BIOM 3200 Lecture Notes - Lecture 3: Trachea, Thyroid, Hypothalamus

• School: University of Guelph
• Department: Biomedical Sciences
• Course: BIOM 3200
• Professor: Tami Martino

Document Summary

Lateral to the first 3-8 tracheal rings. Two lobes + isthmus very fibrous isthmus in cows/horses, indistinct isthmus in dogs/cats) with lots of tyrosine side chains on it. Receptor binding: thyroid receptors: thyroxine t4 + carrier bp, t4-t3 (triiodothyronine, t3 uses binding proteins to enter nucleus, hormone-receptor complex bids. Step 1: enzyme thyroid peroxidase (tpo) removes an electron from iodide to produce iodine. Step 2: iodine binds tyrosine residues in thyroglobulin (tg) to form mono- and di- iodinated tyrosine residues. Step 3: condensation of mit and dit residues to form triiodothyronine (t3) and tetraiodothyronine (t4) Transport of thyroid hormones: >99% of thyroid hormones in blood circulation bound to a plasma carrier protein called thyroxin-binding globulin (tbg, once in carrier protei(cid:374), it (cid:272)a(cid:374)"t do a(cid:374)(cid:455)thi(cid:374)g u(cid:374)til it"s released i(cid:374) target orga(cid:374). Harmless in tbg: only free fractions of thyroid hormones biologically active (so it has to lose the carrier protein to produce effects in target cells, stress/cold increases thyroid.