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Insulin Stimulates Quizlet

Chapter 5 Flashcards | Quizlet

Chapter 5 Flashcards | Quizlet

-converted into fat (adipose tissue) unlimited storage capacity limited source of stored carbohydrate in the liver and skeletal muscle regulated by the actions of pancreatic hormones (insulin and glucagon) pancreas in response to increased blood glucose -secretes insulin in response to increased blood glucose -promotes storage of excess glucose as glycogen in liver and skeletal muscle -promotes conversion of excess glucose to fat in liver and adipose pancreas in response to decreased blood glucose -secretes glucagon in response to decreased blood glucose -signals liver to release glucose into the blood -Gestational diabetes (diabetes during pregnancy) -pancreatic cells that secrete insulin are destroyed by the body's immune system -extremely low insulin levels limit body's ability to use glucose (muscle and adipose tissues cannot take up glucose) -blood glucose levels increase (hyperglycemia) what happens when the use of glucose is limited? the body releases fatty acids from adipose tissue -serve as energy source to minimize breakdown of muscle protein -requires aligning insulin with food intake and activity to maintain desirable blood glucose level -primarily attributed to prevalence of obesity and decreased physical activity -occurs when cells are less sensitive to the effects of insulin -cells resist the effects of insulin, impairing the uptake of glucose into cells -pancreas overworks to make more insulin to attempt to lower blood glucose -lower blood glucose than type 2, but still elevated above normal levels -often turns into type 2 diabetes without intervention or treatment prediabetes and diabetes are diagnosed based on blood glucose concentrations short term effects of elevated blood glucose Continue reading >>

Insulin's Effects On Metabolism

Insulin's Effects On Metabolism

Sort - vesicles carry multiple molecules of glucose transport proteins in their own membrane - transport proteins bind with the cell membrane and facilitate glucose uptake into the cells - when there is no more insulin available, the vesicles seperate from the cell membrane (within 3-5 mins) - then move back to the interior of the cell to be used again How do the intracellular vesicles operate to increase glucose transport? - blood glucose concentration begins to fall - insulin secreation decreases rapidly - liver glycogen is split back into glucose - glucose is released back into the blood - keeping the glucose concentration from falling too low What happens with insulin and glucose (all forms) inbetween meals when food is not available? - decrease secreation of insulin by pancreas - therefore, stops further synthesis of glycogen by the liver and prevents further uptake of glucose by liver -activates phosphorylase, causing the splitting of glycogen into glucose phosphate -activates glucose phosphatase, causing phosphate to split from glucose = free glucose in the blood After a meal, blood glucose begins to fall to a low level; what are the events that cause the liver to release glucose back into the circulation? - (mainly) by decreasing the quantities and activities of the liver enzymes required for gluconeogenesis - (partly) by decreasing the release of amino acids from muscle (and other extrahepatic tissues) - thereby decreasing the availability of necessary precursors required for gluconeogenesis How does insulin inhibit gluconeogenesis? - stimulates the transport of many amino acids into cells - increases the translation of mRNA, forming new proteins - stimulates protein synthesis, especially of enzymes - inhibits protein catabolism - inhibits gluconeogenesis in th Continue reading >>

Insulin Flashcards | Quizlet

Insulin Flashcards | Quizlet

once nutrients have been absorbed, you shift into the "what or what" state? Concentrations of what 2 things fall in the plasma? You shift into a state of BLANK preventing concentrations of what molecules from falling to far? This keeps what from going too low or high? once nutrients have been absorbed, you shift into the "postabsorptive" or "fasted" state. Concentrations of glucose and amino acids fall in the plasma. You shift into a state of Catabolism preventing concentrations of small molecules from falling to far. This keeps plasma glucose from going too low. glucose concentrations should vary from (#s) glucose concentrations should vary from 80-120 mg/dL plasma. limits fluctuations so glucose doesnt go too high or too low This switch between anabolism and catabolism is mediated by hormones secreted by what place in the body, what 2 things are secreted? This switch between anabolism and catabolism is mediated by hormones secreted by the pancreas, insulin and glucagon (stimulates an increase in blood sugar levels, thus opposing the action of insulin). endocrine secretes hormones directly into blood insulin is BLANK. causes what molecule to go to what 3 things? anabolic (causes glucose -> glycogen & amino acid -> protein) beta cells interact with what to secrete what? beta cells interact with glucose to secrete insulin hormones are secreted by "what" of which cells in where? hormones are secreted by "islets" (endocrine) of endocrine cells in the pancreas soon after eating, blood glucose decreases or increases?, acts directly on which cells and causes what secretion? soon after eathing, blood glucose increases, acts directly on beta cells and causes insulin secretion binding activates what? The receptor does what to itself? and also does this to various what? binding Continue reading >>

