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Muscle Metabolism

Muscle Metabolism. Muscle Metabolism. Goals: Describe three ways in which ATP is regenerated during muscle contraction Relate the oxygen deficit to causes of muscle fatigue. Muscle Metabolism. Muscle have only a 4 to 6 second supply of ATP

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Muscle Metabolism

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  1. Muscle Metabolism

  2. Muscle Metabolism Goals: • Describe three ways in which ATP is regenerated during muscle contraction • Relate the oxygen deficit to causes of muscle fatigue

  3. Muscle Metabolism • Muscle have only a 4 to 6 second supply of ATP • ATP must be continually regenerated via one of three pathways in the muscle.

  4. Muscle Metabolism These pathways are: • Direct phosphorylation of ADP by creatine phosphate • Anaerobic glycolysis • Aerobic respiration

  5. Muscle Metabolism Creatine Phosphate Phosphorylation Active muscles can use all ATP within a few twitches. Creatine Phosphate is a high energy storage molecule The transfer of its high energy phosphate to ADP can provide up to 16 seconds of ATP in a muscle. Creatine phosphate is regenerated during rest. Its money for health food companies.

  6. Muscle Metabolism Creatine Phosphate Phosphorylation This pathway is used for very quick bursts of muscle activity, such as sprinting.

  7. (a) Direct phosphorylation Coupled reaction of creatine phosphate (CP) and ADP Energy source: CP CP ADP Creatine kinase Creatine ATP Oxygen use: None Products: 1 ATP per CP, creatine Duration of energy provision: 15 seconds Figure 9.19a Pathways for regenerating ATP during muscle activity.

  8. Muscle MetabolismGlycolysis and Lactic Acid Formation This pathway generates ATP after the Creatine phosphate system is exhausted. Actively contracting muscles compress arteries, reducing blood flow and oxygen. This produces anaerobic conditions which produce lactic acid.

  9. (b) Anaerobic pathway Glycolysis and lactic acid formation Energy source: glucose Glucose (from glycogen breakdown or delivered from blood) Glycolysis in cytosol O2 ATP 2 Pyruvic acid net gain O2 Released to blood Lactic acid Oxygen use: None Products: 2 ATP per glucose, lactic acid Duration of energy provision: 60 seconds, or slightly more Figure 9.19b Pathways for regenerating ATP during muscle activity.

  10. Muscle MetabolismGlycolysis and Lactic Acid Formation This pathway only produces about 5% as much ATP as aerobic respiration but does it twice as fast. This pathway extends the ATP supply up to 1 minute of vigorous activity.

  11. Short-duration exercise ATP stored in muscles is used first. ATP is formed from creatine phosphate and ADP. Glycogen stored in muscles is broken down to glucose, which is oxidized to generate ATP. Figure 9.20 Comparison of energy sources used during short-duration exercise and prolonged-duration exercise(1 of 2).

  12. Muscle MetabolismGlycolysis and Lactic Acid FormationThe Big Lie by State Ed Department The build up of lactic acid leads does NOT lead to muscle soreness following exercise. It coincides with muscle fatigue.

  13. Muscle MetabolismMuscle Fatigue Muscle fatigue is the inability to contract even in the presence of stimuli.

  14. Muscle MetabolismMuscle Fatigue Muscle fatigue is the inability to contract even in the presence of stimuli. It is NOT due to a lack of ATP. This would lead to contractures. This is seen with writers cramp.

  15. Muscle MetabolismMuscle Fatigue Ionic disturbances are the most likely cause of muscle fatigue: • Potassium ion lost from the muscle cells • Interference of Calcium regulation

  16. Muscle MetabolismAerobic Respiration This pathway produces 95% of the ATP. This pathway occurs in the mitochondria and requires oxygen.

  17. Muscle MetabolismAerobic Respiration

  18. Muscle MetabolismAerobic Respiration Muscle glycogen provides the major source of glucose followed by blood glucose and then fats. It provides the most ATP but is slower because of all the enzymatic steps.

  19. (c) Aerobic pathway Aerobic cellular respiration Energy source: glucose; pyruvic acid; free fatty acids from adipose tissue; amino acids from protein catabolism Glucose (from glycogen breakdown or delivered from blood) O2 Pyruvic acid Fatty acids O2 Aerobic respiration in mitochondria Aerobic respiration Amino acids in mitochondria 32 ATP CO2 H2O net gain per glucose Oxygen use: Required Products: 32 ATP per glucose, CO2, H2O Duration of energy provision: Hours Figure 9.19c Pathways for regenerating ATP during muscle activity.

  20. Prolonged-duration exercise ATP is generated by breakdown of several nutrient energy fuels by aerobic pathway. This pathway uses oxygen released from myoglobin or delivered in the blood by hemoglobin. When it ends, the oxygen deficit is paid back. Figure 9.20 Comparison of energy sources used during short-duration exercise and prolonged-duration exercise (2 of 2).

  21. Muscle MetabolismAerobic Respiration This pathway is used for long periods of exercise such as cross county and marathon events.

  22. Muscle MetabolismComparisons

  23. Muscle Fiber Type Deep down we are all turkeys

  24. Muscle Fiber Type Deep down we are all turkeys Remember white meat/ dark meat?

  25. Muscle Fiber Type Muscle fibers are divided into two types based on their metabolism. • Slow oxidative fibers (Red Meat) • Aerobic • Myoglobin present (Red Color) • Large number of mitochondria • Low glycogen content • Slow rate of fatigue • Good for endurance activities

  26. Muscle Fiber Type Muscle fibers are divided into two types based on their metabolism. 2. Fast Glycolytic Fibers • Anaerobic • Myoglobin content is low (White Color) • Glycogen content is high • Fatigues quickly • Few mitochondria • Short term intense movements

  27. Muscle Fiber Type A third muscle type, the Fast Oxidative Fiber has characteristics of both muscle types. These muscle can convert to the other types based on training.

  28. Adaptation to Exercise Endurance exercising will: • Increase the number of capillaries surrounding the muscle fibers (why) • Increase the number of mitochondria (why) • May convert some of the fast glycolytic fibers to fast oxidative fibers • Increase the efficiency of the heart (why)

  29. Adaptation to Exercise Resistance exercising will: • Increase the increase the size of the muscle fibers • Increase the amount of connective tissue between the fibers • May convert some of the to fast oxidative fibers to fast glycolytic fibers

  30. Adaptation to Exercise

  31. Adaptation to Exercise Large bulky muscles are due to the increase size of individual muscle fibers (fast glycolytic fibers)

  32. Adaptation to Exercise • Who has the larger heart?

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