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