Insulin Flashcards | Quizlet

Insulin Flashcards | Quizlet

many biochemical processes that contribute to the breakdown, formation, and inter-conversion of carbohydrates in living organisms. hormone produced by beta cells of the pancreas which allows the body to use glucose from carbohydrates as fuel or store it for when it is needed such as physical activity or in between meals It helps keep blood sugar in check from being to high (hyperglycemia) When blood sugar rises, beta cells in the pancreas are signaled to release insulin into the system The insulin attaches to cells and signals for them to take in the glucose If there is more sugar than the body needs, insulin can also help store it in the liver which can be used when it is needed When glycogen is fully restored, insulin stimulates glycolysis to get rid of blood glucose which can be used to bump up some intermediates of the CAC even all the way down to the mitochondria, which can then make protein synthesis and fat metabolism easier The body can become resistant to or not produce enough insulin if blood sugar levels remain too high for too long (hyperglycemia) - insulin resistance is another hormone responsible for maintaining proper blood sugar levels Glucagon secretion can be inhibited by raised blood sugar levels or high carbohydrate meals Stimulates the liver to convert stored glycogen into glucose to be released into the bloodstream It is also produced in the pancreas but by the alpha cells The role of glucagon is to keep blood glucose levels from dropping too low Glucose uptake in muscle and adipose tissue The GLUT4 transporter is a insulin regulated transporter of glucose Insulin regulates the uptake of glucose into cells through this transporter Insulin stimulates the movement of the GLUT4 transporter to the surface of the cells to take in glucose Once glucose i Continue reading >>

17. Insulin Metabolism

17. Insulin Metabolism

Sort The concept of metabolic homeostasis and the factors that contribute to this process Is control of the balance between substrate need and substrate availability The inter-tissue integration required for metabolic homeostasis is achieved in several ways: 1. the concentration of nutrients or metabolites in the blood affects the rate at which they are used or stored in different tissues 2. Hormones carry messages to their individual target tissues about the physiologic demands of the body and the current level of nutrient supply or demand 3. The central nervous system uses neural signals to control tissue metabolism, either directly or through the release of hormones 4. Insulin and glucagon are the two major hormones that regulate fuel storage and metabolism The role of insulin and glucagon in metabolism Insulin: Is released in response to carbohydrate ingestion Promotes glucose utilization as fuel Promotes storage of glucose as glycogen and of excess glucose as fat Is the major anabolic hormone - increases protein synthesis and cell growth Glucagon: Is the major counterregulatory hormone of insulin Decreases in response to a carbohydrate meal Is elevated during fasting Promotes glucose production (glycogenolysis, gluconeogenesis) Stimulates the mobilization of fatty acids from adipose tissue DOES NOT affect skeletal muscle The processes involving the synthesis of insulin and glucagon Insulin made as a larger precursor called proinsulin in the beta cells of the islets of Langerhans Proinsulin cleaved into mature insulin and C-peptide, which is released into the blood In type I diabetes, the beta cells are destroyed by an autoimmune response and no insulin is made Glucagon is synthesized in the alpha cells of the islets of Langerhans in the pancreas Glucagon is also sy Continue reading >>

