with sulfonylureas, the in vivo administration of these agents did not alter the transglutaminase activity in rat hepatic tissue. The data demonstrate that sulfonylureas potentiate the responsiveness of the target tissues for insulin. Thus, these hypoglycemic agents probably act by correcting some of the cellular lesions associated with the insulin resistance in type II diabetes mellitus. Continue reading >>

Major Hormones: Origin, Target, Function

Major Hormones: Origin, Target, Function

Your online site for school work help and homework help. Science, English, History, Civics, Art, Business, Law, Geography, all free! Triggers secretion of hydrocortisone from the adrenal gland Stimulates female egg maturation and male sperm production Stimulates female ovulation and male secretion of testosterone Stimulates milk production in the breasts after childbirth Regulates water retention and blood pressure Triggers contraction of the uterus during labor Stimulates milk letdown for breast-feeding after childbirth Regulates circadian rhythm (awake/sleep patterns) and prevent jet lag Controls the level of calcium in the blood by depositing it in the bones Increases the bodys metabolic rate; promotes normal growth and development Promotes the growth and development of white blood cells, helping the body fight infection Regulates sodium and potassium levels in the blood to control blood pressure Plays key role in stress response; increases blood glucose levels and mobilizes fat stores; reduces inflammatation Increases blood pressure, heart and metabolic rate, and blood sugar levels; dilates blood vessels. Also released during exercise Continue reading >>

Is Insulin Resistance Caused By Defects In Insulin's Target Cells Or By A Stressed Mind?

Is Insulin Resistance Caused By Defects In Insulin's Target Cells Or By A Stressed Mind?

The importance of understanding insulin action is emphasized by the increasing prevalence of insulin resistance in various populations and by the fact that it plays an important pathophysiological role in many common disorders, for example, diabetes, obesity, hypertension and dyslipidemia. The primary factors responsible for the development of insulin resistance are so far unknown, although both genetic and environmental factors are involved. The genetic defects responsible for the common forms of insulin resistance, for example, in type 2 diabetes, are largely unidentified. Some studies from our group as well as by other investigators suggest that cellular insulin resistance is reversible and that it may be secondary to factors in the in vivo environment. These may include insulin-antagonistic action of hormones like catecholamines, glucocorticoids, sex steroids and adipokines as well as dysregulation of autonomic nervous activity and they could contribute to the early development of insulin resistance. Some of these factors can directly impair glucose uptake capacity and this might be due to alterations in key proteins involved in insulin's intracellular signaling pathways. This article briefly summarizes proposed mechanisms behind cellular and whole-body insulin resistance. In particular, we question the role of intrinsic defects in insulin's target cells as primary mechanisms in the development of insulin resistance in type 2 diabetes and we suggest that metabolic and neurohormonal factors instead are the main culprits. Copyright © 2005 John Wiley & Sons, Ltd. Continue reading >>

Physiologic Effects Of Insulin

Physiologic Effects Of Insulin

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, and the big picture is that it organizes the use of fuels for either storage or oxidation. Through these activities, insulin 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 activa Continue reading >>

Histologic Distribution Of Insulin And Glucagon Receptors

Histologic Distribution Of Insulin And Glucagon Receptors

M. Watanabe, H. Hayasaki, T. Tamayama and M. Shimada Department of Anatomy, Osaka Medical College, Takatsuki, Osaka, Japan Insulin and glucagon are the hormonal polypeptides secreted by the B and A cells of the endocrine pancreas, respectively. Their major physiologic effects are regulation of carbohydrate metabolism, but they have opposite effects. Insulin and glucagon have various physiologic roles, in addition to the regulation of carbohydrate metabolism. The physiologic effects of insulin and glucagon on the cell are initiated by the binding of each hormone to receptors on the target cells. Morphologic studies may be useful for relating biochemical, physiologic, and pharmacologic information on the receptors to an anatomic background. Receptor radioautography techniques using radioligands to label specific insulin and glucagon receptors have been successfully applied to many tissues and organs. In this review, current knowledge of the histologic distribution of insulin and glucagon receptors is presented with a brief description of receptor radioautography techniques. Key words: radioautography, insulin, glucagon, receptor, distribution Introduction Insulin is a hormone secreted by B cells, and glucagon is secreted by A cells of the pancreas. The two hormones play an important role in carbohydrate metabolism. However, the actions of insulin and glucagon in carbohydrate metabolism are opposite. Furthermore, insulin and glucagon have various physiologic roles in addition to the regulation of carbohydrate metabolism. The physiologic effects of insulin and glucagon on the cell are initiated by the binding of each hormone to target cell receptors. To relate biochemical, physiologic, and pharmacologic information on receptors to an anatomic background, morphologic studies Continue reading >>

