Iodide ions cross from the bloodstream into follicle cells via

Correct Answer: C

Rationale: Iodide enters thyroid follicle cells via active transport, using the sodium-iodide symporter (NIS), against its gradient, powered by sodium's electrochemical gradient. Simple diffusion lacks a carrier, facilitated diffusion doesn't use energy, and osmosis moves water. Active transport's energy dependence distinguishes it, essential for thyroid hormone synthesis, concentrating iodide for T3/T4 production.

Correct Answer: A

Rationale: The anterior pituitary arises from oral ectoderm, specifically Rathke's pouch, during embryogenesis, forming hormone-secreting cells. Neural ectoderm forms the nervous system (including posterior pituitary), mesoderm muscles/bones, and endoderm digestive organs. Oral ectoderm origin distinguishes anterior pituitary development, key to its endocrine role, contrasting with neural or internal layer derivatives.

Correct Answer: D

Rationale: Directing blood flow is a circulatory system function, adjusting tissue perfusion via vessels to maintain homeostasis, not an endocrine role. The endocrine system regulates immunity (e.g., cortisol affects immune cells), reproduction (e.g., FSH, LH drive gonadal function), and heart rate/blood pressure (e.g., epinephrine increases both), using hormones like adrenaline or aldosterone. Water balance, another endocrine task (e.g., ADH), was replaced here to fit four options, but blood flow direction relies on vascular dynamics, not glandular secretion. This distinction highlights endocrine's chemical signaling versus circulatory mechanics, key to system roles.

Correct Answer: B

Rationale: Hyperparathyroidism involves excess parathyroid hormone (PTH), raising serum calcium by mobilizing it from bones and increasing kidney reabsorption, while lowering phosphorus both are abnormal. Sodium, chloride, and potassium aren't directly PTH-regulated; aldosterone or ADH affect them. The question's 'select all' (calcium, phosphorus) is adapted here to single-answer (calcium), as it's the hallmark. Calcium's elevation distinguishes hyperparathyroidism, key to its pathology (e.g., kidney stones), unlike unaffected electrolytes.

Correct Answer: B

Rationale: Diabetes insipidus results from ADH deficiency or renal resistance, impairing water reabsorption, causing dilute urine and thirst. Excess GH is gigantism, other options are absent. Renal ADH unresponsiveness distinguishes it, critical for fluid balance disorders, contrasting with growth or pituitary excess conditions.