Cardiac Syncytium and Arrhythmias Quiz
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Questions and Answers

What is the primary function of gap junctions in the cardiac syncytium?

  • To enable synchronized contraction of cardiac cells (correct)
  • To increase the strength of contraction
  • To promote vascular smooth muscle contraction
  • To prevent electrical signals from passing between cells
  • Which ion is primarily responsible for the rapid depolarization in phase 0 of the cardiac myocyte action potential?

  • Chloride (Cl)
  • Calcium (Ca)
  • Potassium (K)
  • Sodium (Na) (correct)
  • What occurs during phase 2 (plateau) of the cardiac myocyte action potential?

  • Rapid depolarization
  • Influx of sodium ions
  • Repolarization via potassium channels
  • Simultaneous entry of calcium and efflux of potassium (correct)
  • Which channels are responsible for pacemaker depolarization in the cardiac nodal action potential?

    <p>Leak currents of sodium and potassium</p> Signup and view all the answers

    What characterizes an ectopic beat?

    <p>It is initiated by myocytes outside the normal conduction pathway</p> Signup and view all the answers

    What describes a common cause of tachycardia associated with after-polarization?

    <p>High [Ca]i triggers trains of action potentials</p> Signup and view all the answers

    What is the mechanism of re-entry in arrhythmias?

    <p>A circulating impulse re-excites previously active tissue</p> Signup and view all the answers

    Which feature is characteristic of Wolfe-Parkinson-White (WPW) syndrome?

    <p>Shortened PR interval due to retrograde conduction</p> Signup and view all the answers

    Study Notes

    Cardiac Syncytium and Action Potential

    • Gap junctions in cardiac syncytium increase the strength of contraction and enable synchronized contraction of cardiac cells
    • The rapid depolarization in the cardiac myocyte action potential phase 0 is primarily due to sodium (Na+) ions
    • Phase 2 (plateau) of the cardiac myocyte action potential involves simultaneous entry of calcium (Ca2+) and efflux of potassium (K+)
    • Pacemaker depolarization in cardiac nodal action potentials is caused by leak currents of sodium and potassium.

    Ectopic Beats and Arrhythmias

    • Ectopic beats originate outside the normal conduction pathway
    • Early afterdepolarization (EAD) can lead to prolonged depolarisation and ventricular arrhythmias like Torsades de Pointes
    • EAD is often linked to high intracellular calcium levels
    • Re-entry in arrhythmias occurs when a circulating impulse re-excites previously active tissue
    • Wolff-Parkinson-White (WPW) syndrome is characterized by a shortened PR interval.

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    Description

    Test your knowledge on cardiac syncytium and action potential, examining how synchronized contractions occur in heart cells. Additionally, explore ectopic beats and arrhythmias, understanding their origins and implications in cardiac health. This quiz covers important concepts related to cardiac physiology and pathophysiology.

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