Medical Terminology For Cancer

Medical Terminology For Cancer

Contents Functions of the Endocrine System About Hormones The Pituitary Gland The Thyroid gland The Parathyroids The Pancreas The Adrenal Glands The Gonads Roots, suffixes, and prefixes Cancer Focus Related Abbreviations and Acronyms Further Resources The Endocrine system (along with the nervous system) controls and regulates the complex activities of the body. The Endocrine system regulates the activities of the body by secreting complex chemical substances (hormones) into the blood stream. These secretions come from a variety of glands which control various organs of the body. The key functions are: To regulate the metabolic functions of the body. To regulate the rate of chemical reactions in various cells. To influence the ability of substances to transport themselves through cell membranes. This is known as the "master gland" because it exerts control over all of the other glands of the endocrine system. Despite its importance the pituitary gland is no larger than a small pea. The Pituitary gland is made up of two separate glands: the Anterior lobe which is an outgrowth of the pharynx, and the Posterior lobe which is an outgrowth of the brain composed of neural (nerve) tissue. The Anterior Lobe of the pituitary plays the 'master' role secreting six major hormones that affect most of the body, including the other Endocrine glands: ACTH (Adrenocorticotrophic hormone) stimulates the adrenal glands to secrete its hormones. hGH (Human growth hormone) also known as somatotrophic hormone is responsible for the growth of long bones, muscles and viscera. TSH (Thyroid stimulating hormone) influences the structure of the thyroid and causes it to secrete thyroid hormone. FSH (Follicle stimulating hormone) stimulates female egg production or male sperm production. PRL (Prolactin Continue reading >>

You And Your Hormones

You And Your Hormones

What is insulin? Insulin is a hormone made by an organ located behind the stomach called the pancreas. Here, insulin is released into the bloodstream by specialised cells called beta cells found in areas of the pancreas called islets of langerhans (the term insulin comes from the Latin insula meaning island). Insulin can also be given as a medicine for patients with diabetes because they do not make enough of their own. It is usually given in the form of an injection. Insulin is released from the pancreas into the bloodstream. It is a hormone essential for us to live and has many effects on the whole body, mainly in controlling how the body uses carbohydrate and fat found in food. Insulin allows cells in the muscles, liver and fat (adipose tissue) to take up sugar (glucose) that has been absorbed into the bloodstream from food. This provides energy to the cells. This glucose can also be converted into fat to provide energy when glucose levels are too low. In addition, insulin has several other metabolic effects (such as stopping the breakdown of protein and fat). How is insulin controlled? When we eat food, glucose is absorbed from our gut into the bloodstream. This rise in blood glucose causes insulin to be released from the pancreas. Proteins in food and other hormones produced by the gut in response to food also stimulate insulin release. However, once the blood glucose levels return to normal, insulin release slows down. In addition, hormones released in times of acute stress, such as adrenaline, stop the release of insulin, leading to higher blood glucose levels. The release of insulin is tightly regulated in healthy people in order to balance food intake and the metabolic needs of the body. Insulin works in tandem with glucagon, another hormone produced by the pan Continue reading >>

The Endocrine System

The Endocrine System

To ensure your clients adapt to exercise in the way they desire you must understand how hormones govern those adaptations. Here it is then; the endocrine system explained. Endocrine system new terms When it comes to the endocrine system there are some commonly used terms that may be new to you. To help you some of these new terms and their definitions are shown in the following table. Term Definition Endocrine system The endocrine system (hormonal system) refers to the glands and hormones that are secreted as part of one of the bodies control systems Hormone Hormones are the chemical messages that are released from the glands of the endocrine system Target tissue Target tissue refers to the intended site that a hormone will affect such as muscle Receptor site Receptor sites are special sites located on every target tissue and only communicate with the specific hormone intended for the target tissue What is the endocrine system? The endocrine system is a control system of the human body much like the nervous system. The endocrine system produces chemical messages in the form of hormones, whereas the nervous system produces electrical messages. The endocrine system is made up of lots of specialised endocrine glands that secrete hormones into the bloodstream. Some of the major endocrine glands are shown on this diagram. What does the endocrine system do? The hormones that are secreted by the endocrine glands are chemical messengers which are carried by the bloodstream to other tissues or organs in the body. The messages they deliver tell these tissues or organs to either increase or decrease their activity. Hormones act only on target tissues or organs that have the appropriate receptor sites for that given hormone. In this way hormonal messages are delivered to, and act o Continue reading >>

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