Energy Systems

Aerobic
1. Glycolysis
  1. Sarcoplasm of muscle cell
  2. Breakdown of glucose to pyruvic acid
  3. 2 molecules of ATP formed
2. Krebs Cycle
  1. 2 acetyl groups diffuse into matrix of mitochondria
  2. Complex cycle of reactions occur
  3. Acetyl groups combine with oxaloacetic acid forming citric acid
  4. Hydrogen removed from citric acid
  5. Rearranged citric acid undergoes oxidative carboxylation
    1. Carbon & Hydrogen given off
  6. Carbon forms CO2, transported to lungs & exhaled. Hydrogen taken to electron transport chain
  7. 2 more ATP molecules produced
3. Electron transport chain (ETC)
  1. Hydrogen carried to ETC by hydrogen carriers
  2. Occurs in cristae of mitochondria, hydrogen splits into ions & electrons; are charged with potential energy
  3. Ions oxidised to form water, electrons provide energy to resynthesise ATP
  4. 34 ATP molecules formed
4. 38 ATP produced
5. No fatiguing by-products
6. Lots of glycogen & triglyceride stores; exercise for long time
7. Complicated system; can't be used straight away. Takes time for oxygen to be available to meet demands of activity
8. Fatty acid transportation to muscles is low & requires 15% more oxygen to be broken down than glycogen
Anaerobic Glycolytic/Lactic Acid
1. Provides energy for high intensity exercise longer than ATP-PC system
2. Anaerobic glycolysis takes place in sarcoplasm of muscle
  1. When PC stores are low, glycogen phosphorylase activated to break down glycogen into glucose
    1. Glucose further broken down into pyruvic acid by the enzyme PFK (phosphofructokinase)
      1. Further broken down into lactic acid by lactate dehydrogenase
      2. 2 ATP
3. 2 molecules of ATP produced for every molecule of glucose broken down
4. ATP can be resynthesised quickly due to few chemical reactions
5. Lasts longer than ATP-PC system
6. Lactic acid can be converted back to fuel in presence of oxygen
7. Can be used to produce extra burst of energy
8. Lactic acid as by-product. Denatures enzymes & prevents increasing rate of chemical reactions
9. Only small amount of energy can be released from glycogen under anaerobic conditions (5%)
10. How lactic acid can be removed
  1. Sweat
  2. Urine
  3. Oxidised back to pyruvic acid
  4. Liver (Cori cycle)
ATP/PC
1. Uses phosphocreatine (PC) as fuel
  1. Energy rich compound
  2. Can be broken down quickly by creatine kinase & easily to release energy to resynthesise ATP (Adenosine Triphosphate)
2. Short, fast release of energy
  1. 5-8 seconds
3. Anaerobic process
4. ATP resynthesised when enzyme creatine kinase detects high levels of ADP (Adenoside Diphosphate)
5. Breaks down PC in muscles to phosphate and creatine, releasing energy
6. Energy -> Pi (phosphate) + ADP -> ATP
7. Every molecule of PC broken down, 1 molecule of ATP created
8. ATP can be resynthesised rapidly using ATP-PC system
9. PC stores resynthesised quickly (30s = 50%, 3 mins = 100%)
10. No fatiguing by-products
11. Can extend time ATP-PC system can be utilised through creatine supplementation
12. Limited PC supply - only 10 sec worth
13. Only 1 molecule of ATP can be resynthesised for every molecule of PC
14. PC resynthesis only occurs when oxygen is present

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	Created by Wesley Spearman about 7 years ago