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 ["A","D"]
Explanation
Signs and symptoms associated with a hypersensitivity reaction to cephalosporin antibiotics can include:
1. Skin rash: Hypersensitivity reactions often manifest as skin rashes, which can range from mild to severe. The rash may be itchy, red, raised, and may spread to different areas of the body.
2. Intense pruritus: Pruritus refers to severe itching, which can be a prominent symptom of a hypersensitivity reaction to cephalosporins.
Dizziness and hyperglycemia are not commonly associated with hypersensitivity reactions to cephalosporins. Dizziness may be a side effect of some medications, including antibiotics, but it is not a specific symptom of a hypersensitivity reaction. Hyperglycemia, or high blood sugar levels, is not typically attributed to a hypersensitivity reaction to cephalosporins. It's important to note that hypersensitivity reactions can vary in severity and may include other symptoms such as fever, swelling, difficulty breathing, wheezing, and anaphylaxis. If a hypersensitivity reaction is suspected, it is crucial to seek immediate medical attention for proper evaluation and management.
Correct Answer is C
Explanation
The pH value of 7.5 indicates alkalosis, as it is above the normal range of 7.35-7.45. The elevated bicarbonate (HCO3-) level of 34 mmol/L suggests metabolic alkalosis, as it is higher than the normal range of 22-28 mmol/L. The PaCO2 level of 40 mm Hg falls within the normal range of 35-45 mm Hg.
In this case, the primary disturbance is metabolic alkalosis, which is likely caused by vomiting leading to excessive loss of gastric acid (hydrogen ions) and chloride ions from the stomach. This loss of acid and chloride results in an imbalance of electrolytes and an increase in bicarbonate levels, leading to metabolic alkalosis.
The arterial blood gas results do not indicate any compensation. Compensation occurs when the body attempts to restore the pH balance by adjusting the respiratory or metabolic systems. In this case, there is no compensation observed because the PaCO2 level is within the normal range and not significantly altered.
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