Resistin, an insulin antagonist, is a hormone produced by the __________.

Correct Answer: A

Rationale: The correct answer is A: adipose tissue. Resistin is primarily produced by adipose tissue and is known to antagonize the action of insulin, leading to insulin resistance. Adipose tissue is a major source of various hormones, including resistin. Option B: heart, and Option C: liver, are not the correct answers because resistin is not known to be produced by these organs. Option D: hypothalamus, is also not the correct answer as resistin is not produced by the hypothalamus. In summary, the correct answer is A because resistin is primarily produced by adipose tissue, which plays a significant role in insulin resistance.

Correct Answer: a

Rationale: The correct answer is A: Isometric contraction. In isometric contraction, the muscle contracts but there is no movement at the joint. In this scenario, Adonis's biceps brachii contract but the weight is not moved, indicating an isometric contraction. In concentric contraction (B), the muscle shortens to move the weight upward. In eccentric contraction (C), the muscle lengthens while under tension, controlling the descent of the weight. Incomplete tetanus (D) refers to a state where muscle fibers are stimulated rapidly but not at the maximum rate to produce sustained contractions.

Correct Answer: A

Rationale: The correct answer is A: calcium. PTH (parathyroid hormone) activates vitamin D, which in turn helps in the absorption of calcium in the intestines. This is crucial for maintaining bone health and normal calcium levels in the blood. Vitamin C (Choice B) is not directly related to PTH or vitamin D in calcium absorption. Iron (Choice C) absorption is influenced by factors other than PTH and vitamin D. Phosphate (Choice D) absorption is primarily regulated by fibroblast growth factor 23 and not by PTH or vitamin D. Thus, the correct answer is A as it directly corresponds to the role of PTH and vitamin D in calcium absorption.

Correct Answer: B

Rationale: The correct answer is B: ADH. Hypothalamic-releasing hormones regulate anterior pituitary hormones. ADH is produced in the hypothalamus but stored and released by the posterior pituitary, not controlled by a hypothalamic-releasing hormone. ACTH, growth hormone, and prolactin are all controlled by hypothalamic-releasing hormones such as CRH, GHRH, and PRH, respectively.

Correct Answer: C

Rationale: The correct answer is C because ACTH (adrenocorticotropic hormone) stimulates the adrenal cortex to secrete cortisol. Step 1: ACTH is released from the anterior pituitary gland. Step 2: ACTH stimulates the adrenal cortex to produce and release cortisol. Choice A is incorrect because CRH is secreted by the hypothalamus to stimulate ACTH release. Choice B is incorrect because cortisol is produced in the adrenal cortex, not the adenohypophysis. Choice D is incorrect because the adrenal medulla secretes adrenaline and noradrenaline, not glucagon.