The correct sequence of parts that carry cardiac impulses is:
AV node, SA node, Purkinje fibers, AV bundle.
SA node, Purkinje fibers, AV node, AV bundle.
SA node, AV node, AV bundle, Purkinje fibers.
AV node, AV bundle, Purkinje fibers, SA node.
The Correct Answer is C
This sequence ensures that the atria contract before the ventricles and that the ventricles contract from the bottom up.
Choice A is wrong because it reverses the order of the SA node and the AV node. The SA node is the pacemaker of the heart and initiates the cardiac impulses.
Choice B is wrong because it places the Purkinje fibers before the AV node.
The Purkinje fibers are the last part of the conduction system and stimulate the ventricular muscle fibers.
Choice D is wrong because it reverses the order of the entire sequence.
The AV node is not the pacemaker of the heart and does not initiate cardiac impulses.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
This is because fibrinogen is a soluble protein in the blood plasma that is converted to insoluble fibrin strands by the enzyme thrombin during blood clotting. Fibrin forms a mesh-like network that traps platelets and other blood cells to form a clot.
Choice A is wrong because thrombin is not converted to prothrombin, but rather prothrombin is converted to thrombin by another enzyme called prothrombinase.
Choice C is wrong because vitamin K is not converted to prothrombin, but rather vitamin K is required for the synthesis of prothrombin and other clotting factors in the liver.
Choice D is wrong because fibrin is not converted to fibrinogen, but rather fibrinogen is converted to fibrin as explained above.
Normal ranges of fibrinogen in the blood are 200 to 400 mg/dL.
Normal ranges of prothrombin time (a measure of how long it takes blood to clot) are 11 to
13.5 seconds.
Correct Answer is A
Explanation
This is the correct sequence of parts through which blood moves from the vena cava to the lungs.
Choice B is wrong because it reverses the order of the right atrium and right ventricle. Blood flows from the right atrium to the right ventricle, not the other way around.
Choice C is wrong because it switches the positions of the tricuspid valve and the pulmonary valve.
Blood flows from the right atrium through the tricuspid valve to the right ventricle, and then through the pulmonary valve to the pulmonary artery.
Choice D is wrong because it also switches the positions of the tricuspid valve and the pulmonary valve, and reverses the order of the right atrium and right ventricle.
Blood flows from the right atrium through the tricuspid valve to the right ventricle, and then through the pulmonary valve to the pulmonary artery.
The normal range of blood pressure in the vena cava is about 0 to 5 mmHg, while in the pulmonary artery, it is about 15 to 25 mmHg.
The normal range of oxygen saturation in the vena cava is about 60% to 80%, while in the pulmonary vein, it is about 95% to 100%.
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