ocr pe energy systems

Energy SystemsGeorge Noorland

Energy

Concept Definition Measure/UnitsEnergy The capacity of the body to perform work/put mass into motion. Joules (J)Work The ability to apply force over s distance. Work = Force (N) x

Distance (m).Joules (J) or Newtons (N)

Power Work performed per unit of time/ the rate at which we can work. Watts (W)

The ATP/PC (Alactic) Energy System:Type of Reaction AnaerobicChemical/Food Fuel Phosphocreatine (PC)Site of Reaction Sarcoplasm (in muscle cells)Controlling Enzyme Creatine KinaseEnergy Yield 1 ATP (NOT EFFICIENT)By-Products None (because it is too quick)Duration Up to 10 seconds (3-8 seconds)Intensity High (maximal)

Adenosine Triphosphate (ATP):ATP- A chemical energy stored as a high energy compound in the body. It is the only immediately usable source of energy in the human body.

- Adenosine – P – P – P = ATP- It is stored as a simple compound in the muscles so that it can be quickly broken down to supply energy for

approximately 2-3 seconds of muscular work. - When broken down by the enzyme ATPase, it releases the potential energy stored in the muscles to apply force

as kinetic energy.

Types of Energy:Chemical Energy- Potential energy that is stored in chemical bonds of molecules, it is the part of energy in a substance that can be released by a chemical reaction. Kinetic Energy- Energy in the form of muscle contraction/ joint movement- extra energy that the body possesses because of its motion.

KE = ½ M x V² (Kinetic Energy = Half of the mass of an object multiplied by the velocity squared).Potential Energy- The energy possessed by an object because of its position (height above ground- field of gravity) - The energy is stored in the object until it moves.

ATP Re-synthesis:- The breakdown of ATP into ADP is reversible in an endothermic reaction. - This re-synthesis requires energy from one of the 3 energy systems.- The ATP/PC, lactic and aerobic energy systems work together to supply energy to re-synthesise ADP back into

ATP via coupled reactions.

Endothermic Reaction- A chemical reaction that requires energy.Exothermic Reaction- A chemical reaction that releases energy.Coupled Reaction- A reaction in which the product (energy) of one reaction is used by a second reaction. Threshold- The point at which there is a switch between from one predominant energy system to another.

Energy SystemsGeorge Noorland

This system will keep going until PC levels drop, at this point you will then move over the threshold into the next system- Lactic Acid System. Phosphocreatrine (PC)- An energy-rich compound found in muscle cells that is used to recycle ATP during activities of very high intensity and short duration.

Advantages Disadvantages- There is no need for oxygen- anaerobic.- No fatiguing by-products. - PC stores in muscles are a readily available energy

source. - This system provides energy for high-intensity,

explosive exercise and movement. - PC can be re-synthesised quickly after activity

stops.- It is a relatively quick process- there are few

reactions.- Automatically stimulated by a decrease in ATP and

an increase in ADP.

- Only enough PC stores for 10 seconds- there is a limited supply of PC in muscles.

- Only 1 ATP is re-synthesised in this system (1 ATP for 1 PC).

- PC stores are only replenished with oxygen- during recovery when the exercise stops.

The Lactic Acid Energy System:Type of Reaction AnaerobicChemical/Food Fuel Glycogen/Glucose (carbohydrates)Site of Reaction Sarcoplasm (in muscle cells)Controlling Enzyme PFKEnergy Yield 2 ATP (NOT EFFICIENT)By-Products Lactic AcidDuration 10 seconds – 3 minutes (peak at 1 minute)Intensity High/medium

Energy SystemsGeorge Noorland

Glycolysis- The breakdown of sugar.Lactic Acid- The by-product of anaerobic exercise produced by anaerobic glycolysis.

Advantages Disadvantages- There are large glycogen stores in the muscle/liver

which is readily available as a potential energy source.

- This system re-synthesises 2 ATP, which is more that the alactic system.

- This system requires fewer reactions that the aerobic system, so provides a quicker supply of energy.

- Lactic acid can be converted back to glycogen/ pyruvic acid.

- This system can be used to increase the intensity during exercise.

- This system is anaerobic- there is no need for oxygen.

- It provides energy for high-intensity exercise lasting between 10-180 seconds.

- This system is not as quick as the ATP/PC system.- Produces lactic acid, which is a fatiguing by-

product. - Reduces the pH (increased acidity) which inhibits

enzyme action. - Stimulates pain receptors. - Only 2 ATP are re-synthesised, this means that it is

not efficient.- To continue exercise, the intensity must be

lowered.

The Aerobic Energy System:Type of Reaction AerobicChemical/Food Fuel Glycogen/Glucose/Carbohydrates/FatsSite of Reaction Sarcoplasm (in muscle cells) and MitochondriaControlling Enzyme PFKEnergy Yield 34 ATP – 38 ATP (EFFICIENT)By-Products Water, CO2Duration Hours - ContinuousIntensity Low (sub-maximal)

Energy SystemsGeorge Noorland

Advantages Disadvantages- There are large potential glycogen and free fatty

acid (FFA) stores available as an efficient energy store.

- Efficient ATP re-synthesis when good O₂ supply guarantees breakdown of FFAs.

- Large ATP re-synthesis: 38 ATP from one molecule of glucose compared to 2 ATP from the LA system and 1 from the ATP/PC.

- Provides energy for low/moderate-intensity and high-duration exercise (3 minutes – 1 hour).

- No fatiguing by-products; CO₂ and H₂O easily removed.

- Slower rate of ATP re-synthesis compared with the LA system due to:

- Requires more O₂ supply (15% more for FFAs).- More complex series of reactions.- Cannot re-synthesise ATP at the start of exercise

due to initial delay of O₂ from the cardiovascular system.

- Limited energy for ATP during high-intensity, short-duration work.