1 SunTrust Bank locations will be closed on July 4 for the holiday. 2  TD Bank will close on the Fourth of July. 3  Wells Fargo is closing most branches on both July 3 and July 4, though there might be some exceptions. 4  Customers can check their local branches or call their local store to verify hours.
As you can see, muscle contraction is regulated by the level of calcium ions in the cytoplasm. In skeletal muscle, calcium ions work at the level of actin (actin-regulated contraction). They move the troponin-tropomyosin complex off the binding sites, allowing actin and myosin to interact.
As an action potential reaches a muscle cell, it triggers calcium to release from the sarcoplasmic reticulum of the cells. The calcium ions then flow into the cytoplasm and bind to the troponin and tropomyosin molecules in the actin filaments of the muscle cells. The binding of calcium allows the troponin to change shape and expose the actin-myosin binding site.