Regulation of the thyroid

on 29.8.08 with 0 comments

  • hypothalamus: TSH-releasing hormone is produced, stimulating the pituitary to release TSH, which stimulates the thyroid gland to secrete thyroxine, T4

  • only 20% of T3 is produced by the thyroid. it is 5-10x more potent than T4 because it binds with higher affinity to the thyroid hormone receptor

  • the remaining 80% comes from peripheral conversion of T4 to T3

  • thyroid binds to a nuclear receptor that directly regulates transcription of genes

Thyroid hormones

  • basic structure comprises two benzene rings connected by an ether bond

  • in T4, each benzene ring has two iodine substituents

  • T3 is missing an iodine on the terminal benzene

  • reverse T3 is missing an iodine from the other (non-terminal) benzene

Category: Endocrinology Notes



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