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Physiology Endocrinology metabolism a9233d86

Thyroid peroxidase will help in all the following except:

A
Iodide trapping
B
Iodide to iodine
C
Binding thyroglobulin
D
Secretion of thyroglobulin into colloid
High-Yield Explanation
Ref: 1. Guyton & Hall. Textbook of Medical Physiology. 12th Edn. Chapter 76. Thy raid - Metabolic Hormones. Page 908-909. (Picture Ref)2 .Berne & Levy. Physiology 6th Ed. Chapter 41. Thyroid glan d. Page 72 7, 729. 3. WF Canong. Review of Medical Physiology 23nlEdn.Chapter 20.The Thyroid Gland Page 304Explanation:Iodide is actively transported into the gland against chemical and electrical gradients by a 2Na+-H'symporter (NTS).The process of concentrating the iodide in the cell is called iodide trapping.Iodide trapping requires energy, which is provided by Na+, K+-ATPase in the plasma membrane.Expression of the NIS gene is inhibited by iodide and stimulated by TSH.The first essential step in the formation of the thyroid hormones is conversion of the iodide ions to an oxidized form of iodine (Oxidation).The binding of iodine with the thyroglobulin molecule is called organification of the thyroglobulin.Thyroglobulin is continually exocytosed into the follicular lumen and is iodinated to form both monoiodotyrosine (MIT) and diiodotyrosine (DID. After iodination. two D1T molecules are coupled to form T4, or one MIT molecule and one DIT molecule are coupled to form TvCoupling also occurs between iodinated tyrosines that remain part of the primary structure of thyroglobulin.This entire sequence of reactions is catalyzed by thyroid peroxidase (TPO)

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