ATP ENERGY PRODUCTION

1. ATP ENERGY PRODUCTION

2. Energy • The body needs a constant supply of energy to perform every day tasks such as respiration and digestion. • Energy is the capacity to perform work and is measured in joules or calories.

3. Calorie, Joule and Watt • Calorie is the amount of heat energy needed to raise the temperature of 1 gram of water through 1oC. • A Kilocalorie (kCal)is 1000 calories. • Joule = 4.2 kCal. • A Watt is equivalent to the use of one joule per second. • Power is the work performed per unit of time and is measured in watts.

4. Work • Work is defined as force x distance. • It can be measured in calories and joules. Food • Food is chemical energy. • It is converted into movement (kinetic energy). • Or is stored as potential energy.

5. Energy release in the body • Energy release in the body is complicated. • There is only one usable form of energy in the body – adenosine triphosphate (ATP). • All food we eat has to be converted into ATP. • ATP is a high energy phosphate compound made up of adenosine and 3 phosphates. • The bonds that hold the compound together are a source of a lot of potential energy. • ATP = adenosine-phosphate-phosphate-phosphate

6. When a compound is broken down( the bonds between the molecules are broken) the energy is released. • ATP is broken down to adenosine diphosphate (ADP) and free phosphate, releasing the stored energy. • ATP → ADP + P + Energy • The energy released from the breakdown of ATP to ADP and P is converted to kinetic and heat energy.

7. Methods of ATP production • Once ATP has been broken down to release energy it has to be put back. • There are three ways that this is achieved in the human body: • 1 The phosphocreatine system (ATP/PC) or alactic system. • 2 The lactic acid system or glycolysis. • 3 The aerobic system. • Each method is good at supplying energy for particular energy demands and duration. • Systems 1 and 2 are anaerobic they take place without oxygen • System 3 is aerobic: it requires oxygen to work.

8. ATP Production by Phosphocreatine or Alactic System • Phosphocreatine is a high- energy phosphate compound. • It is found in the sarcoplasm of the muscle. • Potential energy is stored in the bonds of the compound. Phosphocreatine → P+ Creatine + Energy creatine kinase

9. Creatine kinase is activated when the level of ADP in the muscle cell increases. • It is when the stores of ATP start to diminish. • The energy released by the breakdown of PC is used to convert ADP to ATP. • Energy has to be liberated by the breakdown of PC before ATP can be formed. • Stores of PC in the muscles are enough to sustain all out effort for about ten seconds.

10. This is the only system capable of producing ATP quickly. • During activities that demand large amounts of energy over a short period of time e.g...... • As PC is stored in the muscle it is readily accessible as an energy source. • Energy for ATP can be obtained extremely quickly. • No fatiguing by products are released.

11. ATP production by the lactic acid system or Glycolysis • Also anaerobic taking place in the sarcoplasm. • The energy needed comes from the food we eat. • It involves the partial breakdown of glucose. • Breakdown of PC does not rely on the availability of oxygen. • It is much more complex than Phosphocreatine. • It therefore stores more energy.

12. Glucose is broken down anaerobically (in absence of oxygen). • Because there is no O2 lactic acid is formed. • Breakdown of bonds in glucose release energy. • The energy is used to synthesise ATP. • The lactic acid system takes longer to produce energy than the ATP/PC system. • It supplies energy for high intensity activities for about a minute. • The 400m is a good example. • What causes fatigue from this system?

13. Outline of Lactic Acid SystemProduction of energy for resynthesis of ATP

14. Fatigue • When glycogen is broken down anaerobically lactic acid is produced. • If lactic acid accumulates it lowers the pH. • The drop in pH affects the action of phosphofructokinase. • It also affects lipoprotein kinase that breaks down fat. • The body’s ability to synthesise ATP is temporarily reduced causing fatigue.

15. Production of ATP using the Aerobic System • The aerobic system needs oxygen. • At the onset of exercise there isn’t enough O2 to break down food fuels. • So the 2 anaerobic systems are used. • As heart rate and rate of ventilation increase more oxygen gets to the working muscles. • Within 1-2 minutes the muscles are being supplied with enough O2 to allow effective aerobic respiration.

16. Stage 1:Aerobic glycolysis • Aerobic glcolysis is the same as anaerobic glycolysis. • Glucose is broken down to pyruvic acid. • As O2 is now present the reaction can proceed further than in anaerobic glycolysis. • Lactic acid is not produced. • Two molecules of ATP are synthesised at this stage.

17. Stage 2: The TCA/Citric acid/Krebs’ Cycle • The pyruvic acid produced in the 1st stage diffuses into the matrix of the mitochondria. • A complex cyclical series of reactions now occurs. • During the cycle three important things happen: 1.carbon dioxide is formed. 2.oxidation takes place-hydrogen is removed from the compound. 3.Sufficient energy is released to synthesis 2 molecules of ATP.

20. Stage 3:The Electron transport chain/electron transport system • The H2 atoms removed in stage 2 are transported by coenzymes to the inner membrane of the mitochondria. • The electrons are passed along by electron carries combining with O2 and H2 ions to form water. • Energy is released which combines ADP with phosphate to form ATP. • The energy yield from the electron tranport chain forms 34 molecules of ATP. • The total yield of ATP from aerobic respiration is therefore 38 molecules of ATP.

21. Mitochondrion

23. Mitochondrion Krebs cycle Electron transport chain ATP synthase Pathways (e.g. b-oxidation)

24. Differences betweeen aerobic and anaerobic ATP production McArdle, Katch&Katch term three energy systems: immediate energy system (ATP/PCr) short-term energy system (Glycolysis) long-term energy system (aerobic)

25. The aerobic system of synthesising ATP is the most efficient. • The byproducts (CO2 and H2O) are easily expelled from the body. • However the reactions involved in this system depend on the availability of O2.