Chapter 6: The three energy systems working together to produce ATP Flashcards
ATP
a chemical fuel molecule where the energy is held in the bonds so when split, it provides energy for muscular contractions to occur
- After split it becomes ADP + Pi - ADP + Pi must continually be resynthesise in order to become ATP again - The human body only has enough for 2-3 seconds of muscular work stored in the muscles
Phosphate Creatine(PC/CP)
a chemical fuel molecule made of creatine molecules which serves as a rapid reserve of high energy which recycles ATP
- Broken down to re-synthesise ATP as part of the ATP-PC energy system - Enough for 10 seconds of muscular work
Food Fuels
Carbohydrates(CHO):
- In the body it is known as glycogen
- The preferred source of energy during exercise as it requires less O2 to be broken down - Can be broken down with and without O2 - E.g. Fruit, rice, bread, pasta, nuts, vegetables
Fats:
- The body’s main source of fuel at rest and during prolonged submaximal exercise
- Requires more O2 than CHO to be broken down - E.g. Butter, cheese, dairy products, oils, nuts and fatty meats
Protein:
- Used for mainly growth and repair
- Is a 'last resort' fuel source
- E.g. Lean meat, fish, eggs, legumes, seeds
Energy Sources at Rest
as there is lots of oxygen available:
- 2/3’s of energy comes from the breakdown of fats
- 1/3 of energy comes from the breakdown of CHO’s
Energy Source at Top Aerobic Capacity(85% max)
as there is limited oxygen availble due to the muscles requiring a majority of it:
- 100% of energy comes from the breakdown of CHO’s
Rate
how quickly ATP is re-synthesised
ATP = Fastest CHO = faster Fats = Slower Protein = slowest
Yield
the total amount of ATP that is re-synthesised
ATP = lowest CHO = lower Fats = higher Protein = highest
Energy System Interplay Principle
The three energy systems do not turn on or off like a traffic light are all activated at the start of exercise with different systems being more dominant at different points in times
- ATP-PC is dominant from 1-13 seconds
- Anaerobic Glycolysis is dominant from 13-75seconds
- Aerobic is dominants from 75 seconds onwards
Dominant
the system providing the most amount of energy to re-synthesise ATP at a particular point in time during PA
Factors determining which Energy System is more Dominant:
- Intensity of exercise
- Duration of exercise - Whether or not O2 is present - The availability of chemical or food fuel
ATP-PC
- Anaerobic
- Creates 0.7 ATP molecules
- Fastest rate and smallest yield
- Dominant ATP supplier during activity between 1-5 seconds
- By products are inorganic phosphates and ADP
- Events E.g. Jumps, throws, short sprints
Process of ATP-PC:
- A simple reaction breaks down the PC molecule
- During the PC splitting, energy is released to resynthesise ADP+ Pi back into ATP - The ATP stores will last for 2-3 seconds but with the PC molecules, it will now last for 10-13 seconds - Once PC stores have been depleted, they can be replenished via 3 minutes of passive recover as oxygen is required for PC molecules to be resynthesised
Anaerobic Glycolysis
- Creates 2-3 ATP molecules
- Supplies ATP at a slower rate than ATP-PC due to complex chemical process needed to take place
- Dominant ATP supplier during activities that are between 5-60 seconds long
- By products is Lactic acid and H+ and ADP
- E.g. Events such as 200-400m run, 50m swim, repeated sprints in team sports where there is not enough rest time to resynthesise ATP-PC
Process of Anaerobic Glycolysis:
- Glycogen is broken down in the absence of O2 into glucose which is further broken down into Pyruvic acid
- This breakdown of glucose produces 2-3 ATP molecules
- Pyruvic Acid is broken down to produce Lactic Acid which is further broken down to form metabolic by-products such as lactate and H+
- H+ increases the muscles acidity, reducing glycolysis, causing muscular discomfort and an inability to contract maximally by reducing the ability of glycolytic enzymes
- In recovery(when there is sufficient O2), H+ combines with Pyruvic acid to form lactate which is reconverted into glycogen.
Aerobic
- Oxygen must be present O2
- Creates 38 ATP molecules
- Slowest rate of ATP synthesis as it requires the most chemical process
- Dominant ATP supplier during activities taking longer than 75 seconds
- By products are CO2, H2O and Heat
- E.g. Events such as archery, marathons, road cycling
Process of Aerobic Energy System:
- When using CHO’s, similarly to Anaerobic Glycolysis, it is broken down into glucose creating 2-3 ATP molecules and Pyruvic Acid
- Pyruvic acid is then broken down into H2O, CO2 and 2 ATP molecules via the Krebs Cycle
Further breakdowns occur in the Electron Transport Chain which requires H+ and O2 to produces more H2O, heat and 34 ATP molecules
Oxygen Uptake at Rest
- The body’s need for ATP is relatively small with minimal oxygen requirements
- The amount of oxygen entering the bloodstream is directly proportional to the amount used by the tissues and muscles
- As exercise intensity increases, so to does your oxygen intake
- The amount of oxygen entering the bloodstream is directly proportional to the amount used by the tissues and muscles
Oxygen Deficit
the period in time when exercise begins/increases intensity and therefore oxygen uptake increases in order to meet the body’s increased oxygen demands for the working muscles
- The difference between oxygen supply and demand - Oxygen deficit occurs because the respiratory and circulatory systems take some time to adjust to the new oxygen demand
Steady State
the period in time when the oxygen supply meets the oxygen demand of the working muscles
- Coincides with a plateau in heart rate and ventilation - Can only be held up to and including the lactate inflection point
