The islets of Langerhans:

Correct Answer: B

Rationale: Step 1: Islets of Langerhans are clusters of cells in the pancreas. Step 2: These cells secrete insulin to lower blood sugar levels and glucagon to raise blood sugar levels. Step 3: Therefore, choice B is correct as it accurately describes the function of the islets of Langerhans. Summary: Choices A, C, and D are incorrect as islets of Langerhans are not found in the adenohypophysis, do not secrete steroids, and do not secrete releasing hormones.

Correct Answer: B

Rationale: The correct answer is B: hyperglycemia. Insulin deficiency leads to an inability to regulate blood sugar levels, resulting in elevated blood glucose levels. Without insulin, glucose cannot enter cells for energy utilization, leading to hyperglycemia. The other choices are incorrect because: A: Hypocalcemia is low calcium levels, not caused by insulin deficiency. C: Cushing syndrome is a hormonal disorder caused by prolonged exposure to high levels of cortisol, not related to insulin deficiency. D: Adrenal shock is a life-threatening condition due to insufficient adrenal gland function, not directly caused by insulin deficiency.

Correct Answer: C

Rationale: Rationale: 1. Aldosterone regulates sodium and water balance in the body. 2. Deficiency leads to decreased sodium reabsorption, causing low blood volume. 3. Low blood volume results in hypotension due to reduced blood flow to tissues. 4. Choices A and B are incorrect as aldosterone deficiency does not cause high blood pressure or low potassium levels. 5. Choice D is incorrect as goiter formation is mainly related to thyroid hormone imbalance, not aldosterone deficiency.

Correct Answer: C

Rationale: The correct answer is C: Thyroid. Iodine is essential for thyroid hormone production. A colloid is a gel-like substance found in the thyroid follicles. Goiter is a condition of thyroid enlargement. The other choices are incorrect because the pancreas (A) produces digestive enzymes and hormones like insulin, the parathyroid (B) regulates calcium levels, and the neurohypophysis (D) is part of the pituitary gland responsible for releasing hormones like vasopressin. Thus, the correct choice is the thyroid gland due to its association with iodine, colloid, and goiter.

Correct Answer: D

Rationale: Elevated plasma cortisol levels suppress the secretion of ACTH through negative feedback. High cortisol levels signal the hypothalamus and pituitary to decrease the release of CRH and ACTH, respectively, to maintain homeostasis. This is a regulatory mechanism to prevent excessive cortisol production. A: Elevated blood glucose levels do not directly suppress ACTH secretion. B: Dietary iodine is not related to ACTH secretion. C: CRH stimulates ACTH release, so it does not suppress its secretion.