Excitation-Contraction Coupling

What is excitation-contraction coupling?

The sequence of events by which transmission of an action potential along the sarcolema causes myofilamens to slide

What is the first step in excitation-contraction coupling

The action potential propagates along the sarcolema and down the t-tubules

What is the second step in excitation-contraction coupling

Calcium ions are released. This allows flow of calcium ions from the terminal cisternae (sER) to the cytosol

What is the third step in excitation-contraction coupling

Calcium binds to troponin in the thin filaments and removes the blocking action of tropomyosin

What is the fourth step in excitation-contraction coupling

Contraction begins: myosin binding to actin forms cross bridges and contraction (cross-bridge cycling) beings.