Excitation-Contraction Coupling in Muscle Contraction
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Questions and Answers

What is the role of DHP receptors in excitation-contraction coupling?

  • Open RyR Ca2+ release channels in sarcoplasmic reticulum (correct)
  • Pump Ca2+ back into the sarcoplasmic reticulum
  • Release Ca2+ from the sarcoplasmic reticulum
  • Bind to troponin for actin-myosin binding

    • What happens when a decrease in free cytosolic [Ca2+] occurs during muscle relaxation?

  • Myosin heads execute power stroke
  • Tropomyosin uncovers binding sites
  • Ca2+ unbinds from troponin (correct)
  • Actin filament slides toward the center of the sarcomere

    • During excitation-contraction coupling, what allows actin-myosin binding?

  • Binding of troponin to DHP receptors
  • Release of Ca2+ from sarcoplasmic reticulum
  • Ca2+ binding to troponin (correct)
  • Opening of L-Type Ca channels

    • Which ion enters the cell as part of the muscle action potential initiation process?

    <p>Na+</p> Signup and view all the answers

    In excitation-contraction coupling, what combines with troponin to initiate muscle contraction?

    <p>Calcium ions</p> Signup and view all the answers

    What phase of EC coupling involves the initiation of muscle action potentials?

    <p>Excitation phase</p> Signup and view all the answers

    What is the role of tropomyosin during muscle contraction?

    <p>Shifting to expose the myosin-binding site on actin</p> Signup and view all the answers

    How does ATP contribute to muscle contraction?

    <p>Decreases the binding affinity between actin and myosin</p> Signup and view all the answers

    What initiates the power stroke in muscle contraction?

    <p>Myosin binding to actin</p> Signup and view all the answers

    Which molecule is responsible for pulling tropomyosin away from actin's binding site?

    <p>Troponin-Ca2+ complex</p> Signup and view all the answers

    What is the significance of calcium ions in muscle contraction?

    <p>Inducing the power stroke</p> Signup and view all the answers

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