Your Body’s Metabolism

1. Your Body’s Metabolism

2. Metabolism Sum of all chemical reactions in the body’s cells Generation of energy from carbohydrates, proteins, and fats Anaerobically Aerobically Production of biological compounds Nonessential amino acids Intermediate substances needed for metabolism

3. Metabolism Never stops Adapts to individual needs and the environment Has several metabolic pathways Glycolysis TCA cycle Electron transport chain

4. Overview of Energy Metabolism Figure 8.1

5. Chemical reactions involved in energy production Different cells perform different functions Each cell’s structure in similar Metabolism in the Cell

6. Metabolism Takes Place within Cells Figure 8.2

7. Cell Structure Cell construction is similar for all cells Outside of cell Plasma membrane Holds in the cell contents Inside of cell Includes several special internal structures: organelles

8. Internal Cell Structure Organelles Mitochondrion “Powerhouse of the cell” Aerobic metabolism Ribosomes Help manufacture proteins Smooth endoplasmic reticulum Produces lipids Cytosol Fluid portion of cell Anaerobic metabolism

9. Is the most metabolically active organ in the body First organ to metabolize, store, and distribute nutrients after absorption Proteins, carbohydrates, and fats are absorbed as: Amino acids Monosaccharides Glycerol and fatty acids Liver

10. Proteins, carbohydrates, and fats are in the liver converted to Usable forms of energy Storage forms Glycogen Triglycerides Liver

11. The Metabolic Fate of Food Figure 8.3

12. Metabolic Pathways A sequence of reactions that convert compounds from one form to another in the production of energy Different nutrients follow different pathways All pathways eventually converge into a pathway called the TCA cycle

13. Anabolic and Catabolic Reactions Figure 8.4

14. Enzymes and Hormones Enzymes allow chemical reactions of metabolism to occur at rates sufficient to maintain normal body function Coenzymes assist enzymes Hormones regulate anabolic and catabolic reactions

15. Quick Review Metabolism is the sum of all metabolic processes that occur in the cells Mitochondria is the site of most of the metabolic reactions Metabolic processes follows specific pathways Anabolic which use energy to build new substances Catabolic which produce energy by breaking down molecules Enzymes and coenzymes catalyze reactions Hormones regulate reactions

16. Energy Drinks: Can They Alter Metabolism? Main ingredient is caffeine Promotes lipolysis Overall excess can cause negative health effects Elevated heart rate and blood pressure Anxiety Diminished ability to concentrate Insomnia Limit caffeine intake to no more than 300 milligrams per day

17. Energy Drinks: Can They Alter Metabolism? Mixing energy drinks with alcohol doubles Risk of injury Need for medical attention Driving with intoxicated drivers

18. How Does the Body Fuel Metabolism?

19. Adenosine Triphosphate (ATP) A high-energy molecule composed of adenine, ribose, and three phosphate molecules Part of Figure 8.5

20. Adenosine Triphosphate (ATP) Only source of energy used directly by the cell Energy is stored in the bonds that connect the phosphate groups The body must continually produce ATP to provide a constant supply of energy

21. ATP to ADP (Adenosine Diphosphate) Figure 8.5

22. Creating ATP from ADP and Creatine Phosphate Regenerating ATP from ADP requires inorganic phosphate Sources Inorganic phosphate produced from initial breakdown of ATP Inorganic phosphate in creatine phosphate (a.k.a. phosphocreatine or PCr) Process requires energy

23. Creatine Phosphate High-energy compound in muscle cells Creatine combine plus inorganic phosphate

24. Creatine Phosphate Creatine monohydrate – a supplement sold in stores Marketed to athletes to maximize PCr stores Research Increased performance of short-duration, high-intensity activities Side effects

25. Anaerobic and Aerobic Metabolism Anaerobic metabolism Produces more ATP per minute Limited in use, provides only 1–1.5 minutes of maximal activity Involved in high-intensity, short-duration activities, e.g., sprinting, heavy weight lifting

26. Anaerobic and Aerobic Metabolism Aerobic metabolism Produces less ATP per minute Is able to produce ATP indefinitely Involved in low-intensity, long-duration activities When demand for ATP is greater than the rate of metabolism the activity slows down

27. Quick Review ATP – energy the body uses to fuel all metabolic reactions ATP is not stored Formed from ADP and inorganic phosphate Creatine phosphate can donate inorganic phosphate Produced during anaerobic metabolism Produced during aerobic metabolism

28. Carbohydrates to Energy Carbohydrate metabolism is the backbone of energy production Glucose Important energy source for the brain and red blood cells Generates energy anaerobically and aerobically Transforms to energy via four metabolic pathways Glycolysis Intermediate reaction pyruvate to acetyl CoA Tricarboxylic acid (TCA) cycle Electron transport chain

