1. Ch 9 Muscles and Muscle Tissue … V. ATP for Muscle Contraction

2. V. ATP for Muscle Contraction (Muscle Metabolism)
A. Providing Energy For Contraction
1. ATP is The Only Direct Source of Energy
Limited amount stored in muscles = 4-6 seconds
Chemical Reacton: ATP ↔ ADP + Pi + Energy
Regenerated immediately by chemical pathways:
Creatine Phosphate, Anaerobic & Aerobic Respiration
Prolonged-duration exercise
Short-duration exercise
Stored
ATP.
Anaerobic Pathway).
Aerobic Pathway.
creatine
phosphate
6 seconds
10 seconds
30–40 seconds
End of exercise
Hours
Figure Comparison of energy sources used during short-duration exercise and prolonged-duration exercise.

3. 2. Aerobic Respiration– For Rest & Normal Activity
a) Produced where? By what Organelle?
b) Reactants needed?
c) Products produced?
d) Is a complex set of chemical reactions
i) Glycolysis Breaks Glucose up into two 3-carbon molecules of Pyruvic Acid
Occurs in the cell’s cytoplasm
Creates just a few ATP by itself
Pyruvic Acid enters mitochondria and is completely broken down to create many more ATP
ii) Mitochondria
Citric Acid Cycle
Electron Transport Chain
most ATP made with this pathway

4. e) Carbon Dioxide goes where? f) Fuel converted to ATP Blood Glucose
2. Aerobic Respiration …
e) Carbon Dioxide goes where?
f) Fuel converted to ATP
Blood Glucose
Stored Glycogen
Fatty Acids– after 30 minutes,
stored fat is main energy source
Source of O2: breathing &
myoglobin
g) Efficency: 1 glucose  36 ATP
h) Speed of reactions: Slow
i) How long one can do it: hours
j) Type of Exercise Can Be Used For: moderate
k) Size of Muscle: All, especially small

5. 3. ATP During Vigorous Exercise
As Exercise level increases to vigorous, the ATP generated by Aerobic Respiration becomes inadequate
a) Use of Creatine Phosphate to make more ATP
i) Creatine Phosphate = high energy chemical
ii) Stored in muscles
iii) CP Transfers Phosphate
to ADP forming ATP
iv) No Oxyegen required
v) Next seconds
b) Anaerobic Respiration
i) Oxygen needed?
ii) Fuel = blood glucose OR stored glycogen
iii) Uses Anaerobic Glycolysis
Location: Cell’s cytoplasm

6. 1 Glucose  2 Pyruvic Acids, to make 2 ATP very fast
iii) Uses Anaerobic Glycolysis …
1 Glucose  2 Pyruvic Acids, to make 2 ATP very fast
 Lactic Acid is made from the Pyruvic Acids
= waste product, slight toxic
Pain the Next Day: Caused by It’s Accumulation; Must be converted to less toxic
iv) Efficiency: Incomplete breakdown of Glucose; 5% ATP
v) Speed: Fast
vi) Time Span: seconds
vii) Muscle Type: especially large
viii) Type of Exercise: Only during vigorous exercise
Figure 6.10c

7. Review of ATP Generation And Use
Figure Comparison of energy sources used during short-duration exercise and prolonged-duration exercise.
Review of ATP Generation And Use
Short-duration exercise
Prolonged-duration exercise
6 seconds
10 seconds
30–40 seconds
End of exercise
Hours
ATP stored in
muscles is
used first.
ATP is formed from
creatine phosphate
and ADP (direct
phosphorylation).
Glycogen stored in muscles is broken down to glucose,
which is oxidized to generate ATP (anaerobic pathway).
ATP is generated by breakdown
of several nutrient energy fuels by
aerobic pathway.
© 2013 Pearson Education, Inc.

8. A. Providing Energy For Contraction …
4. Energy Systems Used during Exercise
Aerobic R.– used soley as long as the slow
rate of ATP production is adequate
Marathons– ATP generated =rate produced
Aerobic Endurance: time can continue Aerobic R
Exercise for Short Surge of Power: Stored
ATP/CP; Weight Lifting, Diving, Sprinting
Exercise for Longer Surge of Power: Anaerobic R.
Tennis, Soccer, 100 m run/swim
Power no longer needed  Aerobic R
But Time Limit: 1- 1 ½ minutes max.

