what is the role of calcium ions in muscle contraction?
Calcium ions play a significant role in muscle contraction. The calcium ions are released from sarcoplasm on receiving action potential (signal for contraction). Calcium ions bind with troponin subunits of actin which mask the binding sites for myosin on actin. Binding of calcium to troponin allows the binding of myosin head to actin to form a cross bridge. Cross bridge formation pulls the attached actin filament towards the centre of A band. The Z line attached to the actin is also pulled in, leading to shortening the length of sarcomere.This ultimately causes muscle contraction.