PTH:

Correct Answer: B

Rationale: The correct answer is B: stimulates osteoclastic activity. Parathyroid hormone (PTH) acts on bones to stimulate osteoclasts, which are responsible for breaking down bone tissue to release calcium into the bloodstream. This process helps increase blood calcium levels. Choices A, C, and D are incorrect because PTH actually increases plasma calcium levels, is not an iodine-containing hormone, and does not stimulate osteoblastic activity.

Correct Answer: D

Rationale: Step-by-step rationale: 1. The anterior pituitary gland is connected to the hypothalamus by the portal capillaries. 2. This connection allows for the transport of releasing hormones from the hypothalamus to the anterior pituitary. 3. Releasing hormones stimulate the anterior pituitary to release specific hormones. 4. This communication pathway is essential for regulating hormone production and maintaining homeostasis. Summary of other choices: A: Incorrect. The neurohypophysis refers to the posterior pituitary, not the anterior pituitary. B: Incorrect. ADH and oxytocin are released from the posterior pituitary, not the anterior pituitary. C: Incorrect. Releasing hormones are produced by the hypothalamus, not the anterior pituitary.

Correct Answer: C

Rationale: The correct answer is C: Stimulating hepatic gluconeogenesis. Insulin's primary function is to lower blood glucose levels by promoting glucose uptake in cells and inhibiting gluconeogenesis in the liver. Choice A is correct as insulin helps lower blood glucose levels. Choice B is correct as insulin promotes protein synthesis. Choice D is correct as insulin promotes fatty acid synthesis to store excess glucose as fat. Therefore, choice C is incorrect as insulin actually inhibits hepatic gluconeogenesis rather than stimulating it.

Correct Answer: A

Rationale: The correct answer is A: are concerned with lactation. Both prolactin and oxytocin are hormones involved in lactation. Prolactin promotes milk production in the mammary glands, while oxytocin stimulates the release of milk from the breasts during breastfeeding. Therefore, both hormones play crucial roles in the lactation process. Choice B is incorrect because oxytocin is secreted by the posterior pituitary gland, not the adenohypophysis. Choice C is incorrect because oxytocin specifically stimulates the contraction of the muscles around the mammary glands to release milk, not the production of milk. Choice D is incorrect because oxytocin is also involved in milk ejection, not just lactation itself.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Glucagon is a hormone secreted by the pancreas. 2. It is released in response to low blood glucose levels to increase blood sugar. 3. Glucagon stimulates the liver to release stored glucose into the bloodstream. 4. Choice A is correct as it accurately describes the function of glucagon. Summary: Choice B is incorrect because glucagon does not regulate sodium and water balance. Choice C is incorrect as glucagon is not a steroid hormone. Choice D is incorrect as glucagon is not a glucocorticoid hormone.