IPHY 4440 1st Edition Lecture 16 Outline of Last Lecture I Nonspeptides Outline of Current Lecture II Thyroid Gland III Origin of thyroid gland IV T4 synthesis and Metabolism Current Lecture I Thyroid gland Single unpaired gland Honda shaped in human Located ventral to trachea Paired in most non mammals A Thyroid deficiencies 13 million Americans 11 million are women Half of the cases are probably going undiagnosed Hypothyroid Coma II Origin of thyroid gland A Develops from pharynx ventral evagination and later detaches B The thyroid follicle unit of structure function i Follicular epithelium single layer of cells filled with colloid Tgb Follicle Follicular cell makes thyroid hormones C cell makes calcitonin Highly vascularized most vascularized organ entire blood volume 3x per hour C Parafollicular cells C Cells secrete calcitonin CT Hypocalcemic hormone lowers plasma calcium Blood Ca2 Bone Ca2 Note parathyroid glands embedded in thyroid Secrete Parathyroid Hormone PTH Hypercalcemic raises plasma calcium These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute C Thyroid Follicular Cell Follicular cells are not smooth have Mv and SP protein solutions containing Tg D Mv increase surface area III T4 synthesis and Metabolism TSH stimulates synthesis TPO levels Tgb synthesis iodide uptake TPO tyrosine active I MIT DIT DIT T4 TSH stimulates release endosome and endolysosome for Tgb digestion by enzymes T4 T3 deiodinase A Accumulation of iodide i Dietary source Na I co transporter symporter NIS located in basal membrane and concentrates iodide ii Goitrogens cause goiters black iodide uptake block NIS iii Goitrogens that block formation of active iodide decrease TPO Natureal substances Goitrin TH antagonist and PCBs other anti thyroid organic chemicals B Iodide Deficiency reduced T4 plasma levels increase TSH secretion iv hypertrophy cell size v hyperplasia extreme case cell number vi Enlarged thyroid goiter
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