The nurse administers a drug that stimulate the parasympathetic nervous system. What physiologic response would indicate that the drug is working?
Pupil dilation
Increased gastrointestinal motility
Vasoconstriction
Increased heart rate
The Correct Answer is B
A) Pupil dilation:
Pupil dilation is typically a response from stimulation of the sympathetic nervous system, not the parasympathetic system. The parasympathetic system tends to cause pupil constriction, so pupil dilation would not be an expected response to a parasympathetic agonist.
B) Increased gastrointestinal motility:
Stimulation of the parasympathetic nervous system, which is responsible for the "rest and digest" response, promotes the movement of food through the digestive tract, increasing gastrointestinal motility. This response is a classic sign that the parasympathetic system is being activated. Drugs that stimulate the parasympathetic nervous system often aim to enhance digestive functions.
C) Vasoconstriction:
Vasoconstriction is typically mediated by the sympathetic nervous system, not the parasympathetic system. The sympathetic nervous system activates alpha-adrenergic receptors that cause blood vessels to constrict, raising blood pressure. The parasympathetic system, on the other hand, typically promotes vasodilation, lowering blood pressure.
D) Increased heart rate:
Increased heart rate is generally associated with the sympathetic nervous system, which prepares the body for "fight or flight." The parasympathetic nervous system, in contrast, slows down the heart rate through vagal stimulation, so an increase in heart rate would not be the expected response to parasympathetic stimulation.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
A) Acts directly on alpha-adrenergic receptor sites: Ephedrine does not act exclusively or directly on alpha-adrenergic receptors. While it can have some alpha-adrenergic effects, its primary mechanism is through the release of norepinephrine, which then activates both alpha and beta receptors. Therefore, this option is not entirely accurate for describing ephedrine's mode of action.
B) Stimulates the release of norepinephrine: Ephedrine primarily works by stimulating the release of norepinephrine from nerve terminals. The released norepinephrine then acts on both alpha and beta adrenergic receptors, leading to vasoconstriction (via alpha receptors) and increased heart rate and force of contraction (via beta receptors). This dual action helps raise blood pressure and improve cardiac output, making this the most accurate description of ephedrine's mechanism of action.
C) Acts directly on beta-adrenergic receptor sites: Although ephedrine does have beta-adrenergic effects (increasing heart rate and contractility), its primary mechanism is the indirect release of norepinephrine. It does not act directly on beta-receptors to the same extent as medications like isoproterenol. Therefore, while it does have beta-receptor activity, the main action is through norepinephrine release.
D) Stimulates the release of dopamine: Ephedrine does not primarily stimulate dopamine release. Dopamine release is more associated with drugs like levodopa or certain dopaminergic agents used in conditions like Parkinson’s disease. Ephedrine primarily affects norepinephrine and, to a lesser extent, acts on dopamine receptors, but it is not primarily a dopamine-releasing agent.
Correct Answer is C
Explanation
A) Tacrine (Cognex): Tacrine is an acetylcholinesterase inhibitor used in the treatment of Alzheimer's disease to improve cognitive function. It is not typically used for Parkinson's disease, which is characterized by motor symptoms such as tremors, shuffling gait, and rigidity.
B) Rivastigmine (Exelon): Rivastigmine is another acetylcholinesterase inhibitor, similar to Tacrine, primarily used to treat Alzheimer's disease or dementia-related symptoms. While it helps with cognitive symptoms, it is not effective in treating the motor symptoms of Parkinson's disease.
C) Carbidopa-levodopa (Sinemet): This is the correct answer. Carbidopa-levodopa (Sinemet) is the gold standard treatment for Parkinson's disease. Levodopa is a precursor to dopamine, which helps address the dopamine deficiency in the brain that causes symptoms like tremors, shuffling gait, and lack of facial expression (masked facies). Carbidopa is added to prevent levodopa from being broken down before it reaches the brain, enhancing its effectiveness.
D) Donepezil (Aricept): Donepezil is also an acetylcholinesterase inhibitor used primarily in Alzheimer's disease. Like Tacrine and Rivastigmine, it works to improve cognitive function but does not treat the motor symptoms seen in Parkinson's disease. It would not be appropriate for managing the patient's Parkinsonian symptoms.
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