Download Recovery period

Recovery period
• Begins immediately after activity ends
• Pyruvate from lactate; requires O2
– Glucose back to muscle (stored as glycogen)
• Oxygen debt (excess post-exercise oxygen
consumption)
– Amount of oxygen required during resting period to
restore muscle to normal conditions
• Heat Loss- Body temperature regulation role
Types of skeletal muscle fibers
• Fast fibers
• Slow fibers
• Intermediate fibers
Figure 10.21 Fast versus Slow
Fibers
Figure 10.21
Fast fibers
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Large in diameter
Contain densely packed myofibrils
Large glycogen reserves
Relatively few mitochondria
Produce rapid, powerful contractions of short
duration
Slow fibers
• Half the diameter of fast fibers
• Take three times as long to contract after
stimulation
• Abundant mitochondria
• Extensive capillary supply
• High concentrations of myoglobin
• Can contract for long periods of time
Intermediate fibers
• Similar to fast fibers
• Greater resistance to fatigue
Muscle performance and the
distribution of muscle fibers
• Pale muscles dominated by fast fibers are called
white muscles
• Dark muscles dominated by slow fibers and
myoglobin are called red muscles
• Training can lead to hypertrophy of stimulated
muscle
Hypertrophy
Hypertrophy- increased mitochondria, glycolytic
enzymes, glycogen, and myodibrils
- opposite of atrophy
Physical conditioning
• Anaerobic endurance
– Time over which muscular contractions are
sustained by glycolysis and ATP/CP reserves
• Aerobic endurance
– Time over which muscle can continue to contract
while supported by mitochondrial activities
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Structural characteristics of
Located only in heart
cardiac
muscle
Cardiac muscle cells are small
– One centrally located nucleus
– Short broad T-tubules (no triads)
– Dependent on aerobic metabolism
• No terminal cisternae (flattened membrane disks)
of SR; SR tubules contact PM
• More myogloblin (O2 storing protein in muscle cells)
and mitochondria
• Intercalated discs where membranes contact one
another
Figure 10.22 Cardiac Muscle
Tissue
Figure 10.22
Functional characteristics of cardiac
muscle tissue
• Automaticity- due to pacemaker cells of the
Sinoatrial node
• Contractions last longer than skeletal muscle
• Do not exhibit wave summation
– No tetanic contractions (s.: tetanus) possible
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Structural characteristics of
Nonstriated smooth muscle
– Lack myofibrils and sarcomeres
– Thin filaments anchored to dense bodies
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Involuntary
No T tubules
loose network of SR
Thick filaments scattered with more cross-bridges
Thin filaments anchored to dense bodies (desmin)
Adjacent cells bound at dense bodies
Figure 10.23 Smooth Muscle
Tissue
Figure 10.23
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Functional characteristics of
Contract when calcium ions interact with
calmodulin smooth muscle
– Activates myosin light chain kinase
• Functions over a wide range of lengths
– Plasticity
• Multi-unit smooth muscle cells are innervated by
more than one motor neuron, thus are motor units
• Visceral smooth muscle cells are not always
innervated by motor neurons
– Neurons that innervate smooth muscle are not under
voluntary control