BIOM 3200 Lecture Notes - Lecture 2: Circadian Rhythm, Hypothalamus, Membrane Transport Protein
4 Feb 2017
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Just below the larynx, lateral to the first 3-8 tracheal rings. Connected by the isthmus (very fibrous in cows/horse; indistinct in dogs/cats) The parathyroid gland sits on top of the thyroid gland. Follicles: thyroglobulin is made by the follicle cells and transported into the colloid, thyroglobulin: long peptide chain with tyrosine rings attached. Iodide is brought form the blood into the follicular cells via a sodium-iodide transporter. Iodide is transported to the colloid via the pendrin transporter. Iodide is converted to iodine by tpo (thyroid peroxidase) and added to thyroglobulin. Attachment of 1 iodine on a tyrosine ring = mono-iodotyrosine. Attachment of 2 iodine on a tyrosine ring = diiodotyrosine. A mono and di combine to form triiodothyronine (t3) Two di combine to form tetra-iodothyronine aka thyroxine (t4) T3 and t4 molecules can be on the same thyroglobulin. These thyroglobulin molecules are transported back into the follicles where they are cut up so t3 and t4 are broken apart.
