Tick a hypnotic agent – a barbituric acid derivative:

Correct Answer: C

Rationale: The correct answer is C: Thyopental. Thyopental is a barbituric acid derivative known for its hypnotic properties by inducing sleep. Flurazepam (A) is a benzodiazepine used for treating insomnia. Zaleplon (B) is a non-benzodiazepine hypnotic agent. Triazolam (D) is also a benzodiazepine used for insomnia. Therefore, the correct choice is C as it is the only barbituric acid derivative among the options.

Correct Answer: B

Rationale: The correct answer is B because carbidopa inhibits dopa decarboxylase enzyme, preventing the conversion of levodopa into dopamine outside the brain. This allows more levodopa to reach the brain and be converted into dopamine, improving its efficacy in treating Parkinson's disease. Choice A is incorrect as carbidopa does not directly affect the synthesis, release, or reuptake of dopamine. Choice C is incorrect because carbidopa does not stimulate dopamine receptors but rather works on the enzymatic conversion of levodopa to dopamine. Choice D is incorrect as carbidopa does not inhibit catechol-O-methyltransferase (COMT), which is another enzyme involved in dopamine metabolism.

Correct Answer: D

Rationale: The correct answer is D because intravenous morphine in dyspnea from pulmonary edema helps in reducing the perception of shortness of breath, patient anxiety, and also reduces cardiac preload and afterload. Morphine acts as a vasodilator, reducing venous tone and decreasing peripheral resistance, which in turn reduces cardiac preload and afterload. This leads to improved cardiac function and decreased workload on the heart, resulting in relief from dyspnea. Choices A, B, and C are all interconnected mechanisms through which morphine exerts its effects in alleviating dyspnea in pulmonary edema.

Correct Answer: C

Rationale: The correct answer is C, the mesolimbic and mesofrontal systems, as they are directly involved in regulating behaviors related to motivation, reward, and decision-making. The mesolimbic system projects from the ventral tegmental area to the limbic system, influencing emotions and reinforcement. The mesofrontal system connects the prefrontal cortex to the ventral tegmental area, modulating executive functions and cognitive control of behavior. A: The hypothalamic-pituitary system primarily regulates hormone production and homeostasis, not behavior. B: The extrapyramidal system is involved in motor control and not directly linked to behavior. D: The chemoreceptor trigger zone of the medulla is related to vomiting reflex and not behavior.

Correct Answer: D

Rationale: The correct answer is D: All of the above. MAO inhibitors can lead to dangerous interactions with selective serotonin reuptake inhibitors, tricyclics, and sympathomimetics due to the risk of serotonin syndrome or hypertensive crisis. The inhibition of monoamine oxidase enzyme by MAO inhibitors can increase the levels of serotonin, norepinephrine, and dopamine, resulting in potentially life-threatening effects when combined with these medications. It is crucial to avoid this combination to prevent serious adverse reactions.