Energy Transfer

ATP “Energy Currency” Potential energy in ATP used for all energy requiring processes of cells

Energy Transformation Formation of ATP from food Use of chemical energy in ATP for metabolic work

ATP Hydrolysis ATP + H2O ADP + Pi – 7.3 kcal/mol ATPase Anaerobic Process – generates energy for immediate use Energy Liberating

Energy Currency CHO, Lipids, and Proteins + O2 CO2 + H2O ADP + Pi ATP Synthesized End Products Precursors

ATP stored only in cells total quantity  3.5 oz. energy for few seconds

ATP Generation ATP-CP system glycolytic system oxidative system

Creatine Phosphate ATP  ADP + P + Energy CP  C + P + Energy Biological Work ATPase CK

Creatine Phosphate 4 - 6x conc. of ATP Energy released when C & P bond broken Energy used to phosphorylate ADP Used in activities < 15-20 sec. Anaerobic

Cellular Oxidation – Aerobic Metabolism Cellular oxidation-reduction is the mechanism for energy metabolism Electron Transport Oxidative Phosphorylation

Electron Transport Oxidation of hydrogen Exergonic transport of electrons to oxygen electrons  oxygen  H2O ADP is phophorylated (energized)

Electron Transport (Respiratory Chain) ATP NADH + H+ FADH2 ATP 2e- NAD+ Coenzyme Q 2e- FAD 2e- Coenzyme b 2e- ATP Coenzyme c Coenzyme c1 2e- Coenzyme aa3 ½ O2 2e- 2H+ H2O

Oxidative Phosphorylation 10 means for extracting & trapping energy (PO4) >90% of ATP synthesis takes place in respiratory chain via oxidative reactions w/ phosphorylation

Oxidative Phosphorylation ATP is synthesized when electrons transferred from NADH to O2 NADH + H+ + 3ADP +3P + ½ O2  NAD+ +H2O + 3ATP

Electron Transport-Oxidative Phosphorylation Efficiency Oxidation of 1 mole of NADH  52 kcal 3 moles of ATP regenerated (3 moles * 7 kcal/mole = 21 kcal) 21/52 = 40% efficient 60% dissipates - body heat

Role of Energy Release from Food Phosphorylate ADP  ATP

Regeneration of ATP Liver - amino acid - glycogen  glucose Adipocytes  fatty acids Mitochondrion Muscle - ATP, CP, triglycerides, glycogen, AA

Energy Release - CHO Only macronutrient to generate ATP anaerobically Light-moderate exercise provides ½ of energy C6H12O6 + 6O2  6 CO2 + 6 H2O – 689 kcal/mol

Glycolysis - anaerobic - glucose  pyruvate (2) Pyruvate  lactic acid (2) net gain 2 ATP  5% of total ATP generated in glucose breakdown (rapid)

Lactic Acid If energy demands exceed O2 supply or rate of H+ production exceeds usage High intensity exercise  LA in muscle  blood (buffered)  lactate  energy metabolism used during moderate exercise

Aerobic Metabolism Kreb’s Cycle (2 ATP) Electron Transport (2 ATP) Oxidative Phosphorylation (32 ATP)

Lipid Catabolism Greatest source of potential energy 90,000 - 110,000 kcal

Sources Triglycerides stored in muscle Triglycerides in lipoprotein complexes FFA (triglyceride + 3 H2O  glycerol + 3 FA)

Utilization FA diffuse from adipocytes  FFA controlled by epi, norepi, glucagon, GH Meal  triglyceride synthesis Moderate exercise   FA utilization  triglyceride breakdown

Energy Transfer - Lipid 18 carbon FA  146 ATP (438 ATP total) + 19 ATP (glycerol) 40% efficiency 30-80% of energy for biological work is provided by lipids

Energy Release - Protein 20 sustained exercise / intense training AA (deaminated)  carbon skeleton  Kreb’s cycle AA (deaminated )  pyruvate (gluconeogenesis)

Interrelationships Kreb’s Cycle - link between food energy & chemical energy - provides intermediate substances  mitochondria  bionutrients for growth & maintenance

Interrelationships Lipids more efficiently used in presence of CHO lipid catabolism is dependent on oxaloacetate (Kreb’s - generated from pyruvate in CHO catabolism)

Interrelationships Power output by lipids alone is only 1/2 that of when CHO is primary source serve CHO depletion  acetyl-CoA & FFA  ketone bodies (ketosis) Liver