Describe the hypothalamic-pituitary-thyroid-axis
- Neurosecretory cells of the hypothalamus will secrete TRH via portal circulation
- This will stimulate anterior pituitary cells to secrete TSH
- This will stimulate the thyroid gland to produce large amounts of T4 and smaller amounts of T3
What is the biologically active thyroid hormone?
- This is mainly formed by the peripheral conversion of T4 through deiodinase enzymes
What is the function of the thyroid hormone
- Essential for normal growth and development
- Increase basal metabolic rate (BMR) and affect many metabolic processes
How are thyroid hormones synthesised?
Synthesised in the thyroid via a series of enzyme catalysed reactions
Iodine is taken up into the gland, follicular cells will export iodine into the colloid where the thyroid hormone wil be synthesised via multiple enzymes such as TPO
Synthesis will be controlled via TSH