Which of the following nitrates and nitrite drugs is a short-acting drug?

Correct Answer: C

Rationale: The correct answer is C: Amyl nitrite, inhalant. Amyl nitrite is a short-acting drug used for the treatment of angina pectoris and cyanide poisoning. It works quickly to dilate blood vessels and relieve chest pain. Nitroglycerin ointment and sustained-release tablets have longer durations of action, making them not short-acting. Sustac is not a nitrate or nitrite drug, so it is an incorrect choice. Overall, the rapid onset and short duration of action of amyl nitrite make it the correct choice for a short-acting nitrate/nitrite drug.

Correct Answer: D

Rationale: Thyroid stimulating hormone (TSH) regulates all the mentioned functions. 1. A: TSH stimulates iodine uptake by thyroid follicular cells for thyroid hormone synthesis. 2. B: TSH promotes the biosynthesis of iodothyroglobulin, a precursor of thyroid hormones. 3. C: TSH triggers the release of thyroid hormones into the bloodstream. Therefore, the correct answer is D as TSH regulates all these processes essential for thyroid hormone production and release. Other choices are incorrect as they do not encompass all the functions regulated by TSH.

Correct Answer: C

Rationale: Step-by-step rationale for why choice C (Progesterone) is correct: 1. Progesterone is a major natural progestin produced by the corpus luteum in the ovaries. 2. It plays a crucial role in the menstrual cycle and maintaining pregnancy. 3. Estradiol (choice A), Estron (choice B), and Estriol (choice D) are all estrogens, not progestins. 4. Estradiol is a predominant estrogen in premenopausal women, while Estron and Estriol are less potent estrogens. 5. Therefore, the correct answer is choice C, Progesterone, as it is the primary natural progestin in the body.

Correct Answer: A

Rationale: The statement accurately describes the immune system, making choice A true. The immune system indeed consists of organs, tissues, cells, and cell products that distinguish self from nonself and combat harmful pathogens. Choice B is incorrect as the statement is true. Choice C is incorrect as it implies all choices are correct, which is not the case. Choice D is incorrect as the statement is true, so it is not "none."

Correct Answer: B

Rationale: The correct answer is B: Immunosuppressive agents. Tacrolimus (FK-506) belongs to this class as it suppresses the immune system. It is commonly used in transplant patients to prevent organ rejection by inhibiting T-cell activation. Immunoglobulins (A) are antibodies produced by the immune system. Interferons (C) are signaling proteins released by cells in response to pathogens. Monoclonal antibodies (D) are antibodies produced by identical immune cells and used for targeted therapies. Therefore, the most appropriate classification for tacrolimus is as an immunosuppressive agent due to its mechanism of action and therapeutic use in modulating the immune response.