Muscle Physiology: Skeletal Muscle Structure
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Questions and Answers

What is the name of the plasma membrane of a muscle cell?

  • Sarcolemma (correct)
  • Sarcoplasmic reticulum
  • Myofibril
  • Transverse tubule

    • Which element of a muscle cell contains the contractile components?

  • Transverse tubules
  • Myofibrils (correct)
  • Sarcolemma
  • Sarcoplasmic reticulum

    • What is the name of the dark region in the center of the A band of a sarcomere?

  • I band
  • M line
  • Z line
  • H zone (correct)

    • Which structure anchors the thin filaments at the borders of a sarcomere?

    <p>Z lines</p> Signup and view all the answers

    What provides the attachment between actin (thin) and myosin (thick) filaments in a muscle cell?

    <p>Cross bridges</p> Signup and view all the answers

    Which protein uncovers binding sites on actin subunits when bound to calcium?

    <p>Troponin</p> Signup and view all the answers

    What is the role of titin in muscle contraction?

    <p>Anchors the thick filaments in the proper position</p> Signup and view all the answers

    What occurs during the power stroke in the cross bridge cycle?

    <p>The myosin head pivots toward the middle of the sarcomere and pulls the attached actin filament</p> Signup and view all the answers

    What is the role of excitation-contraction coupling in muscle contraction?

    <p>Linking the action potential to contraction</p> Signup and view all the answers

    What is the main function of tropomyosin in muscle contraction?

    <p>Uncovers binding sites on actin subunits</p> Signup and view all the answers

    What is the name of the smooth endoplasmic reticulum surrounding the myofibrils in a muscle cell?

    <p>Sarcoplasmic reticulum</p> Signup and view all the answers

    What is the main function of the Z lines in a sarcomere?

    <p>Anchoring of the thin filaments</p> Signup and view all the answers

    Which region of the sarcomere appears dark and contains the thick filaments?

    <p>A band</p> Signup and view all the answers

    What is the role of titin in muscle cells?

    <p>Stabilizes the position of myosin filaments within the sarcomere</p> Signup and view all the answers

    What provides the attachment between actin (thin) and myosin (thick) filaments in a muscle cell?

    <p>Cross bridges</p> Signup and view all the answers

    What occurs during the power stroke in the cross bridge cycle?

    <p>Release of ADP and inorganic phosphate from myosin</p> Signup and view all the answers

    What is the role of the myosin molecule in muscle contraction?

    <p>To hydrolyze ATP and detach from actin</p> Signup and view all the answers

    Which sequence of events accurately describes the cross bridge cycle in muscle contraction?

    <p>Binding of myosin to actin, release of ADP and Pi, attachment of myosin to ATP, hydrolysis of ATP, detachment of myosin from actin</p> Signup and view all the answers

    What is the function of the regulatory protein tropomyosin in muscle contraction?

    <p>To extend over and cover binding sites on actin subunits</p> Signup and view all the answers

    What is the primary role of troponin in muscle contraction?

    <p>To release calcium and uncover binding sites on actin</p> Signup and view all the answers

    What is the function of the elastic protein titin in muscle contraction?

    <p>To provide elasticity and anchor the thick filaments in position</p> Signup and view all the answers

    During which phase of the cross bridge cycle does the myosin head detach from actin?

    <p>Unbinding of myosin and actin</p> Signup and view all the answers

    What occurs when troponin binds to calcium during muscle contraction?

    <p>Tropomyosin uncovers binding sites on actin</p> Signup and view all the answers

    What is the significance of the sliding-filament model in explaining muscle contraction?

    <p>It describes the sliding of thick and thin filaments over one another during muscle contraction</p> Signup and view all the answers

    What is involved in excitation-contraction coupling in muscle cells?

    <p>The sequence of events linking the action potential generated in a muscle cell to contraction</p> Signup and view all the answers

    What is the primary function of neuromuscular junction in muscle contraction?

    <p>To link the action potential generated in a muscle cell by the motor neuron to contraction</p> Signup and view all the answers

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