Indicate the competitive antagonist of BZ receptors:

Correct Answer: A

Rationale: Step-by-step rationale: 1. Flumazenil is a competitive antagonist of BZ receptors by binding and blocking their activity. 2. Buspirone is a partial agonist at serotonin receptors, not BZ receptors. 3. Picrotoxin is a non-competitive antagonist at GABA receptors, not BZ receptors. 4. Diazepam is a positive allosteric modulator at BZ receptors, not a competitive antagonist. Summary: Flumazenil is the correct answer as it specifically targets BZ receptors as a competitive antagonist, while the other options act on different receptors or in different ways.

Correct Answer: D

Rationale: The correct answer is D: Carbonate mineral waters. Carbonate mineral waters do not intensify the secretion of gastric glands. Pepsin is an enzyme that aids in digestion, Gastrin is a hormone that stimulates gastric acid secretion, and Histamine is a neurotransmitter that also stimulates gastric acid secretion. Carbonate mineral waters do not have the same effect on gastric glands as the other agents listed. Therefore, the correct answer is D.

Correct Answer: D

Rationale: The correct answer is D: Protamine sulfate. Protamine sulfate is an antagonist of heparin because it binds to heparin molecules, forming a stable complex that neutralizes the anticoagulant effects of heparin. This interaction helps to reverse the effects of heparin in cases of heparin overdose or when immediate cessation of anticoagulation is required. A: Aspirin is an antiplatelet agent that inhibits platelet aggregation by irreversibly inhibiting cyclooxygenase. It is not an antagonist of heparin. B: Dicumarol is a vitamin K antagonist that inhibits the synthesis of vitamin K-dependent clotting factors. It is not an antagonist of heparin. C: Dalteparin is a low-molecular-weight heparin that acts as an anticoagulant by inhibiting the activity of factor Xa. It is not an antagonist of heparin. In summary, Protamine sulfate

Correct Answer: A

Rationale: Step-by-step rationale for why A (Digoxin) is the correct answer: 1. Digoxin is a cardiac glycoside that slows conduction through the AV node, making it effective in controlling supraventricular tachycardias. 2. It increases the refractory period of the AV node, reducing the heart rate. 3. Digoxin is not a vasopressor like Dobutamine or Dopamine, which are used for different indications. 4. Amrinone is a phosphodiesterase inhibitor, primarily used in heart failure, not specifically for supraventricular tachycardias.

Correct Answer: D

Rationale: The correct answer is D: Nifedipine. Nifedipine is a calcium channel blocker that directly acts on vascular smooth muscle to cause vasodilation by inhibiting calcium influx. Labetalol and Clonidine are alpha and beta blockers, Enalapril is an ACE inhibitor, which all indirectly cause vasodilation. Therefore, Nifedipine is the only directly acting vasodilator among the choices.