How does an antihistamine work?
By blocking the effects of histamine in the body
By reducing inflammation in the body
By increasing the production of histamine in the body
By stimulating the immune system
The Correct Answer is A
A) By blocking the effects of histamine in the body:
Antihistamines are pharmacological agents that work by antagonizing the effects of histamine, a chemical mediator released by mast cells and basophils in response to allergens or other triggers. Histamine contributes to various allergic symptoms such as itching, sneezing, nasal congestion, and watery eyes. Antihistamines exert their effects by competitively binding to histamine receptors (specifically H1 receptors) on target cells, thereby preventing histamine from binding and exerting its physiological effects. By blocking histamine receptors, antihistamines inhibit the action of histamine, leading to the alleviation of allergy symptoms.
B) By reducing inflammation in the body:
While some medications, such as corticosteroids, exert anti-inflammatory effects by suppressing the immune response and inhibiting the production of inflammatory mediators, antihistamines primarily target histamine receptors and do not directly reduce inflammation. Although histamine release can contribute to inflammation, antihistamines mitigate allergic symptoms primarily by blocking the action of histamine rather than by directly reducing inflammation.
C) By increasing the production of histamine in the body:
This statement is inaccurate. Antihistamines do not increase the production of histamine; instead, they counteract the effects of histamine by blocking its activity at receptor sites. The primary mechanism of action of antihistamines involves blocking histamine receptors to prevent histamine from exerting its physiological effects.
D) By stimulating the immune system:
Antihistamines do not stimulate the immune system. Instead, they act as antagonists to histamine receptors, thereby inhibiting histamine-induced responses. While histamine is involved in immune responses and allergic reactions, antihistamines do not directly modulate immune function or stimulate immune activity. Their primary role is to alleviate allergy symptoms by blocking the effects of histamine."
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is ["B","C","E"]
Explanation
A) Hypoglycemia:
Propranolol, a nonselective beta-blocking agent, can mask some of the symptoms of hypoglycemia, such as tachycardia and tremors, by blocking the sympathetic response. Therefore, it is not typically used in the treatment of hypoglycemia and may even exacerbate low blood sugar levels.
B) Arrhythmias:
Propranolol is commonly used in the treatment of various cardiac arrhythmias. By blocking beta-adrenergic receptors in the heart, it reduces the heart rate and myocardial contractility, thereby helping to control arrhythmias such as atrial fibrillation and ventricular tachycardia.
C) Hypertension:
Propranolol is effective in lowering blood pressure and is often prescribed for the management of hypertension. Its beta-blocking action reduces cardiac output and suppresses renin release, leading to decreased systemic vascular resistance and blood pressure.
D) Hypokalemia:
Propranolol does not have a direct role in the treatment of hypokalemia. While it can potentially exacerbate hypokalemia through its effects on potassium metabolism, it is not a primary treatment for this electrolyte imbalance.
E) Angina:
Propranolol is indicated for the treatment of angina pectoris, particularly in cases of stable angina. By reducing myocardial oxygen demand through its negative chronotropic and inotropic effects, it helps relieve anginal symptoms and improve exercise tolerance."
Correct Answer is C
Explanation
A) Respiratory rate 18/min:
A respiratory rate of 18/min is within the normal range for adults and is not a contraindication for administering atenolol. This finding does not warrant withholding the medication.
B) Oxygen saturation 95%:
An oxygen saturation of 95% is within the normal range and does not indicate any acute respiratory compromise. It is not a contraindication for administering atenolol.
C) Heart rate 46/min:
A heart rate of 46/min is below the normal range (typically 60-100 beats per minute for adults). Atenolol is a beta-blocker that primarily acts to reduce heart rate and blood pressure. Administering atenolol to a client with bradycardia (heart rate less than 60/min) can further decrease heart rate and may lead to symptomatic bradycardia or heart block. Therefore, the nurse should withhold atenolol in this case and notify the healthcare provider.
D) Blood pressure 160/94 mm Hg:
A blood pressure of 160/94 mm Hg indicates hypertension (elevated blood pressure). While atenolol is often prescribed for the management of hypertension, this blood pressure reading alone does not warrant withholding the medication. However, the client's bradycardia (heart rate 46/min)’is a more immediate concern that requires action."
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