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Insulin

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Summary

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Key Points

  • Insulin
    • Peptide hormone
      • Binds to external cell receptors and initiates secondary messenger cascade
        • Causes membrane-bound glucose transporters to open, resulting in glucose movement into cells
    • Origin: beta cells of the pancreas
      • Produced in response to high blood glucose (hyperglycemia)
      • Produced as proinsulin precursor, which must be cleaved in the endomembrane system to produce active insulin (also producing C-peptide)
    • Function:
      • Decreases blood glucose
        • Increased glucose uptake by all cells
        • Increased glycogen production by liver (glycogenesis)
        • Promotes glycolysis
        • Promotes lipogenesis
      • Inhibits glucagon production in alpha cells of pancreas