The pacemaker of the heart is the
A. right bundle branch.
B. left bundle branch.
C. AV node.
D. SA node.
E. PM node.
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Question 2) Action potentials pass from one myocardial cell to another through areas of low electrical resistance called
A. gap junctions.
B. fibrous heart rings.
C. electromagnetic discs.
D. sarcolemma sclerotic plaques.
E. tight junctions.
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Question 3) Cardiac muscle cells
A. have smooth ER but no T tubules.
B. form the heart valves.
C. are maintained by an extensive capillary network.
D. develop a significant oxygen debt during systole.
E. do not contain actin and myosin like skeletal muscle cells.
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Question 4) Which of the following is a function of the heart skeleton?
A. Provides electrical insulation between the atria and ventricles.
B. Supplies support and reinforcement for the valves.
C. Provides a rigid site for cardiac muscle attachment.
D. All of the choices are functions of the heart skeleton.
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Question 5) Which of the following heart chambers is correctly associated with the blood vessel that enters or leaves it?
A. right atrium - pulmonary veins
B. left atrium - aorta
C. right ventricle - pulmonary trunk
D. left ventricle - superior vena cava and inferior vena cava
E. right atrium - aorta
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Question 6) An incompetent pulmonary semilunar valve could result in less blood reaching the
A. lungs.
B. heart muscle.
C. right ventricle.
D. aorta.
E. right atrium.
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Question 7) Which of the following phrases would apply to cardiac muscle cells?
A. are organized in parallel columns or bundles
B. contain actin but no myosin
C. develop a significant oxygen debt during systole
D. are multinucleated like skeletal muscle cells
E. possess special cell-to-cell contacts called intercalated discs
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Question 8) Which vessels transport blood to the right and left lungs?
A. aorta
B. right atrium
C. pulmonary trunk
D. pulmonary arteries
E. pulmonary veins
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Question 9) From the right ventricle, blood flows directly into the _____.
A. aorta
B. right atrium
C. pulmonary trunk
D. pulmonary arteries
E. pulmonary veins
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Question 10) The chordae tendineae
A. connect the atria to the ventricles.
B. are found in the interventricular septum.
C. are part of the conducting system of the heart.
D. connect the flaps of the AV valves to the papillary muscles.
E. are a part of the myocardium.
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