Muscle Physiology Quiz: Excitation-Contraction Coupling
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Questions and Answers

What is the primary function of the DHP receptor in muscle contraction?

  • Binding of ATP to the myosin head
  • Binding of ACh to the motor end plate
  • Initiation of muscle action potential
  • Regulation of Ca2+ release from the sarcoplasmic reticulum (correct)
  • What is the purpose of the tropomyosin and troponin complex in muscle contraction?

  • To regulate the binding of actin and myosin (correct)
  • To generate the power stroke
  • To release Ca2+ from the sarcoplasmic reticulum
  • To transmit the muscle action potential
  • What is the source of immediate energy for muscle contractions?

  • ATP stored in the muscle fiber (correct)
  • Breakdown of muscle proteins
  • Anaerobic glycolysis
  • Aerobic cellular respiration
  • What is the effect of Ca2+ binding to troponin?

    <p>Enhanced actin-myosin binding</p> Signup and view all the answers

    What is the role of the T-tubule in muscle contraction?

    <p>Transmission of the muscle action potential</p> Signup and view all the answers

    What is the net effect of the muscle contraction process?

    <p>Actin filament moves towards the M line</p> Signup and view all the answers

    What is the angle of the crossbridge relative to the filaments when 2 ATP binds to its binding site on the myosin?

    <p>45°</p> Signup and view all the answers

    What is the main mechanism of muscle contraction according to the sliding filament theory?

    <p>Thin actin filaments sliding past thick myosin filaments</p> Signup and view all the answers

    What happens to the ATP after the ATPase activity of myosin?

    <p>It is converted into ADP and Pi</p> Signup and view all the answers

    What is the role of tropomyosin in the relaxed state of muscle?

    <p>It blocks the binding sites on actin, preventing myosin binding</p> Signup and view all the answers

    What is the energy source for muscle contraction?

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

    What initiates the power stroke in muscle contraction?

    <p>The release of Pi from the myosin head</p> Signup and view all the answers

    What is the result of the movement of actin filaments in relation to myosin filaments during muscle contraction?

    <p>The sarcomere shortens</p> Signup and view all the answers

    What is the state of the myosin head at the end of the power stroke?

    <p>Tightly bound to the actin molecule</p> Signup and view all the answers

    What is the purpose of the myosin head rotating on its hinge during the power stroke?

    <p>To push the actin filament past it</p> Signup and view all the answers

    What is the role of troponin in muscle contraction?

    <p>It binds to calcium ions and pulls tropomyosin away from actin's myosin-binding site</p> Signup and view all the answers

    What is the result of the binding of calcium ions to troponin?

    <p>Tropomyosin is pulled away from actin's myosin-binding site</p> Signup and view all the answers

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