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

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Presentation on theme: "Muscle Metabolism. Goals: Describe three ways in which ATP is regenerated during muscle contraction Relate the oxygen deficit to causes of muscle fatigue."— Presentation transcript:

1 Muscle Metabolism

2 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 Copyright © 2010 Pearson Education, Inc. Figure 9.19a Pathways for regenerating ATP during muscle activity. Coupled reaction of creatine phosphate (CP) and ADP Energy source: CP (a) Direct phosphorylation Oxygen use: None Products: 1 ATP per CP, creatine Duration of energy provision: 15 seconds Creatine kinase ADPCP Creatine ATP

8 Muscle Metabolism Glycolysis 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 Copyright © 2010 Pearson Education, Inc. Figure 9.19b Pathways for regenerating ATP during muscle activity. Energy source: glucose Glycolysis and lactic acid formation (b) Anaerobic pathway Oxygen use: None Products: 2 ATP per glucose, lactic acid Duration of energy provision: 60 seconds, or slightly more Glucose (from glycogen breakdown or delivered from blood) Glycolysis in cytosol Pyruvic acid Released to blood net gain 2 Lactic acid O2O2 O2O2 ATP

10 Muscle Metabolism Glycolysis 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 Copyright © 2010 Pearson Education, Inc. Figure 9.20 Comparison of energy sources used during short-duration exercise and prolonged-duration exercise (1 of 2). 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.

12 Muscle Metabolism Glycolysis and Lactic Acid Formation The 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 fatigueIt coincides with muscle fatigue.

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

14 Muscle Metabolism Muscle 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 Metabolism Muscle Fatigue Ionic disturbances are the most likely cause of muscle fatigue : Potassium ion lost from the muscle cells Interference of Calcium regulation

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

17 Muscle Metabolism Aerobic Respiration

18 Aerobic 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 Copyright © 2010 Pearson Education, Inc. Figure 9.19c Pathways for regenerating ATP during muscle activity. Energy source: glucose; pyruvic acid; free fatty acids from adipose tissue; amino acids from protein catabolism (c) Aerobic pathway Aerobic cellular respiration Oxygen use: Required Products: 32 ATP per glucose, CO 2, H 2 O Duration of energy provision: Hours Glucose (from glycogen breakdown or delivered from blood) 32 O2O2 O2O2 H2OH2O CO 2 Pyruvic acid Fatty acids Amino acids Aerobic respiration in mitochondria Aerobic respiration in mitochondria ATP net gain per glucose

20 Copyright © 2010 Pearson Education, Inc. Figure 9.20 Comparison of energy sources used during short-duration exercise and prolonged-duration exercise (2 of 2). 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.

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

22 Muscle Metabolism Comparisons

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. 1. 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 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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