Glucose Homeostasis and Hormonal Regulation
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Glucose Homeostasis and Hormonal Regulation

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Questions and Answers

Which type of diabetes is characterized primarily by insulin deficiency?

  • Gestational diabetes
  • Type 2 diabetes
  • Type 1 diabetes (correct)
  • Secondary diabetes

    • Chronic hyperglycaemia is the primary characteristic of diabetes mellitus.

    True

    What hormone is primarily responsible for lowering blood glucose levels?

    Insulin

    Diabetes mellitus can be classified broadly into ____, Type 2 diabetes, and secondary diabetes.

    <p>Type 1 diabetes</p> Signup and view all the answers

    Match the following hormones with their functions in glucose regulation:

    <p>Insulin = Lowers blood glucose Glucagon = Raises blood glucose Somatostatin = Inhibits insulin and glucagon secretion Adrenaline = Stimulates glycogen breakdown</p> Signup and view all the answers

    What percentage of global deaths in 2017 were attributed to diabetes?

    <p>10.7%</p> Signup and view all the answers

    The normal range for plasma glucose levels is between 3.5-6 mmol/L.

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

    Identify one source of glucose derived from dietary sources.

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

    Which type of glucose transporter is insulin-dependent?

    <p>GLUT-4</p> Signup and view all the answers

    GLUT-5 is primarily responsible for transporting glucose into muscle and adipose tissue.

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

    What is gluconeogenesis?

    <p>Formation of glucose from non-carbohydrate molecules.</p> Signup and view all the answers

    Glycogen serves as stored energy in the liver and __________ muscle.

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

    Which glucose transporter is specifically a fructose transporter?

    <p>GLUT-5</p> Signup and view all the answers

    Name two conditions that can be life-threatening due to glucose imbalances.

    <p>Hypoglycaemia and hyperglycaemia.</p> Signup and view all the answers

    GLUT-2 is an insulin-dependent glucose transporter found in the liver and pancreatic beta cells.

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

    Match the following glucose transporters with their corresponding tissues:

    <p>GLUT-1 = Most cells GLUT-3 = Brain (neurons) GLUT-4 = Muscle and adipose tissue SGLUT = Intestinal tissue</p> Signup and view all the answers

    What is the primary function of glycogenolysis?

    <p>To break down glycogen to release glucose</p> Signup and view all the answers

    Insulin decreases plasma glucose levels.

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

    Who were the scientists credited with the discovery of insulin?

    <p>Frederick Banting and Charles Best</p> Signup and view all the answers

    Glycogen is stored primarily in the ______ and ______.

    <p>liver, muscles</p> Signup and view all the answers

    Which hormone primarily increases plasma glucose levels?

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

    Insulin was discovered after observations were made in diabetic dogs.

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

    Match the following hormones with their effects on blood glucose levels:

    <p>Insulin = Decreases plasma glucose Glucagon = Increases plasma glucose Cortisol = Increases plasma glucose Growth Hormone = May increase plasma glucose</p> Signup and view all the answers

    What is the primary action of glucokinase within cells when glucose enters?

    <p>To phosphorylate glucose to G6P</p> Signup and view all the answers

    What stimulates the opening of voltage-gated calcium channels?

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

    Insulin secretion occurs in a uniphasic manner.

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

    Name one type of molecule that can stimulate insulin secretion.

    <p>Amino acids</p> Signup and view all the answers

    The action of insulin promotes the synthesis of _____ from excess glucose.

    <p>fatty acids</p> Signup and view all the answers

    Which process is promoted by insulin in the liver?

    <p>Glycogen synthesis</p> Signup and view all the answers

    Match the actions of insulin with their corresponding effects:

    <p>Facilitates glucose transport = Increases glucose uptake Promotes fatty acid synthesis = Converts glucose to fat Inhibits gluconeogenesis = Reduces glucose production Activates glycogen synthase = Increases glycogen storage</p> Signup and view all the answers

    Insulin has predominantly catabolic effects on metabolism.

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

    What receptor does insulin bind to on target cells?

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

    What state does glucagon favor?

    <p>Catabolic state</p> Signup and view all the answers

    Insulin deficiency is a characteristic of Type 2 diabetes.

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

    What are incretins and their role in glucose homeostasis?

    <p>Incretins are hormones like GLP and GIP that augment insulin secretion in response to oral glucose.</p> Signup and view all the answers

    The autoimmune destruction of β-cells leads to __________ diabetes.

