USMLE

Glucagon

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Endocrine & Hormones
  1. Leptin
  2. Ghrelin
  3. Protein Hormones
  4. Steroid Hormones
  5. Insulin
  6. Diabetes
  7. Glucagon
  8. Epinephrine
  9. Cortisol
  10. Thyroid Hormones
  11. Calcitonin
  12. Parathyroid Hormone (PTH)
  13. Anterior Pituitary
  14. Prolactin
  15. Luteinizing Hormone (LH)
  16. Follicle-Stimulating Hormone (FSH)
  17. Growth Hormone (GH)
  18. Posterior Pituitary

Summary

Glucagon is a protein hormone produced by alpha cells in the pancreas. Glucagon functions to increase blood glucose levels when they are too low, a condition known as hypoglycemia. Glucagon then works on organs like the liver to promote processes like glycogenolysis and gluconeogenesis. Ultimately, this leads to the increase of glucose in the bloodstream.

Key Points

  • Glucagon
    • Peptide hormone
      • Binds to external cell receptors and initiates secondary messenger cascade
    • Origin: alpha cells of the pancreas
      • Produced in response to low blood glucose (hypoglycemia)
    • Function:
      • Increases blood glucose
        • Increases glycogenolysis and gluconeogenesis in the liver
          • Mobilizes glucose stores in liver
      • Promotes ketogenesis
        • Ketone bodies can be used as an alternative source of energy in hypoglycemic states