Insulin's Role in Blood Glucose Regulation
45 Questions
1 Views

Insulin's Role in Blood Glucose Regulation

Created by
@ShinyLongBeach6025

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary feature of diabetes mellitus?

  • Increased intracellular glucose uptake
  • Reduction in blood glucose levels
  • Elevation in blood glucose levels (correct)
  • Increased insulin sensitivity

    • What condition is caused by glucosuria in diabetes mellitus?

  • Increased blood pressure
  • Increased appetite and weight gain
  • Hypoglycaemia
  • Osmotic diuresis resulting in dehydration (correct)

    • What was one of the extreme dietary treatments for diabetes before the introduction of insulin?

  • Complete calorie restriction
  • Starvation diets (correct)
  • High-protein diets
  • Carbohydrate-rich diets

    • What severe outcome occurred to a 12-year-old boy suffering from diabetes who was subjected to extreme dietary measures?

    <p>Went blind and died of starvation</p> Signup and view all the answers

    What physiological issue occurs in cells of individuals with diabetes mellitus after a meal?

    <p>Cells cannot take up glucose properly</p> Signup and view all the answers

    What is one consequence of dyslipidaemia related to plasma triglycerides (TG)?

    <p>Decrease in HDL cholesterol</p> Signup and view all the answers

    What role does insulin play in the liver after a meal?

    <p>Stimulates fatty acid synthesis</p> Signup and view all the answers

    Which transport mechanism is primarily affected by diabetes leading to hyperlipidaemia?

    <p>Production and transport of VLDL</p> Signup and view all the answers

    Which of the following substances is produced by the liver that is crucial for fat transport?

    <p>Very low-density lipoprotein (VLDL)</p> Signup and view all the answers

    What counterregulatory hormone opposes the effects of insulin in metabolic processes?

    <p>Glucagon</p> Signup and view all the answers

    What is the primary requirement for diagnosing type 1 diabetes?

    <p>Presence of anti-GAD antibodies</p> Signup and view all the answers

    Which of the following criteria indicates pre-diabetes according to the ADA?

    <p>HbA1C of 5.7-6.4%</p> Signup and view all the answers

    What is a significant characteristic distinguishing type 2 diabetes from type 1?

    <p>No requirement for insulin treatment</p> Signup and view all the answers

    What factor can significantly influence HbA1c results, particularly in under-resourced countries?

    <p>Abnormalities of hemoglobin</p> Signup and view all the answers

    Which statement is true regarding the age of onset for type 1 and type 2 diabetes?

    <p>Type 1 diabetes typically presents in childhood.</p> Signup and view all the answers

    How is type 2 diabetes generally diagnosed?

    <p>By exclusion of type 1 diabetes and other conditions</p> Signup and view all the answers

    What condition is indicated by an FPG of 7.0 mmol/L or more?

    <p>Diabetes mellitus</p> Signup and view all the answers

    What type of diabetes does MODY refer to?

    <p>Monogenic diabetes</p> Signup and view all the answers

    Which hormone is primarily responsible for reducing blood glucose levels?

    <p>Insulin</p> Signup and view all the answers

    What physiological action does insulin promote in the liver?

    <p>Stimulation of glycogen synthesis</p> Signup and view all the answers

    How does insulin affect glucose uptake in cells?

    <p>Translocates GLUT4 to the cell membrane</p> Signup and view all the answers

    What is the net effect of insulin's actions on blood glucose levels?

    <p>Decreased blood glucose concentration</p> Signup and view all the answers

    Which process is inhibited by insulin in the liver?

    <p>Gluconeogenesis</p> Signup and view all the answers

    What role does Akt play in insulin signaling?

    <p>Mediating multiple responses to insulin</p> Signup and view all the answers

    How does insulin signaling affect the enzyme GSK3?

    <p>GSK3 is inhibited to stimulate glycogen synthesis</p> Signup and view all the answers

    Which of the following processes is promoted when insulin levels are high?

    <p>Glycogenesis</p> Signup and view all the answers

    What happens to FOXO during insulin signaling?

    <p>FOXO is inactivated to suppress gluconeogenesis</p> Signup and view all the answers

    What is the primary action of insulin on adipose tissue?

    <p>Enhancing glucose uptake</p> Signup and view all the answers

    Which pathway is essential for insulin-mediated glucose uptake?

    <p>PI3K/Akt signaling pathway</p> Signup and view all the answers

    What effect does insulin have on glycogenolysis?

