4.4. Aerobic System Flashcards
What happens in stage 1 (aerobic glycolysis)?
- Glycogen is broken down into glucose by GPP
- Glucose is broken down into pyruvic acid by PFK
- Pyruvic acid combines with coenzyme A to produce acetyl CoA and 2 ATP are also produced
- The presence of o2 prevents the accumulation of lactic acid
What happens in stage 2 (Kreb’s Cycle)?
- The Acetyl CoA from stage 1 combines with Oxaloacetic acid and enters the Kreb’s cycle to form citric acid
- Co2 is produced and 2 ATP are formed.
- It’s an oxidative reaction because hydrogen atoms are lost and transferred to stage 3
- Oxaloacetic acid is regenerated and the cycle repeats
What happens in stage 3 (electron transport chain)?
- The hydrogen atoms bind with NAD and FAD to form NADH and FADH.
- These molecules are carried down the ETC which splits hydrogen into ions (H+) and electrons (H-).
- Hydrogen ions are oxidised and removed as H2O (H+ combines with o2)
- The splitting of H+ and H- provides sufficient energy to resynthesise 34 ATP molecules.
What is the overall net production of ATP from one cycle of the aerobic system?
38 ATP
1:38
Site of reaction for aerobic glycolysis
muscle sarcoplasm
Type of reaction for aerobic glycolysis
aerobic
Chemical fuel for aerobic glycolysis
glycogen/ glucose/ FFAs
Controlling enzymes for aerobic glycolysis
GPP
PFK
Recovery process for aerobic glycolysis
lactacid
varies from 1-24 hrs
By products of aerobic glycolysis
none
Yield of aerobic glycolysis
2 ATP
1:2
Site of reaction for the Kreb’s Cycle
mitochondrial matrix
Type of reaction for Kreb’s Cycle
aerobic
Chemical fuel for Kreb’s Cycle
glycogen/ glucose/ FFAs
Controlling enzymes for Kreb’s Cycle
Acetyl CoA
Recovery process for Kreb’s Cycle
lactacid
varies from 1-24 hrs
By products of Kreb’s Cycle
Co2
easily removed
Duration of the aerobic system
180 secs to 2+ hrs
Intensity of the aerobic system
60-85%
varies
Yield of Kreb’s Cycle
2 ATP
1:2
Site of reaction of ETC
mitochondrial cristae
Type of reaction of ETC
aerobic
Chemical fuel of ETC
glycogen/ glucose/ FFAs
Controlling enzymes of ETC
NAD/ FAD
Recovery process of ETC
lactacid
varies from 1-24 hrs
By products of ETC
H2O
easily removed
Yield of ETC
34 ATP
1:34
Adaptations of aerobic system to training
- Increases stores of muscle liver glycogen, mobilisation of aerobic enzymes and earlier use of FFAs
- Aerobic threshold is prolonged and OBLA is delayed = quicker/ more efficient recovery
Advantages of aerobic system
- Large potential glycogen and FFAs stores available as efficient energy fuel
- Efficient ATP resynthesis when good oxygen supply
- Large ATP resynthesis -1 glucose molecule: 38 ATP
- Provides energy for low/ moderate intensity exercise and high duration exercise
- No fatiguing products - co2 and h2o easily removed
Disadvantages of aerobic system
- Slower rate of ATP resynthesis
- Requires constant o2 supply (and 15% more when breaking FFAs down)
- Complex series of reactions = slower reaction/ recovery
- Cannot resynthesise ATP at start of exercise due to initial delay of o2 from the cardiovascular system
- Limited energy for ATP during high intensity, short duration work
