Course Home Extrafud mufber Secondary Primary Secondary afferent 100 tout, length, and position Golgi tendon orgaforce Reset Help ATP An action potential arrives at the axon terminal and triggers terminal to open channels in the axon decreases Ca2 When muscle contracts, the actin filaments slide past the myosin and the length of the muscle troponin ligand Glycerination removes ions and ATP and exposes the binding sites on the actin. myosin Both muscle contraction and relaxation require ATP lons as a source of energy The solution caused the greatest contraction At the neuromuscular junction, acetylcholine binds to end plate gated ion channels in the motor During muscle contraction, Ca? binds to on the actin filament.