29. Glycolysis Breakdown of glucose First step in forming ATP from glucose Takes place in the cytosol of the cell Ten-step catabolic process One six-molecule glucose process to two three-carbon molecules of pyruvate and two molecules of ATP

30. Glycolysis The other monosaccharides can also be used to produce ATP Fructose enters glycolysis after going through seven metabolic steps Galactose enters after going through four metabolic steps

31. Glycolysis Summary Ten-step process that produces Two molecules of ATP Two molecules of pyruvate Two energized coenzyme molecules Two hydrogen ions that are transported to the electron transport chain Two water molecules

32. The Fate of Pyruvate Figure 8.7

33. The Cori Cycle Figure 8.8

34. Glycolysis Process by which carbohydrates provide energy to the cell Backbone of metabolism One glucose molecule yields Two pyruvate Two ATP Two energized coenzymes Pyruvate Reduce to lactate during anaerobic metabolism Converted to acetyl CoA during aerobic metabolism Quick Review • Two hydrogen ions • Two water molecules

35. Fats to Energy Dietary fat (triglycerides) yields six times more energy Triglycerides Glycerol backbone Three fatty acids Stored in adipose tissue Glycerol and fatty acids can be used for fuel Glycerol produces little energy

36. Triglycerides Hydrolyzed to fatty acids and glycerol during lipolysis Reaction catalyzed by an enzyme in the adipose tissue Glucagon during times of fasting or starvation Epinephrine or cortisol when under stress Once in the blood stream, they travel to the tissues and enter the metabolic pathway

37. Fatty Acids and Glycerol Glycerol Glucogenic – can be transformed to glucose Fatty acids Ketogenic – can be transformed to ketone bodies Ketones are the backup fuel for brain and nerve function when glucose is limited

38. Glycerol In the liver Converted to glucose through gluconeogenesis Enters glycolysis to produce ATP and pyruvate Path entered depends on body’s need for glucose Brains and nerves prefer to use glucose for fuel Red blood cells can only use glucose for fuel When the diet is low in carbohydrates glucose must come from other sources

39. Quick Review Both the glycerol and fatty acid portions of triglycerides provide energy Fatty acids are the more concentrated sources of energy and are ketogenic, nonglucose forming Glycerol is glucogenic forming glucose through gluconeogenesis

40. How Does Protein Provide Energy? Amino acids Primary use/most important function is building protein If the amino acid is not used to build protein the amine group must be removed through deamination Excess can be used for energy production, converted to glucose, or stored as fat Used, in a limited extent, for energy in diets low in kilocalories and/or carbohydrate

41. Ketogenic verses Glucogenic Amino Acids Ketogenic amino acids Leucine Lysine Both ketogenic and glucogenic amino acids Isoleucine Tryptophan Phenylalanine Tyrosine Glucogenic amino acids The fourteen other amino acids

42. Glucogenic and Ketogenic Amino Acid Metabolism • Acetyl CoA cannot be used to make glucose Figure 8.10

43. Amino Acids to Glucose Glucogenic amino acids Major source of blood glucose when the diet is lacking in carbohydrate Can come from food Can come from the breakdown of muscle

44. Quick Review Amino acids can Be used to produce energy Be used to produce glucose Convert to fatty acids and can be stored as triglycerides Must be deaminated to be used for energy Once deaminated can be transformed into: Pyruvate Acetyle CoA TCA cycle compounds Glucogenic amino acids can be converted to glucose

45. Where Do the Macronutrients Come Together? Acetyl CoA “Gateway” molecule for aerobic metabolism Carbohydrates, proteins, and fat all eventual converted to acetyl CoA Alcohol also converted to acetyl CoA Macronutrients enter the TCA cycle as acetyl CoA

46. The Tricarboxylic Acid (TCA) Cycle Gathers electrons from the carbons in the energy nutrients Transfers stored energy to two coenzyme hydrogen ion carriers to be released in the electron transport chain One molecule of acetyl CoA enters the TCA cycle at a time

47. The TCA Cycle Figure 8.11

48. The Tricarboxylic Acid Cycle Each cycle produces Two carbons that are lost to CO2 Eight hydrogen atoms and their electrons Small amount of energy as GTP Provides the starting material for creating nonessential amino acids through transamination

49. Transamination The transfer of an amino group from one amino acid to an alpha-keto acid to form a new nonessential amino acid Carbon skeleton for nonessential amino acids come from Pyruvate from glycolysis Alpha-ketoglutarate from the TCA cycle

50. Transamination Figure 8.12