Energy Systems OCR PE

• sun gives off light energy
• plants convert light energy into stored chemical energy
• humans consume this energy by eating plants
• energy is then stored in humans as carbohydrates, fats or proteins
• chemical energy stored as a high energy compound of adenosine triphosphate (ATP)
• energy stored within this compound ATP is called potential energy
• Potential energy is readily available as energy for muscles to contract
• The energy made to make muscles move is called kinetic energy

Adenosine Triphosphate (ATP) - chemical energy stored as a high energy compound in the body. it is the only immediate usable source of energy

potential energy - 'stored' energy which is ready to be used when required

Kinetic energy - energy in the form of muscle contraction/joint movement

'energy is the ability to perform work or put mass into motion and usually measure in joules'

'work is done when a force is applied to a body to move it over a certain distance'

work (Joules) = force(N) x distance moved(M)

one molecule of adenosine and three phosphates

importance? - only usable form of energy in the body - food has to be converted to ATP first

Energy released - Breaking the high energy bond

ATPase - enzyme used to break bonds (exothermic)

ATP + ATPase -->  ADP(Adenosine diphospate) + energy

ATP ---> ADP + P + energy

exothermic reaction, energy converted into kinetic or heat energy

ADP + P + energy - - - > ATP      (endothermic reaction)

3 ways in which it can be re synthesised...

1) phosphocreatine system (ATP-PC) = 0-10 seconds - anaerobic

2) Lactic acid system = 10 secs - 3 minutes - anaerobic

3) the aerobic process = excess 3 mins - must use oxygen

Uses high energy compound phosphocreatine to join ADP and P

PC = P + C + energy (EXO)              

Energy +ADP + P = ATP (endo)   Known as a coupled reaction

reactions take place on the sarcoplasm of the muscle cell and does not need oxygen

Creatinekinase is the enzyme that breaks down the phosphocreatine

Advantages

• does not require oxygen
• PC store already in muscle cells as an energy source
• simple compound to break down so quick energy source
• automatically stimulated by a decrease in ATP
• provides energy for explosive, high intensity movement
• no fatigue due to by products
• PC can itself be quickly re synthesise

Disadvantages

• small amount of PC stored
• 1 PC = 1 ATP
• only lasts between 8-10 seconds

Occurs in the sarcoplasm and doesn't require oxygen. Glucose and Gylcogen stored in the liver

the system starts when there's a reduction in PC or an increase in calcium

it stops due to a reduction in PH or an increase in PC

Lactic acid system is effected by onset of Blood Lactate Accumulation (OBLA)

• Glycogen is found stored in the liver and broken down by glycogen phosphorylase
• ATP is added to the system
• broken down glycogen produces glucose - 6 - phosphate
• Phosphofructokinase (PFK) is added to break down glucose - 6 - phosphate
• pyruvic acid is formed which also prodcues 2 ATP
• this is broken down by lactate dehydrogenase to form lactic acid
• the change in PH occurs from the H+ ions joining to pyruvic acid and lactic acid

Advantages

• 2 ATP produced
• requires fewer reactions
• can occur in the absense of oxygen
• glycogen readily available
• large glycogen store
• provides energy for high intensity activity

Disadvantages

• only 3 minutes of energy
• PH decrease making a by product
• not as quick as atp/pc
• stimulates pain receptors
• net effect is muscle fatigue