Indicate the chemical mediator in the antinociceptive descending pathways:

Correct Answer: D

Rationale: The correct answer is D: All of the above. In the antinociceptive descending pathways, multiple endogenous opioids play a role in pain modulation. Beta-endorphin, met- and leu-enkephalin, and dynorphin all act as chemical mediators to inhibit pain signals. Each of these opioids bind to different opioid receptors in the central nervous system, contributing to the overall analgesic effect. Therefore, the correct answer includes all three options as they collectively participate in the antinociceptive pathways. Choices A, B, and C alone are not sufficient to fully explain the complexity of the pain modulation system, making option D the most comprehensive and accurate choice.

Correct Answer: C

Rationale: The correct answer is C: Haloperidol. Haloperidol is preferable in patients with coronary and cerebrovascular disease due to its lower risk of causing cardiovascular adverse effects compared to the other options. Chlorpromazine (A) can cause orthostatic hypotension and prolong QT interval. Fluphenazine (B) can lead to QT prolongation and hypotension. Perphenazine (D) also carries a risk of QT prolongation and orthostatic hypotension. In contrast, Haloperidol has a more favorable cardiovascular safety profile, making it the preferred choice for patients with coronary and cerebrovascular disease.

Correct Answer: A

Rationale: The correct answer is A: Meridil. Psychostimulants are substances that can increase alertness, attention, and energy levels. Meridil, also known as methylphenidate, is a commonly prescribed psychostimulant used to treat conditions like ADHD. Camphor (B) is a topical analgesic, Piracetam (C) is a nootropic agent, and Pantocrin (D) is a herbal supplement with purported energy-boosting properties. Therefore, only Meridil (A) fits the classification of a psychostimulant among the choices provided.

Correct Answer: C

Rationale: The correct answer is C: Buspirone. Buspirone is an anxiolytic agent that relieves anxiety without causing marked sedative effects. It works by specifically targeting serotonin receptors in the brain to reduce anxiety, unlike benzodiazepines like Diazepam, Chlordiazepoxide, and Clorazepate which act on GABA receptors leading to sedative effects. Buspirone's unique mechanism of action makes it an ideal choice for treating anxiety without causing sedation.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Nitrous oxide, Desflurane, and Sevoflurane are all inhaled anesthetics known for their rapid onset and recovery. Nitrous oxide is rapid due to its low blood-gas solubility, while Desflurane and Sevoflurane are quick-acting because of their low solubility and fast elimination from the body. Therefore, all three options meet the criteria of having rapid onset and recovery. The other choices are incorrect because they do not fully encompass all the anesthetics that exhibit these characteristics.