Explain the relation between muscles, ATP energy, and the calcium ion.
Muscle is a form of tissue that primarily allows the movement or support to the body of many living organisms. It contains proteins actin and myosin that allows the muscle contraction and relaxation. According to the sliding filament theory, contraction/relaxation of muscles is a series of steps that require the use of energy to produce movement. Calcium ions regulate the binding of actin and myosin. Once the calcium ions are diffused in the sarcoplasm, the myosin binding site is exposed, allowing the binding of actin. as myosin binds with actin, the cross bridge is formed, splitting an ATP molecule into ADP (adenosine diphosphate) and an inorganic phosphate. ATP (adenosine triphosphate) is needed in order to supply the necessary energy for the contraction to happen.