Muscle Contraction Mechanism
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Questions and Answers

What happens to the troponin molecule when calcium ions bind to it?

  • It releases the myosin head from the actin filament
  • It pulls the tropomyosin molecule away from the F actin (correct)
  • It moves towards the F actin
  • It breaks the actomyosin complex

    • What is the name of the theory that explains how actin filaments slide over myosin filaments during muscular contraction?

  • Sliding Theory
  • Walking Theory
  • Ratchet Theory
  • All of the above (correct)

    • What is the result of the tilting movement of the myosin head during muscle contraction?

  • The actin filament is dragged along with the myosin head (correct)
  • The actin filament is pushed away from the sarcomere
  • The tropomyosin molecule moves towards the F actin
  • The myosin head breaks away from the actin filament

    • What is the name of the complex formed during muscle contraction when actin filaments slide over myosin filaments?

    <p>Actomyosin complex</p> Signup and view all the answers

    What is the role of calcium ions in the muscle contraction mechanism?

    <p>They bind to the troponin molecule</p> Signup and view all the answers

    What is the result of the repeated tilting movement of the myosin head during muscle contraction?

    <p>The actin filaments are pulled towards the centre of the sarcomere</p> Signup and view all the answers

    What happens when acetylcholine is released from the motor endplate?

    <p>It opens the ligand-gated sodium channels.</p> Signup and view all the answers

    What is the function of the 'T' tubules?

    <p>To rapidly spread action potential into the muscle fibre</p> Signup and view all the answers

    What is the role of calcium ions in muscle contraction?

    <p>To form the link between excitation and contraction of the muscle</p> Signup and view all the answers

    What happens to the active site of F actin in the relaxed condition?

    <p>It is covered by tropomyosin</p> Signup and view all the answers

    What is the result of the action potential reaching the cisternae of 'L' tubules?

    <p>The release of calcium ions into the sarcoplasm</p> Signup and view all the answers

    What happens when calcium ions move towards the actin filaments?

    <p>The muscle fibre contracts</p> Signup and view all the answers

    What is the result of the graded potential hyperpolarizing the membrane potential?

    <p>Increased negativity</p> Signup and view all the answers

    During muscle contraction, what happens to the actin filaments?

    <p>They glide over the myosin filaments</p> Signup and view all the answers

    What is the process that occurs between the excitation and contraction of the muscle?

    <p>Excitation contraction coupling</p> Signup and view all the answers

    What is the name of the complex formed during muscle contraction?

    <p>Actomyosin complex</p> Signup and view all the answers

    What is the zone that is broad in the relaxed state of the muscle?

    <p>H zone</p> Signup and view all the answers

    How many stages are involved in the molecular mechanism of muscular contraction?

    <p>3</p> Signup and view all the answers

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