What Is the Role of Ca²⁺ in the Control of Muscle

question 135

Multiple Choice

What is the role of Ca²⁺ in the control of muscle contraction?

• A) It causes depolarization of the T tubule system.
• B) It changes the conformation of troponin, which ultimately results in myosin-binding sites being exposed.
• C) It changes the conformation of myosin heads, causing actin and myosin filaments to slide past each other.
• D) It binds to tropomyosin and breaks actin-myosin cross-bridges.
• E) It blocks the ATP-binding site on myosin heads, enabling muscles to relax.

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