energy systems Flashcards
ATP
Adenosine Triphosphate
Food we eat is stored in the body as glycogen = converted in ATP
What does ATP release energy for when broken down?
- muscle contractions
- nerve transmission
- digestion
How is ATP broken down?
Enzyme ATPase breaks ATP down into ADP (adenosine diphosphate) + releasing energy
Previously ATP made up of 1 adenosine + 3 phosphates
ATP re synthesis
- ATP only lasts for 2-3 secs so stores are depleted quickly
- constantly re synthesised
- to re synthesise, the loose phosphate need to rejoin the ADP
- ATP resynthesis: ADP + P + energy = ATP
- stored in 3 systems
3 energy systems
- ATP-PC
- glycolytic
- aerobic system
ATP-PC system
- used during high intensity exercise
- lasts for 2 secs
- as ATP is used quickly, ADP + P stores build up
- triggers the enzyme creatine kinase to be released
e.g. gymnastics vault
Describe how the ATP-PC system works
- Start with phosphocreatine (P + C)
- creatine kinase breaks down PC into P + C + energy
- energy is used to resynthesise ATP
- energy is used to resynthesise the phosphate with ADP
- we end up with 1 resynthesise dad ATP
Glycolytic energy system - lactic acid
- system kicks in after 10 secs where PC + ATP levels have fallen
- enzyme GPP breaks down glycogen into glucose
- ADP and P levels rise which releases the enzyme PFK
- this enzymes breaks down glucose
- glucose is broken down to access energy to resynthesise ATP = anaerobic glycolysis
- anaerobic glycolysis results in the production of pyruvic acid
- once O2 levels have lowered too much (around 3 mins in) the enzyme LDL (low density lipoprotein) is released
- LDL helps convert pyruvic acid into lactic acid = accumulates + slows down ATP synthesis (which we don’t want to wait)
- caused by absence of O2
- lactic acid causes fatigue
e.g. 100m swim
Role of lactic acid (glycolytic energy system)
- as lactic acid levels rise, pH in muscle cells decrease (increasing acidity)
- this inhibits enzyme activity = preventing further ATP resynthesis
- OBLA: The Onset of Blood Lactate Accumulation = the point at which blood lactate accumulation significantly rises
Glycolytic energy system summary - Type of reaction
Anaerobic
Site of reaction
Sarcoplasm
Food fuel used
Glycogen/ glucose
Enzyme
GPP, PFK, LDH
ATP yield
1 glucose = 2 ATP
By-products
Lactic acid
Activity intensity
High
Duration of system
Up to 3 mins
Strengths
Weaknesses
Aerobic system
- aerobic energy system kicks in during low to moderate intensity activity
3 stages of aerobic system
- aerobic glycolysis
- the Krebs cycle
- the electron transport chain (ETC)
Aerobic glycolysis
- first stage
- PFK catalyses the conversion of glucose into pyruvic acid = releases energy to resynthesise 2 ATP
- process is maintained by GPP converting glycogen into glucose = more glucose available
- presence of O2 prevents pyruvic acid being converted into lactic acid
- instead goes through a link reaction catalysed by coenzyme A (produces Acetyl CoA) = alllws access to the mitochondria
Mitochondria
A structure within the cell where aerobic respiration + energy production occur
The Krebs cycle
- Acetyl CoA combined combines with oxaloacetic acid to form citric acid
- the citric acid is oxidised through a cycle of reactions = the Krebs cycle
- the Krebs cycle releases CO2 + hydrogen + enough energy to resynthesise 2 ATP
- all this occurs in the matrix of the mitochondria
ETC
- electron transport chain (ETC)
- the hydrogen atoms are carried through the ETC in the mitochondrial Cristae = carried by NAD + FAD (hydrogen carriers)
- theyre split into ions (H+) and electrons (H-)
- H+ ions are oxidised = released as H2O
- H- electrons are carried by NAD and FAD (NADH2/ FADH2)
- NADH2 releases energy for 30 ATP
- FADH2 releases enough energy for 4 ATP
The aerobic system + free fatty acids (FFA)
- glycogen is the main fuel for endurance performers
- however, triglycerides or fats can also be metabolised aerobically as FFA’s allow us to conserve glycogen / glucose stores
- the enzyme lipase is released (catalyses the breakdown of fats) = converted into FFA’s + glycerol
- FFA’s are converted into Acetyl CoA c follow the path through the Krebs cycle + ETC
2 factors that help us indicate which energy system is being used
- intensity of activity
- duration of activity
Energy continuum
2 Pic on iPad
Intensity very high energy system
Intensity very High: duration < 10 secs
E.g. jumpers, throwers, sprinters etc..
ATP-PC system will be predominant
Intensity high: duration 10 secs - 3 mins
Intensity high: duration 10 secs - 3 mins
E.g. 400m, 200m freestyle, competitive squash game
Glycolytic energy system will be predominant
Intensity low-moderate
Intensity low-moderate: duration > 3 mins
E.g. marathon, triathlon, cross country skiing etc..
Aerobic energy system will be predominant
Intermittent exercise
- intensity alternates either during interval training or between rest + work intervals during a game
- leads to athlete switching between the 3 energy systems during the same game
- point where an athlete moves from one energy system to another known as a THRESHOLD
- e.g. defender in football while team is attacking (using a different energy system to when defending and other team attacking)
Graph on ipad
ATP-PC system switching to Glycolytic system EXAMPLE
Apply to netball GD getting an intercept
2 Pic on ipad
Recovery periods: (ATP-PC)
Although PC stores are depleted quickly, also replenished quickly
PC replenished:
- 50% in 30 secs
- 100% in 3 mins
- useful for e.g. netball + basketball = time outs + play 4 quarters instead of 2 half’s (lots of bursts of speed, few periods of time where they’re out of play)
- O2 stored in myoglobin can also be restored fully within 3 mins
Recovery periods: (Glycolytic)
- as exercise duration increases, glycogen levels decrease
- at same time = lactic acid levels increase
- however, some lactic acid is removed during periods of low intensity exercise/ activity recovery = creates zig zag
Pic on iPad
Recovery periods: (Aerobic)
Endurance athletes often have breaks in play, providing the chance to rehydrate + replenish glycogen/ glucose levels through:
- drinking water
- glucose tablets
- gels
- bananas
- isotonic drinks
- e.g. jelly babies
