Extracellular calcium ions are important for the contraction of what type(s) of muscle tissue?

Extracellular calcium is important for the contraction of smooth muscle tissue as well as the cardiac muscle tissue. Both smooth muscles and cardiac muscles do not have the sarcoplasmic reticulum and t-tubule system found in skeletal muscles where calcium ions are stored for the initiation of excitation contraction coupling. In smooth muscles and cardiac muscles, calcium comes from the extracellular space which triggers the excitation contraction coupling.