Energy systems Flashcards
What are the 3 stages of the aerobic system?
- Glycolysis
- Krebs cycle
- Electron transport chain (ETC)
Where does glycolysis occur?
In the sarcoplasm
What happens during glycolysis?
Glucose is broken down into pyruvic acid
Pyruvic acid is split into 2 acetyl groups
Carried into Krebs cycle by coenzyme A
Where does the Krebs cycle occur?
Matrix (mitochondria)
What happens during the Krebs cycle?
Acetyl coenzyme A combines with oxaloacetic acid to form citric acid
Carbon released forms carbon dioxide (exhaled)
Fats entering Krebs cycle undergo beta oxidation
What is beta oxidation?
Where fatty acids are broken down to generate acetylCoA
Where does the ETC occur?
Cristae (mitochondria)
What happens during the ETC?
Hydrogen carriers transport H to the ETC
H splits into H+ ions and electrons
H+ oxidised to form water (electrons re-synthesise ATP)
How many molecules of ATP are produced during the aerobic system?
38
(glycolysis = 2, Krebs cycle = 2, ETC = 34)
What are the 2 anaerobic systems better known as?
ATP-PC system
Anaerobic glycolytic system (lactic acid system)
How long does the ATP-PC system last?
Between 8-10 seconds
Write the coupled reaction of phosphocreatine (PC) and ATP?
Phosphocreatine (PC) —> Phosphate (Pi) + Creatine (C) + Energy
Energy —> Pi + ADP —> ATP
How long does the anaerobic glycolytic system last?
Between 10-180 seconds
What are the enzymes in the anaerobic glycolytic system?
Phosphofructokinase (PFK)
Lactate dehydrogenase (LDH)
What is the energy continuum?
Shows which energy system is used for which type of physical activity / sport
Depends on intensity and duration of exercise
How does the ATP generation differ between slow and fast twitch muscle fibres?
Slow twitch:
aerobic system
produces maximum ATP from each glucose
slower production but less likely to fatigue
Fast twitch:
lactate anaerobic system
not as efficient in absence of oxygen
faster production but more likely to fatigue
What is the submaximal oxygen deficit?
When there is not enough oxygen is available at the start of exercise to provide all the ATP aerobically
What is EPOC?
Excess Post-exercise Oxygen Consumption:
amount of oxygen consumed during the recovery phase of exercise
How is lactic acid removed from the body after exercise?
Converted into protein
Removed in sweat and urine
Explain how lactate accumulation causes muscle fatigue
Higher intensity = more lactic acid produced
Lactic acid breaks down quickly, releasing H+ ions
More H+ ions increases acidity
Slows down enzyme activity
Results in muscle fatigue
What is the lactate threshold?
Point at which lactic acid is being produced faster than the rate it’s being removed from the body
What is OBLA?
Onset of Blood Lactate Accumulation:
when lactate levels rise above 4mmol per litre
Explain some of the factors that affect lactate accumulation
Exercise intensity —> higher intensity has greater demands for ATP, faster OBLA occurs
Muscle fibre type —> slow twitch produce less lactate than fast twitch
Rate of blood lactate removal —> lower rate allows more lactate to accumulate before OBLA
How does buffering aid a sprinter?
Aids the removal of lactate
Maintains acidity levels in the blood / muscles
Therefore lower lactate levels
