Control of blood glucose

• Why control blood glucose?

  • Prevents cells swelling or shrivelling
  • Cellular respiration
  • Manufacturing other cellular products
• How does glucose affect water potential?

  Hypoglycemia causes water to move into a cell and make it burst

  Hyperglycemia causes water to move out of the cell and shrivel
• What organ monitors blood glucose levels?

  Pancreas
• What receptors monitor blood glucose change?

  Islets of Langerhans
• What do alpha cells do?

  Detect low glucose concentration and secrete glucagon
• What do beta cells do?

  Detect high glucose concentration and secrete insulin
• Glycogenolysis


  Glycogen -> glucose
• What hormone is glycogenolysis activated by?

  Glucagon
• Gluconeogenesis


  Glycerol / amino acids -> glucose
• What hormone is gluconeogenesis activated by?

  Glucagon
• Glycogenesis


  Glucose -> glycogen
• What hormone is glycogenesis activated by?

  Insulin
• Lipogenesis


  Glucose -> lipids
• Insulin lowers blood sugar by:

  1. Stimulating glucose use in respiration
  2. Stimulate the uptake of glucose- open transport proteins
  3. Activate enzymes in the muscle and liver to increase glycogenesis
  4. Activates enzymes for lipogenesis
• What is the name of the glucose transporters in skeletal and cardiac muscles?

  GLUT4
• Where is GLUT4 stored?

  Vesicles in the cytoplasm of cells
• What triggers the movement of GLUT4?

  Insulin
• How is glucose transported into the cell?

  GLUT4 protein by facilitated diffusion
• What does glucagon do?

  Binds to receptor proteins and activates glycogenolysis
• What does glucagon also stimulate?

  The conversion of amino acids and glycerol into glucose- gluconeogenesis
• Increasing blood glucose levels

  1. Alpha cells in islet of Langerhans detect low levels of glucose and release glucagon
  2. Glucagon binds to liver receptor cells
  3. Activates membrane-bound enzyme adenylate cyclase
  4. Adenylate cyclase catalyses conversion of ATP to cAMP
  5. cAMP activates a protein kinase enzyme
  6. Activates enzymes that cause glycogenolysis
• What does cAMP stand for?

  cyclic adenosine monophosphate
• Name a secondary messenger

  cAMP
• What gland releases adrenaline?

  Adrenal gland
• When is adrenaline released?

  In the fight or flight response
• What does adrenaline bind to?

  Specific receptors on muscle cells
• What does adrenaline activate?

  The same response as glucagon
• Does adrenaline increase or lower blood glucose levels?


  Increase
• Role of adrenaline


  1. Activates glycogenolysis
  2. Inhibits glycogenesis
  3. Activates glucagon and inhibit insulin
• How does adrenaline get the body ready for action?

  Makes more glucose available for muscles to respire
• What happens to insulin in type 1 diabetes?


  It is not produced
• When does type 1 diabetes occur?

  Childhood
• Why does type 1 diabetes occur?

  The immune system attacks insulin-producing beta cells
• How can type 1 diabetes be treated?

  Regular insulin injections, careful monitoring, exercise and diet
• What type of diabetes is insulin-dependent?

  Type 1
• What type of diabetes is insulin-independent?

  Type 2
• When does type 2 diabetes occur?

  Over 40
• How is type 2 diabetes caused?

  Glycoprotein receptors lose their responsiveness to insulin or an inadequate supply of insulin from the pancreas
• How is type 2 diabetes controlled?

  Through diet regulation and exercise
• Why is type 2 diabetes becoming increasingly common?

  • High levels of obesity
  • Unhealthy diets
  • Low levels of exercise