A nursing instructor is teaching a group of nursing students about antihistamines. Which statement by a student indicates an understanding of the mechanism of action of the antihistamines?
"Antihistamines block release of histamine from mast cells and basophils."
"Antihistamines block H1 receptors to prevent actions of histamine at these sites."
"H1 antagonists can bind to H1 receptors, H2 receptors, and muscarinic receptors."
"First-generation antihistamines are more selective than second-generation antihistamines."
The Correct Answer is B
Antihistamines primarily work by blocking the H1 receptors, which are the receptors responsible for mediating the actions of histamine in the body. By blocking these receptors, antihistamines prevent or reduce the effects of histamine, such as itching, sneezing, runny nose, and watery eyes. This is the main mechanism by which antihistamines provide their therapeutic effects. "Antihistamines block release of histamine from mast cells and basophils." This statement is incorrect. Antihistamines do not block the release of histamine; instead, they block the histamine receptors to prevent the effects of histamine.
"H1 antagonists can bind to H1 receptors, H2 receptors, and muscarinic receptors." This statement is incorrect. H1 antagonists, or H1 receptor blockers, specifically bind to H1 receptors and do not have significant affinity for H2 receptors or muscarinic receptors. "First-generation antihistamines are more selective than second-generation antihistamines." This statement is incorrect. First-generation antihistamines are generally less selective and can have more sedating and anticholinergic effects compared to second-generation antihistamines, which are designed to be more selective for H1 receptors and have reduced sedative properties.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Rhinoplasty is a surgical procedure performed on the nose, and it often involves the placement of nasal packing to control bleeding, support the nasal structures, and promote healing. Nasal packing can cause mouth breathing and oral dryness, which can lead to increased swallowing as the patient tries to alleviate the discomfort.
While bleeding posterior to the nasal packing is a potential complication of rhinoplasty, it typically presents with other symptoms such as active bleeding, nasal discharge, or changes in vital signs. Without additional information or signs of active bleeding, it is less likely to be the cause of the patient's frequent swallowing in this scenario.
An adverse reaction to the analgesic is possible, but it would typically present with other symptoms such as allergic reactions (rash, swelling, difficulty breathing) or gastrointestinal symptoms (nausea, vomiting). In the absence of these symptoms, an adverse reaction to the analgesic is less likely.
Lastly, a normal response to the analgesic and surgery would not typically manifest as frequent swallowing. While pain medication can cause side effects, such as drowsiness or nausea, increased swallowing is not a common response.
Correct Answer is ["A","C","D","F"]
Explanation
Muscle rigidity is a hallmark sign of malignant hyperthermia. It commonly affects the muscles of the jaw and upper chest.
Malignant hyperthermia can lead to rapid and shallow breathing, resulting in tachypnea. Malignant hyperthermia is characterized by a significant increase in body temperature, often exceeding 38.8°C (101.8°F).
Malignant hyperthermia can cause irregular heart rhythms or dysrhythmias, including tachycardia or arrhythmias.
The manifestations of hypertension and skin mottling are not typically associated with malignant hyperthermia. Hypertension (high blood pressure) is more commonly seen in conditions such as hypertensive emergencies or certain cardiovascular disorders. Skin mottling, which refers to irregular or patchy skin coloration, is not a specific manifestation of malignant hyperthermia.
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