Muscles

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  1. Thick muscle filament structure
    Made up of several hundred myosin protein molecules
  2. Muscle deactivation step 1
    Ca2+ levels decrease
  3. Muscle deactivation step 2
    Troponin reverts to its original confirmation
  4. Muscle deactivation step 3
    Tropomyosin reverts, covering the myosin binding sites on the actin thin filament
  5. Muscle deactivation step 4
    Myosin heads are no longer able to bind actin and the thick and thin filaments slide back to their original positions (muscle relaxes)
  6. Thin filament structures (3)
    • Actin
    • Tropomysin
    • Troponin
  7. Sliding filament mechanism of contraction step 1
    Cleavage of ATP do ADP and Pi causes the myosin hinge to open, extending the head to a position further along the F-actin filament. High energy confirmation
  8. Sliding filament mechanism of contraction step 2
    Myosin heads in the high-energy confirmation attach to a binding site on F-actin
  9. Sliding filament mechanism of contraction step 3
    • Pi is released from myosin, causing the hinge to close. This is called a power stroke and causes the thick and thin filaments to slide past one another
    • ADP is also released during the power stroke
  10. Sliding filament mechanism of contraction step 4
    Actin-bound myosin heads bind ATP, which releases the heads from the actin.
  11. Tropomysin structure
    A coiled, a-helical, fibrous protein that threads alont the F-actin fibers. It normally blocks the myosin binding sites on actin, unless shifted by troponin
  12. Troponin scructure
    A trimeric, globular complex that binds the tropomysin strands at regular intervals. Troponin binds Ca2+, this binding stimulates a conformation change that results in troponin moving tropomysin away from the myosin binding sites on actin.
  13. Muscle contraction activation step 1
    Muscle fiber Ca2+ concentrations increase as a resulf ot a nerve signal
  14. Muscle contraction activation step 2
    Troponin binds the Ca2+ and undergoes a conformational change
  15. Muscle contraction activation step 3
    The troponin conformational change induces a shift in the position of the tropomysin strand, exposing muyosin binding sites on the surface of the actin filament.
  16. Myosin structure (4)
    • Protein containing two intertwining a-helical tails and two globular heads
    • head contains a site that allows myosin to bind to the thin filament protein actin
    • Protein hinges on the head allow it to extend out and rock back and forth
    • Head also contains an ATP binding site
  17. Actin structure (3)
    • Globular protein that polymerizes to form fibers (F-actin).
    • Two F-actin fibers coil around each other to make the thin filament core.
    • Contains binding sites for myosin on the thick filament.
  18. Thick muscle filament structure (1)
    Made up of several hundred myosin protein molecules.
  19. Thin filament structures (3)
    • Actin
    • Tropomysin
    • Troponin

Card Set Information

Author:
jaguavai
ID:
105824
Filename:
Muscles
Updated:
2011-10-02 22:07:35
Tags:
Pharm 410
Folders:

Description:
Muscle contraction and relaxation
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