Carbohydrate Metabolism and Hormonal Control in the Body

1. Review: can you… Explain how Carbs are digested & absorbed Draw the steps involved in Glycolysis Compare and contrast aerobic respiration to two different types of fermentation Discuss the 3 possible fates of Pyruvate

3. Energyyield fromcompleteoxidation ofglucose • (e- loss) via aerobicrespiration anaerobic fermentation results in just 2 ATP 30 to 34

4. Yield of ATP from the Complete Oxidation of One Glucose Molecule in a Skeletal Muscle Cell.

5. How is all of that ATP used? Just focusing on building molecules (synthesis); gives you a taste of ATP driven reactions.

6. Glucose is stored in muscles and liver : Glycogen = animal starch (glucose storage molecule).   Muscle: glucose source for glycolysis Liver: glucose source for maintenance of blood glucose levels

7. Comparing glycogenesis to glycogenolysis Separate pathway energy needs. Separate control of each pathway.

8. What does your body do if you don’t have enough glucose? Gluconeogenesis: Needed to produce glucose for the brain when food isn’t available. Glycogen stores are depleted in 12 to 18 hours. Use other non-carbohydrate sources (glycerol,lactate, some amino acids, & (in plants) acetyl-CoA) to make glucose for brain fuel. The liver is the major site ofgluconeogenesis.

9. The “opposite” (sort of) processes of gluconeogenesis (pyruvate to glucose) & glycolysis (glucose to pyruvate) are not exact opposites. Additional step due to energy needs

10. The relationships among 4 common metabolic pathways that involve glucose.

11. Gerti and Carl Cori won 1947 Nobel Prize in physiology / medicine for discovery of the enzyme that starts the conversion of glycogen to glucose. The Cori cycle is named after them.

12. The Cori cycle: processing lactate made during anaerobic exercise

13. The Pentose Phosphate Pathway (PPP) DNA & RNA need 5-C sugar ribose, formed in pentose phosphate pathway (PPP). PPP is a network of reactions (Glycolysis is largely a straight-thru pathway). We can make different products depending upon body’s needs. PPP generates various sugars (e.g. ribose), & also produces NADPH, required by cells for biosynthesis rxns.

14. Hormonal Control of Carbohydrate Metabolism Enzymes control the metabolism of carbohydrates, but... Several hormones also affect Carb. metabolism Insulin Glucagon Epinephrine

15. Insulin reducesglucose in the blood and stimulates conversion of glucose to fats, proteins, ribulose 5-phosphate and glycogen; inhibits the conversion of fats, proteins, glycogen and ribulose 5-phosphate to glucose

16. Types of diabetes mellitus Type 1: autoimmune disorder against the lslet cells of pancreas: deficiency in insulin. Usually diagnosed between 5-20. Insulin shots necessary. Hypoglycemia (too little glucose) may result. Type 2: 80-90 % of all diabetics in US: usually diagnosed over age 40. relative insulin deficiency: either decreased production of insulin, or cells become insulin resistant. Strong genetic component: very high in Native Americans; high in Blacks & Hispanics. Obesity major risk factor (often controlled with weight loss).

17. Epinephrine a.k.a. adrenalin

18. Glucagon is a 29 amino acid peptide hormone formed and released from the  cells of the islets of Langerhans, in the pancreas. Glucagon is a hormone that opposes the action of insulin - mainly in the liver.

19. Epinephrine & glucagon have opposite effects to insulin. Act to increase glucose in the blood. Stimulate conversion of fats, glycogen and pyruvate to glucose Inhibit conversion of glucose to fats, glycogen and pyruvate

20. The series of events by which the hormone epinephrine stimulates glucose production. Stimulates adenyl cyclase to make cAMP Quick energy molecule glucose 6-phosphate forms cAMP released to interior activates… Glycogen phosphorylase, which starts glycogenolysis