Choose the drug irritating the gut and causing increased peristalsis:

Correct Answer: A

Rationale: The correct answer is A: Phenolphthalein. Phenolphthalein is a stimulant laxative that irritates the gut lining, leading to increased peristalsis and bowel movements. This mechanism helps relieve constipation. Methyl cellulose (B) is a bulk-forming laxative that works by absorbing water to form a soft bulk, not by irritating the gut. Proserine (C) is a cholinesterase inhibitor used for myasthenia gravis, not for gut stimulation. Mineral oil (D) is a lubricant laxative that works by coating the stool and preventing water absorption, not by irritating the gut.

Correct Answer: D

Rationale: The correct answer is D because increased myocardial oxygen consumption is not a mechanism of nitrate's beneficial clinical effect. Nitrate works by decreasing myocardial oxygen requirement, relieving coronary artery spasm, and improving perfusion to ischemic myocardium, which collectively help in managing angina. Increased myocardial oxygen consumption would worsen ischemia, contradicting the purpose of using nitrates.

Correct Answer: C

Rationale: Step 1: Vasoconstrictors cause constriction of blood vessels. Step 2: Constriction of blood vessels leads to decreased peripheral blood flow. Step 3: Decreased peripheral blood flow can result in reduced oxygen delivery to tissues. Step 4: General unwanted effects of vasoconstrictors include decreased peripheral blood flow, making choice C correct. Summary: A: Incorrect - Vasoconstrictors do not always directly increase arterial pressure. B: Incorrect - Vasoconstrictors may not always increase cardiac output. D: Incorrect - Vasoconstrictors do not directly increase blood volume; they may redistribute blood flow.

Correct Answer: C

Rationale: The correct answer is C because thyrotrophin, also known as thyroid-stimulating hormone (TSH), stimulates the release of thyroxine (T4) and triiodothyronine (T3) from the thyroid gland. This occurs through the activation of adenylate cyclase and the subsequent increase in cAMP levels, leading to the synthesis and secretion of thyroid hormones. Choices A and B are incorrect as they pertain to the iodine-related processes within the thyroid follicles, but TSH itself does not directly stimulate these processes. Choice D is also incorrect as TSH does not promote the de-iodination of thyroid hormones; instead, it supports their synthesis and release.

Correct Answer: D

Rationale: The correct answer is D, "All of the above." Progestins have noncontraceptive clinical uses such as hormone replacement therapy, dysmenorrhea, and endometriosis. Progestins can help regulate hormone levels during menopause (A), reduce menstrual pain (B), and manage symptoms of endometriosis (C). Each of these uses is supported by scientific evidence and clinical practice. Therefore, the correct answer includes all the possible noncontraceptive clinical uses of progestins. The other choices are incorrect because they do not encompass all of the noncontraceptive clinical uses of progestins as listed in the question.