    <p>Inhibits glycogenolysis</p> Signup and view all the answers

    Which of the following molecules is NOT directly involved in insulin signaling?

    <p>Acetyl CoA</p> Signup and view all the answers

    What is the main role of insulin in glucose metabolism?

    <p>Promotes conversion of glucose to fatty acids</p> Signup and view all the answers

    Which enzyme is primarily responsible for gluconeogenesis from pyruvate?

    <p>Phosphoenolpyruvate carboxykinase</p> Signup and view all the answers

    Which factor induces the phosphorylation of PFK2/FBPase-2, thereby inhibiting glycolysis?

    <p>Glucagon</p> Signup and view all the answers

    What is one consequence of insulin treatment in diabetes?

    <p>Tends to result in weight gain</p> Signup and view all the answers

    What is the effect of fructose-2,6-bisphosphate on glycolysis?

    <p>Promotes glycolysis</p> Signup and view all the answers

    What role does malonyl CoA play in fatty acid metabolism?

    <p>Stimulates fatty acid synthesis</p> Signup and view all the answers

    In the context of diabetes, what leads to hyperlipidaemia?

    <p>Dysregulation of transport mechanisms</p> Signup and view all the answers

    Which of the following compounds is primarily produced in the liver during gluconeogenesis?

    <p>Glucose</p> Signup and view all the answers

    What is the function of liver FBPase-2?

    <p>Activates gluconeogenesis</p> Signup and view all the answers

    Which enzyme is inhibited by high levels of glucose in the liver?

    <p>Fructose-1,6-bisphosphatase</p> Signup and view all the answers

    During which metabolic state is glycolysis promoted in the liver?

    <p>When insulin levels are elevated</p> Signup and view all the answers

    What is the key allosteric regulator of phosphofructokinase-1 (PFK-1)?

    <p>AMP</p> Signup and view all the answers

    Which statement best describes the role of GLUT2 in glucose metabolism?

    <p>Facilitates glucose transport into liver cells</p> Signup and view all the answers

    How does citric acid influence pyruvate metabolism?

    <p>Enhances production of oxaloacetate</p> Signup and view all the answers

    Study Notes

    Insulin's role in blood glucose regulation

    • Insulin is the only hormone that lowers blood glucose levels.
    • Insulin promotes glucose uptake into cells.
    • Insulin stimulates glycogen synthesis (glycogenesis) in skeletal muscle and liver.
    • Insulin inhibits glycogen breakdown (glycogenolysis) and glucose production from non-carbohydrate sources (gluconeogenesis).

    Insulin signaling pathway

    • Insulin binds to its receptor, initiating a protein kinase cascade.
    • The key protein in this cascade is Akt, a protein kinase that mediates many of insulin's responses, including glucose uptake, glycogen synthesis, and suppression of gluconeogenesis.
    • GSK3 (glycogen synthase kinase-3) is also activated by insulin signaling, which inhibits glycogen synthesis.
    • FOXO (forkhead box O) transcription factors are also inactivated by insulin signaling, which suppresses gluconeogenesis.
    • In skeletal muscle and adipose tissue, insulin promotes GLUT4 translocation to the cell membrane, increasing glucose uptake.

    Insulin's impact on fuel utilization

    • Insulin's effects extend beyond glucose regulation.
    • Insulin influences fatty acid synthesis and breakdown.
    • Insulin regulates the production of malonyl CoA, a key regulator of fatty acid synthesis.
    • In the liver, insulin promotes the production of acetyl-CoA carboxylase, which converts acetyl-CoA to malonyl CoA, stimulating fatty acid synthesis.

    Insulin's Impact on Liver

    • Insulin increases glucose uptake in the liver through GLUT2.

    • Insulin stimulates glycogen synthesis in the liver by increasing the activity of glycogen synthase and glucokinase.

    • Insulin decreases gluconeogenesis by inhibiting the activity of glucose 6-phosphatase, PEPCK, and pyruvate kinase.

    • Insulin increases glycolysis by increasing the activity of phosphofructokinase (PFK).

