Which of the following inhaled anesthetics decreases metheonine synthase activity and causes megaloblastic anemia?

Correct Answer: C

Rationale: The correct answer is C: Nitrous oxide. Nitrous oxide inhibits methionine synthase activity by inactivating vitamin B12, leading to megaloblastic anemia. Desflurane, Halothane, and Sevoflurane do not affect methionine synthase or cause megaloblastic anemia. Nitrous oxide is the only anesthetic among the choices known for this specific mechanism of action.

Correct Answer: A

Rationale: Step-by-step rationale for why Aminocaproic acid (A) is the correct answer: 1. Aminocaproic acid is a fibrinolytic inhibitor that prevents the breakdown of blood clots. 2. It works by inhibiting the activation of plasminogen to plasmin, which is essential for clot dissolution. 3. Therefore, Aminocaproic acid belongs to the class of fibrinolytic inhibitors. Summary of why the other choices are incorrect: - Ticlopidine (B) is a platelet aggregation inhibitor, not a fibrinolytic inhibitor. - Streptokinase (C) is a fibrinolytic drug that promotes clot breakdown, not an inhibitor. - Vitamin K (D) is essential for clotting factors synthesis, not a fibrinolytic inhibitor.

Correct Answer: B

Rationale: Verapamil is a calcium channel blocker that decreases heart rate by blocking L-type calcium channels in the heart. Choice B, stating it increases heart rate, is incorrect. Verapamil relaxes coronary artery smooth muscle (Choice C) and depresses cardiac contractility (Choice D), making them true statements. So, the correct answer is B as it contradicts the pharmacological effects of verapamil.

Correct Answer: C

Rationale: The correct answer is C: Decreasing of heart work. Beta-blockers reduce blood pressure by decreasing the heart's workload through blocking the effects of adrenaline on the heart, resulting in lowered heart rate and force of contraction. This reduces the amount of blood pumped by the heart, leading to decreased blood pressure. The other choices are incorrect because: A: Peripheral vasodilatation - Beta-blockers actually cause vasoconstriction, not vasodilatation. B: Diminishing of blood volume - Beta-blockers do not directly affect blood volume. D: Depression of vasomotor center - Beta-blockers primarily act on the heart, not the vasomotor center.

Correct Answer: A

Rationale: The correct answer is A: TRUE. The hypothalamus secretes thyrotropin-releasing hormone (TRH) which stimulates the anterior pituitary to release thyroid-stimulating hormone (TSH), which in turn stimulates the thyroid gland to produce thyroid hormones. This demonstrates the hypothalamic control over the thyroid gland. Choices B, C, and D are incorrect because the hypothalamus does indeed play a crucial role in regulating the thyroid gland, making the statement true rather than false, all-encompassing, or none at all.