Block 3 Cardiophysiology Part 1

25 Questions | Total Attempts: 1675

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Block 3 Cardiophysiology Part 1

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Questions and Answers
  • 1. 
    Which of the following normally has the most prominent prepotential?
    • A. 

      Sinoatrial node

    • B. 

      Atrial muscle cells

    • C. 

      Bundle of His

    • D. 

      Purkinje fibers

    • E. 

      Ventricular muscle cells

  • 2. 
    Currents caused by opening of which of the following channels contribute to the repolarization phase of the action potential of ventricular muscle fibers?
    • A. 

      Na+ channels

    • B. 

      Cl- channels

    • C. 

      Ca2+ channels

    • D. 

      K+ channels

    • E. 

      HCO3- channels

  • 3. 
    In the sinoatrial (SA) node, phase 4 depolarization (pacemaker potential) is attributable to
    • A. 

      An increase in K+ conductance

    • B. 

      An increase in Na+ conductance

    • C. 

      A decrease in C1- conductance

    • D. 

      A decrease in Ca2+ conductance

    • E. 

      Simultaneous increases in K+ and C1- conductances

  • 4. 
    During which phase of the ventricular action potential is the membrane potential closest to the K+ equilibrium potential?
    • A. 

      Phase 0

    • B. 

      Phase 1

    • C. 

      Phase 2

    • D. 

      Phase 3

    • E. 

      Phase 4

  • 5. 
    During which phase of the ventricular action potential is the conductance to Ca2+ highest?
    • A. 

      Phase 0

    • B. 

      Phase 1

    • C. 

      Phase 2

    • D. 

      Phase 3

    • E. 

      Phase 4

  • 6. 
    Which phase of the ventricular action potential coincides with diastole?
    • A. 

      Phase 0

    • B. 

      Phase 1

    • C. 

      Phase 2

    • D. 

      Phase 3

    • E. 

      Phase 4

  • 7. 
    During which phase of the cardiac cycle does the mitral valve open?
    • A. 

      Atrial systole

    • B. 

      Isovolumetric ventricular contraction

    • C. 

      Rapid ventricular ejection

    • D. 

      Reduced ventricular ejection

    • E. 

      Isovolumetric ventricular relaxation

  • 8. 
    The ventricles are completely depolarized during which isoelectric portion of the electrocardiogram (ECG)?
    • A. 

      PR interval

    • B. 

      QRS complex

    • C. 

      QT interval

    • D. 

      ST segment

    • E. 

      T wave

  • 9. 
    Cardiac output of the right side of the heart is what percentage of the cardiac output of the left side of the heart?
    • A. 

      25%

    • B. 

      50%

    • C. 

      75%

    • D. 

      100%

    • E. 

      125%

  • 10. 
    If the ejection fraction increases, there will be a decrease in
    • A. 

      Cardiac output

    • B. 

      End-diastolic volume

    • C. 

      End-systolic volume

    • D. 

      Heart rate

    • E. 

      Pulse pressure

  • 11. 
    A ventricle has a volume of 100ml and an ejection fraction of 75%:   If the heart rate is 70 beats/min, then cardiac output of this ventricle is closest to  
    • A. 

      3.45 L/min

    • B. 

      4.55 L/min

    • C. 

      5.25 L/min

    • D. 

      8.00 L/min

    • E. 

      9.85 L/min

  • 12. 
    The second heart sound is caused by
    • A. 

      Closure of the aortic and pulmonary valves

    • B. 

      Vibrations in the ventricular wall during systole

    • C. 

      Ventricular filling

    • D. 

      Closure of the mitral and tricuspid valves

    • E. 

      Retrograde flow in the vena cava

  • 13. 
    The fourth heart sound is caused by
    • A. 

      Closure of the aortic and pulmonary valves

    • B. 

      Vibrations in the ventricular wall during systole

    • C. 

      Ventricular filling

    • D. 

      Closure of the mitral and tricuspid valves

    • E. 

