Agents Affecting theThyroid Gland
Agents Affecting the Thyroid Gland
Thyroid Hormones (TH)Thyroid gland is one of the most importantendocrine glands.Thefolliclecellscansynthesize and secrete thyroid hormones thatregulate the growth and metabolism of body
Thyroid Hormones (TH) Thyroid gland is one of the most important endocrine glands. The follicle cells can synthesize and secrete thyroid hormones that regulate the growth and metabolism of body
Thyroid GlandAnterior View@Novartis
Thyroid Histology
Thyroid Histology
Synthesis of Thyroid HormonesIodide trapping. Oxidation of iodide by thyroidal peroxidase to iodine· Iodinated tyrosine residues within the thyroglobulinmolecule to form monoiodotyrosine(MIT)anddiodotyrosine (DIT)Coupled by peroxidase:MIT+DIT-→triiodothyronine(T3)DIT+DIT-→thyroxine(T4)
Synthesis of Thyroid Hormones • Iodide trapping • Oxidation of iodide by thyroidal peroxidase to iodine • Iodinated tyrosine residues within the thyroglobulin molecule to form monoiodotyrosine (MIT) and diiodotyrosine (DIT) • Coupled by peroxidase: MIT+DIT→triiodothyronine(T3 ) DIT+DIT→thyroxine(T4 )
THYROIDGLANDPeroxidaseThyroglobulinTransportMIT-DIT-T3-TlodidesProteolysislodides,thioamidesSCN-,CIO4T4, T3PERIPHERALBLOODTISSUESTAIpodate,β-blockers,corticosteroidsT3
H工HH一H-C-HHO0C~C~NH2H-C-HH-C-HH-C-HHHO0C~C~NH2HO0C~CNH2HO0CC~NH2TyrosineHHHTriiodothyronineThyroxine (T4]"Reverse T3"[T3](inactive]
Storage and Release ofThyroid HormonesTH is stored in the gland as thyroglobulinform in which enzymatic hydrolysis releases Tand little T into the circulation. About 80% ofthe released T is deiodinated in the peripheraltissues to the biologically active T3 (30-35%)and biologically inactive reverse T (45-50%);thus most circulating T, is derived from T4
Storage and Release of Thyroid Hormones TH is stored in the gland as thyroglobulin form in which enzymatic hydrolysis releases T4 and little T3 into the circulation. About 80% of the released T4 is deiodinated in the peripheral tissues to the biologically active T3 (30-35%) and biologically inactive reverse T3 (45-50%); thus most circulating T3 is derived from T4
HypothalamusTRH一AnteriorPituitary+TSHThyroidT3, T4
Anterior Pituitary Hypothalamus Thyroid TRH TSH T3, T4
Physiologic Roles of Thyroid Hormones. Regulating growth and physical development·Affecting metabolism· Stimulating CNS and cardiovascular system
Physiologic Roles of Thyroid Hormones • Regulating growth and physical development • Affecting metabolism • Stimulating CNS and cardiovascular system