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| Unit 8: Demos |
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Insulin
structure (9b) Thyroid hormones (12b) Other hormones involved in regulation of blood sugar (14b) Adrenal cortex negative feedback (15e) Estrogen receptor (optional) External versus internal fertilization |
Two Thyroid Hormones
Two Thyroid Hormones
These two thyroid hormones are structurally identical, except that T3 has three iodine atoms and T4 has four. The function of these hormones is to regulate metabolism in most body cells. The thyroid secretes mainly T4, most of which is converted to T3 by an enzyme in target cells. T3 binds more avidly than T4 to receptors in the target cells. The secretion of both of these thyroid hormones is controlled by the hypothalamus and pituitary in a complex negative feedback system.
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