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Energy Production

Energy Production. conversion of chemical energy to mechanical energy stored in the form of ATP breakdown of ATP releases energy and produces heat used by muscle sliding of myosin and actin transport of molecules glucose, Ca++ and other ions across cell membranes for repair

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Energy Production

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  1. Energy Production • conversion of chemical energy to mechanical energy stored in the form of ATP • breakdown of ATP releases energy and produces heat • used by muscle • sliding of myosin and actin • transport of molecules • glucose, Ca++ and other ions across cell membranes • for repair • conduction of nervous system

  2. rest • ATP synthesis and breakdown remain steady • stored ATP only lasts a few seconds during contraction • maximal exercise • ATP breakdown is 200 times faster than rest • insufficient ATP to meet demand causes fatigue

  3. Protein • very little used for energy (<5%) • proteins > AA • some AA to glucose (gluconeogenesis), pyruvic acid or acetyl CoA • used in oxidative process • nitrogen forms other AA • excess to urea • uses energy

  4. CHO (C6H12O6) • faster energy - short duration • stored as liver glycogen and muscle glycogen • blood glucose immediate energy • 38 ATP (70% of energy for ATP, 30% lost as heat ) • muscle glycogen depleted 20-30% with short, high-intensity bout of exercise • depletion rate of 18.8 umol/g per minute • ? glycogen availability causes fatigue • moderate intensity exercise of 56 minutes • depletion rate of 1.1 umol/g per minute • prolonged exercise results in greatest depletion of muscle glycogen • glycogen concentration fell 50-60%

  5. Fats • triglycerides, phospholipids and cholesterol • triglycerides • used for energy (69% for energy, 31% lost as heat) • stored in muscle and adipose tissue • 1 glycerol and 3 FFA (lypolisis) • FFA in blood enter fibers by diffusion • rate of entry regulated by it’s own concentration gradient • increased FFA in blood drives FFA into muscle

  6. Metabolic Pathways • aerobic (oxidative phosphorylation) • anaerobic alactic (ATP-PCr) • anaerobic lactic (anaerobic glycolytic) • all active at all times • % contribution varies with exercise intensity and duration • anaerobic used for high intensity, short duration exercise • aerobic used for low to moderate, longer duration exercise • condition to most important pathway • “sport specific”

  7. ATP-PCr • start-up system • simplest pathway, readily available energy • phosphocreatine (PCr) rebuilds ATP • not used for direct cellular work • creatine kinase releases Pi from PCr, binds to ADP • O2 not needed • sprint for 10 - 20 sec, majority of energy from PCr • > 20 sec, very little contribution to energy supply • rapid depletion of PCr and ATP • no toxic waste product • replenish supply of PCr in 3 min at rest • barrels, roping, ect.

  8. Anaerobic Glycolytic • ATP produced from breakdown of glucose via special enzymes; lactate dehydrogenase (LDH) • no O2 needed • lactate produced • duration of energy supply 20-120 sec • glucose - 99% of all sugars in blood • digestion of CHO • breakdown of liver glycogen • glycogen  glucose-1-phosphate (glycogenolysis) • breakdown of G-6-P to pyruvate (glycolysis)

  9. Glycolysis • early use with high intensity exercise • ATP-PCr system • does not produce large amounts of ATP • glycogen (anaerobic pathway) • 3 ATP + 2 NADH = 9 ATP • glucose (anaerobic pathway) • 2 ATP + 2 NADH = 8 ATP • glycogen produces pyruvate, O2 determines fate of pyruvate • O2 to Kreb’s cycle • no O2, lactic acid

  10. Oxidative Pathway • most complex pathway • disassembles fuels with O2 • O2 production of ATP in mitochondria • next to myofibrils and in sarcoplasm • high energy yield • slow production of energy • oxidative production of ATP requires 3 processes • glycolysis • Kreb’s cycle • electron transport chain

  11. glycolysis  pyruvate • pyruvate + O2 acetyl CoA • Kreb’s cycle (per pyruvate:1/2 glucose) • complete oxidation of acetyl CoA • 2 ATP + 1 FADH2 + 3 NADH • C + O2 CO2 expired • electron transport chain • glycolysis produces H+ (too acidic) • FADH2 and NADH transport H+ to electron transport chain • H+ split into protons and electrons • phosphorylation produces ATP • H+ + O2  H2O expelled

  12. Energy Stores

  13. Lactic Acid • lactate • lactic acid combined with Na+ or K+ to form salt • regulated by feedback system • accumulation of lactate in muscle inhibits further glycogen breakdown • acidity decreases pH of muscle and Cal-binding capacity • slows reactions for energy production resulting in fatigue • lactate concentration in muscle • production level • rate of removed from muscle by blood • detoxified in liver • amount used as energy by aerobic metabolism

  14. recovery at rest - 3 hours • light exercise aids in removal of lactate • additional increase in blood lactate concentration at end of work bout • > 5 min • removal rate exceeds release from muscle • decreased blood lactate concentration • measure of fitness • decrease level of lactate following conditioning for same work load

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