MUSCLE STRUCTURE AND PHYSIOLOGY
J. Rosenbluth, April 2009
MUSCLE
• Skeletal muscle – Contraction mechanism– Excitation-contraction coupling
• Gross properties of skeletal muscle
• Cardiac, obliquely striated and smooth muscles
• Pathology/Clinical examples
Skeletal muscle band pattern
Double “antiparallel” array of myofilamnts (H.E.Huxley)
Myosin filament formation
Low-angle X-ray diffraction of skeletal muscle (meridional pattern)
Decorated F-actin attached to Z-disc
Double hexagonal array (vertebrate skeletal muscle)
Low-angle X-ray diffraction of skeletal muscle (equatorial pattern)
Crossbridge position during relaxation (top) vs contraction (bottom)
Focal contraction (amphibian skeletal muscle)
Skeletal muscle triad (amphibian)
Triad model(Franzini-Armstrong, C.)
Actin filament with Tr and Tm
Load-Velocity Relationship
Twitch vs Tetanic Tension
Muscles Have Heterogenous Properties
Twitch Contractions
Obliquely striated muscle (Ascaris), stretched
Ascaris obliquely striated muscle
Smooth muscle (“Myoelastic tissue”)
Smooth muscle (cross section)
Smooth muscle (Science 148:1337-1339)
“Pseudohypertrophy” (Duchenne dystrophy)
Charcot-Marie-Tooth disease