The average menstrual cycle is

Correct Answer: D

Rationale: The correct answer is D: 28 days. The average menstrual cycle typically lasts around 28 days, starting from the first day of one period to the first day of the next. This duration allows for the completion of the hormonal changes and phases involved in the menstrual cycle, including menstruation, the follicular phase, ovulation, and the luteal phase. Choices A, B, and C are incorrect because they do not align with the typical duration of a menstrual cycle and may not provide sufficient time for these hormonal processes to occur properly.

Correct Answer: A

Rationale: The correct answer is A: Anticholinergics. Drug-induced parkinsonism is caused by certain medications such as antipsychotics. Anticholinergics help alleviate the symptoms by blocking the activity of acetylcholine, which is increased in parkinsonism. Levodopa and Carbidopa are typically used in Parkinson's disease, not drug-induced parkinsonism. Seligiline is a monoamine oxidase inhibitor used in Parkinson's disease, but not specifically for drug-induced parkinsonism. Therefore, anticholinergics are the drug of choice for drug-induced parkinsonism due to their mechanism of action in blocking acetylcholine.

Correct Answer: A

Rationale: The correct answer is A: Methadone. Methadone is a full opioid agonist because it activates opioid receptors fully, resulting in analgesia and other opioid effects. Methadone is used for opioid dependence treatment due to its agonistic properties. Buprenorphine (B) is a partial agonist with less intrinsic activity than full agonists. Naloxone (C) is an opioid antagonist used for opioid overdose reversal. Flumazenil (D) is a benzodiazepine receptor antagonist, not an opioid agonist. In summary, methadone is the correct choice as it is a full opioid agonist compared to the other options with different mechanisms of action.

Correct Answer: C

Rationale: Inverse agonists bind to the same receptor as an agonist but produce the opposite effect. Beta carbolines act as inverse agonists by decreasing basal activity of GABA receptors. Buspirone is a partial agonist of serotonin receptors. Flumazenil is a benzodiazepine antagonist. Zolpidem is a positive allosteric modulator of GABA receptors.

Correct Answer: D

Rationale: Step-by-step rationale: 1. Prostacyclin is a vasodilator, so it causes vasodilation, not vasoconstriction. 2. Prostacyclin inhibits platelet aggregation, so it does not promote it. 3. Prostacyclin helps decrease blood pressure by promoting vasodilation. 4. Prostacyclin is synthesized from vascular endothelium, making choice D the correct answer. Summary: A: Incorrect - Prostacyclin causes vasodilation, not vasoconstriction. B: Incorrect - Prostacyclin inhibits platelet aggregation, not promotes it. C: Incorrect - Prostacyclin helps decrease blood pressure, not increase it. D: Correct - Prostacyclin is synthesized from vascular endothelium.