Kappa and delta agonists:

Correct Answer: C

Rationale: Rationale: 1. Kappa and delta agonists inhibit postsynaptic neurons by opening K+ channels. 2. They also close voltage-gated Ca2+ channels on presynaptic nerve terminals. 3. Therefore, choice C (Both a and b) is correct, as it encompasses both actions. Summary: - Choice A is incorrect because it only mentions the action of opening K+ channels. - Choice B is incorrect as it only refers to closing voltage-gated Ca2+ channels. - Choice D is unrelated to the actions of kappa and delta agonists on neuronal transmission.

Correct Answer: B

Rationale: Lithium carbonate is commonly used to treat bipolar disorder due to its mood-stabilizing effects. It helps regulate neurotransmitters in the brain, specifically serotonin and norepinephrine, which are implicated in mood regulation. For petit mal seizures, anti-epileptic drugs like ethosuximide are typically prescribed. Neurosis is treated through psychotherapy and medication targeting specific symptoms. Trigeminal neuralgia is usually managed with anticonvulsants like carbamazepine. In summary, lithium carbonate's mechanism of action aligns with the treatment goals of bipolar disorder, making it the correct choice.

Correct Answer: C

Rationale: The correct answer is C: General tonics. General tonics are CNS stimulants that help mitigate conditions of weakness or lack of tone in the entire organism or specific organs by providing a non-specific boost in energy and vitality. Psychostimulants (A) primarily target mental alertness and focus, not overall weakness. Analeptics (B) are CNS stimulants that specifically stimulate the respiratory centers and are not general tonics. Antidepressants (D) are used to treat mood disorders and do not directly address physical weakness or lack of tone.

Correct Answer: B

Rationale: The correct answer is B: Triazolam. Triazolam has a short half-life and rapid onset of action, making it more likely to cause "hangover" effects the next day due to its fast clearance from the body. This can lead to residual sedation, drowsiness, dysphoria, and mental or motor depression. In contrast, choices A, C, and D have longer half-lives and slower onset of action, reducing the likelihood of significant hangover effects. Oxazepam (A) is known for its long half-life and minimal hangover effects. Clorazepate (C) and Lorazepam (D) also have longer durations of action compared to Triazolam, making them less likely to cause next-day hangover effects.

Correct Answer: A

Rationale: The correct answer is A: Sevoflurane. Sevoflurane is the inhaled anesthetic that increases cerebral blood flow the least due to its minimal effect on cerebral vasodilation. Sevoflurane has a lower blood-gas partition coefficient compared to the other choices, resulting in faster onset and offset of action. This rapid clearance from the blood reduces its impact on cerebral blood flow. In contrast, Nitrous oxide (Choice B) is a potent cerebral vasodilator, Isoflurane (Choice C) and Desflurane (Choice D) also have higher blood-gas partition coefficients leading to more significant effects on cerebral blood flow compared to Sevoflurane.