Regulation of blood glucose

• Glycogenesis= production of glycogen from glucose.

  When blood glucose is too high, excess glucose is converted into glycogen which is stored in the liver.
• Glycogenolysis= glycogen stored in liver and muscle cells is broken down into glucose which is released into the bloodstream increasing blood glucose concentration.
• Gluconeogenesis= production of glucose from non-carbohydrate sources (glycerol, amino acids)

  Increases the blood glucose concentration.
• Insulin

  • Attaches to receptors on surface of target cells.
  • Changes tertiary structure of glucose transport protein, opening them so more glucose can diffuse into cells by facilitated diffusion.
  • Increases the number of carrier proteins.
  • Activates enzymes involved in conversion of glucose to glycogen= glycogenesis.
  • Increases respiratory rate
• Glucagon

  • Attaches to surfaces of liver cells.
  • Activates enzymes involved in conversion of glycogen to glucose= glycogenolysis.
  • Activates enzymes involved in conversion of glycerol and amino acids into glucose= gluconeogenesis.
• Increases blood glucose

  • Glycogenolysis
  • Gluconeogenesis
  • Digestion 
• Decreases blood glucose

  • Glycogenesis
  • Respiration
  • Inhibiting glucagon
  • Converting glucose to fat
  • Opening glucose transport protein channels.
• Control of insulin secretion

  1 blood glucose concentration high outside beta cell so glucose enters cell.

  2 glucose is metabolised inside the mitochondria, producing ATP.

  3 ATP binds to potassium channels and causes them to close.

  4 potassium can no longer diffuse out so depolarisation occurs.

  5 depolarisation occurs calcium ion channels to open.

  6 calcium ions diffuse in and cause vesicles to fuse with the membrane and releases insulin by exocytosis.