A patient tells a nurse, “My doctor thinks my problem may lie with the neurotransmitters in my brain. What are neurotransmitters?” The reply that will give the patient the best understanding of neurotransmitters is, “Neurotransmitters are:

Correct Answer: A

Rationale: The correct answer is A: "the chemical messengers that cause brain cells to turn on or off." This is the best answer because neurotransmitters are indeed chemical substances that transmit signals across synapses between neurons, either exciting or inhibiting the receiving neuron. This explanation accurately describes the essential function of neurotransmitters in regulating brain cell activity. Explanation for why the other choices are incorrect: B: "small clumps of cells that alert the other brain cells to receive messages." This is incorrect as neurotransmitters are not clumps of cells but rather individual molecules that facilitate communication between neurons. C: "tiny areas of the brain that are responsible for controlling our emotions." This is incorrect as neurotransmitters are not specific areas of the brain but rather chemicals that play a role in various brain functions, including emotions. D: "weblike structures that provide connections among various parts of the brain." This is incorrect as neurotransmitters are not physical structures but chemical substances that facilitate communication between neurons.

Correct Answer: C

Rationale: The correct answer is C: Korsakoff’s psychosis. Chronic alcohol use can lead to a thiamine deficiency, resulting in Korsakoff’s psychosis characterized by severe memory loss and confabulation. Renal failure (A) is not directly linked to chronic alcohol use. Cerebrovascular accident (B) is more commonly associated with high blood pressure or atherosclerosis. Alzheimer’s disease (D) is a neurodegenerative disorder not directly caused by chronic alcohol use. In summary, Korsakoff’s psychosis is the most likely condition to result from chronic alcohol use due to thiamine deficiency.

Correct Answer: D

Rationale: The correct answer is D because heparin is a fast-acting anticoagulant that is used initially to rapidly thin the blood while warfarin takes time to reach therapeutic levels. By using both medications together, the patient is protected against blood clots during this transition period. Choices A and B are incorrect because there is no evidence that the oral and injection forms work synergistically or result in fewer adverse effects when used together. Choice C is incorrect because heparin alone can achieve adequate anticoagulation levels, but the combination is more about the timing of onset of action for each medication.

Correct Answer: B

Rationale: The correct answer is B: "Take the bronchodilator inhaler first." The rationale for this instruction is that bronchodilators work by relaxing the muscles around the airways, allowing for easier breathing. Taking the bronchodilator first helps open up the airways, making it easier for the corticosteroid to reach deeper into the lungs and be more effective. If the corticosteroid is taken first, it may not reach the lower airways as effectively. Choice A is incorrect because taking the corticosteroid first may not optimize the effectiveness of both medications. Choice C is incorrect as it is important to take these inhalers in a specific order for optimal effect. Choice D is incorrect because the order of inhaler use can impact the effectiveness of the medications.

Correct Answer: A

Rationale: The correct answer is A because the volume of distribution (Vd) is a pharmacokinetic parameter that describes the extent of drug distribution in the body. It is calculated by dividing the total amount of drug in the body by the concentration of the drug in the plasma. Therefore, the concentration of a substance in plasma is essential for determining Vd. Choice B (Concentration of substance in urine) is incorrect because Vd is not calculated based on urine concentration but rather on plasma concentration. Choice C (Therapeutical width of drug action) is unrelated to Vd calculation as it refers to the range of drug concentrations in the body that produce the desired therapeutic effect. Choice D (A daily dose of drug) is also incorrect as Vd is not directly calculated from the daily dose but rather from the concentration of the drug in the plasma.