Energy Transfer In the Body Flashcards
What is the ATP-PC system and what does it stand for?
- ATP-PC - Adenosine Triphosphate Phosphocreatine- the only usable form of energy in the body
- Its an energy system using phosphocreatine (PC) as its fuel
- PC is an energy-rich phosphate compound found in the sarcoplasm of the muscles & can be broken down quickly & easily to release energy to resynthesise ATP
How long does the ATP-PC system last for?
- There is only enough PC to last for 5-8 seconds
What does ATP consist of?
- Consists of one molecule of adenosine and three (tri) phosphates
How does the ATP-PC system work to provide energy?
- ATP-PC system is an anaerobic process & re-synthesises ATP when the enzyme creatine Kinase detects high levels of ADP
- It breaks down the phosphocreatine in the muscles to phosphate & creatine, releasing energy
- This energy is then used to convert ADP to ATP in a coupled reaction
- For every 1 molcule of PC broken down there is enough energy released to create 1 molecule of ATP
What are the advantages and disadvantages of the ATP-PC system?
Advantages:
- ATP can be resynthesised rapidly using the ATP-PC system
- PC stores can be resynthesised quickly - (30s=50% replenishment & 3mins=100%)
- There are no fatiguing by products
- It is possible to extend the time the ATP-PC system can be utilised through use of creatine supplementation
Disadvantages:
- There is only a limited supply of phosphocreatine in the muscle cell, i.e can only last for 10 seconds
- Only one mole of ATP can be re-synthesised for every mole of PC
- PC re-synthesis can only take place in the prescence of oxygen (i.e when the intensity of the exercise is reduced)
How does the body constantly rebuild ATP?
- By converting the ADP & Pi back into ATP
- We can resynthesise ATP from 3 different types of chemical reactions in the muscle cells
- These chemical reactions are fuelled by either a food or a chemical called phosphocreatine found in the muscles
What are the three energy systems that the conversion of energy into this fuel takes place in?
- The aerobic system
- The ATP-PC system
- The anaerobic glycolytic system
When is the aerobic system used and what does it do?
- Used when exercise intensity is low & oxygen supply is high
- This system breaks down glucose into carbon dioxide & water which in the prescence of oxygen is much more efficient
- Up to 38 molecules of ATP can be produced
What are the 3 stages of the aerobic system?
- Glycolysis
- Krebs Cycle
- Electron Transport Chain
REMEMBER ORDER: Get Kintetic Energy (GLYCOLYSIS, KREBS,ELECTRON)
What is the glycolysis stage?
- This 1st stage is anaerobic so it takes place in the sarcoplasm of the muscle cell
- Glycolysis is the breakdown of glucose to pyruvic acid
- For every molecule of glucose undergoing glycolysis, a net of two molecules of ATP is formed
- Before the pyruvic acid produced in glycolysis can enter the next stage (Krebs cycle) it is oxidised into two acetyl groups & is then carried into Krebs cycle by coenzyme A
What happens in the Krebs cycle?
- The two acetyl groups diffuse into the matrix of the mitochondria where Krebs cycle occurs
- Here the acetyl groups combine with oxaloacetic acid, forming citric acid
- Hydrogen is removed from the citric acid & the rearranged form of citric acid undergoes ‘oxidative carboxylation’ means that carbon & hydrogen are given off.
- The carbon forms carbon dioxide which is transported to the lungs & breathed out & the hydrogen is taken to the electron transport chain
- The reactions that occur result in the production of two molecules of ATP
What happens during the electron transport chain?
- Hydrogen is carried to the electron transport chain by hydrogen carriers
- This occurs in the cristae of the mitochondria & the hydrogen splits into hydrogen ions & electrons & they are charged with potential energy
- The hydrogen ions are oxidised to form water while the hydrogen electrons provide the energy to re-synthesise ATP
- Through this process 34 ATP are formed
What is beta oxidisation?
- Stored fat is broken down into glycerol & free fatty acids for transportation by the blood
- These fatty acids then undergo a process called beta oxidisation whereby they are converted into acetyl coenzyme A, which is the entry molecule for the Krebs cycle
- From this point on, fat metabolism follows the same path as glycogen metabolism.
- More ATP can be made from one molecule of fatty acids than one molecule of glucose
- Which is why in long duration, low intensity exercise fatty acids will be the predominent energy source
(Fat in regards to the aerobic system)
What are the advantages & disadvantages of the aerobic system?
Advantages:
- More ATP can be produced 36 ATP
- There are no fatiguing by-products (co2 & water)
- Lots of glycogen & triglyceride stores so exercise can last a long time
Disadvantages:
- This is a complicated system so cannot be used straight away, it takes a while for enough oxygen to become avaliable to meet the demands of the activiy & ensure glycogen & fatty acids are completely broken down
- Fatty acid transportation to muscles is low & also requires 15% more oxygen to be broken down than glycogen
What does the short-term lactate anaerobic system/ anaerobic glycolytic system do?
- Provides energy for high intensity activity for longer than the ATP-PC system
- However how long this system lasts depends on the fitness of the indiviudal & how high the exercise intensity is
- Working flat out to exhaustion will mean the system will last a much shorter time as demand for energy is extremely high
- The anaerobic glycotic system re-synthesises ATP from the breakdown of the fuel glucose- this is supplied from the digestion of carbohydrates & is stored in the muslces & liver as glycogen, where it is readily avaliable
e.g. in practice an elite athlete who has just run the 400m in under 45 seconds will not be able to immediately run it again at the same pace, however reduce the intensity a little & the system can last up to 2-3 minuets because the demand for energy is slightly less
