Matching Pairs Skeletal Muscle ContractionOnline version Match the various steps of a skeletal muscle contraction with the descriptions of that action. by Lindsay Spielman 1 Toponin 2 Acetylcholinesterase 3 Tropomyosin 4 Muscle relaxation 5 Calcium release by the SR 6 Directly causes cross-bridge detachment 7 End Plate Potential 8 Directly causes cross bridge formation 9 Acetylcholine ATP attaches to the myosin head. Calcium binds to this regulatory protein on the thin filaments. Local sarcolemma depolarization of the neuromuscular junction. Calcium is actively pumped back into the SR. Regulatory protein that covers the myosin-binding sites of the actin. Triggered by depolarization of the t-tubules. Hydrolysis of ATP to ADP and Pi by the ATPase of the myosin head. Degrades acetylcholine in the synapse. Neurotransmitter released by somatic neurons at the neuromuscular junction.