Class IV antidysrhythmics or calcium channel blockers have what action on the cardiovascular system?
Increase blood vessel spasm.
Decrease flow of calcium ions thus decreasing heart rate and contractions.
Decrease refractory period.
Increase heart rate.
The Correct Answer is B
Class IV antidysrhythmics or calcium channel blockers decrease the flow of calcium ions into cardiac and vascular smooth muscle cells, thus decreasing heart rate and contractions. By reducing the calcium influx, they also decrease the slope of phase 0 and 4 and prolong phase 2 of the cardiac action potential. This results in vasodilation, reduced myocardial oxygen demand, and decreased conduction through the AV node.
Choice A is wrong because calcium channel blockers do not increase blood vessel spasm, but rather cause vasodilation.
Choice C is wrong because calcium channel blockers do not decrease refractory period, but rather prolong it by extending phase 2 of the cardiac action potential.
Choice D is wrong because calcium channel blockers do not increase heart rate, but rather decrease it by slowing down the pacemaker activity and AV nodal conduction.
Normal ranges for heart rate are 60 to 100 beats per minute, and for blood pressure are 120/80 mmHg or lower.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Phenazopyridine hydrochloride (Pyridium) is a urinary tract analgesic that can relieve the pain, burning, and discomfort caused by infection or irritation of the urinary tract.However, it can also cause some side effects, one of which is changing the color of bodily secretions to reddish orange. This is due to the excretion of the drug in the urine, saliva, sweat, and tears.The color change is harmless and usually disappears when the drug is stopped.
Choice A is wrong because phenazopyridine does not change bodily secretions to alkaline.In fact, it may interfere with the urine test that measures acidity (pH) and glucose.
Choice B is wrong because phenazopyridine does not change bodily secretions to pinkish.However, some other drugs, such as rifampin and doxorubicin, may cause urine to turn red or pink.
Choice D is wrong because phenazopyridine does not change bodily secretions to black.However, some other drugs, such as metronidazole and nitrofurantoin, may cause urine to turn brown or dark yellow.
Some other common side effects of phenazopyridine include headache, dizziness, indigestion, and stomach pain.Some serious side effects include skin itching, interference with the oxygen-carrying capacity of red blood cells, hemolytic anemia, and renal and hepatic toxicity.
These problems are more common in people who have existing kidney problems or take more than recommended.If you experience any of these symptoms, stop taking phenazopyridine hydrochloride and talk to a healthcare provider right away.
Correct Answer is B
Explanation
Nitroglycerin transdermal patches are used to prevent episodes of angina (chest pain) in people who have coronary artery disease (narrowing of the blood vessels that supply blood to the heart).Nitroglycerin is a vasodilator that works by relaxing the blood vessels so that the heart does not need to work as hard and therefore does not need as much oxygen.However, if nitroglycerin is used continuously, the body may develop tolerance to its effects, meaning that it will not work as well to prevent angina attacks.Therefore, it is important to remove the patch at bedtime and apply a new one in the morning, leaving a 10-12 hour nitrate-free interval.This way, the body can restore its sensitivity to nitroglycerin and avoid angina episodes during the day.
Choice A is wrong because allergic response is not a common reason to remove the patch at night.Although some people may experience skin irritation or rash from the patch, this is usually mild and does not require discontinuation of the medication.If the skin reaction is severe or bothersome, the patch can be applied to a different area of the skin or switched to another form of nitroglycerin.
Choice C is wrong because overdose is unlikely to occur from using the patch as prescribed.Nitroglycerin patches come in doses ranging from 0.1 milligrams per hour to 0.8 mg/hr, and should be placed on clean, dry, and hairless skin for 12-14 hours and removed for 10-12 hours.If a patch loosens or falls off, it should be replaced with a fresh one.Overdose symptoms may include severe headache, dizziness, blurred vision, nausea, vomiting, sweating, chest pain, fast or irregular heartbeat, difficulty breathing, fainting, or seizures.If these occur, the patch should be removed immediately and medical attention should be sought.
Choice D is wrong because management of BPH (benign prostatic hyperplasia) is not related to nitroglycerin use.
BPH is a condition
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