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25 Cards in this Set
- Front
- Back
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Skeletal muscle |
-Large (up to 20cm), striated cells (banding pattern) - multinucleated - voluntary motor control |
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Cardiac muscle |
- small, branched, striated cells - intercalated disk, gap junctions - single nucleus |
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Smooth muscle |
-small cells with no striations -single nucleus |
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Thick filaments |
bundle of myosin proteins anchored in place by titian fibers |
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Thin filaments |
bundle of actin proteins (structural backbone) anchored to z-lines |
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Myofibrils |
arrangement of characteristic proteins |
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I-band |
area of adjacent sarcomeres with only thin filaments |
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A-band |
area of sarcomere with thick filaments |
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H-zone |
middle of sarcomere, only find thick filaments, no overlap |
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titin |
helps anchor and hold thick filaments in place -returns muscle to resting length after contraction (like a spring) |
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Sliding filament theory |
myosin head binds to actin, and slides it, pulling z-lines closer together, and reducing the width of the I-bands |
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Molecular basis of contraction: |
energized resting state --> cross-bridge formation --> power stroke --> rigor state --> back to resting state |
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muscle fatigue |
the inability to generate or maintain muscle contraction |
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temporal summation |
the increase in muscle tension from successive action potentials |
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unfused tetanus |
partial dissipation of tension between subsequent stimuli |
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Fused tetanus |
no time for dissipation of tension between rapidly recurring stimuli |
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Series elastic elements |
titin, connective tissues, tendons. 'absord' tension and must be overcome to shorten the muscle |
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Isometric contraction |
muscle has not shortened. Sarcomeres shorten, generating force, but elastic elements stretch, allowing muscle length to remain the same |
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Isotonic contraction |
Sarcomeres shorten more but, because elastic elements are already shortened, the entire muscle must shorten |
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Optimal length sarcomere |
lots of actin-myosin overlap and plenty of room to slide |
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short sarcomere |
actin filaments lack room to slide, so little tension can be developed |
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long sarcomere |
actin and myosin do not overlap much, so little tension can be developed |
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Motor unit recruitment |
the activation of additional motor units - the strength of muscle contraction depends on the number of motor units that are stimulated |
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motor unit |
consists of a motor neuron and all the muscle fibers it controls |
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Muscular dystrophy |
genetic diseases that result in the progressivedegeneration of skeletal and cardiac muscle fibers |
