Feed-fast

Question 1

Role of growth hormone and cortisol in blood glucose regulation

Answer 1

-counteract insulin action over long-term

Question 2

Main regulators of blood glucose

Answer 2

-insulin (down) and glucaon (up)

Question 3

Post-prandial

Answer 3

• refers to period 2-3 hours after a meal
• high blood insulin/glucagon ration
• insulin increases
• glucagon decreases
• blood glucose increases
• dietary monosaccharides are taken up by intestinal mucosal cells via SGLT-1 (glu and gal) and GLUT-5 (fru, high concentration glu), released into portal circulation via GLUT-2 (all 3)
• liver takes up sugars via GLUT-2; phosphorylated with glucokinase, galactokinase, and fructokinase respectively
• at very high blood glucose and following extensive glycolysis–>fatty acid and cholesterol de novo synthesis (high ATP–|IDH, PFK-1, citrate transported to cytosol inhibits PFK-1)
• Adipose cells move GLUT-4 to plasma membrane take in glucose, use glycerol-phosphate from glycolysis to do TAG synthesis
• Muscle cells move GLUT-4, do glycogen synthesis and protein synthesis

Question 4

Post-absorptive phase

Answer 4

•5-7 hrs after food intake and food absorption

• blood glucose levels have since postprandial phase
• insulin levels drop, glucagon rise, low insulin/glucagon
• glucagon stimulates glycogenolysis and gluconeogenesis and release of glucose into the blood by the liver, glycogen synthesis and glycolysis stop
• low insulin and elevated epinephrine and cortisol levels lead to mobilization of TAG stores in fat cells and release of free fatty acids into blood
• glycogen stores low after 4-6 hrs, and depleted after 1 day, only gluconeogenesis provides blood glucose

Question 5

Cortisol

Answer 5

• in responsee to stress pituitary releases ACTH which stimulates release of cortisol from adrenal cortex
• cortisol in medulla leasd to methylation of norepinepherine to epinepherine (PNMT, with SAM) and release of both into blood
• epinepherine inhibits insulin release and stimulates glucagon release

Question 6

Insulin

Answer 6

• signals high blood glucose, acts via insulin receptors in many tissues, favors degredation or storage of glucose, has general anabolic effect (proteins, fatty acids, TAGSs, Cholesterol), release VLDLs
• release inhibited by epinepherine and stimulated by glucose and amino acids (especially leucine (essential) and arg)
• activates protein phosphatases which dephospohrylate key enzymes
• induce glucokinase, PFK-1, pyruvate kinase, glucose 6-P dehydrogenase (PPP), acetyl-CoA carboxylase (FA synthesis), and HMG-CoA reductase (cholesterol synthesis)
• activate HMG-CoA reductase in liver
• Activate lipoprotein lipase in capillaries (TAG synthesis)

Question 7

Glucaon

Answer 7

• signals low glucose, acts at glucagon receptors found in liver
• rise in blood glucose from glycogenolysis and gluconeogesis
• degradation of fatty acis and ketogenesis
• release inhibited by glucose, stimulated by epinepherine adn amino acids (especially alanine (high in fasting because sent from muscle to glucose for gluconeogenesis) and arg
• activate adenylate cyclase to cAMP to active PKA that phosphorylate key enzymes
• induce pep carboxykinase, fructose-1, 6-bisphosphatase, adn glucose-6-phosphatase

Question 8

Liver

Answer 8

• glucagon: glycogen degradation and gluconeogenesis
• epinepherine-glycogen degredation (phosphorylation cascade)
• cortisol-induction of PEP carboxykinase–>gluconeogesis

Question 9

Effects of epinepherine

Answer 9

• glycogen degredation and glycolysis in muscle
• glycogen degredation in liver
• fatty acid degradation adn use of ketone bodies
• TAG degredation in fat cells and release of fatty acids and glycerol into blood
• degredation of proteins in muscle
• activate hormone sensitive lipase in fat cells

Question 10

Cortisol

Answer 10

• induce PEP carboxykinase

- help activate hormone-sensitive lipase

Question 11

muscle after meal

Answer 11

• high insulin/glucagon
• glucose uptake glut4
• glycogen synthesis
• glycolysis
• amino acid uptake, protein sythesis
• usage of branch-chain amino acids for energy metabolism (muscle has much more branced chain transaminase than liver)