Endocrine - Thyroid Physiology High Yield Concepts Flashcards
Thyroid hormones consist of…
T3
T4
rT3
Thyroid intermediates consist of…
MIT
DIT
_ is the predominate hormone secreted by the thyroid gland
T4
_ is the most potent thyroid hormone at the receptor level.
T3
The steps of thyroid hormone synthesis are:
Uptake → Oxidation → Iodination → Coupling → Endocytosis → Proteolysis → Secretion
What parts of the hypothalamus are involved in T3 and T4 synthesis?
Follicular Cells
Colloid
What are the functions of TSH?
Regulation of T3 and T4
Enlargement of the thyroid gland
How does TSH regulate T3 and T4?
via its actions on NIS, TPO, and proteolytic enzymes
How do T3 and T4 travel through the body?
In the blood, majority are bound to TBG rendering them inactive, but some are in active free form
What occurs to T4 once T3 and T4 enter a cell?
The majority of the T4 is converted to T3 catalyzed by 5’-monodeidodenase
T3 has a high binding affinity for…
Thyroid-binding receptor
How do thyroid hormones function?
Thyroid hormones work via nuclear receptors and transcription and translation to increase protein synthesis
What are thyroid hormones important for?
Normal growth and development
What do thyroid hormones result in?
Based on which proteins are synthesized the net result is an ↑ in metabolic rate, heat production, and CO
The most common cause of hypothyroidism is…
Hashimoto’s thyroiditis presenting with decreases metabolic rate, ,weight gain, fatigue, and a puffy face
