The mechanism of Cytiton action is:

Correct Answer: B

Rationale: The correct answer is B: The reflex mechanism. Cytiton acts by triggering a reflex mechanism, which involves a response to a stimulus that is automatic and involuntary. This mechanism is distinct from direct activation of the respiratory center (choice A) or a mixed mechanism (choice C). Choice D is incorrect as Cytiton does have a specific action mechanism. In summary, the correct choice is B because it accurately describes how Cytiton works through a reflex mechanism, while the other choices do not align with the known pharmacological action of Cytiton.

Correct Answer: A

Rationale: Step 1: Digitalis increases vagal tone by enhancing parasympathetic activity. Step 2: This results in a decrease in heart rate and improved contractility. Step 3: Therefore, choice A is correct as it accurately states that digitalis increases vagal tone. Summary: Choices B, C, and D are incorrect because digitalis does increase vagal tone, which is a specific action of the medication.

Correct Answer: D

Rationale: The correct answer is D, "All of the above," because all three choices are nitrates used for the prevention of angina attacks. Nitroglycerin, in both ointment and oral sustained-release forms, works by dilating blood vessels to improve blood flow to the heart, reducing angina symptoms. Isosorbide mononitrate is another nitrate used for the same purpose. Therefore, all three options are effective in preventing angina attacks. Options A, B, and C are incorrect because each drug listed is individually used for angina prevention, making the correct answer D, as it includes all the effective drugs for this purpose.

Correct Answer: D

Rationale: The correct answer is D: Angiotensinamide. This is because angiotensinamide is a hormone produced endogenously by the body that acts as a potent vasoconstrictor. It plays a crucial role in regulating blood pressure by constricting blood vessels. Rationale: 1. Angiotensinamide is a naturally occurring hormone in the body. 2. It acts specifically as a vasoconstrictor, narrowing blood vessels. 3. This physiological function of angiotensinamide helps regulate blood pressure. 4. In contrast, choices A, B, and C are exogenous substances with pharmacological vasoconstrictive effects, not endogenously produced hormones like angiotensinamide. Summary: A, B, and C are incorrect because they are synthetic substances with vasoconstrictive properties, whereas angiotensinamide is the correct answer as it is an endogenous vasoconstrictor hormone in the body.

Correct Answer: A

Rationale: The correct answer is A. Thyroid hormones actually increase the basal metabolic rate, not decline it. This is because thyroid hormones stimulate cellular metabolism and energy production. Choice B is incorrect as thyroid hormones do increase the rate and force of contraction of the heart. Choice C is incorrect as thyroid hormones decrease blood cholesterol levels. Choice D is correct as thyroid hormones do increase heat production through their effects on metabolism.