Regulation Of Blood Glucose Part 2

Question 1

Describe the post prandial blood glucose and fasting blood glucose

Answer 1

• 2 hours after meal (postprandial blood glucose level)
• Fasting blood glucose
• Why is it critical to maintain blood glucose level in fasting state???
– Brain
– RBC….

Question 2

What are the hormonal changes in fasting?

Answer 2

• β-cells of pancreas inhibited
• α-cells of pancreas stimulated
• Decreased insulin: glucagon ratio
• Glucagon activates adenylate cyclase
• Activation of protein kinase A
• Phosphorylation of regulatory enzymes (covalent modification)

Question 3

What are the effects of glucagon in liver?

Answer 3

• Glycogen metabolism
– Glycogen phosphorylase (rapid)
– Glycogen synthase(inhibited)

• Effect on
– Gluconeogenesis (slower effect)
– Glycolysis(inhibited)

Question 4

What enzymes are upregulated in fasting?

Answer 4

• Pyruvate carboxylase
• Fructose 1,6-bisPase
• PEPCK
• Glucose 6-phosphatase
• Pyruvate kinase
• Long-term

Question 5

What are the changes in carbohydrate metabolism during fasting?

Answer 5

• Liver produces glucose (Compare to fed state) – Glycogenolysis
– Glycogen synthesis
– Gluconeogenesis active
• Amino acids
– Liver Glycolysis

• Muscle and adipose tissue
• Brain

Question 6

Summarize hormonal regulation of blood glucose level

Answer 6

Insulin- decrease blood glucose level

Increase blood glucose level- counter regulatiry hormones (glucagon, epibephrine, cortisol, growth hormone)

Question 7

What is the role of epinephrine?

Answer 7

• Beta-adrenergic receptors
• Activates protein kinase A in liver
• Glycogenolysis (rapid effect)
• Increases gluconeogenesis (slower effect)
• Epinephrine or glucagon: Hypoglycemia
• In muscle, glycogenolysis
• Adrenergic symptoms in patients with ‘hypoglycemia

Question 8

What is the role of cortisol(glucocorticoid)?

Answer 8

• Binds intracellular receptors and gene expression
• Induces synthesis key gluconeogenic enzymes
• Hyperglycemia: Cushing syndrome, Chronic stress
• Hypoglycemia: Addison disease, CAH (CYP21)

Question 9

What conditions present with hypoglycemia?

Answer 9

• Acute alcohol intoxication
• Glycogen storage disorders:
– von Gierke disease, Cori disease

• Hereditary fructose intolerance
• Classical galactosemia
• Liver fatty oxidation defect

• ER module:
 – Insulinoma
– Addison disease
– Congenital adrenal hyperplasia (CYP21)
– Insulin overdose and sulfonylurea overdose