This drug is a selective beta-1 agonist:

Correct Answer: B

Rationale: Step-by-step rationale for why B (Dobutamine) is the correct answer: 1. Dobutamine is a selective beta-1 agonist, primarily targeting β1-adrenergic receptors in the heart. 2. It increases cardiac contractility and heart rate, making it useful in treating heart failure and cardiogenic shock. 3. Digoxin (A) is a cardiac glycoside, Amrinone (C) is a phosphodiesterase inhibitor, and Dopamine (D) acts on multiple receptors. 4. Thus, the specific action of dobutamine on beta-1 receptors distinguishes it as the correct choice.

Correct Answer: C

Rationale: The correct answer is C: Plasmoexpanders. Plasmoexpanders are used to increase circulating blood volume in cases of hypovolemic shock. By increasing plasma volume, plasmoexpanders help restore tissue perfusion and improve blood pressure. Positive inotropic drugs (A) increase the force of heart contractions, vasoconstrictors (B) constrict blood vessels, and analeptics and tonics (D) stimulate the central nervous system - none of which directly address the issue of reduced circulating blood volume in shock. Plasmoexpanders are the most appropriate choice for treating hypovolemic shock as they specifically target the underlying cause of reduced blood volume.

Correct Answer: A

Rationale: The correct answer is A. Daily administration of large doses of iodides causes involution of the thyroid gland. Iodides inhibit thyroid hormone synthesis, leading to a decrease in thyroid size. This effect peaks in about two weeks. Choice B is incorrect as iodides actually decrease vascularity of the thyroid gland. Choice C is incorrect because iodides increase the storage of colloid in the thyroid gland. Choice D is incorrect as iodides make the thyroid gland softer and more vascular, not firm and less vascular.

Correct Answer: A

Rationale: Rationale: Answer A is correct as it accurately defines inflammation as a localized protective response to irritation, injury, or infection. Pain, redness, swelling, and loss of function are typical characteristics. Answer B is incorrect as inflammation is not a deficiency of the immune response. Answer C is incorrect as it describes an autoimmune reaction, not inflammation. Therefore, the correct answer is A.

Correct Answer: A

Rationale: The correct answer is A because H1 histamine receptors are primarily found in smooth muscle, endothelium, and the brain. Smooth muscle and endothelium are major sites of action for H1 receptors, regulating functions like vasodilation and bronchoconstriction. The presence of H1 receptors in the brain also plays a role in neurotransmission. Choice B is incorrect because gastric mucosa, cardiac muscle, and mast cells are associated with H2 histamine receptors, not H1. Choice C is incorrect because presynaptic H3 receptors are found in the brain, whereas H1 receptors are primarily postsynaptic. Choice D is incorrect because not all locations listed in the other choices are where H1 receptors are predominantly found.