MUSCLES

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MUSCLES

• ORGANIZATION
• FASCICLES
• MYOFIBER MUSCLE CELL
• MYOFIBRILS
• CELL TYPES
• MYOCYTES
• MYOTUBES
• MYOFIBERS

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MUSCLE

• SUBCELLULAR STRUCTURE
• SARCOLEMMA
• SARCOPLASM
• T-TUBULES
• SARCOPLASMIC RETICULUM

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MUSCLE

• SUBCELLULAR STRUCTURE
• SARCOMERES
• ISOTROPIC AND ANISOTROPIC BANDS
• Z-LINE, I-BAND, A-BAND, M-LINE, H-ZONE
• ACTIN
• MYOSIN
• TROPOMYOSIN
• TROPONIN

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http//www.sci.sdsu.edu/movies/actin_myosin.html
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STEPS IN CONTRACTION

• DEPOLARIZATION AT MOTOR END PLATE
• SPREAD OF DEPOLARIZATION ACROSS SL AND DOWN T-
  TUBULES
• ACTIVATION OF CA CHANNELS IN SR
• CA BINDS TROPONIN-C
• TROPONIN CHANGES CONFORMATION

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CONTRACTION CONTD

• SITES ON ACTIN OPEN FOR MYOSIN BINDING
• MYOSIN BINDS ACTIN
• MYOSIN UNDERGOES RACHET MOVEMENT
• ATP BINDS TO RELEASE AND RESET MYOSIN HEAD

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ROLE OF ATP

• PROVIDES ENERGY FOR MYOSIN CONFORMATIONAL CHANGE
• ATP BINDS MYOSIN TO CAUSE RELEASE FROM ACTIN
• ATP HYDROYZED TO ADP TO RESET MYOSIN HEAD
• ADP RELEASED AFTER NEXT RACHET MOVEMENT

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