Unit 3- Insulin And Glucagon

Unit 3- Insulin And Glucagon

Sort steps of biosynthesis of insulin in beta-cells 1. insulin gene expressed in nucleus of B-cells (insulin mRNA) 2. translation in cytosol, synthesis of N-terminal signal sequence directs complex to RER 3. signal sequence hydrophobic and directs to lumen of RER; preproinsulin is formed 4. in RER, preproinsulin is cleaved-->proinsulin and signal sequence; disulfide bridges between A and B chains are correctly aligned with help of PDI (protein disulfide isomerase) and a molecular chaperone protein 5. properly folded proinsulin -->cis-Golgi apparatus; cleaved into C-peptide and insulin 6. C-peptide and insulin stored in vesicles ready for secretion 7. upon arrival of signal, equimolar amounts of active insulin and C-peptide are released how beta cells detect blood glucose variations 1. glucose enters B-cells via GLUT-2 (insulin INDEPENDENT glucose transporter) *glucose transport exceeds rate of glucose utilization and is not limiting 2. glucose trapped in beta cells through phosphorylation to glucose-6-P catalyzed by glucokinase 3. G6P->glycolysis->TCA cycle->ETC to produce ATP *ATP/ADP ratio increases in cell with glucose concentration 4. elevated ratio inhibits ATP-sensitive potassium channel 5. accumulation of K+ in cytosol of B-cells = membrane depolarization 6. opening of a voltage-gated calcium channel = influx of calcium 7. increase in cytosolic calcium triggers regulated exocytosis of insulin in secretory vessels minor regulators of glucagon secretion -certain amino acids stimulate secretion *note: amino acids can stimulate both glucagon and insulin -Insulin and incretins (GLP-1) inhibit secretion Neural factors: -epinephrine- stimulates release of glucagon (regardless of glucose concentration) -neural input from CNS can stimulate secretion -cortisol and growth h Continue reading >>

Insulin And Glucagon

Insulin And Glucagon

it helps keep blood sugar in check from being to high (hyperglycemia) when blood sugar rises, beta cells in the pancreas are signaled to release __________ into the system attaches to cells and signals for them to take in the glucose if there is more sugar than the body needs, ________ can also help store it in the liver which can be used when it is needed when glycogen is fully restored, ________ stimulates glycolysis to get rid of blood glucose which can be used to bump up some intermediates of the CAC even all the way down to the mitochondria, which can then make protein synthesis and fat metabolism easier the body can become resistant to or not produce enough ___________ if blood sugar levels remain too high for too long hyperglycemia) - ____________ resistance is another hormone responsible for maintaining proper blood sugar levels it is also produced in the pancreas but by the alpha cells the role of _______________ is to keep blood glucose levels from dropping too low _______________ secretion can be inhibited by raised blood sugar levels or high carbohydrate meals stimulates the liver to covert stored glycogen into glucose to be released into the bloodstream glucagon levels in the body can vary depending on the kind of meals we eat -high carbohydrate - lower levels of glucagon -high protein - higher levels of glucagon glucagon increases blood glucose in several ways: -stimulating the breakdown of liver glycogen -inhibiting glucose breakdown in the liver -stimulating gluconeogenesis in the liver (amino acids and glycerol) -the GLUT4 transporter is an insulin regulated transporter of glucose -insulin regulates the uptake of glucose into cells through this transporter -insulin stimulates the movement of the GLUT4 transporter to the surface of the cells to take in Continue reading >>

Phys Exam 5: Regulation Of Metabolism

Phys Exam 5: Regulation Of Metabolism

- Normal fasting blood glucose = 70-110 mg/dL - Minimal glucose needed for brain = 40 mg/dL (below this cognitive deficits, even coma) - Saturating glucose concentration for renal proximal tubules = 180 mg/dL (no glucose in urine unless blood glucose is above this level) - Insulin is the most important regulator of plasma glucose concentration! - Absorptive state = elevated levels of insulin - Postabsorptive state = lowered levels of insulin - Secreted from Beta cells of pancreatic Iselts of Langerhans - Absorptive State: Increased blood glucose stimulates insulin secretion - Target cells express insulin receptor that responds to increase in plasma insulin concentration to stimulate storage of nutrients Preproinsulin: is an amino acid chain with a signaling sequence. Proinsulin: Signal sequence removed, insulin folded with C-chain connecting A-chain and B-chain, which are connected by disulfide bonds. Insulin: A-Chain and B-Chain, C chain has been removed. 1. Increases uptake of nutrients into tissues (mainly skeletal muscle and adipose tissue, NOT LIVER) 2. Stimulates synthesis of storage form of nutrients (Glycogen, protein, triglycerides) 3. Inhibits metabolism of stored nutrients (Glycogenolysis, proteolysis, lipolysis) Insulin does NOT increase liver uptake of glucose. Adipose tissue and muscle express insulin-responsive Glut4, liver does not. Insulin stimulates rate limiting enzyme for glycogen synthesis in muscle and liver. Protein is not storage form of energy, but it is important for maintaining cell health and function, so want to produce and conserve protein. Insulin stimulates amino acid uptake into liver and skeletal muscle and promotes protein synthesis (by stimulating ribosomal enzymes). Insulin also inhibits enzymes involved in protein catabolism. *Insu Continue reading >>

