Mineralocorticoid is to aldosterone as glucocorticoid is to ________.

Correct Answer: C

Rationale: Mineralocorticoids regulate electrolyte and fluid balance, with aldosterone being the primary mineralocorticoid. Glucocorticoids regulate metabolism and immune response, with cortisol being the primary glucocorticoid. Therefore, the correct answer is C: cortisol. Testosterone (A) and estrogen (B) are sex hormones, not corticosteroids. Epinephrine (D) is a hormone produced by the adrenal medulla, not a corticosteroid.

Correct Answer: B

Rationale: The correct answer is B because steroid hormones bind to receptor proteins in the nucleus, forming a hormone-receptor complex that directly influences the expression of specific genes. This process leads to the activation or repression of particular genes, resulting in changes in cellular functions. Choices A and C are incorrect because steroid hormones do not bind to receptors in the plasma membrane or use second messengers for signal transduction. Choice D is incorrect as steroid hormones do not directly regulate genes at the plasma membrane level.

Correct Answer: C

Rationale: The correct answer is C: positive feedback. Oxytocin release is triggered by the positive feedback mechanism. When oxytocin is released in response to a stimulus, it further stimulates the release of more oxytocin, intensifying the effect. This continuous loop enhances the initial response, leading to a cascade effect. Negative feedback (choice A) works to maintain homeostasis by counteracting the initial stimulus, which is not the case for oxytocin release. Neutral feedback (choice B) does not play a significant role in regulating hormone release. Choice D is incomplete and irrelevant.

Correct Answer: A

Rationale: Rationale: 1. Hashimoto's disease is characterized by the immune system attacking the thyroid gland, leading to hypothyroidism. 2. It is an autoimmune condition where the body produces antibodies that target and destroy thyroid cells. 3. This results in a decrease in thyroid hormone production. 4. Graves disease (choice B) is a form of hyperthyroidism caused by an overactive thyroid gland. 5. Myxedema (choice C) refers to severe hypothyroidism but is not autoimmune. 6. Acromegaly (choice D) is a disorder caused by excess growth hormone production, unrelated to thyroid function.

Correct Answer: B

Rationale: The correct answer is B: right atrium of the heart. Atrial natriuretic hormone (ANH) is produced by specialized cells in the right atrium of the heart called atrial myocytes. When the heart senses an increase in blood volume or pressure, these cells release ANH to help regulate fluid and electrolyte balance by promoting sodium and water excretion by the kidneys. Choices A, C, and D are incorrect because ANH is not produced by the kidney tubules, adrenal cortex, or pancreas. The primary site of ANH production is specifically within the cardiac atria.