1. Metabolism Chapter 25

2. Nutrients Essential nutrients - those that cannot be synthesized by body cells and must be ingested in the diet Nutrients- a substance in food that is used by the body to promote normal growth, maintenance, and repair

3. Classes of Nutrients 1. Carbohydrates 2. Lipids 3. Proteins 4. Minerals 5. Vitamins

4. Metabolism all chemical reactions of the body some reactions produce energy stored in ATP that other reactions consume Food Functions source of energy provides essential nutrients stored for future use All molecules eventually broken down and recycled or excreted

5. Catabolism and Anabolism Anabolic reactions synthesize complex molecules from small molecules requires energy (endergonic/endothermic) Catabolic reactions breakdown complex organic compounds provides energy (exergonic/exothermic) glycolysis, Krebs cycle and electron transport

6. ATP-Anabolism and Catabolism

7. ATP Generation Phosphorylation is bond attaching phosphate contains stored energy Mechanisms of phosphorylation within animals substrate-level phosphorylation in cytosol oxidative phosphorylation in mitochondria

8. Cellular Respiration

9. Carbohydrate Metabolism In GI tract –polysaccharides broken down into simple sugars for absorption In liver –fructose & galactose transformed into glucose –storage of glycogen - glycogen In body cells –oxidized to produce energy –conversion into something else –storage energy as triglyceride in fat

10. What Happens to Glucose? ATP production during cell respiration Converted to one of several amino acids Glycogenesis –hundreds of glucose molecules combined to form glycogen for storage in liver & skeletal muscles Lipogenesis (triglyceride synthesis) –converted to glycerol & fatty acids within liver

11. Glycolysis

12. Pyruvic Acid

13. Krebs Cycle

14. Electron Transport Chain

15. Electron Carriers Flavin mononucleotide (FMN) Cytochromes are proteins with heme group (iron) existing either in reduced form (Fe 2+ ) or oxidized form (Fe 3+ ) Iron-sulfur centers contain 2 or 4 iron atoms bound to sulfur within a protein Copper (Cu) atoms bound to protein Coenzyme Q is nonprotein carrier

16. Electron Carriers

17. Summary of Cellular Respiration

19. Glycogenesis & Glycogenolysis

20. Gluconeogenesis

21. Classes of Lipoproteins Chylomicrons (2 % protein) –form in intestinal epithelial cells to transport dietary fat VLDLs (10% protein) –transport triglycerides formed in liver to fat cells LDLs (25% protein) --- “bad cholesterol” –carry 75% of blood cholesterol to body cells –apo B100 is docking protein for receptor-mediated endocytosis of the LDL into a body cell HDLs (40% protein) --- “good cholesterol” –carry cholesterol from cells to liver for elimination

22. Classes of Lipoproteins

23. Blood Cholesterol Sources of cholesterol in the body –food (eggs, dairy, organ meats, meat) –synthesized by the liver All fatty foods still raise blood cholesterol –liver uses them to create cholesterol –stimulate reuptake of cholesterol containing bile normally lost in the feces Desirable readings for adults –total cholesterol under 200 mg/dL; triglycerides 10-190 mg/dL –LDL under 130 mg/dL; HDL over 40 mg/dL –cholesterol/HDL ratio above 4 is undesirable risk Raising HDL & lowering cholesterol can be accomplished by exercise, diet & drugs

24. What Happens to Lipids? Oxidized to produce ATP Excess stored in adipose tissue or liver Synthesize structural or important molecules – phospholipids of plasma membranes –lipoproteins that transport cholesterol –thromboplastin for blood clotting –myelin sheaths to speed up nerve conduction –cholesterol used to synthesize bile salts and steroid hormones.

25. Triglyceride Storage Adipose tissue removes triglycerides from chylomicrons and VLDL and stores it Fats in adipose tissue are ever-changing Triglycerides store more easily than glycogen

26. Lipid Metabolism

27. What Happens to Proteins? Proteins are broken down into amino acids –transported to the liver Usage –oxidized to produce ATP –used to synthesize new proteins enzymes, hemoglobin, antibodies, hormones, fibrinogen, actin, myosin, collagen, elastin & keratin –excess converted into glucose or triglycerides no storage is possible Absorption into body cells is stimulated by insulinlike growth factors (IGFs) & insulin

28. Amino Acids and Kreb’s Cycle

29. Key Molecules and Metabolism

30. Summary of Metabolism

31. Absorptive State

32. Hormones and Absorptive State

33. Post-Absorptive State

34. Hormones and Post-Absorptive State

35. Heat and Energy Balance Heat – form of energy that can be measured as temperature and can be expressed in calories –calorie (cal) – amount of heat required to raise 1 gram of water 1°C –Kilocalorie (kcal) or Calorie (Cal) is 1000 calories Metabolic rate – overall rate at which metabolic reactions use energy –Some energy used to make ATP, some lost as heat –Basal metabolic rate (BMR) – measurement with body in quiet, resting, fasting condition

36. Body Temperature Homeostasis –Despite wide fluctuations in environmental temperatures, homeostatic mechanisms maintain normal range for internal body temperature –Core temperature (37°C or 98.6°F) versus shell temperature (1-6°C lower) –Heat produced by exercise, some hormones, sympathetic nervous system, fever, ingestion of food, younger age, etc.

37. Heat and Energy Balance Heat can be lost through –Conduction to solid materials in contact with body –Convection – transfer of heat by movement of a gas or liquid –Radiation – transfer of heat in form of infrared rays –Evaporation exhaled air and skin surface (insensible water loss) Hypothalamic thermostat in preoptic area –Heat-losing center and heat-promoting center

38. Thermoregulation

39. Nutrition Nutrients are chemical substances in food that body cells use for growth, maintenance, and repair 6 main types –Water – needed in largest amount –Carbohydrates –Lipids –Proteins –Minerals –Vitamins Essential nutrients must be obtained from the diet

40. Guidelines for Healthy Eating –We do not know with certainty what levels and types of carbohydrates, fat and protein are optimal –Different populations around the world eat radically different diets adapted to their particular lifestyle –Basic guidelines Eat a variety of foods Maintain a healthy weight Choose foods low in fat, saturated fat and cholesterol Eat plenty of vegetables, fruits and grain products Use sugars in moderation only

41. Food Guide Pyramid

42. Minerals

43. Minerals continued…

44. Vitamins

45. Vitamins continued…