Cardiac Muscle Contraction

Cardiac Muscle Contraction - Cardiac Muscle Contraction

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Cardiac Muscle Contraction The sarcolemma (plasma membrane)  of an unstimulated muscle cell is  polarized—that is, the inside of the  sarcolemma is negatively charged with  respect to the outside. The  unstimulated state of the muscle cell,  called the resting potential, is created  by the presence of large, negatively  charged proteins and nucleic acids  inside the cell. A balance between  K +  inside the cell and Na +  outside the  cell contributes to the polarization.  During an action potential, the balance 
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of Na +  and K +  is upset so that the cell  becomes depolarized. The series of  events that occurs during and following  an action potential in contractile muscle  fibers of the heart is similar to that in  skeletal muscle. Here is a description of  these events: 1. Rapid depolarization occurs  when fast-opening Na +  channels  in the sarcolemma open and 
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Cardiac Muscle Contraction - Cardiac Muscle Contraction

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