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BIO 220 Human Anatomy & Physiology
Energy Sources for Muscle Contraction
Text Reference: Chapter 10
This also reviews and/or uses some basic principles of cellular respiration.
I.
ATP—the direct source for energy.
A.
ATP
1.
2.
3.
B.
II.
Direct source of energy for muscle fiber contraction
a.
Resting muscle
b.
Active muscle
c.
ATP needed for
1)
2)
3)
d.
Only available for very short periods (few seconds) of
strenuous exercise.
e.
ATPase
a.
Enzyme that hydrolyzes ATP and activates myosin
b.
Myosin head binds to myosin binding site on actin
c.
Actin acts as a cofactor that allows ATPase to work
ATP is also necessary for muscle relaxation—explain (refer to
previous notes)
Sources for ATP in a muscle fiber (each will be discussed in detail)
1.
Creatine Phosphate (this is a new concept)
2.
Aerobic Cellular Respiration (dredge up those old notes)
3.
Anaerobic Cellular Respiration (dredge up those old notes)
Where do your muscle cells get their ATP? (See Figure 10.12)
A.
Creatine Phosphate (Phosphagen System)
1.
2.
3.
4.
5.
6.
7.
8.
Revised Fall 2005
Creatine is produced in the liver.
Creatine phosphate is only synthesized when ATP is in adequate
quantities.
Creatine phosphate is 3-6 times more plentiful in skeletal muscle
cell sarcoplasm than is ATP
Energy is stored in high energy phosphate bones of creatine
phosphate.
This stored energy can then be used to synthesize ATP as ATP is
being decomposed during exercise.
ATP + CreatineÆ Creatine Phosphate + ADP (resting muscle)
ADP + Creatine Phosphate Æ ATP + Creatine (exercising muscle)
Creatine kinase (what is its function?)
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BIO 220 Human Anatomy & Physiology
Energy Sources for Muscle Contraction
9.
10.
11.
12.
This helps maintain a constant level of ATP in the cell as long as
you have creatine phosphate.
This lasts for about 15 seconds—important for high bursts of energy
(sprinting-100 meter dash)
Can creatine phosphate directly supply the cell’s energy needs?
Improving creatine phosphate level
a.
Creatine is broken down into creatinine and is secreted in the
urine.
b.
Adults need about 2gms of creatine daily to make up for this
loss.
c.
Interval training (sprint-rest-sprint-rest-sprint-rest …)
d.
Creatine supplementation (pros and cons—see pg. 306)
B.
Anaerobic Cellular Respiration (cytoplasm)
1.
First phase of cellular respiration
2.
Glycolysis—anaerobic—glucoseÆ____________________
3.
Pyruvic acid would normally go into the _________ where it would
be oxidized (needs oxygen) through (aerobic/anaerobic) cellular
respiration to produce lots more ATP
4.
When insufficient oxygen is available then most of the pyruvic acid
is converted to _________________________.
a. 80% goes to the _________________.
b. 20% stays in the _________________.
c. Heart, liver, and kidney can use lactic acid to produce ________.
d. Most of the lactic acid will eventually have to be converted to
glucose (or other products) and oxygen is needed for this.
e. You build up your lactic acid (and also an oxygen dept—more
below).
5.
Anaerobic respiration provides enough energy for _______ seconds
of strenuous exercise (200 meter race).
C.
Aerobic Cellular Respiration
1.
When exercising strenuously for more than 30 seconds you need to
turn to _______________ cellular respiration.
2.
When exercising for greater than 10 minutes _______________
cellular respiration provides 90% of your ATP.
3.
Oxygen must be available
a.
Sources of oxygen
1) Hemoglobin
2) Myoglobin
Revised Fall 2005
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BIO 220 Human Anatomy & Physiology
Energy Sources for Muscle Contraction
b.
Don’t forget—you’re breathing at a rate that is sufficient to
supply your body with sufficient oxygen for the amount of
exercise
c. When you’re exercising, muscle contraction squeezes on the
blood vessels and blood supply is not as abundant—so why is
myoglobin such a good thing?
III.
4.
5.
6.
7.
8.
Occurs in the _________________________
Acetyl coenzyme A (remember the doorman?)
Krebs cycle
Electron transport chain
Formula for cellular respiration (keep those old notes out)
9.
Aerobic cellular respiration works for rest or moderate exercise.
What do you do to accommodate this exercise?
a. Respiratory and circulatory system can supply adequate amounts
of O2 and ATP for this.
b. Increased respiratory rate
c. Increased blood flow to muscle tissue
d. Nutrients must be available
e. Glycogen stores (glycogen Æ glucose…what’s that G-word?)
f. This is called aerobic exercise
What happens when you exercise?
A. Oxygen Dept and Oxygen Consumption After Exercise—You're dipping
into anaerobic respiration. During exercise, most available O2 is used for
synthesis of ATP for energy for muscle fiber contraction and relaxation. It is
not used for “cleaning up” after exercise.
1.
2.
Revised Fall 2005
Lactic acid build up
a.
Strenuous exercise and continuous increased respiratory rate
after exercise—you’re out of breath and you’ve used up your
glycogen stores.
b.
Oxygen debt—oxygen payback needed to convert lactic acid
to pyruvic acid
Recovery oxygen uptake: You need to clean up a few other things
a.
Lactic acid Æpyruvic acid Æglucose
b.
Glycogen
c.
Creatine phosphate
d.
Increased temperature and increased cellular activities
e.
Increased heart rate
f.
Increased respiratory muscles
g.
Tissue repair
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BIO 220 Human Anatomy & Physiology
Energy Sources for Muscle Contraction
B. Muscle Fatigue—a fatigued muscle loses its ability to contract
1.
Central fatigue—protective mechanism (tells you that you are
______________).
2.
Calcium supply low
3.
Decrease creatine phosphate
4.
Glycogen supply low
5.
Lactic acid buildup--pH
6.
Inadequate blood supply/oxygen supply
7.
Acetylcholine supply
8.
Why are you sore after exercise?
a.
Build up of lactic acid?
b.
pH change in tissues?
c.
DOMS (detail) and exercise-induced muscle damage
9.
IV.
Describe the benefits of stretching (Chpt. 11, p. 330-331)
a.
b.
c.
d.
Athletes vs. non-athletes (Why do athletes perform better than non-athletes and
what do they do to make their performance better?)
Revised Fall 2005
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