Metabolic Effects Of Insulin And Glucagon

Metabolic Effects Of Insulin And Glucagon

beta cells of pancreas sense glucose via activation of glucokinase activity; must reach a certain concentration (has higher Km than hexokinase=lower affinity) plasma amino acid levels increase after ingestion of proteins high amino acid levels induce insulin secretion insulin stimulates synthesis of enzymes necessary for protein synthesis Arginine especially stimulates insulin synthesis and secretion Gastrointestinal Hormone Impact on Insulin Release GI hormones are secreted post food ingestion that induces insulin secretion examples are: Secretin and Glucagon-Like hormone (GLP-1) mechanism for insulin secretion is ATP-dependent stress causes adrenal medulla to synthesize ephinephrine in response; ie fever, trauma, infection, extreme exercise, etc. epinephrine works with glucagon (antagonizes insulin) epi secretion under control of nervous system; secreted by stimulation of the adrenal medulla glycogenolysis=glycogen degradation releasing glucose lipolysis= releases FA's + glycerol= fuel for gluconeogenesis overrides normal glucose-stimulated release of insulin prevents uptake by skeletal and muscle; reserved for glucose-essential tissues such as the brain body corrects for hypoglycemia by way of: --important in short term regulation of blood glucose correction for hypoglycemia fails when levels of 2 are low play an important role in long term regulation of blood glucose Insulin Effect on Carbohydrate Metabolism (glucose uptake by brain, RBC's and liver are NOT insulin dependent) inhibits hormone-sensitive lipase in adipose tisse=decrease release of FA's into circulation=decrease triglyceride breakdown 1. increase entry of glucose into adipose=synthesis of glycerol-3-phosphate 2. activation of lipoprotein lipase synthesis=increase free FA's from hepatic VLDL and dietar Continue reading >>

Metabolic Effects Of Insulin & Glucagon

Metabolic Effects Of Insulin & Glucagon

Sort 4 Major organs that play a dominant role in fuel metabolism ("LAMB") 1)Liver 2)Adipose 3)Muscle 4)Brain -- -->Each of the aforementioned contains a unique set of enzymes such that eaach organ is specialized for the storage, use, and generation of **specifice fuels** -->Communicate with each to provide substrates to antoher or process compounds produced by other organs -->Communication btwn tissues is mediated by the NS, by the availibility of CIRCULATING SUBSTRATES, & by variation in the levels of PLASMA HORMONES 2 Hormones that control the integration of energy metabolism 1)Insuln 2)Glucagon (***Catecholamines play a supporting role) -- -->Changes in the circulatin levels of insulin & glucagon allow the body to store energy when food is availible in ABUDANCE or to make stored energy available during **2 major situations** 1)Survival Crises (famine, severe injury) 2)Flight or Flight Situations Structure of Insulin -->See Slide #9 for details -- NOTE: -->Pig (porcine) AND Beef (bovine) insulin differ from human insulin at **1* and *3** amino acid positions, respectively 1)When used in humans for the treatment of DIABETES, *antibodies to these foreign proteins develop* -->Use of *human recombinant insulin has eliminated this problem* Features of Synthesis of Insulin -->Involves 2 inactive precusors (preproinsulin & proinsulin), which are sequentially cleaved to form the ACTIVE HORMONE + C-PEPTIDE -->Stored in the **cytosol in granules that are released via *exocytosis** --->Is degraded by *inuslinase** (found mostly in the LIVER, & the kidney [lesser extent] ) -->Has a **SHORT HALF LIFE*(plasma half-life of approx. 6 minutes* 1)Short duration of actions permits rapid changes in CIRCULATING LEVELS OF THE HORMONE Factors that stimulate insulin secretion 1)Glucose -->β Continue reading >>

Insulin Metabolism

Insulin Metabolism

Sort What are the ways in which the inter-tissue integration required for metabolic homeostasis is achieved? concentration of nutrients or metabolites in blood affects rate at which they are used and stored hormones carry messages to target tissues about physiologic demands of the body and the current level of nutrient supply or demand CNS uses neural signals to control tissue metabolism, either directly or through release of hormones Insulin and glucagon structure of insulin Insulin is made as a larger precursor called proinsulin in the beta cells of the islets of Langerhans Proinsulin is cleaved into mature insulin and C-peptide, which is released into the blood (posttranslational modification) When insulin is secreted from vesicles, the C peptide is also secreted and used as a measure of insulin production The C peptide stays in the circulation for a period of time, allowing it to provide a measure of the capacity of the beta cells to synthesize insulin Continue reading >>

