What is the process of contraction?

1. Calcium enters the sarcoplasm from the sarcoplasm reticulum or extracellular fluid and makes it way to the cytosol. 2. Calcium binds and activates calmodulin 3. The activated calmodulin activates the kinase enzymes 4. Kinase enzymes catalyze transfer of phosphate to myosin 5. Activated myosin forms cross bridges with actin of the thin filaments and shortening begin.