Compare the half-life of digoxin and the half-life of digitoxin:

Correct Answer: B

Rationale: The correct answer is B: Digitoxin is greater than digoxin. This is because digitoxin has a longer half-life compared to digoxin. Digitoxin is a more potent cardiac glycoside with a slower elimination rate, leading to a longer duration of action in the body. Digoxin, on the other hand, has a shorter half-life and is eliminated more rapidly. Therefore, digitoxin remains in the body for a longer duration, making it have a greater half-life compared to digoxin. Choices A, C, and D are incorrect as they do not relate to the comparison of half-lives between digoxin and digitoxin.

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.

Correct Answer: A

Rationale: Rationale: 1. Innate immunity is the body's immediate, nonspecific defense against pathogens. 2. It is present from birth and acts quickly to eliminate microbes. 3. It includes physical barriers, chemical barriers, and immune cells like macrophages and natural killer cells. 4. This initial response is crucial for preventing infection. 5. Options B, C, and D do not accurately describe innate immunity, as they refer to other concepts unrelated to the immediate, nonspecific defense mechanisms of the body.