Which Statement Regarding Contraction in Skeletal and Smooth Muscle Is

question 283

Multiple Choice

Which statement regarding contraction in skeletal and smooth muscle is correct?

• A) In skeletal muscle, calcium ion mediates changes in thin filaments that lead to cross-bridge activity; in smooth muscle, calcium ion mediates changes in thick filaments that lead to cross-bridge activity.
• B) In skeletal muscle, troponin and tropomyosin are regulatory proteins; in smooth muscle, troponin is the only regulatory protein on thick filaments.
• C) In skeletal muscle, calcium ion binds to troponin; in smooth muscle, calcium ion binds to calmodulin.
• D) In skeletal muscle, calcium ion binds to calmodulin and in smooth muscle, calcium ion binds to troponin.

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