How does ephedrine act on the body?
Acts directly on alpha-Adrenergic receptor sites
Stimulates the release of norepinephrine
Acts directly on Beta-Adrenergic receptor sites
Stimulates the release of Dopamine
The Correct Answer is B
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.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A) Increased intraocular pressure: Sympathomimetic drugs stimulate the sympathetic nervous system and promote "fight or flight" responses, often resulting in vasoconstriction and other effects. Some sympathomimetics, especially those that affect alpha-adrenergic receptors, can lead to increased intraocular pressure, which is a concern in conditions like glaucoma.
B) Decreased blood pressure: Sympathomimetic drugs generally increase blood pressure by stimulating alpha and beta receptors that cause vasoconstriction and increased heart rate. In contrast, drugs that would decrease blood pressure are usually parasympathomimetics or other agents designed to block sympathetic responses.
C) Decreased heart rate: Sympathomimetic drugs typically increase heart rate by stimulating beta-1 adrenergic receptors in the heart. These drugs are used in situations requiring increased cardiac output or to counteract bradycardia. Decreased heart rate would typically occur with parasympathomimetic drugs or medications that block sympathetic activity (e.g., beta blockers).
D) Increased respiration: Sympathomimetic drugs can increase respiratory rate by promoting bronchodilation through beta-2 adrenergic receptor activation in the lungs. However, "increased respiration" as a general effect is not as specific or consistent as the other cardiovascular and ocular effects of these drugs. The primary and most prominent physiological change would be related to the cardiovascular effects.
Correct Answer is A
Explanation
A) Decreased bowel sounds:
When the sympathetic nervous system (SNS) is activated, such as during stress or a "fight-or-flight" response, blood is redirected away from the gastrointestinal (GI) tract to vital organs like the heart and muscles. This results in decreased gastrointestinal motility and function, which is reflected in a reduction in bowel sounds. Decreased bowel sounds are a direct consequence of reduced blood flow and decreased activity in the GI system.
B) Increased blood glucose level:
While it is true that SNS activation can lead to an increase in blood glucose due to the release of catecholamines (e.g., epinephrine), this response is related to the body’s preparation for physical exertion and not directly a result of blood being diverted from the GI tract. The increase in glucose levels is more about energy mobilization rather than an effect on blood flow to the GI tract.
C) Decreased immune reaction:
Sympathetic stimulation can indeed have effects on immune function, typically suppressing immune responses during a stress response. However, this is not directly linked to blood being diverted away from the GI tract. Immune suppression is more about the body prioritizing immediate survival (e.g., diverting energy to muscles for fight-or-flight) rather than a specific physiological consequence of GI blood flow changes.
D) Increased blood pressure:
Sympathetic nervous system activation does lead to an increase in blood pressure due to vasoconstriction and increased heart rate. However, increased blood pressure is a broader systemic response to SNS stimulation, and it is not directly related to blood being diverted from the GI tract. Blood pressure increases as part of the general "fight-or-flight" response, but it does not specifically indicate changes in GI blood flow.
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