A 45-year-old woman comes to her physician complaining of nervousness and an unexplained weight loss of 25 pounds over the last 3 months, despite that she is not dieting or exercising. On her physical examination, the doctor notices protruding eyes, her skin is moist and warm and her fingers have a tremor. Compared to a normal individual, the biopsy of her thyroid gland would most likely reveal which of the following?

a) Hepatic portal system: This carries blood from the gastrointestinal tract to the liver, not the brain.

b) Coronary circulatory system: This system supplies the heart muscle, not involved in hormone transport from hypothalamus.

c) hypophyseal portal system: The hypophyseal portal system is a specialized vascular system that transports releasing and inhibiting hormones from the hypothalamus to the anterior pituitary.

d) Hypothalamus-hypophysial tract: This is a neural pathway used to transport ADH and oxytocin to the posterior pituitary, not the anterior.

a) Synthesis of thyroglobulin by the follicular cells: This occurs after iodide has been trapped and transported into the follicular lumen.

b) Oxidation of iodide by the follicular cells: This is a later step; iodide must first be trapped before it can be oxidized into iodine.

c) Coupling of T1 and T2: This is one of the final steps in T₃/T₄ synthesis where iodinated tyrosines are joined.

d) lodide trapping by the follicular cells

Iodide trapping is the first step, where follicular cells actively transport iodide from the bloodstream into the thyroid follicle using sodium-iodide symporters.