Select the Statement That Best Describes the Formation of Triiodothyronine

question 4

Multiple Choice

Select the statement that best describes the formation of triiodothyronine (T₃) and thyroxine (T₄) .

• A) The secretion of T₃ and T₄ is under the control of the hypothalamic-anterior pituitary-thyroid axis. The hypothalamus secretes TSH (thyroid-stimulating hormone), which travels in the portal vein to the anterior pituitary. The anterior pituitary is then stimulated to secrete TRH (thyrotropin-releasing hormone) into the bloodstream. TRH binds to receptors on the plasma membrane of the thyroid gland, stimulating the production of T₃ and T₄.
• B) The secretion of thyrocalcitonin is under the control of the hypothalamic-anterior pituitary-thyroid axis. The hypothalamus secretes thyrocalcitonin, which travels in the portal vein to the anterior pituitary. The anterior pituitary is then stimulated to secrete TSH (thyroid-stimulating hormone) into the bloodstream. TSH binds to receptors on the plasma membrane of the thyroid gland, stimulating the production of T₃ and T₄.
• C) The secretion of T₃ and T₄ is under the control of the hypothalamic-anterior pituitary-thyroid axis. The hypothalamus secretes TRH (thyrotropin-releasing hormone), which travels in the portal vein to the anterior pituitary. The anterior pituitary is then stimulated to secrete TSH (thyroid-stimulating hormone) into the bloodstream. TSH binds to receptors on the plasma membrane of the thyroid gland, stimulating the production of T₃ and T₄.
• D) None of these are correct.

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