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Lecture

York University Kine 1020 Bioenergetics and Muscle Contraction.docx

4 Pages
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Department
Kinesiology & Health Science
Course Code
KINE 1020
Professor
Angelo Belcastro

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Description
Bioenergetics and Muscle Contraction January 7/8, 2014 • ATP concentrations are held relatively stable- therefore as muscle contractions continues energy must be regenerated • as more force is generated, more ATP is needed Energy Sources and Muscle Metabolism Energy systems are used to replenish ATP: Phosphagen (immediate) • occurs in sarcoplasm • Doesn't need oxygen, Anaerobic Glycotic (glucose) • occurs in sarcoplasm • occurs in the presence or absence of oxygen Oxidative (glucose and lipids) • mitochondria • aerobic energy system Energy Production Pathways: Phosphagen • number of different enzymes (creatine kinase & adenylate kinase/myokinase) • Enzymes involved in providing ATP energy when high rates of force requirement by muscle Creatine kinase near equilibrium reaction ATP + Cr ADP + PCRr+ H: • enzyme runs reaction in either direction in the same degree of effectiveness left and right • products and substrates determine which direction enzyme will move • ex. when ATP is used in the reaction ATP + H20 —> ADP +Pi + H to generate force, the concentration of ADP and H are increasing, this is where CK enzyme works to regenerate ATP. The enzyme is working towards left. • Myosin ATPase (located at the head of myosin, it hydrolyses ATP to release chemical energy) and CK need to be in close proximity to be effective • continue high rates of force production • Phosphocreatine (PCr): substrate that sets limits of muscle • is in limited supply 25mmol/kg, 6-8 seconds of function • PCr can be consumed to increase high speed performance time • as PCr decrease, and ADP levels go up myokinase is activated to create ATP • ATP + AMP —> 2ADP Glycolysis • When PCr has depleted, and built up ADP glycotic system is recruited to supply ATP needed by Mysosin ATPase Anaerobic Metabolism/glycolysis • source of glucose is muscle glycogen, also determines capacity of anaerobic glycolysis o enzyme glycogen phosphorylase breaks it down • Pyruvate turns into lactic acid production o lactate dehydrogenase • NAD is essential • no ATP is produced, only 2 ATP that is made in Glycolysis Aerobic • source of glycolysis is blood glucose o hexokinase • Pyruvate turns into acetyl CoA o Pyruvate dehydrogenase (PDH) • Mitochondria • Close to actin and myosin • many ATP created • Uses glucose which can come from many different sources • Glucose 6-phosphate is metabolized into Fructose 6 phosphate o phosphofructokinase (PFK) controls rate at which glucose 6 is metabolizes into fructose
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