Energy Systems Flashcards
What is the only useable form of chemical energy in the body ?
ATP = adenosine triphosphate
ATP = 1 x molecule of adenosine & 3 x molecules of phosphate
The energy we get from foods is broken down to release the energy that is used to form ATP
How is ADP formed ?
ATPase is used to break down ATP, leaving ADP + Pi, releasing energy as it does.
What are the 3 energy systems ?
Aerobic
ATP-PC
Anaerobic glycolytic
What is the aerobic system ?
Glucose + oxygen > energy + carbon dioxide + water
Complete oxidation of glucose can produce 38 molecules of ATP
Fat and protein can also be broken down
Products of fat and protein are reduced to the molecule acetyl coenzyme A
What are the 3 stages of the aerobic system ?
Glycolysis (or Beta Oxidation)
Krebs Cycle
Electron Transport Chain
Explain the 1st stage of the aerobic system
This anaerobic stage takes place in the sarcoplasm of the muscle cell
Each molecule of glucose generates 2 molecules of ATP
Before the pyruvic acid can enter Krebs cycle it is oxidised into two acetyl groups by coenzyme A
What enzyme breaks down glycogen into glucose ?
Phosphofructokinase
Explain the 2nd stage of the aerobic system
The two acetyl groups diffuse into the matrix of the mitochondria
The acetyl groups combine with oxaloacetic acid forming citric acid
Hydrogen is removed and citric acid undergoes oxidative carboxylation (carbon and hydrogen are given off)
Carbon forms carbon dioxide
2 ATP molecules are produced from the Krebs cycle
Explain the 3rd stage of the aerobic system
Hydrogen is carried to the electron transport chain
Occurs in the cristae of the mitochondria
Hydrogen splits into hydrogen ions and electrons
Hydrogen ions are oxidised to form water
Hydrogen electrons provide energy to re-synthesise ATP
34 ATP molecules are produced
What is beta oxidation in the aerobic system ?
Stored fat broken down into glycerol and free fatty acids for transportation by the blood
Beta oxidation causes these fatty acids to be converted into acetyl coenzyme A
Fat metabolism then follows the same path as glycogen metabolism
More ATP can be produced from one fat molecule
Advantages and disadvantages of the aerobic system
Advantages:
More ATP is produced (38)
No fatiguing by-products
Plenty fuel stores
Disadvantages:
Takes a while before enough oxygen is available for the process
Fatty acid transportation to muscles is low
What is the ATP-PC system ?
Uses Phosphocreatine as its fuel
PC is an energy-rich compound found in the sarcoplasm of the muscle
Can be broken down quickly and easily to release energy
Rapid availability is for single maximal movements
Only enough PC to last for 5-8 seconds
Can only be replenished during low intensity work
How does the ATP-PC system work ?
Anaerobic process
Resynthesises ATP when the enzyme creatine kinase detects high levels of ADP
It breaks down the phosphocreatine in the muscles to phosphate and
creatine, releasing energy
Energy is then used to convert ADP to ATP in a coupled reaction
Advantages and disadvantages of the ATP-PC system
Advantages:
ATP Can be re-synthesised rapidly
Phosphocreatine stores can be re-synthesised quickly
There are no fatiguing by-products
Can extend the time the ATP-PC system through use of creatine supplementation
Disadvantages:
There is only a limited supply of phosphocreatine in the muscles
Only one molecule of ATP can be re-synthesised for every molecule of PC
PC re-synthesis can only take place in the presence of oxygen
What is the Anaerobic glycolytic system ?
This system provides energy for high intensity activity for longer
How long this system lasts depends on the fitness of the individual
Lasts about 45 seconds - 3 minutes
How does the Anaerobic glycolytic system work ?
Glucose is stored in the muscles and liver as glycogen
When PC stores are low, the enzyme glycogen phosphorylase is activated to break down the glycogen into glucose
Glucose is then further broken down in pyruvic acid by the enzyme phosphofructokinase
Takes place in the sarcoplasm of the muscle
The pyruvic acid is then further broken down into lactic acid by the enzyme lactate dehydrogenase
The net result is 2 molecules of ATP
Advantages and disadvantages of the Anaerobic glycolytic system
Advantages:
ATP can be re-synthesised quite quickly
In the presence of o2, lactic acid can be converted into liver glycogen
It can be used for a sprint finish
Disadvantages:
Lactic acid acts as the by-product
Accumulation of acid in the body de-natures enzymes
Only a small amount of energy can be released from glycogen
What is the energy continuum ?
The Energy continuum describes which energy system is used for different types of exercise
Depends on the duration and intensity
How do muscle fibres and energy systems work together ?
Slow twitch:
Main pathway for ATP production is in the aerobic system
Produces up to 38 ATP from each glucose molecule
Production of ATP is slow but these fibres are more endurance based
Fast twitch:
Main pathway for ATP is the lactate anaerobic energy system
ATP production in the absence of oxygen is not efficient (2 ATP)
Production of ATP this way is fast but cannot last for long
Which energy system is used during low intensity exercise ?
Aerobic