The adrenal medulla:

Correct Answer: B

Rationale: The correct answer is B because the adrenal medulla secretes epinephrine and norepinephrine, which are hormones involved in the body's response to stress or danger. These hormones help increase heart rate, blood pressure, and energy levels. Choices A, C, and D are incorrect because: A: The adrenal medulla is actually part of the sympathetic division of the autonomic nervous system, which is responsible for the "fight-or-flight" response, not the "feed-and-breed" division. C: Steroids are produced by the adrenal cortex, not the adrenal medulla. D: Cushing syndrome is caused by overactivity of the adrenal cortex, not the adrenal medulla.

Correct Answer: B

Rationale: The correct answer is B because PTH (Parathyroid Hormone) acts on the kidneys by increasing calcium reabsorption and increasing the excretion of phosphate in the urine. PTH stimulates the kidney to reabsorb more calcium to maintain normal blood calcium levels. It also enhances the excretion of phosphate in the urine, helping to lower blood phosphate levels. Option A is incorrect because PTH does not block sodium reabsorption or increase water excretion in the kidneys. Option C is incorrect as PTH does not decrease the reabsorption of both calcium and phosphate. Option D is incorrect because PTH does not increase the excretion of H+ or bicarbonate.

Correct Answer: D

Rationale: The correct answer is D because gonadotropins are secreted by the anterior pituitary gland, aldosterone is produced by the adrenal cortex, and epinephrine is released by the adrenal medulla. The anterior pituitary gland secretes gonadotropins such as FSH and LH. The adrenal cortex synthesizes aldosterone, which regulates sodium and potassium balance. The adrenal medulla produces epinephrine, involved in the fight or flight response. Choices A and C are incorrect because they do not match the correct associations of the hormones with their respective glands. Choice B is incorrect as the adrenal cortex and adrenal medulla are not part of the anterior pituitary gland.

Correct Answer: C

Rationale: The correct answer is C: rapid acting effects. Endocrine properties involve hormones reaching targets through the blood, causing slow and cyclic effects. Rapid acting effects are more characteristic of the nervous system, not the endocrine system. Endocrine effects are caused by chemicals, so choice D is incorrect.

Correct Answer: A

Rationale: The correct answer is A: Negative feedback mechanism. This is because most hormones in the endocrine system are regulated by a negative feedback loop, where the release of a hormone is inhibited once a certain level of that hormone is reached in the body. This helps maintain homeostasis. Incorrect choices: B: Positive feedback mechanism - This is less common in hormone regulation as it leads to amplification of a response rather than maintaining balance. C: Hormone-receptor complex - While hormones bind to receptors to exert their effects, this is not the primary mechanism of hormone regulation. D: Hormone-gene complex - While hormones can affect gene expression, this is not the primary mechanism of hormone regulation in the endocrine system.