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