Biochem 501 Lecture 25 Hormonal Control of Glucose

The flashcards below were created by user mprosenberg on FreezingBlue Flashcards.

  1. Blood Glucose Facts
    Blood glucose can sustain metabolism for about an hour. About 5 mM (5 gm)
  2. Glucose tolerance test
    Diabetics keep higher levels longer
  3. Hormones Produced In Pancreas
    • Glucagon (alpha cells)
    • Insulin (beta cells)
    • Somatostatin (delta cells)
  4. Regulation of Insulin Secretion
    • ATP made in pancreas cells from Glucose pumped in by GLUT2
    •      -hexokinase/glycolysis/TCA/Oxidative
    • ATP pumps K+ out of cell
    • Depolarization lets Ca2+ voltage gated channel open
    • Ca2+ acts as promoter for creation of insulin.
  5. Insulin Levels and Circadian Rhythm
    Levels fluctuate an peak at 9, 1, and 7-8
  6. Model of glucose transport
    Image Upload

    Can go backwards, but NOT WITH G-6-P
  7. Glucose Transporters
    • GLUT2: Liver, pancreas islets, intestine
    • Low binding affinity/high Kt, not regulated by insulin
    • GLUT4: Muscle, fat, heart
    • High binding affinity/low Kt, regulated highly by insulin
    • Transporter opens to outside, binds glucose, opens to inside, releases glucose, repeat
  8. Kinetics of glucose transport
    • Resemble M-M dynamics
    • Image Upload
  9. Rate limiting steps of glucose clearance in Muscles and Adipose/Liver
    • Muscles and Adipose: Transportation
    • Liver: Phosphorylation after transport
  10. What does presence of Glucokinase do to blood glucose levels
    • Lowers it, glucokinase in liver keeps switching glucose and glucose-6-p, only one of which can be sent to blood stream
    • Insulin stimulates glucokinase
  11. Summary of Glucose Action
    • Image Upload
    • Intercellular proteins autophosphorylate to signal intake of glucose
  12. Upregulation of Blood Glucose Levels
    • Glucagon (Pancreas -> Liver)
    • and Epinephrine (Adrenal -> Muscles):
    • Produced in response to low [glucose]
    • Bind to target cells, increase intracellular cAMP
    • Glucose released into blood stream
  13. cAMP
    • Universal starvation signal
    • Made from ATP by adenylate cyclase
    • Binds Protein Kinase
    •      -Binds to regulatory subunit
    •      -Releases Active catalytic subunits
  14. Signaling Cascade
    One initial signal can turn into 10 in next step, turn into 100 into 1,000 into 10,000
  15. Glycogen Phosphorylase b/a
    • B is less active
    • B is phosphorylated when exposed to glucagon/epinephrine (from raised Ca2+ and AMP levels in muscle), becomes A
    • A is more active
  16. PKA Regulation of PFK-2/F-2,6Pase
    Image Upload
  17. Regulation of Liver Glycolysis
    Image Upload
Card Set:
Biochem 501 Lecture 25 Hormonal Control of Glucose
2013-11-11 15:59:26
Biochem 501

Biochem 501
Show Answers: