When blood Calcium level is elevated, the body is in a state of hypercalcemia. Which gland is responsible for secreting a hormone to return Ca2+ level to normal and therefore maintain homeostasis?

Correct Answer: c

Rationale: The correct answer is D: Parathyroid. The parathyroid gland secretes parathyroid hormone (PTH) when blood calcium levels are elevated. PTH acts to increase calcium reabsorption in the kidneys, release calcium from bones, and enhance calcium absorption in the intestines, ultimately lowering blood calcium levels back to normal. A: The hypothalamus plays a role in regulating body temperature, thirst, hunger, and circadian rhythms, but not in calcium homeostasis. B: The pituitary gland secretes various hormones, but none specifically involved in regulating blood calcium levels. C: The thyroid gland secretes thyroid hormones that regulate metabolism and growth, not calcium levels.

Correct Answer: A

Rationale: Step-by-step rationale for why choice A is correct: 1. Enlargement of the thyroid gland is known as a goiter. 2. A goiter can result from various conditions like iodine deficiency or thyroid disorders. 3. It is a common sign of thyroid dysfunction. 4. Goiter may or may not cause symptoms depending on the underlying cause. 5. Therefore, choice A is the correct answer. Summary: - Choice B (Addisonian crisis) is incorrect as it is associated with adrenal insufficiency, not thyroid enlargement. - Choice C (cushingoid appearance) is incorrect as it is related to excess cortisol production, not thyroid enlargement. - Choice D (hypocalcemic tetany) is incorrect as it is due to low calcium levels, not thyroid enlargement.

Correct Answer: A

Rationale: The correct answer is A: Second chemical messenger. cAMP is a second messenger in cellular signaling pathways, relaying signals from extracellular molecules to intracellular targets. It is not a catecholamine (B), steroid (C), or releasing hormone (D). Catecholamines are a class of neurotransmitters, steroids are lipids with different functions, and releasing hormones are secreted by the hypothalamus to stimulate the release of other hormones. Thus, the most descriptive term for cAMP is a second chemical messenger.

Correct Answer: D

Rationale: The correct answer is D: hyperglycemia. Hyperglycemia refers to high blood sugar levels, a hallmark of diabetes mellitus. Insulin therapy is commonly prescribed to individuals with diabetes to help regulate their blood sugar levels. Myxedema (choice A) is associated with hypothyroidism, Graves' disease (choice B) is an autoimmune disorder affecting the thyroid, and diabetes insipidus (choice C) involves the kidneys and has no direct relation to insulin therapy for diabetes. Therefore, hyperglycemia is the most appropriate condition for receiving insulin therapy.

Correct Answer: C

Rationale: The correct answer is C because epinephrine is not a steroid hormone. Steroids are synthesized from cholesterol and have a specific chemical structure, while epinephrine is a catecholamine. Cortisol, aldosterone, and testosterone are examples of steroid hormones, but epinephrine belongs to the class of catecholamines. Therefore, C is incorrect. A, B, and D are correct as they accurately list hormones produced by the anterior pituitary gland, posterior pituitary gland, and gonads respectively.