Class 3 Thyroid Flashcards
What does the thyroid gland regulate?
Metabolic rate
No thyroid gland will decrease metabolic rate by how much? Excess can raise metabolic rate by how much?
- Decrease 40-50%
- Increase 60-100%
Where is the thyroid located and how much does it weigh?
- Below the larynx, anterior and on each side of trachea
- 15-20 grams
Name the 4 hormones produced by the thyroid?
- Thyroxine (T4)
- Triiodothyronine (T3)
- Reverse T3 (rT3)
- Calcitonin
Thyroid gland is made up of what type of cells?
-Cubodial epithelial cells which surrounds a colloid matrix
What is required for thyroid hormone synthesis?
-Iodine
What two thyroid hormones are most important metabolic control?
T4, and T3
How are T4 and T3 different?
- Thyroid secretes 93% T4 compared to 7% T3
- T3 is more potent and cleared more rapidly
Explain how thyroid hormone is released?
- TRH is released by the hypothalamus
- TRH causes the release of TSH by the Pituitary
- TSH causes the release TH
What happens to T4 in the tissues?
Converted to T3
99% of TH is bound to what?
-Protein (TGB and Albumin)
TH activates what two intracellular processes?
- Gene transcription
- Protein and enzyme production
The increase in gene transcription and protein/enzyme production by TH does what?
-Increase the metabolic rate
TH increases the size and number of __________.
Mitochondria
In general the TH effect what 3 things
- Metabolism
- Growth and development
How does TH stimulate carbohydrate metabolism?
- Increase uptake of glucose
- enhances glycolsis and insulin secretion
How does TH stimulate fat metabolism?
- Mobilize lipids
- Decrease fat stores
- Decrease cholesterol
How does TH effect vitamins?
-Increase the need for vitamins
TH can decrease body weight, what can counter act that?
-TH increases appetite
How does TH effect Beta and alpha adrenergic receptors?
- Increases Beta
- Decreases Alpha