Iodine Flashcards
Where is most of bi iodide located
Why’s it there
In the thyroid gland
To make thyroid hormone
How is iodide transported into the thyroid gland
Active transport through a Na / I symporter (NIS)
Explain the first 2 steps of synthesis of thyroid hormone
Iodide is transported into thyroid cell by symporter, and then Iodide binds to thyroglobulin
Once inside the thyroid cell or colloid what is iodine always bound to
Thyroglobulin
What enzyme condenses iodide with thyroglobulin
Thyroid peroxidase
What is primary enzyme in thyroid gland to make thyroid hormone
Thyroperoxidase
Once hormones are made in the colloid what is their fate?
They go back into the cell via endocytosis and then sent into circulation
Once hormones leave the cell what is their fate
They usually bind to proteins like albumin
What happens to the small percentage of hormones that don’t bind to a protein when they leave the cell
Goes on to exert its effects on the body
Which hormone is more potent T3 or T4
T3
Which is more prevalent in plasma T3 or T4
T4
How can T4 be changed into T3
What tissues can do this?
Gets de iodinated to T3
By liver, kidneys, brain, pituitary, and brown adipose tissue
What enzyme deiodinates T4
What is it dependent upon?
5-deiodinase
Selenium dependent
Why is iodine important for energy metabolism
It is part of the thyroid hormones
Where do thyroid hormones mediate their effects in the cells
Nucleus