    <p>Type 1</p> Signup and view all the answers

    Match the diabetes types with their characteristics:

    <p>Type 1 diabetes = Autoimmune destruction of β-cells Type 2 diabetes = Insulin resistance Secondary diabetes = Acquired causes of diabetes Pre-diabetes = Impaired fasting glycaemia</p> Signup and view all the answers

    Which hormone is directly inhibited by cortisol?

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

    Catecholamines promote insulin secretion.

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

    Chronic hyperglycaemia is characteristic of __________ Mellitus.

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

    Study Notes

    Glucose Homeostasis

    • The brain requires glucose as its primary energy source.
    • High glucose levels can damage cellular proteins.
    • Hypoglycaemia and hyperglycaemia can be life-threatening.
    • Glucose homeostasis balances glucose delivery and demand.
    • The system regulates glucose in response to changes in glucose delivery (fed vs. fasted) and demand (exercise/physiological stress).
    • Gluconeogenesis is the process of creating glucose from molecules such as lactate, glycerol, glutamine and alanine.
    • Glycogen is stored energy in the liver and skeletal muscle.
    • Glycogenolysis is the process of breaking down glycogen to release glucose.

    Hormones & Blood Glucose Regulation

    • Insulin lowers blood glucose levels and is released from beta cells in the pancreas.
    • Glucagon, catecholamines, cortisol, free fatty acids and growth hormone increase blood glucose levels.

    Insulin

    • Insulin was identified as pancreatic in origin in the early 1900s.
    • Frederick Banting and Charles Best injected pancreatic extract into diabetic dogs, which improved their condition.
    • In 1922, the first patient was successfully treated with refined pancreatic extract.
    • Insulin secretion is biphasic with an initial surge followed by a plateau phase that persists as long as blood glucose levels are high.
    • Insulin secretion is stimulated by an increase in plasma glucose, amino acids, GI hormones, glucagon, growth hormone and cortisol.
    • Insulin acts by binding to a receptor on the target cell membrane and activating secondary pathways.
    • Insulin is predominantly anabolic.

    Actions of Insulin on Glucose

    • Insulin facilitates glucose transport into cells.
    • It inactivates liver phosphorylase and increases the activity of glucokinase, promoting glucose storage in the liver.
    • Insulin promotes glycogen synthesis by increasing the action of glycogen synthase.
    • It inhibits gluconeogenesis by decreasing the activity of liver enzymes and by decreasing available precursors like amino acids.

    Actions of Insulin on Fats

    • Insulin promotes fatty acid synthesis.
    • It promotes the storage of fat in adipose cells.
    • Insulin inhibits the release of free fatty acids from adipose tissue and promotes glucose transport into fat cells.

    Insulin vs Glucagon

    • Insulin is associated with an anabolic state.
    • Glucagon is associated with a catabolic state.

    Other Influencers in Glucose Homeostasis

    • Glucagon-Like Peptide (GLP) and Gastric Inhibitory Peptide (GIP), also known as 'incretins', are produced in the small intestine and augment insulin secretion.
    • Cortisol and growth hormone promote gluconeogenesis, inhibit glucose transport, and can directly inhibit insulin secretion.
    • Catecholamines, released during stress, promote glucagon release, inhibit insulin secretion, and stimulate sympathetic neurons that innervate the pancreatic islets.

    Diabetes Mellitus

    • Diabetes Mellitus is characterized by chronic hyperglycaemia.
    • It is caused by either insulin deficiency or insulin resistance.
    • It is commonly divided into:
      • Type 1 diabetes: Insulin deficiency caused by an autoimmune destruction of beta cells.
      • Type 2 diabetes: Insulin resistance +/- less severe insulin deficiency.
      • Secondary diabetes: Acquired causes of diabetes, such as those caused by drugs or genetic defects.
    • Impaired fasting glycaemia and impaired glucose tolerance are pre-diabetic conditions.

    Type 1 Diabetes Mellitus

    • Type 1 diabetes is characterized by the autoimmune destruction of beta cells, leading to complete insulin deficiency.
    • Presence of antibodies to islet cells can precede the onset of the disease by years.
    • Often asymptomatic in the initial stages.
    • Symptoms appear when the remaining beta cells can no longer meet the body’s insulin needs.
    • Represents 5-10% of all diabetes cases.
    • Typically presents in children and young adults.
    • Genetic susceptibility is a factor.

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    Description

    This quiz covers the essential concepts of glucose homeostasis, including the importance of glucose for brain function and the processes of gluconeogenesis and glycogenolysis. Additionally, it explores the role of insulin and other hormones in regulating blood glucose levels. Test your understanding of these critical metabolic pathways.

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