3. Write a step-by-step description of the "sliding filament theory." Think about the requirements for contraction. What stimuli, sources of energy and other ions are needed to shorten a muscle?

The sliding filament theory of muscle contraction was developed to fit the differences observed in the named bands on the sarcomere at different degrees of muscle contraction and relaxation. The mechanism of contraction is the binding of myosin to actin, forming cross-bridges that generate filament movement.