What causes cross bridge detachment after a power stroke?

The process of cross bridge detachment following a power stroke is primarily facilitated by the binding of ATP to the myosin head. During muscle contraction, the myosin heads attach to actin filaments and pull them along, a process known as the power stroke. After this stroke has occurred, for the myosin head to detach from the actin filament, ATP must bind to the myosin. This binding causes a conformational change in the myosin head, reducing its affinity for actin and allowing it to release from the filament. Once detached, the myosin head can hydrolyze the ATP to ADP and inorganic phosphate, preparing it for another cycle of attachment and movement along the actin filament.

The other options do not directly facilitate detachment of the cross bridge after the power stroke. Calcium ion release, for instance, is crucial for initiating contraction but does not mediate the release of myosin from actin. Actin fiber contraction itself refers to the shortening of the muscle fiber, which occurs during the power stroke but does not directly influence the detachment of the myosin head. Motor neuron stimulation is essential for triggering muscle contraction by releasing acetylcholine and causing an action potential, but it does not play a role in the det