Norepinephrine produces:

Correct Answer: A

Rationale: Norepinephrine is a neurotransmitter that acts on alpha-adrenergic receptors causing vasoconstriction by stimulating smooth muscle contraction in blood vessels. This leads to increased blood pressure. Vasodilatation (B) is incorrect as norepinephrine does not cause blood vessels to dilate. Bronchodilation (C) is incorrect because norepinephrine primarily affects blood vessels, not bronchioles. Decreased potassium concentration in the plasma (D) is incorrect as norepinephrine does not directly impact potassium levels. Therefore, the correct answer is A: Vasoconstriction.

Correct Answer: C

Rationale: The correct answer is C: Flurazepam. Flurazepam is a benzodiazepine commonly used for its sedative-hypnotic properties, making it ideal for treating insomnia and inducing sleep. Clonazepam (A) is mainly used for seizure disorders and panic disorder. Lorazepam (B) is primarily used for anxiety and agitation. Midazolam (D) is commonly used for sedation before medical procedures. Therefore, Flurazepam is the most appropriate choice for hypnosis among the options provided.

Correct Answer: B

Rationale: The correct answer is B: Zonisamide. Zonisamide is a sulfonamide derivative that blocks Na+ channels and also inhibits T-type Ca2+ channels. This dual mechanism of action helps in controlling seizures. Tiagabine (A) inhibits GABA reuptake, Ethosuximide (C) blocks T-type Ca2+ channels only, and Primidone (D) is metabolized into phenobarbital, which enhances GABAergic activity.

Correct Answer: B

Rationale: The correct answer is B: Dynorphin. Dynorphin is mainly found in long descending pathways from the midbrain to the dorsal horn. It acts as an endogenous opioid peptide that modulates pain perception. Prostaglandin E, Enkephalin, and Glutamate are not primarily found in these pathways. Prostaglandin E is involved in inflammation and fever, Enkephalin acts as an endogenous opioid peptide in pain modulation, and Glutamate is a major excitatory neurotransmitter in the central nervous system. Thus, B is the correct choice based on its specific localization in the described pathways.

Correct Answer: A

Rationale: The correct answer is A: TRUE. Both naltrexone and disulfiram are known to potentially cause liver toxicity individually. When used together, the risk of hepatotoxicity is significantly increased due to their combined effects on the liver. Therefore, the combination of naltrexone and disulfiram should be avoided to prevent liver damage. Choice B: FALSE is incorrect because combining two hepatotoxins like naltrexone and disulfiram can indeed lead to liver toxicity. Choice C: None is incorrect as there is a clear recommendation to avoid the combination of these two drugs due to the risk of hepatotoxicity. Choice D: All is incorrect as not all combinations of drugs are hepatotoxins, but specifically the combination of naltrexone and disulfiram poses a risk of liver damage.