decrease in blood glucose

• Decrease in blood glucose concentration
• If decrease in blood glucose concentration occurs

  It is detected by the alpha and beta cells in the pancreas
• Response to decrease in blood glucose concentration

  1. Alpha cells secrete glucagon

  2. Beta cells stop secretion of insulin

  3. Decreased insulin reduces glucose use by liver and muscle cells

  4. Glucagon binds to liver cell receptors

  5. Binding causes conformational change in receptor protein

  6. Activates G protein

  7. G protein activates Adenylyl Cyclase

  8. Active Adenylyl Cyclase converts ATP to cAMP

  9. cAMP activates protein kinase A enzymes

  10. Active protein kinase A activates phosphorylase kinase enzymes

  11. Active phosphorylase kinase activates glycogen phosphorylase enzymes

  12. Active glycogen phosphorylase catalyzes breakdown of glycogen to glucose
• Glycogenesis

  Breakdown of glycogen to glucose
• The enzyme cascade amplifies the original signal from glucagon
• The enzyme cascade results in the releasing of extra glucose by the liver to increase the blood glucose concentration back to normal
• ONLY OCCURS IN LIVER CELLS, NO GLUCAGON RECEPTORS ON MUSCLE CELLS
• effect of Glucagon on liver cells diagram