Thyroid gland
From Iusmphysiology
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(Created page with '===TSH and the rest of the family=== *TSH is closely related to FSH, LH, and hCG. **hCG is placental in source. *There is a common alpha-GSU subunit to TSH, FSH, and LH. *There i…')
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Revision as of 15:54, 22 March 2011
Contents |
TSH and the rest of the family
- TSH is closely related to FSH, LH, and hCG.
- hCG is placental in source.
- There is a common alpha-GSU subunit to TSH, FSH, and LH.
- There is a unique beta subunit to each of TSH, FSH, and LH.
- There are many disulfide bridges that hold these hormones together.
Regulation of TSH by TRH
- TRH from the hypothalamus stimulates release of TSH and PRL at the pituitary.
- TRH activates the IP3/DAG pathway in thyrotrope cells of the anterior pituitary.
Thyroid development
- Recall from anatomy that the thyroid develops partially from neural tissue (ectoderm, C cells = parafollicular cells, calcitonin) and partially from the tongue (endoderm).
- The parathyroids are also pulled along by the developing thyroid.
- The female thyroid is larger than the male thyroid.
Sodium / Iodide symporter protein (NIS)
- Note that iodide ions are transported, not iodine molecules.
- The Na / I- symporter is a 13 transmembrane protein.
- Generates a 30x gradient.
Pendrin iodide transporter
- Pendrin is on the apical surface and can move iodide into the colloid via transport coupled with chloride.
