Actin-Myosin Cross Bridge in muscle contraction

Why is troponin measured in blood tests after a suspected heart attack?

• Troponin is produced in excess during muscle activity

• Troponin fragments are released into the blood when cardiac muscle is damaged

• Troponin levels indicate calcium availability in the muscles

• Troponin prevents blood clotting after heart damage

What is the role of calcium in the cross bridge cycle?

• It causes myosin to fall off actin

• It allows myosin to bind to actin

• It allows ADP to bind to myosin

• It recocks the myosin head

What occurs during the power stroke phase of the cross bridge cycle?

• ADP is ejected as myosin moves actin

• Calcium binds to troponin

• ATP binds to myosin

• The myosin head is recocked for the next cycle

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What causes myosin to detach from actin in the cross bridge cycle?

• The presence of calcium

• The power stroke

• The binding of ATP to myosin

• The hydrolysis of ATP to ADP

What causes rigor mortis to occur after death?

• Excess calcium binding to troponin

• Lack of ATP to detach myosin from actin

• Overproduction of ADP in muscle tissue

• The breakdown of actin filaments