Transcript Muscle Metabolism - White Plains Public Schools

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
 ATP must be continually regenerated via one of
three pathways in the muscle.
Muscle Metabolism
These pathways are:
 Direct phosphorylation of ADP by creatine
phosphate
 Anaerobic glycolysis
 Aerobic respiration
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.
Muscle Metabolism
Creatine Phosphate Phosphorylation
This pathway is used
for very quick bursts
of muscle activity,
such as sprinting.
Figure 9.19a Pathways for regenerating ATP during muscle activity.
(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
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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.
Figure 9.19b Pathways for regenerating ATP during muscle activity.
(b)
Anaerobic pathway
Glycolysis and lactic acid formation
Energy source: glucose
Glucose (from
glycogen breakdown or
delivered from blood)
Glycolysis
in cytosol
2
O2
ATP
net gain
Released
to blood
Pyruvic acid
O2
Lactic acid
Oxygen use: None
Products: 2 ATP per glucose, lactic acid
Duration of energy provision:
60 seconds, or slightly more
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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.
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 ATP is formed
muscles is
from creatine
used first.
phosphate
and ADP.
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Glycogen stored in muscles is broken
down to glucose, which is oxidized to
generate ATP.
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.
Muscle Metabolism
Muscle Fatigue
Muscle fatigue is the inability to contract
even in the presence of stimuli.
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.
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
Muscle Metabolism
Aerobic Respiration
This pathway produces 95% of the ATP.
This pathway occurs in the mitochondria and
requires oxygen.
Muscle Metabolism
Aerobic Respiration
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.
Figure 9.19c Pathways for regenerating ATP during muscle activity.
(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
Aerobic respiration
in mitochondria
mitochondria
Amino
acids
32
CO2
H2O
ATP
net gain per
glucose
Oxygen use: Required
Products: 32 ATP per glucose, CO2, H2O
Duration of energy provision: Hours
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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.
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Muscle Metabolism
Aerobic Respiration
This pathway is used
for long periods of
exercise such as cross
county and marathon
events.
Muscle Metabolism
Comparisons
Muscle Fiber Type
Deep down we are all turkeys
Muscle Fiber Type
Deep down we are all
turkeys
Remember white
meat/ dark meat?
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
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
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.
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)
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
Adaptation to Exercise
Adaptation to Exercise
Large bulky muscles are
due to the increase size of
individual muscle fibers
(fast glycolytic fibers)
Adaptation to Exercise
 Who has the larger heart?