The mechanism of stimulant purgatives is:

Correct Answer: B

Rationale: The correct answer is B because stimulant purgatives work by increasing motility and secretion in the intestines. This leads to enhanced peristalsis, resulting in the expulsion of fecal matter. Choice A is incorrect as stimulant purgatives do not directly affect the volume of non-absorbable solid residue. Choice C is incorrect as altering fecal consistency is not the primary mechanism of stimulant purgatives. Choice D is incorrect as stimulant purgatives primarily work by increasing motility and secretion, not the water content in the intestines.

Correct Answer: A

Rationale: The correct answer is A: 10-30 minutes. Nitroglycerin is rapidly absorbed sublingually and has a short duration of action due to rapid metabolism. This short duration is crucial for managing acute conditions like angina. Choice B (6-8 hours) is incorrect because sublingual nitroglycerin does not have such an extended duration of action. Choice C (3-5 minutes) is too short as the effects of nitroglycerin last longer. Choice D (1.5-2 hours) is also incorrect as it overestimates the duration of action. Thus, the correct answer is A due to the rapid onset and short duration of sublingual nitroglycerin.

Correct Answer: D

Rationale: Certainly! Angiotensinamide is a peptide derived from angiotensinogen that activates angiotensin receptors. Step 1: Angiotensinamide is a component of the renin-angiotensin system and binds specifically to angiotensin receptors. Step 2: Angiotensin receptors are a distinct class of receptors that respond to angiotensin peptides, including angiotensinamide. Therefore, the correct answer is D. Choices A, B, and C are incorrect because angiotensinamide does not activate adrenergic, cholinergic, or dopaminergic receptors, but rather specifically binds to angiotensin receptors.

Correct Answer: D

Rationale: The correct answer is D because the synthesis and release of thyroid hormones are controlled by a complex feedback loop involving multiple glands and organs. The hypothalamus secretes thyrotropin-releasing hormone (TRH) which stimulates the anterior pituitary to release thyroid-stimulating hormone (TSH). TSH then acts on the thyroid gland to stimulate the synthesis and release of thyroid hormones (T3 and T4). The blood levels of thyroid hormones provide feedback to the hypothalamus and pituitary to regulate the secretion of TRH and TSH, completing the feedback loop. Choices A, B, and C are incorrect because the control of thyroid hormone synthesis and release involves the interaction of multiple glands and is not solely regulated by any single gland or factor.

Correct Answer: A

Rationale: The correct answer is A because the normal ovary does indeed produce small amounts of androgens such as testosterone, androstenedione, and dehydroepiandrosterone. This is a well-established fact in endocrinology. Choice B is incorrect because it contradicts the established knowledge about hormone production in the ovary. Choice C is incorrect as it doesn't provide any relevant information to confirm or deny the statement in the question. Choice D is incorrect because not all of the statements are true. Only option A correctly reflects the fact that the normal ovary produces small amounts of androgens.