Blood glucose

• What are the hormones involved in regulation of blood glucose?

  Adrenaline and glucagon
• What is the model used in regulation of blood glucose?

  Secondary messenger model
• What is the secondary messenger model?

  How glycogen is converted to glucose, through use of adrenaline
• What is the role of adrenaline in the secondary messenger model?

  • Adrenaline binds to a protein receptor on the liver cell
  • The protein changes shape, which leads to activation of adenyl cyclase
  • Adenyl cyclase converts ATP to cyclic AMP (cAMP)
• What does cyclic AMP do?


  Acts as a secondary messenger that binds to protein kinase and activates it
• What does protein kinase do?


  Converts glycogen to glucose, which moves into blood via facilitated diffusion
• What are the three processes that occur when regulating blood sugar?

  • Glycogenesis
  • Glycogenolysis
  • Gluconeogenesis
• What is glycogenesis?

  The conversion of glucose to glycogen, when glucose levels are higher than normal
• What is glycogenolysis?

  The breakdown of glycogen to glucose, when blood glucose is lower than usual
• What is gluconeogenesis?


  The process of synthesizing glucose from non-carbohydrate sources
• What are some factors affecting blood glucose concentration?

  Diet

  Exercise
• What is the pancreas made up of?

  Islets of Langerhans containing a-cells and b-cells
• What do a-cells produce?

  Glucagon
• What do b-cells produce?

  Insulin
• Which cells detect a rise in blood glucose concentration?

  B cells
• What happens when insulin binds to glycoprotein receptors?

  • Increases amount of carrier proteins responsible for glucose transport
  • Activates enzymes that convert glucose to glycogen
  • Changes tertiary structure of glucose carrier proteins so they open allowing more glucose to enter
• What does lowering blood glucose do?

  makes the b cells reduce their secretion of insulin (negative feedback)
• What defects a fall in blood glucose levels?

  A cells
• What does glucagon do to increase glucose levels?

  • Activate enzymes that convert glycogen to glucose
  • Activate enzymes that stimulate gluconeogenesis