What class of antiarrhythmic drugs blocks potassium channels prolonging phase 3 of the action potential and slowing the rate and conduction of the heart?
I.
IV.
III.
II.
The Correct Answer is C
Choice A rationale
Class I antiarrhythmic drugs block sodium channels, affecting phase 0 of the action potential, not phase 3.
Choice B rationale
Class IV antiarrhythmic drugs block calcium channels, which affects phase 2 of the action potential and slows heart rate and conduction.
Choice C rationale
Class III antiarrhythmic drugs block potassium channels, prolonging phase 3 of the action potential. This results in a prolonged repolarization period, reducing the risk of arrhythmia.
Choice D rationale
Class II antiarrhythmic drugs are beta-blockers that primarily affect phase 4 of the action potential, reducing heart rate and conduction, but they do not block potassium channels.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Choice A rationale
Aleve (naproxen) is not recommended for children under 12 years old due to the risk of side effects such as gastrointestinal bleeding and kidney issues.
Choice B rationale
Motrin (ibuprofen) is commonly used for pain and inflammation in children but is not the best option for mild pain like that caused by an elbow injury.
Choice C rationale
Acetaminophen (Tylenol) is recommended for children experiencing mild to moderate pain, such as elbow pain, due to its safety profile and effectiveness.
Choice D rationale
Aspirin is not recommended for children due to the risk of Reye's syndrome, a rare but serious condition that can cause swelling in the liver and brain.
Correct Answer is D
Explanation
Choice A rationale
The auricle is an ear-shaped appendage on the surface of the atrium and does not separate the right and left halves of the heart. Its function is to increase the capacity of the atrium, allowing for more blood to be collected and passed to the ventricles.
Choice B rationale
Syncytia refer to a multinucleated cell that can result from the fusion of multiple cells, which is not a structure that separates the right and left sides of the heart. They are typically related to muscle tissue and coordinated contractions.
Choice C rationale
The Bundle of His is a collection of heart muscle cells specialized for electrical conduction that transmits the electrical impulses from the AV node to the point of the apex of the fascicular branches. It does not act as a separator between the right and left halves of the heart.
Choice D rationale
The septum is the structure that separates the right and left halves of the heart. It is a robust wall that divides the atria (interatrial septum) and the ventricles (interventricular septum), ensuring the segregation of oxygenated and deoxygenated blood.
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