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Energy Systems Copy Mixed Units
Transcript of Energy Systems Copy Mixed Units
All movement requires energy. The methods by which the body generates energy is determined by the intensity and duration of the activity.
Activities that require short bursts of effort like sprinting or jumping requires the body to produce large amounts of energy over a short period of time. Whereas marathon running or cycling require the body to provide continued energy production over a longer period and at a slower rate
We get energy from the food we eat. This is known as chemical energy. This chemical energy is stored in the body until needed. The body is constantly using and remaking (resynthesising) energy.
Adenosine triphosphate (ATP) is the usable form of chemical energy for muscular activity. It is stored in most cells, particularly in muscle cells.
Chemical energy is converted into kinetic energy (movement energy) when ATP is broken down (chemical reaction).
ATP - PCr System
PC → P + C + Energy AND Energy + P + ADP = ATP
For every molecule of PC broken down, one molecule of ATP can be resynthesised.
No oxygen is required.
Energy is released very rapidly and there are no waste products.
Stores only last for 5-8s of high intensity exercise.
It is therefore excellent for very high intensity short activities (e.g. 100m sprint, golf swing or power lifting) but not for anything longer
ATP needs to be resynthesised for the body to continue to work
ATP is resynthesised by the breakdown of Creatine Phosphate (PCr). This energy resynthesises ADP to ATP
Lactic Acid System
The Lactic Acid system supplies energy for exercises lasting less than 2 minutes. An example of an activity of the intensity and duration that this system works under would be a 400 m sprint.
Lactic acid is a by-product of this process. Lactic acid accumulates if not removed by the circulatory system and causes fatigue. This feels like a burning sensation in the muscles.
What are the features of the following three cars?
Energy is released from ATP by breaking the bonds that hold the molecules together.
are broken down by
The enzyme that breaks down ATP into ADP + Pi is ATPase
represents a free
This type of reaction is an
reaction, because energy is released
A reaction that requires energy to work is called an
Regenerating ATP from ADP +Pi is an
Enzyme Creatine Kinase
Advantages & Disadvantages of the ATP - CP System
- ATP can be regenerated rapidly using the ATP - CP system
- Phosphocreatine stores can be regenerated quickly (after 30 secs = 50% replenishment and 4 minutes = Full replenishment with the presence of oxygen.
- There are no fatiguing by-products
- It is possible to extend the time the ATP - CP system can be utilised through the use of creatine supplements.
- There is only a limited supply of Phosphocreatine in the muscle cells i.e. It can only last for 10 secs.
- Only one molecule of ATP can be regenerated for every molecule of PC.
- PC regeneration can only take place in the presence of oxygen (i.e. when the intensity of exercise is reduced).
The Lactic Acid System / Anaerobic Glycolysis
The energy needed at this stage comes from the food we eat. This process involves the partial breakdown of glucose (glucose can only be fully broken down in the presence of Oxygen).
Put in its simplest terms means the breakdown of glucose.
So Anaerobic Glycolysis is simply the break down of glucose without the presence of Oxygen.
Carbohydrate in the diet is digested to glucose, enters the bloodstream and travels to the muscles and the liver as 'Glycogen'
'Glycogen is a much more complex compound than phosphocreatine and therefore stores more energy.
Glucose is broken down anaerobically by the enzyme
, which is ativated by a drop in the level of phosphocreatine.
The glucose molecules are broken down into two molecules of 'Pyruvic acid'. Then because of the absence of Oxygen, lactic acid is formed from the 'Pyruvic acid'
Breakdown of the bonds in glucose releases energy, which is used to synthesise ATP (2 molecules of ATP of each molecule of glucose).
The aerobic system has 3 Stages in which glucose is broken down by a process of oxidation to carbon dioxide and water.
The Kreb Cycle
The Electron Transport Chain/System
Aerobic Glycolysis is the same as anaerobic glycolysis: glucose is broken down to pyruvic acid. However, as Oxygen is now present the reaction can proceed through the energy systems as Lactic Acid is not produced.
The reaction takes place in the 'Sarcoplasm' of the muscle site and the energy yield is sufficient to synthesise 2 molescules of ATP
The Kreb Cycle
The pyruvic acid produced in the first stage diffuses into the matrix of mitochondria where it is broken down
This combines with
Coenzyme A (CoA)
This is changed into a number of different compounds in a series of reactions that produces more energy resulting in the regeneration of
The whole cycle can then repeat itself and is known as the
The Kreb Cycle
During this cycle three important things happen:
Carbon Dioxide is formed
Oxidation takes place - hydrogen is removed from the compound
Sufficient energy is released to synthesis two molecules of ATP
Carbon Dioxide Formed
ATP x 2
Stage 3 -
The Electron Transport Chain
At this stage the hydrogen atoms removed during stage 2 enter the 'Electron Transport Chain'
Simplification of a very complex system
At this point high energy carbon-hydrogen bonds are being broken (Glucose) to form low energy carbon-oxygen bonds (Carbon Dioxide) and hydrogen-oxygen bonds (Water)
Thus releasing energy to combine ADP and Phosphate to form ATP
Energy yield =
= 2 ATP
= 2 ATP
= 34 ATP
= 38 ATP
Energy from Fats
Fat is stored in adipose tissue in the form of triglycerides
Fat enters the Kreb Cycle in the same manner as the by products of glycogen breakdown
The amount of ATP synthesised by the breakdown of fat is much higher than the amount obtained by the breakdown of carbohydrate, which makes it a much more economical fuel in terms of energy yield.
However, the breakdown of triglycerides requires roughly 15% more oxygen
Although it is possible to use protein as an energy source for ATP synthesis we very rarely do so.
Protein is oxidised only when the body is in a state of starvation or near exhaustion.