9. B. Muscle Fatigue
= physiological inability of muscle to contract even with stimulus
Causes
Not completely understood
Ionic Imbalances:
Accumulation of inorganic Phosphate interferes with Ca release from SR which alters excitation-contraction coupling
Primarily w/ short duration of intense exercise
Recovery is usually rapid

10. C. Excess Postexercise Oxygen Consumption (EPOC)
1. EPOC (oxygen debt) = Extra O2 needed immediately after Anaerobic Respiration to restore resting state:
Restore ATP, CP, O2 reserves in myoglobin
Convert Lactic acid  Pyruvic Acid
Restore glycogen stores
How long this takes determines recovery time = when are ready to do Anaerobic R. again (Health Measure)
2. Aerobic Respiration is Required:
So extra vigorous breathing after Anaerobic R. brings in the needed O2 for Aerobic Respiration to make more ATP for restoration of the above
Use of Anareobic R. defers when the oxygen is consumed to later

11. VI. Force of Muscle Contraction
A. # of Muscle Fibers Recruited
1. Need Stronger Total Stimulus
More Action Potentials to More Motor Neurons of Motor Units
2. Frequency of Stimulation
a) If more action potentials are sent to the
Motor Units per Time, Summation occurs.
b) Complete Tetanus will eventually occur = maximum contraction

12. See previous powerpoint (part B) for a review: “C
* See previous powerpoint (part B) for a review: “C. Graded Muscle Responses,” “1. Varying Stimulus Frequency ” and “2. Variation in Stimulation Strength”

13. 3. Size (diameter) of Muscle Fibers
a) Large Motor Units have Fibers that are larger
Produce the most powerful contractions
b) Found mostly in the largest muscles
c) Regular Resistance Exercise
causes hypertrophy of muscles
4. Degree of Muscle Stretch
a) Length-Tension Relationship = As
muscle is stretched, the contraction force increases
b) Ideal Amount of Stretch—slight: % of
rest length; optimal overlap of thin & thick
myofilaments
= Longer distance for thin filaments to slide
c) Maximal Cross-Bridge Attachment ideal Stretch leads to the most Cross-Bridges formed & strongest contraction
Maintained by how muscles attach at Joints
Large
number
Of fibers
recruited
Large
muscle
fibers

14. Contractile force (more cross bridges attached)
Figure Factors that increase the force of skeletal muscle contraction.
High
frequency of
stimulation
(wave
summation
and tetanus)
Large
number of
muscle
fibers
recruited
Muscle and
sarcomere
stretched to
slightly over 100%
of resting length
Large
muscle
fibers
Contractile force (more cross bridges attached)
© 2013 Pearson Education, Inc.

15. B. Velocity and Duration of Contraction
2 Major Factors To Classify Muscle Fibers
1. Speed of Contraction: How fast ATPase does “ATP  ADP + P”
2 types general fibers = slow and fast
2. ATP-forming pathways
Oxidative fibers – use aerobic pathways: resist fatigue w/ high endurance
Glycolytic fibers – use anaerobic glycolysis; high fatigue, low endurance
Combine “Slow” and “Fast” with “Oxidative fibers” and “Glycolytic fibers”

16. 3. 3 categories of Fibers and Their Characteristics:
slow oxidative fibers
fast oxidative fibers (least common)
fast glycolytic fibers
most muscles have
all 3 types
a) Speed of
Contraction
b) Myosin ATPase
Activity
c) ATP Pathway
d) Myoglobin Content
e) Glycogen Stores
f) Order of Activation
Memorize
a-c
Based on ATP Pathway

17. Activity best suited for Fiber Diameter Mitochondria
3. 3 categories of Fibers and Their Characteristics …
Order of Activation
Rate of Fatigue
Activity best suited for
Fiber Diameter
Mitochondria
Amount of Capillaries
Related to O2 need
4. Load & Recruitment
Speed is faster w/out
Load
5. Other Factors
Genetic Differences
Affect of Exercise
Based on ATP Pathway

18. © 2013 Pearson Education, Inc.
3. …
Structural and Functional Characteristics of the Three Types of Skeletal Muscle Fibers
© 2013 Pearson Education, Inc.

19. A. Aerobic Exercise–results in an increase of:
VII. Response of Skeletal Muscles to Exercise Effects of Aerobic Exercise
A. Aerobic Exercise–results in an increase of:
Muscle capillaries
Number of mitochondria
Myoglobin synthesis
Occurs mostly in Slow Ox.
Possibly: Fast glycolytic fibers become fast oxidative fibers
No hypertrophy of muscles
Muscle metabolism more efficient
Higher Endurance
Higher Strength (< than Resistance Exercise)
Less Fatigue
These Changes are Not Permanent– one must continue the exercise

20. B. Effects of Resistance Exercise
Vigorous Exercise & Isometric
Typically anaerobic, results in:
Muscle hypertrophy
More myofibrils
Cells may split into two
Significant increase in Strength
Increased mitochondria, myofilaments, and glycogen stores
Possibly: Fast oxidative fibers converted to fast glycolytic fibers
These changes are not permanent
Reversibility: Use it or lose it

