The Thyroid Gland Flashcards
What does TH produce?
Thyroid Hormones (T3 and T4)
What cells do the thyroid gland contain?
C cells - secretes calcitonin
Follicular Cells - Support thyroid hormone synthesis and surround hollow follicles
What is thyroglobulin?
A large protein rich in tyrosine residues
Describe the link between iodide and follicular cells?
Follicular cells concentrate iodide cells from plasma and transport it to colloid where is combines with tyrosine to form thyroid hormones
How does iodide enter follicular cells?
Na+/I- transporter
How does iodide enter the colloid?
Via the pendrin transporter
How is iodide added on to tyrosine?
Enzymes are exocytosed into the colloid, alongside thyroglobulin. This catalises the reaction of the addition of iodide to tyrosine
What occurs when one iodine molecule to tyrosine?
Monoiodotyrosine is made
What occurs when two molecules of iodide are added to tyrosine?
Diiodotyrosine
What happens when MIT is added to DIT?
T3 is formed
What happens when two molecules of DIT are added together?
T4 is formed
How do cells respond to TSH?
Portions of the colloid are taken back up into the follicular cell by endocytosis. Within the cells, vesicles which contain proteolytic enzymes that cut the thyroglobulin to release thyroid hormones
Where do T3 and T4 circulate?
The plasma
To what does T3 and T4 bind to?
Thyroxine-binding Globulin
When is Thyroid Hormone release stimulated?
During exercise, pregnancy and when you’re cold