Cardiac Muscle and Mitral Valve Properties
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Questions and Answers

Which of the following types of muscle fibers are responsible for conducting the impulse to the heart?

  • Contractile muscle fibers
  • Nodal muscle fibers (correct)
  • Specialized conducting fibers
  • Conducting muscle fibers
  • Where are the Nodal muscle fibers located in the heart?

  • Right atrium and left ventricle
  • Left atrium and right ventricle
  • Interatrial septum and interventricular septum
  • Sinoatrial node (SAN) and Atrioventricular node (AVN) (correct)
  • What is the function of the Atrioventricular node (AVN)?

  • Conducts the impulse to the heart (correct)
  • Acts as a pacemaker of the heart
  • Connected to the Bundle of His
  • Located in the right atrium
  • What is the main function of the atrial muscles?

    <p>Act as blood reservoirs during ventricular systole</p> Signup and view all the answers

    Where do the Specialized conducting fibers connect in the heart?

    <p>Atrial and ventricular muscles sheets</p> Signup and view all the answers

    What is the region where the cardiac impulse arises known as?

    <p>Pacemaker of the heart</p> Signup and view all the answers

    How are the ventricular muscle fibers arranged?

    <p>In a spiral manner from base to apex in 3 layers</p> Signup and view all the answers

    Which valve separates the right atrium from the right ventricle?

    <p>Tricuspid valve</p> Signup and view all the answers

    Which part of the heart has Conducting muscle fibers located in it?

    <p>Atrial and ventricular wall</p> Signup and view all the answers

    What is the function of cardiac valves?

    <p>To allow passage of blood only in one direction</p> Signup and view all the answers

    Which structure is important in the regulation of arterial blood pressure?

    <p>Atrial muscles</p> Signup and view all the answers

    What is the main characteristic of atrioventricular valves?

    <p>They separate atria from ventricles</p> Signup and view all the answers

    What is the function of the mitral valve?

    <p>Prevents eversion of the AV valves into atria during systole</p> Signup and view all the answers

    Which component is responsible for the regular beating of the heart?

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

    What is the role of cordae tendinae in relation to the mitral valve?

    <p>Prevent eversion of AV valves into ventricles</p> Signup and view all the answers

    Which component of cardiac muscle converts potential energy into mechanical energy?

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

    What is the origin of heart rhythm according to the text?

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

    'Pacemaker of the heart' refers to which component mentioned in the text?

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

    What is the main cause of the diastolic depolarization during atrial diastole in the SAN action potential?

    <p>Na+ influx through funny (slow) Na+ channels</p> Signup and view all the answers

    Which ion is responsible for the upstroke phase (phase 0) of the SAN action potential?

    <p>Ca++ through L (long-lasting) Ca++ channels</p> Signup and view all the answers

    What triggers the repolarization phase (phase 3) in the SAN action potential?

    <p>K+ efflux through potassium channels</p> Signup and view all the answers

    What is the role of calcium ions in the SAN action potential?

    <p>Cause the upstroke phase via L-type calcium channels</p> Signup and view all the answers

    Which channel is responsible for the gradual rise in membrane potential during atrial diastole in the SAN action potential?

    <p>Funny (slow) Na+ channels</p> Signup and view all the answers

    What is the resting membrane potential of contractile cardiac muscle fibers?

    <p>-85 mV</p> Signup and view all the answers

    What is the main cause of the rapid depolarization in Phase 0 of the action potential of contractile cardiac muscle fibers?

    <p>Opening of fast Na+ channels leading to rapid Na+ influx</p> Signup and view all the answers

    What characterizes Phase 2 of the action potential in contractile cardiac muscle fibers?

    <p>Slow prolonged repolarization</p> Signup and view all the answers

    Which ion plays a crucial role in the slow prolonged repolarization phase (plateau) of the action potential in cardiac muscle fibers?

    <p>Ca++</p> Signup and view all the answers

    What happens during Phase 3 of the action potential in contractile cardiac muscle fibers?

    <p>Marked increase in K+ efflux causing rapid repolarization</p> Signup and view all the answers

    During which phase does the membrane potential return to its resting level in the action potential of contractile cardiac muscle fibers?

    <p>Phase 4</p> Signup and view all the answers

    What is the duration of depolarization in Phase 2 for atrial muscles compared to ventricular muscles?

    <p>0.30 seconds in atrial muscles and 0.15 seconds in ventricular muscles</p> Signup and view all the answers

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