Cardiac Muscle Refractory Period Quiz
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Questions and Answers

During which phase of the cardiac action potential does the absolute refractory period mainly occur?

  • Phase 1
  • Phase 2
  • Phase 3
  • Phase 0 (correct)
  • What is the significance of the long refractory period of cardiomyocytes in relation to muscle contraction?

  • Enhances the ability to generate multiple action potentials
  • Facilitates sustained tetanic contractions
  • Allows rapid refilling of ventricles during systole
  • Prevents the heart from being tetanized (correct)
  • Which type of channels are primarily responsible for the rapid depolarization in Phase 0 of the cardiac action potential?

  • Fast Na+ channels (correct)
  • L-type Ca2+ channels
  • Cl- channels
  • K+ channels
  • What characterizes the relative refractory period in cardiomyocytes?

    <p>Requires a stronger stimulus to elicit a response</p> Signup and view all the answers

    Why can't the heart be tetanized unlike skeletal muscle?

    <p>Presence of gap junctions between cardiac myocytes</p> Signup and view all the answers

    How does the long refractory period of cardiomyocytes contribute to the pumping function of the heart?

    <p>Limits sustained muscle contractions</p> Signup and view all the answers

    During which phase of the action potential do Na+ channels recover and become capable of reopening?

    <p>Phase 1</p> Signup and view all the answers

    Why do cardiomyocytes have a longer refractory period compared to skeletal muscle cells?

    <p>Due to the presence of slow Ca2+ channels in cardiomyocytes</p> Signup and view all the answers

    What defines the Absolute Refractory Period in the cardiac muscle?

    <p>The period when Na+ channels are closed</p> Signup and view all the answers

    What is the mechanical response during the Absolute Refractory Period?

    <p>Systole and early diastole</p> Signup and view all the answers

    What characterizes the Relative Refractory Period in cardiac muscle?

    <p>Reduced sensitivity to additional stimulation</p> Signup and view all the answers

    What is the key difference between Absolute and Relative Refractory Periods?

    <p>Sensitivity to stimulation</p> Signup and view all the answers

    What is the interval of time during which a normal cardiac impulse cannot re-excite an already excited area of cardiac muscle known as?

    <p>Absolute refractory period</p> Signup and view all the answers

    Which property describes the ability of the cardiac muscle to generate an action potential followed by contraction?

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

    What is the term for the feature of the cardiac muscle that makes it capable of responding to an adequate stimulus?

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

    Which of the following principles states that once a threshold stimulus is reached, the cardiomyocyte responds with a complete contraction?

    <p>All-or-None principle</p> Signup and view all the answers

    During which period does the cardiac muscle have reduced excitability but could respond to a very strong stimulus?

    <p>Relative refractory period</p> Signup and view all the answers

    Which term describes the ability of the heart muscle to transmit electrical impulses efficiently?

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

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