Thyroid Hormone Production Flashcards
Where is the thyroid gland located in the body?
It is located on the anterior and lateral aspects of the trachea, between the laryngeal prominence (Adam’s apple) and suprasternal notch.
What is the functional unit of the thyroid gland called?
Thyroid follicles, consisting of a single layer of follicular cells surrounding a lumen filled with colloid.
What are follicular cells also known as?
Thyrocytes.
What two components are necessary to produce thyroid hormones in the colloid?
Iodine and thyroglobulin.
How is iodine absorbed and stored in the body?
Iodine is absorbed from food, converted into iodide, and stored in the thyroid gland.
What is the daily recommended intake of iodine for an adult?
150 micrograms per day.
What enzyme helps iodide and thyroglobulin combine in the colloid?
Thyroid peroxidase.
What are MIT and DIT?
MIT (Monoiodotyrosine) and DIT (Diiodotyrosine) are intermediate products of thyroid hormone synthesis.
What thyroid hormones are formed from MIT and DIT?
T3 (from MIT + DIT) and T4 (from DIT + DIT).
What is the more active thyroid hormone, T3 or T4?
T3 is the active form; T4 is converted into T3 in the body.
What enzyme converts T4 into T3?
Deiodinase (Type 1 in liver/kidney, Type 2 in brain/pituitary).
What trace element is required for deiodinase to function?
Selenium.
What proteins mainly bind thyroid hormones in the bloodstream?
Thyroxine-binding globulin (TBG) and albumin.
Where do thyroid hormones exert their effects in a cell?
Inside the nucleus, directly on DNA to alter transcription.
What are some physiological effects of thyroid hormones?
Regulate metabolism, growth, cholesterol clearance, heart rate, mental alertness, bone remodeling, and fetal brain development.
