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ENDOCRINE PHYSIOLOGY

Thyroid Cland: Function

Thyroid Follide Lumen

G₀|gj    Endoplasmic

appanlui Thyroglobulin ^re,itulum

Peroxidase

Deiodinase

Proteolysis

Er.dinIom-

Colloid

droplrls

Lysosomes

Apic.nl ^;

membranę

J. Perkins ^CI®SJ

Figurę 8.9 Thyroid Gland Function_

The thyroid gland is composed of follides tormed by epithelial cells. These follicular epithelial cells synthesize, storę, and secrete thyrox-ine (l₄l and triiodothyronine (Ty). The thyroid gland actively takes up iodide, iodinates tyrosine molecules (MIT = monoiodotyrosine;

DIT = diiodotyrosine), couples these together to form T₄ and T„ and Stores these linked to thyroglobulin in the thyroid follide. In the pros

ence of thyroid-stimulating hormone (T$H), thyroglobulin is end<-« tosed and T, and T_t are released into the blood (TSH also stimula’*-the synthesis of T„ T*, and thyroglobulin). Most of the secreted h-monę (90%) is in the form of T*. which serves as a prehormone. because is converted to the morę active form T-, by peripherć sues.

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