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MUSCLE STRUCTURE AND PHYSIOLOGY J. Rosenbluth, April 2012. MUSCLE. Skeletal muscle fibers Contraction mechanism Excitation-contraction coupling Gross properties of skeletal muscle Pathology/Clinical examples. Myofibrils. Skeletal muscle band pattern. - PowerPoint PPT Presentation
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MUSCLE STRUCTURE AND PHYSIOLOGY
J. Rosenbluth, April 2012
MUSCLE• Skeletal muscle fibers
– Contraction mechanism– Excitation-contraction coupling
• Gross properties of skeletal muscle
• Pathology/Clinical examples
Myofibrils
Skeletal muscle band pattern
Double “antiparallel” array of myofilamnts (H.E.Huxley)
Sliding filament model
Myosin filament formation
Low-angle X-ray diffraction of skeletal muscle (meridional pattern)
Decorated F-actin
Antiparallel array of myofilaments
Double hexagonal array (vertebrate skeletal muscle)
Crossbridge position during relaxation (top) vs contraction (bottom)
Cross-bridge Cycle
– Attached
– Released
– Cocked
– Force generating
– Attached
Triads (amphibian)
Skeletal muscle triad (amphibian)
Triad structure
Actin filament with Tr and Tm
Tropomyosin movement
Pennate Muscles
Length-TensionRelationship
Load-Velocity Relationship
Twitch vs Tetanic Tension
Fiber types (cat gastrocnemius)
Twitch contraction times
Skeletal Muscle Fatigue
“Winging”(facio-scapulo-humeral dystrophy)
“Pseudohypertrophy” (Duchenne dystrophy)
Charcot-Marie-Tooth disease
Spinal muscular atrophy