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 Direct phosphorylation of ADP by creatine phosphate
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. 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
ADP CP
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. 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 O2
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. Short-duration exercise
Figure 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. It coincides with muscle fatigue.
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 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. Muscle Metabolism 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. 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, CO2, H2O
Duration of energy provision: Hours
Glucose (from
glycogen breakdown or
delivered from blood) 32 O2
H2O
CO2
Pyruvic acid
Fatty
acids
Amino
Aerobic respiration
in mitochondria
ATP
net gain per
glucose

20. Prolonged-duration exercise
Figure 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. Deep down we are all turkeys
Muscle Fiber Type
Deep down we are all turkeys

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