🚶🏻Tyrosine derived from thyroglobulin is combined with iodine to produce T3 & T4 (Thyroxin)
🚶🏻T3 is 5 times more active than T4, though T4 is produced in larger amounts
🚶🏻'ACTIVITIES OF TSH'
✔️ Increase the size & number of thyroid gland cells
✔️ Increase iodide binding
✔️ Increase the release of thyroglobulin into the colloid of the gland
✔️Increase pinocytosis of colloid by the thyroid cells
✔️Increase hormone production
✔️ Increase release of already produced hormone from the bound thyroglobulin and into the bloodstream
🚶🏻In bloodstream the hormones are 99% protein bound.
🚶🏻Thyroxin Binding Globulin (TBG) has the greatest affinity; but Albumin has the greatest capacity for binding the hormones. Thyroxine-binding prealbumin (TBPA) also bind them
🚶🏻REGULATION OF HORMONAL ACTIVITY
✔️ For regulation of the hormonal levels, the negative feedback is mediated by the unbound free fraction
✔️ Stress inhibits production
✔️ Warmth decreases production
✔️ Cold increases production
✔️ Glucocorticoids, dopamine & somatostatin inhibit TSH secretion
Reference: Smith T, Pinnock C, Lin T. Fundamentals of Anaesthesia, 3rd edn. Cambridge: Cambridge University Press, 2009; p. 474 .
#Thyroid , #Thyroxin , #Medicine , #Physiology
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