Blood Glucose Conc.

• Factors affecting blood glucose concentration


  • Amount of carbohydrate digested from diet
  • Rate of glycogenolysis
  • Rate of gluconeogenesis
• Liver processes in regulation of blood glucose


  1. Glycogenesis - liver converts glucose into glycogen

  2. Glycogenolysis - liver hydrolyses glycogen into glucose

  3. Gluconeogenesis - liver converts glycerol & amino acids into glucose
• Blood glucose concentration is too low

  • α cells in Islets of Langerhans in pancreas detect decrease & secrete glucagon into bloodstream
  • Glucagon secretion inhibits beta cell action
  • Glucagon binds to surface receptors on liver cells & activates hepatocytes for glycogenolysis
  • Glucose diffuses from the liver into the bloodstream
  • Cells use fatty acids & amino acids for respiration instead
• Glycogen breakdown into glucose using adrenaline

  1. Adrenaline fuses to receptor of liver cell, causing receptor to change shape

  2. Conformational change to the receptor activates adenylyl cyclase, which converts ATP to cyclic AMP (cAMP)

  3. cAMP activates protein kinase which catalyses glycogenolysis
• Blood glucose concentration is too high

  • β cells in Islets of Langerhans in pancreas detect increase
  • Insulin is secreted by beta cells, thus inhibiting the action of alpha cells
  • Insulin travels in blood to target cells (hepatocytes) in the liver, fat & muscle cells
  • Binding of insulin to receptors on plasma membranes causes adenyl cyclase to convert ATP into cAMP
  • cAMP activates the opening of glucose channels in the cell surface membrane, thus causing more glucose to enter the cell, which is then converted to glycogen or fats & subsequently used for respiration
• Insulin binding to target cells


  • Increase cellular glucose uptake
  • Activate enzymes for glycogenesis (liver & muscles)
  • Stimulate adipose tissue to synthesise fat
• How insulin increases permeability of cells to glucose

  • Increasing the number of glucose carrier proteins
  • Triggering conformational change which opens glucose carrier proteins
• How insulin increases glucose concentration gradient

  • Activates enzymes for glycogenesis in liver & muscles
  • Stimulates fat synthesis in adipose tissue
  • Triggers inhibition of enzymes for glycogenolysis
• Cause of Type 1 diabetes is the body can't produce insulin e.g. due to autoimmune response which attacks β cells of Islets of Langerhans. Treated by injecting insulin.
• Causes of Type 2 diabetes is a decrease in insulin production or by glycoprotein receptors on target cells becoming unresponsive to insulin. There is a strong positive correlation with poor diet / obesity. Treated by controlling diet and exercise regime.
• Signs & symptoms of diabetes

  • High blood glucose concentration
  • Blurred vision & Sudden weight loss
  • Glucose in urine - High concentration of glucose in blood; Not all glucose is reabsorbed at the PCT; Carrier/co-transport proteins are working at maximum rate