21. The Overload Principle
State of fitness after adaptation to overload
Working muscles = increased muscular strength
Muscles adapt to demands
Muscles must be overloaded to produce further gains
Reversibility:
Use it or lose it
Increased exercise overload
State of fitness after adaptation to overload
Exercise overload
Current fitness state
Fig. 5-3, p. 113

22. END

23. Availability of Ca2+ in sarcoplasm rises after initial contraction
Graded Muscle Responses … Treppe: The Staircase Effect (muscles warm up after long relaxation periods)
Treppe – contraction strength increases with time despite same degree of stimulus
Availability of Ca2+ in sarcoplasm rises after initial contraction
Muscle enzymes more efficient because heat added by prior contractions.

24. Review Questions Isotonic isometric
____________ contractions change muscle length; ____________ contractions produce tension but no length change.
__________ __________ stores phosphates for quick ATP generation. Pyruvic acid is used to make ______ in the aerobic respiration, but is converted to __________ _______ in anaerobic respiration.
Creatine phosphate
ATP
lactic acid
Figure 9.20

25. Review Questions
Muscle contractions are precisely controlled by stimulus _____________, the number of action potentials a muscle fiber receives in a given time period, and stimulus __________, the actual number of fibers recruited. Recruitment of fibers usually progresses from __________ to _____________. The stair step effect seen in contraction strength of fully relaxed muscles despite no change in stimulus is known as what?
frequency
strength
smallest biggest
Treppe
Figure 9.18

26. Sources of ATP …

27. QUICK ENERGY SLOW ENERGY
For Heavy Exertion For low to moderate Exertion
4-6 s Stored ATP Aerobic Respiration
14-16 s Creatine Phosphate ↓
30-40 s Anaerobic Glycolysis Aerobic Respiration
O2: does not need O2 Requires O2, myoglobin
Energy: uses muscle glycogen uses blood glucose and fat
# ATP: 2 ATP ATP
Speed: 2 ½ times faster slow
Where in Cell: cytoplasm mitochondria
Pyruvic Acid: pyruvic acid  pyruvic acid completely broken
lactic acid down
Muscle Size: Especially large All sized muscles, especially small
Muscles

29. Participate #4 Slow oxidative
_______ _____________ fibers have high endurance and lots of myoglobin. _______ ____________ fibers have fast acting ATPases and rely mainly on aerobic respiration for fuel. _______ _____________ fibers are anaerobic and subject to quick fatigue.
Fast oxidative
Fast glycolytic

30. QUICK ENERGY SLOW ENERGY
REVIEW
QUICK ENERGY SLOW ENERGY
For Heavy Exertion For low to moderate Exertion
4-6 s Stored ATP Aerobic Respiration
14-16 s Creatine Phosphate ↓
30-40 s Anaerobic Glycolysis Aerobic Respiration
O2: does not need O2 Requires O2, myoglobin
Energy: uses muscle glycogen uses blood glucose and fat
# ATP: 2 ATP ATP
Speed: 2 ½ times faster slow
Where in Cell: cytoplasm mitochondria
Pyruvic Acid: pyruvic acid  pyruvic acid completely broken
lactic acid down
Muscle Size: Especially large All sized muscles, especially small
Muscles

31. QUICK ENERGY SLOW ENERGY
HANDOUT
QUICK ENERGY SLOW ENERGY
For Heavy Exertion For low to moderate Exertion
4-6 s Stored ATP Aerobic Respiration
14-16 s Creatine Phosphate ↓
30-40 s Anaerobic Glycolysis Aerobic Respiration
does not need O2 Requires O2, myoglobin
uses muscle glycogen uses blood glucose and fat
2 ATP ATP
2 ½ times faster slow
Cytoplasm Mitochondria
Pyruvic Acid  Pyruvic Acid completely broken
Lactic Acid down
Especially large muslces All sized muscles, especially small

32. QUICK ENERGY SLOW ENERGY For Heavy Exertion For low to moderate
4-6 s Stored ATP Aerobic Respiration
14-16 s Creatine Phosphate ↓
30-40 s Anaerobic Glycolysis Aerobic Respiration
does not need O2 Requires O2, myoglobin
uses muscle glycogen uses blood glucose and fat
2 ATP ATP
2 ½ times faster slow
cytoplasm mitochondria
pyruvic acid  pyruvic acid completely broken
lactic acid down
Especially large muscles All sized muscles, especially small
lg diameter fibers sm diameter fibers, sm motor
recruited last units recruited first
ADD fast fibers slow fibers & fast
fast glycolytic slow oxidative & fast oxidative