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 erythroblastosis fetalis, also known as hemolytic disease of the newborn, is caused by Rh incompatibility between the mother and the fetus.
Rh incompatibility occurs when a Rh-negative mother is impregnated by a Rh-positive father, resulting in a Rh-positive fetus.
The mother’s immune system can detect the Rh factor on the fetus’s red blood cells as foreign and produce antibodies against them.
These antibodies can cross the placenta and destroy the fetus’s red blood cells, causing anemia, jaundice, edema, and other complications.
Choice A is wrong because a second Rh-negative fetus developing in an Rh-negative woman will not cause erythroblastosis fetalis.
The mother and the fetus have the same Rh factor, so there is no immune reaction.
Choice C is wrong because a first Rh-positive fetus developing in an Rh-negative woman will not cause erythroblastosis fetalis.
The mother’s immune system will not produce antibodies against the Rh factor until after the first exposure to it, which usually happens during delivery.
Therefore, the first pregnancy is usually unaffected.
Choice D is wrong because a first Rh-negative fetus developing in an Rh-negative woman will not cause erythroblastosis fetalis.
The mother and the fetus have the same Rh factor, so there is no immune reaction.
The normal range of red blood cell count for newborns is 4.1 to 6.1 million cells per microliter of blood.
The normal range of bilirubin level for newborns is 0.3 to 1.9 milligrams per deciliter of blood.
Correct Answer is A
Explanation
The right atrium receives blood directly from the superior vena cava, inferior vena cava, and coronary sinus.
The superior vena cava and inferior vena cava bring deoxygenated blood from the upper and lower body, respectively.
The coronary sinus brings blood from the heart muscle.
Choice B is wrong because it excludes the coronary sinus, which also empties into the right atrium.
Choice C is wrong because it includes the pulmonary veins, which carry oxygenated blood from the lungs to the left atrium, not the right atrium.
Choice D is wrong because it only includes the pulmonary veins, which are not connected to the right atrium at all.
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