Insulin

Insulin

Sort What happens in normal metabolism? a shift from carb to fat metabolism occurs within the body in between meals, when our blood glucose levels are low. Following a meal we enter an absorptive state in which ingested nutrients such as glucose enter the blood from the GI tract. During this absorptive state glucose is used by many tissues for energy metabolism. The high levels of glucose in the absorptive state stimulate the pancreas to release insulin, which lowers the blood glucose levels. Because of decreasing blood glucose levels, there is a shift in the tissue energy metabolism from cars to fatty acids, as the body enters the postabsorptive state, which occurs about four hours after a meal and continues until the next meal. Continue reading >>

Glucose Transport Flashcards | Quizlet

Glucose Transport Flashcards | Quizlet

major site = skeletal muscle, adipose tissue proposed function = insulin mediated glucose uptake GLUT 4= skeletal muscle and adipose tissue GLUT 2 = respond to blood glucose, B-cells release insulin How does glucose stimulate insulin release? GLUT2 transporters transport glucose to pancreatic B-cells, which release insulin How does insulin stimulate glucose uptake? Insulin stimulates GLUT4 transporters, which bring glucose to skeletal muscle and adipose tissue for storage In which tissues does insulin stimulate glucose uptake? Insulin regulates translocation of GLUT4 from intracellular compartment to the cell surface -glucose in small intestine anaerobically metabolized to lactate, rest sent to liver via portal vein -liver performs glycolysis and glycogenesis and fat conversion - non uptaken/metabolized glucose released into circulation -GLUT 2 transporters in pancreas stimulate insulin release -GLUT 1 and 3 in brain stimulate glycolysis -GLUT 4 in skeletal muscle and adipose tissue stimulated by insulin release --skeletal muscle performs glycolysis and glycogenesis --adipose tissue performs glycolysis and CHO conversion to fat Continue reading >>

Insulin & Glucagon

Insulin & Glucagon

Sort What biological actions INCREASE due to glucagon? INCREASE IN: - Glycogenolysis - Gluconeogensis* - Fatty acid oxidation - Ketogenesis - uptake of AA (*Glucagon STIMULATES gluconeogenesis by increase gene expression of PEPCK. Does so by binding to CREB-P-a leucine zipper binding domain) Continue reading >>

Insulin Versus Glucagon/epinephrine

Insulin Versus Glucagon/epinephrine

it is produced by Beta-cells in the islets of Langerhans. This is produced by alpha-cells in the islets of Langerhans. Describe the metabolic relationship between insulin, glucagon and epinephrine. The metabolic effects of glucagon and epinephrine are similar to each other but opposite to that of insulin in that they RAISE the level of blood glucose. Describe the differences between the roles of glucagon and epinephrine Epinephrine has pronounced effects on heart rate, and blood pressure, whereas glucagon has much greater effects on liver and only epinephrine affects muscle cells. This is produced in the WELL FED STATE (glucose is plentiful in blood) and promotes the storage of energy and glucose. What is the molecular process with which insulin stimulates the storage of energy and glucose? It does this in part by stimulating protein phosphatase which removes phosphates from enzymes. Therefore, enzymes which are activated by insulin (phosphatase) will be in their non-phosphorylated form. Describe when glucagon and epinephrine are produced. Glucagon and epinephrine are secreted when the body is in the NEED STATE for either glucose or energy. They control enzymes through initiating a phosphorylation cascade and therefore enzymes stimulated by glucagon and epinephrine will be active in their phosphorylated state (using kinase, which phosphorylates things). If we are witnessing glucose uptake in muscle and adipose tissue, then what key metabolic hormone is being triggered? If we are witnessing glycolysis, then what key metabolic hormone is being triggered? Glycolysis- the conversion of glucose to pyruvate- INSULIN If we are witnessing glycogenesis, then what key metabolic hormone is being triggered? Glycogenesis- the production of glycogen from glucose- INSULIN If we are w Continue reading >>

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