MUSCLE STRUCTURE AND PHYSIOLOGY

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• MUSCLE STRUCTURE AND PHYSIOLOGY
• J. Rosenbluth, April 2012

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MUSCLE

• Skeletal muscle fibers
• Contraction mechanism
• Excitation-contraction coupling
• Gross properties of skeletal muscle
• Pathology/Clinical examples

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Myofibrils
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Skeletal muscle band pattern
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Double antiparallel array of myofilamnts
(H.E.Huxley)
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Sliding filament model
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Myosin filament formation
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Low-angle X-ray diffraction of skeletal muscle
(meridional pattern)
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Decorated F-actin
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Antiparallel array of myofilaments
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Double hexagonal array (vertebrate skeletal
muscle)
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Crossbridge position during relaxation (top) vs
contraction (bottom)
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Cross-bridge Cycle

• Attached
• Released
• Cocked
• Force generating
• Attached

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Triads (amphibian)
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Skeletal muscle triad (amphibian)
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Triad structure
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Actin filament with Tr and Tm
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Tropomyosin movement
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Pennate Muscles
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• Length-Tension
• Relationship

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Load-Velocity Relationship
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Twitch vs Tetanic Tension
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Fiber types (cat gastrocnemius)
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Twitch contraction times
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Skeletal Muscle Fatigue
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Winging(facio-scapulo-humeral dystrophy)
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Pseudohypertrophy (Duchenne dystrophy)
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Charcot-Marie-Tooth disease
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Spinal muscular atrophy
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