All of the following physiologic reactions are involved in the control of bleeding EXCEPT:

Correct Answer: C

Rationale: The correct answer is C: Activation of the antifibrinolytic system. This system is involved in clot dissolution, not bleeding control. Platelet adhesion, release, and triggering the coagulation process are essential physiological reactions that help control bleeding by forming a stable blood clot. Platelet adhesion allows platelets to stick to the site of injury, platelet release releases factors that promote clot formation, and triggering the coagulation process leads to the formation of fibrin strands that strengthen the clot. Therefore, choices A, B, and D are involved in the control of bleeding, while choice C is not.

Correct Answer: C

Rationale: The correct answer is C: Guanethidine. Guanethidine is a sympatholytic drug that blocks the release of norepinephrine from sympathetic nerve terminals, thus reducing sympathetic activity. This leads to a decrease in blood pressure. A: Labetalol is a non-selective beta blocker with alpha-blocking activity. B: Prazosin is an alpha-1 adrenergic receptor antagonist. D: Clonidine is a centrally acting alpha-2 adrenergic agonist. Therefore, the correct choice for a sympatholytic drug is Guanethidine due to its mechanism of action in inhibiting sympathetic activity.

Correct Answer: C

Rationale: The correct answer is C: Dysfunction of regulation of cerebral vessel tonus. Migraine is a neurological disorder characterized by recurrent headaches. The underlying cause is believed to involve abnormal brain activity and the dysfunction of regulating cerebral vessel tonus, leading to vasodilation and inflammation. Thrombosis of cerebral vessels (choice A), brain hemorrhage (choice B), and malignant growth in the brain (choice D) are not directly associated with the pathophysiology of migraine.

Correct Answer: C

Rationale: The correct answer is C: Crystalline insulin. Diabetic coma is a severe complication of diabetes characterized by extremely high blood sugar levels. Administration of crystalline insulin helps lower blood sugar rapidly. Lente insulin (A) is not fast-acting enough for diabetic coma treatment. Glucose (B) would further elevate blood sugar levels. Oral anti-diabetic drugs (D) are not suitable for immediate treatment of diabetic coma.

Correct Answer: A

Rationale: Prednisolone is the correct answer because it does not contain any fluoride atoms in its chemical structure. Prednisolone is a synthetic corticosteroid that lacks fluorine atoms, making it safer for long-term use compared to other glucocorticoids like dexamethasone, fluocinolone, and triamcinolone, which all contain fluorine atoms. Fluorine atoms in glucocorticoids can increase their potency but also lead to potential adverse effects, such as bone density loss and increased risk of fractures. Therefore, prednisolone is the safest option among the choices provided.