Tropic hormones ________.

Correct Answer: A

Rationale: The correct answer is A because tropic hormones are hormones that regulate the function of other endocrine glands, such as ACTH (adrenocorticotropic hormone) and TSH (thyroid-stimulating hormone). These hormones stimulate the target glands to release their own hormones. Choice B is incorrect because tropic hormones specifically regulate other endocrine glands. Choice C is incorrect because tropic hormones typically exert their effects by binding to specific receptors on target cells, rather than directly activating genes. Choice D is incorrect because GH (growth hormone) and PRL (prolactin) are not tropic hormones as they do not directly regulate the function of other endocrine glands.

Correct Answer: D

Rationale: The correct answer is D because steroids act by binding to intracellular receptors, forming a hormone-receptor complex that directly interacts with the cell's DNA to regulate gene expression. This leads to changes in protein synthesis and cell function. A: Extracellular receptors do not have specificity for a single amino acid sequence on the hormone. Steroids act intracellularly. B: Formation of cyclic AMP is associated with G-protein coupled receptors, not steroid receptors. C: Second-messenger systems are typically involved in signaling cascades triggered by extracellular ligands, not steroids.

Correct Answer: A

Rationale: The correct answer is A because glucocorticoids, like cortisol, increase blood glucose levels through gluconeogenesis, elevate fatty acid levels for energy production, and promote amino acid breakdown for energy. This helps the body respond to stress by providing necessary energy sources. Additionally, glucocorticoids can enhance blood pressure to ensure adequate blood flow during stress. Option B is incorrect because glucocorticoids typically increase heart rate and blood pressure to support the stress response. Option C is incorrect as glucocorticoids do not stimulate the release of insulin; instead, they can have an anti-insulin effect. Option D is incorrect as glucocorticoids do not block neurotransmitters but rather modulate the stress response at various levels.

Correct Answer: A

Rationale: The correct answer is A: Adrenal gland. The adrenal gland is located atop the kidneys and is responsible for producing hormones such as adrenaline and cortisol. This gland plays a crucial role in the body's stress response and regulation of metabolism. The other choices are incorrect because the hypothalamus is located in the brain and regulates hormone secretion, the pancreas is located in the abdomen and is involved in insulin production, and the thyroid gland is located in the neck and controls metabolism.

Correct Answer: B

Rationale: The correct answer is B: prolactin. Prolactin is the hormone responsible for the development of the breast tissue and milk production in females. It is secreted by the anterior pituitary gland and plays a key role in lactation. Oxytocin is involved in milk ejection, not breast development. Estrogen plays a role in breast development but not specifically in milk production. Antidiuretic hormone regulates water balance and has no direct role in breast development or milk production.