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Unformatted text preview: Behavior of Muscle Cells and Whole Muscles It should be obvious that the contraction of a single muscle cell is not sufficient to exert enough tension to cause the movement of a body part. Thus, muscles must contract optimally and usually several muscle cells in a muscle must be recruited at the same time. Optimal contraction of a muscle cell is ensured by the length-tension relationship . This principle states that the amount of tension generated by the contraction of a muscle depends on the length of that muscle cell at the start of a contraction. If a muscle is already shortened at the start of another contraction, the second contraction will result in a weak contraction and decreased tension. This is because in a contracted muscle, the thick myosin filaments overlap the thin filaments and are too close to the Z discs; thus little additional shortening can occur. Similarly, if the muscle is significantly stretched, there is too little overlap of the myofilaments and not enough myosin...
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- Fall '10