Physiology True regarding excitation contraction coupling in smooth muscle is A Presence of troponin is essential B Sustained contraction occurs with high calcium concentration C Phosphorylation of actin is required for contraction D Presence of cellular calcium is essential to cause muscle contraction 💡 Explanation True regarding excitation contraction coupling in smooth muscle is ✓ Correct Answer: D. Presence of cellular calcium is essential to cause muscle contraction