      Retrograde flow in the vena cava

  • 14. 
    Inspiration "splits" the second heart sound because
    • A. 

      The aortic valve closes before the pulmonic valve

    • B. 

      The pulmonic valve closes before the aortic valve

    • C. 

      The mitral valve closes before the tricuspid valve

    • D. 

      The tricuspid valve closes before the mitral valve

    • E. 

      Filling of the ventricles has fast and slow components

  • 15. 
    During exercise, a man consumes 1.8 L of oxygen per minute. His arterial O2 content is 190 ml/L, and the O2 content of his mixed venous blood is 134 ml/L. His cardiac output is approximately
    • A. 

      3.2 L/min

    • B. 

      16 L/min

    • C. 

      32 L/min

    • D. 

      54 L/min

    • E. 

      160 ml/min

  • 16. 
    The work performed by the left ventricle is substantially greater than that performed by the right ventricle, because in the left ventricle
    • A. 

      The contraction is slower

    • B. 

      The wall is thicker

    • C. 

      The stroke volume is greater

    • D. 

      The preload is greater

    • E. 

      The afterload is greater

  • 17. 
    When a person moves from a supine position to a standing position, which of the following compensatory changes occurs?
    • A. 

      Decreased heart rate

    • B. 

      Increased contractility

    • C. 

      Decreased total peripheral resistance (TPR)

    • D. 

      Decreased cardiac output

    • E. 

      Increased PR intervals

  • 18. 
    During exercise, total peripheral resistance (TPR) decreases because of the effect of
    • A. 

      The sympathetic nervous system on splanchnic arterioles

    • B. 

      The parasympathetic nervous system on skeletal muscle arterioles

    • C. 

      Local metabolites on skeletal muscle arterioles

    • D. 

      Local metabolites on cerebral arterioles

    • E. 

      Histamine on skeletal muscle arterioles

  • 19. 
    The greatest pressure decrease in the circulation occurs across the arterioles because
    • A. 

      They have the greatest surface area

    • B. 

      They have the greatest cross-sectional area

    • C. 

      The velocity of blood flow through them is the highest

    • D. 

      The velocity of blood flow through them is the lowest

    • E. 

      They have the greatest resistance

  • 20. 
    Pulse pressure is
    • A. 

      The highest pressure measured in the arteries

    • B. 

      The lowest pressure measured in the arteries

    • C. 

      Measured only during diastole

    • D. 

      Determined by stroke volume

    • E. 

      Decreased when the capacitance of the arteries decreases

  • 21. 
    • A. 

      Aorta

    • B. 

      Central vein

    • C. 

      Pulmonary artery

    • D. 

      Right atrium

    • E. 

      Renal artery

  • 22. 
    During which phase of the cardiac cycle is ventricular volume lowest?
    • A. 

      Atrial systole

    • B. 

      Isovolumetric ventricular contraction

    • C. 

      Rapid ventricular ejection

    • D. 

      Reduced ventricular ejection

    • E. 

      Isovolumetric ventricular relaxation

  • 23. 
    The physiologic function of the relatively slow conduction through the atrioventricular node is to allow sufficient time for
    • A. 

      Runoff of blood from the aorta to the arteries

    • B. 

      Venous return to the atria

    • C. 

      Filling of the ventricles

    • D. 

      Contraction of the ventricles

    • E. 

      Repolarization of the ventricles

  • 24. 
    Which of the following parameters is decreased during moderate exercise?
    • A. 

      Arteriovenous O2 difference

    • B. 

      Heart rate

    • C. 

      Cardiac output

    • D. 

      Pulse pressure

    • E. 

      Total peripheral resistance (TPR)

  • 25. 
    Starling’s law of the heart
    • A. 

      Does not operate in the failing heart

    • B. 

      Does not operate during exercise

    • C. 

      Explains the increase in heart rate produced by exercise

    • D. 

      Explains the increase in cardiac output that occurs when venous return is increased

    • E. 

      Explains the increase in cardiac output when the sympathetic nerves supplying the heart are stimulated