    • Insulin stimulates fatty acid synthesis by increasing the activity of acetyl-CoA carboxylase and fatty acid synthase.### PEPCK & Insulin Signaling

    • The liver is a critical organ for glucose homeostasis

    • The liver utilizes PEPCK, an enzyme responsible for converting oxaloacetate into phosphoenolpyruvate (PEP)

    • PEPCK is vital for gluconeogenesis, the pathway to produce glucose from non-carbohydrate precursors

    • Insulin promotes dephosphorylation of the PFK2/FBPase-2 complex

    • Dephosphorylation of PFK2/FBPase-2 results in an increase in F2,6BP levels, a potent activator of PFK1 (phosphofructokinase-1)

    • This ultimately promotes glycolysis, the breakdown of glucose for energy

    • Conversely, glucagon induces phosphorylation of PFK2/FBPase-2 complex, a process which activates FBPase-2

    • FBPase-2 is an enzyme responsible for breaking down Fructose 2,6-bisphosphate (F2,6BP)

    • F2,6BP is a critical regulator of glycolysis and gluconeogenesis

    • Lowering F2,6BP levels promotes gluconeogenesis, the process that produces glucose from non-carbohydrate sources

    • Insulin promotes glucose uptake into the liver.

    • Insulin promotes glucose storage as glycogen in the liver.

    • Insulin promotes glucose use in glycolysis and the TCA cycle.

    • Insulin suppresses gluconeogenesis.

    • Insulin promotes the conversion of glucose into fatty acids and their transport to adipose tissue.

    • Insulin inhibits triglyceride breakdown in adipose tissue.

    Diabetes Mellitus

    • Diabetes mellitus is a common endocrine disorder marked by hyperglycemia.
    • Hyperglycemia refers to elevated blood glucose levels, often exceeding 200 mg/100 ml or 16 mmol/l.
    • Glucosuria is the presence of glucose in urine, associated with osmotic diuresis, leading to dehydration and potentially circulatory failure, brain damage, and renal failure.
    • Many cells cannot effectively uptake glucose after meals, resulting in high extracellular and low intracellular glucose levels.
    • Starvation diets were previously used to manage diabetes, leading to tragic outcomes due to inadequate nutrition.
    • The invention of insulin dramatically revolutionized treatment, saving countless lives.
    • A diagnosis of diabetes requires fasting plasma glucose (FPG) ≥ 7.0 mmol/l or a 2-hour oral glucose tolerance test (OGTT) ≥ 11.1mmol/l following a 75g glucose load.
    • HbA1c levels, reflecting long-term glucose control, can also aid in diabetes diagnosis.
    • The American Diabetes Association (ADA) uses HbA1c > 6.5% for diabetes and 5.7-6.4% for pre-diabetes.
    • The World Health Organization (WHO) recognizes the influence of factors like anemia, hemoglobin abnormalities, pregnancy, and uremia on HbA1c values.

    Classifications of Diabetes

    • Type 1 diabetes (T1DM) involves destruction of pancreatic beta cells, necessitating insulin for survival.
    • T1DM is often characterized by anti-GAD and anti-islet cell antibodies.
    • Type 2 diabetes (T2DM) is often diagnosed by exclusion and typically involves insulin resistance.
    • MODY (monogenic diabetes) is a rare form with single-gene mutations.
    • Secondary causes of diabetes can include medications, pancreatic pathology, or endocrine conditions.

    Comparison of Type 1 and Type 2 Diabetes

    Feature Type 1 Type 2
    Insulin Status No insulin Normal or increased
    Age of onset Childhood Adulthood
    Defect Loss of beta cells Decreased sensitivity of cells to insulin (insulin resistance)
    Obesity No Yes
    Speed of development Fast Slow
    Dyslipidemia No Plasma triglycerides increased, HDL cholesterol decreased, small dense LDL cholesterol increased

    VLDL and Fatty Acid Transport

    • Very low-density lipoprotein (VLDL) transports fatty acids and triglycerides between the liver and adipose tissue.
    • Lipoprotein lipase breaks down triglycerides in VLDL, releasing fatty acids into adipose tissue for storage.
    • Hormone-sensitive lipase (HSL) in adipose tissue hydrolyzes triglycerides into fatty acids and glycerol when energy is required.
    • Dysregulation of these transport mechanisms in diabetes contributes to hyperlipidemia.

    Learning Outcomes

    • Insulin plays a vital role in regulating glucose homeostasis, influencing glucose uptake, storage, utilization, and conversion to fatty acids.
    • Glucagon counteracts many of the effects of insulin.
    • There are different types of diabetes characterized by distinct mechanisms: Type 1, Type 2, and MODY.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Fuel Use: Insulin Action on Liver and Adipose Tissues PDF

    Description

    Explore the critical functions of insulin in regulating blood glucose levels. This quiz covers the insulin signaling pathway, including how insulin promotes glucose uptake and glycogen synthesis while inhibiting gluconeogenesis. Test your knowledge on the mechanisms behind insulin action!

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser