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
Hormones that the posterior pituitary secretes are synthesized in the hypothalamus.
They are made by neurons in the hypothalamus and stored and released by the posterior lobe of the pituitary gland, a small organ at the base of the brain.
They regulate water balance, blood pressure, and uterine contraction in the body.
Choice A is wrong because the anterior pituitary synthesizes its own hormones, such as growth hormone, thyroid-stimulating hormone, and prolactin.
Choice C is wrong because the thalamus is not involved in hormone synthesis or secretion. It is a part of the brain that relays sensory and motor signals to the cerebral cortex.
Choice D is wrong because the posterior pituitary does not synthesize hormones. It only stores and releases hormones made by the hypothalamus.
Correct Answer is A
Explanation
Red blood cells do not contain a large nucleus; in fact, they do not contain a nucleus at all when they are mature.
This is an adaptation that allows them to carry more hemoglobin, the protein that binds oxygen, and to squeeze through narrow capillaries.
Choice B is wrong because it contradicts the fact that red blood cells are enucleated (lacking a nucleus) in humans and most mammals.
Some vertebrates, such as birds and fish, have nucleated red blood cells, but they are not thick near the center and thin around the rim of the cell.
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