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Energy

Energy Metabolism. Metabolism - All chemical reactions that take place in the body.Anabolism - Synthesis of molecules.Catabolism - Degradation of molecules.. Adenosine Triphosphate (ATP). Is the means of energy generation in all cells.Supply limited by duration and intensity of exercise.Is the

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Energy

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    2. Energy Metabolism Metabolism - All chemical reactions that take place in the body. Anabolism - Synthesis of molecules. Catabolism - Degradation of molecules.

    3. Adenosine Triphosphate (ATP) Is the means of energy generation in all cells. Supply limited by duration and intensity of exercise. Is the immediate form of chemical energy for muscular activity. NRG released form ATP goes directly to facilitate muscular contractions). Chemical energy from food is transferred to chemical energy stored in ATP.

    5. ATP is converted into Adenosine Diphosphate (ADP) and a Phosphate Group. NRG is released during this process. ATP Y ADP + Pi + energy Later ATP is recreated via one of three different mechanisms, called energy systems.

    6. Coupled reactions Coupled reactions link exothermic with endothermic processes so that some of the NRG is transferred to the endothermic process In the body, such reactions conserve a large portion of the chemical a large portion of the chemical NRG in food nutrients in a usable form. NRG released from AB is coupled with the NRG demand of C + D to form CD AB Y A + B + NRG NRG + C + D Y CD Exothermic reactions A physical or chemical process that releases NRG to its surroundings is termed exothermic. Endothermic reactions A process that takes in energy is termed endothermic.

    7. Aerobic - series of chemical reactions resulting in the complete degradation of CHO and fats to CO2 , H2O and NRG in the presence of O2 (called oxidation and occurs in the mitochondria). Anaerobic - series of chemical reactions resulting in the partial degradation of CHO to an intermediate compound and small quantities of NRG without O2.

    8. The alactic anaerobic system (ATP-PC or the phosphogen system) In activity lasting longer than a couple of seconds resynthesis relies on phosocreatine (PC). Closely related to ATP and is stored in the muscle cells. 1 mole of PC required to resynthesise 1 mole of ATP. NRG provision short duration lasting only a few seconds, all out sprint, or rapid high intensity, repetitive activities. PC concentrations in muscle drop to very low levels resulting in fatigue in 10-30 seconds. PC stores can be regenerated rapidly to near normal within a few minutes of cessation of activity. Total stores of ATP and PC very small. PC concentrations 3 times that of ATP. Usefulness of this system limited by initial levels of ATP and PC. Usefulness of ATP-PC lies in rapid availability of NRG and rapid recovery of PC levels.

    9. ATP-PC System

    10. The lactic acid system (anaerobic glycolysis or sugar breakdown) The lactic acid system depends on the chemical process known as glycolysis -the breakdown of sugar CHO is stored in the muscle as glycogen. These stores are high in power but low in capacity because not much is stored. It is a series of chemical reactions in the cytoplasm of cell that converts a 6-carbon molecule of glucose into two 3-carbon molecules of pyruvic acid Involves 10 reactions catalysed by specific enzymes. 2 molecules of ATP are required to get the process started and 4 are generated - the net gain is 2 ATP for each molecule of glucose.

    11. When there is no O2 present (demand for NRG from ATP exceeds normal glycolytic and oxidative rates) anaerobic metabolism takes place. Pyruvic acid, formed during glycolysis, is temporarily converted to lactic acid.

    12. As lactic acid accumulates muscle fatigue and pain occur. This is because the resultant low pH within the cell inhibits enzyme action in the cell mitochondria, which normally promotes the change of glycogen into NRG. Hence the effect of lactic acid fatigue is to inhibit muscle action so that physical performance deteriorates. Anaerobic processes happen in the sarcoplasm of the cell. For exercise performed at maximum rates for between 1-3 minutes eg running 400-800 metres or swimming 100 - 200 metres.

    13. A considerable amount of NRG remains in the lactic acid molecules. The NRG can be used by conversion back to pyruvic acid. Often occurs in the muscle that produced the lactic acid, however if no O2 present then diffuses into the blood. Then taken up by the muscles for NRG or delivered to liver to be changed into glycogen. After events that rely heavily on the lactic acid system, extra O2 is taken to remove the lactic acid back into pyruvic acid. This is known as repaying the oxygen debt.

    14. The Aerobic System Relies on the presence of O2 to completely breakdown CHO and fats to CO2, H2O and NRG. NRG yield is high 1 molecule of glucose yields 36 molecules of ATP. First stage is glycolysis in the sacroplasm. From then on all chemical reactions involved in the aerobic system take place within the muscle cell mitochondria, sometimes called the powerhouse of the cell.

    16. Krebs cycle (citric acid cycle) Two molecules of pyruvic acid are converted to a form of Acetyl - CoA (2-carbon compound). This enters the citric acid cycle by combining with oxaloacetic acid (4-carbon compound) to form citric acid (6-carbon compound). The process takes place in the inner fluid filled matrix of the mitochondrion, containing the enzymes of the citric acid cycle. Within this cycle there are a large number of reactions in which the 2 molecules go through a series of changes until they are degraded to pairs of hydrogen atoms and CO2. Fatty acids are taken up by the cycle at this point. The total NRG release from acetyl-CoA, as a result of fat metabolism, is 34 ATP. Fat is said to burn in a CHO flame because oxaloacetic acid is derived from breakdown of CHO.

    17. The Electron Transport System O2 is given off from muscle myoglobin or made available from haemoglobin and is taken in by the mitochondria to be used to oxidise the hydrogens. H Y H+ + e- (hydrogen atom) (hydrogen ion) (electron) The hydrogen ions and electrons are charged with potential NRG. The electron transport chain consists of a chain of hydrogen ion-electron pairs, linked to the folds of the inner membrane (critae) of the cell mitochondria. NRG is released in a controlled step by step manner (exothermic). For each pair of hydrogen atoms that enter the pathway, the net effect is the production of 2 molecules of ATP (endothermic) and one molecule of H2O. This is an aerobic process, with the final pair being accepted by molecular oxygen which combines with H+ to produce water.

    18. Aerobic Respiration The total possible yield produced by aerobic metabolism is 36 or 38 molecules of ATP. The total NRG yield is dependent on the biochemical pathway taken by the food fuel. The aerobic route is 18 or 19 times more efficient than the anaerobic route depending on the food fuel. ATP yield varies as this process is more or less complete. The overall equation expressing aerobic respiration is: 1 molecule glucose + 36ADP + 36Pi + 6O2 Y6CO2 + 36ATP + 6H2O

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