Term
| Which cells are responsible for synthesis of thyroid hormones? |
|
Definition
| Thyroid epithelial cells. |
|
|
Term
| The thyroid epithelial cells - the cells responsible for synthesis of thyroid hormones - are arranged in spheres called what? |
|
Definition
|
|
Term
| The thyroid follicles are filled with what? |
|
Definition
|
|
Term
| Thyroid follicles are filled with colloid. What is colloid? |
|
Definition
| A proteinaceous depot of thyroid hormone precursor. (Proteinaceous means made of or containing protein). |
|
|
Term
| The thyroid gland also houses other cells other than the epithelial cells. Which cell is it (2 names) and what hormone does it secrete? |
|
Definition
| Parafollicular or C cells. They secrete the hormone calcitonin. |
|
|
Term
| Thyroid hormones are derivatives of the amino acid ________ bound covalently to _______. |
|
Definition
|
|
Term
| T4 is also known as ______. Where does the 4 in the name come from? |
|
Definition
| Thyroxine. There are 4 Iodine molecules. |
|
|
Term
| T3 is also known as _____. Where does the 3 in the name come from? |
|
Definition
| Triiodothyronine. There are 3 Iodine molecules. |
|
|
Term
| Since thyroid hormones are poorly soluble in water, almost all T4 & T3 circulating in the blood is bound to _________. |
|
Definition
|
|
Term
| What is the principle carrier of thyroid hormones? Where is this carrier synthesized and what kind of protein is it? |
|
Definition
| Thyroxine-binding globulin. Synthesized in the liver and is a glycoprotein. |
|
|
Term
| Besides the main carrier thyroxine-binding globulin, what are 2 carriers of theyroid hormones are there? |
|
Definition
|
|
Term
| Thyroid follicles serve as both a _______ and ______ for production of thyroid hormones. |
|
Definition
|
|
Term
| The recipe for making thyroid hormones calls for what 2 principle raw materials? |
|
Definition
|
|
Term
| Explain how Tyrosines, 1 of the 2 principle raw materials of thyroid hormones, are made & where they come from. |
|
Definition
| Tyrosines are provided from a large glycoprotein scaffold called thyroglobulin, which is synthesized by thyroid epithelial cells and secreted into the lumen of the follicle - colloid is essentially a pool of thyroglobulin. A molecule of thyroglobulin contains 134 tyrosines, although only a handful of these are actually used to synthesize T4 and T3. |
|
|
Term
| Explain how Iodine, 1 of the 2 principle raw materials of thyroid hormones, is made and where it comes from. |
|
Definition
| Iodine, or more accurately iodide (I-), is avidly taken up from blood by thyroid epithelial cells, which have on their outer plasma membrane a sodium-iodide symporter or "iodine trap". Once inside the cell, iodide is transported into the lumen of the follicle along with thyroglobulin. |
|
|
