Thyroid physiology and biochemistry Flashcards
what are the biologically active thyroid hormones? which is most important / most biologically active?
T3 and T4
T3
where is the apical side of the follicular cell?
facing colloid
in which cells is thyroglobulin syhnthesized?
follicular cell
how is sodium pumped into the cell, to allow for sodium / iodide symport?
sodium / potassium ATPase
where does organification of iodide take place?
exocytotic vesicles
oragnification of iodide: enzyme, reaction, substrate, yield
- enzyme: thyroid peroxidase (accepts electrons from iodide)
- reaction: thyroid peroxidase oxidizes and attaches iodide
- substrate: iodide is attached to tyrosyl residues of thyroglobulin
- yield: MIT and DIT
TRH release is mediated by what type of signaling?
GPCR (PLC - IP3 - calcium)
TSH binding involves what type of signaling?
GPCR (cAMP protein kinase A)
TSH triggers what processes?
iodide transport
transcription of thyroglobulin
transcription of TPO
what are the carrier proteins for T4 and T3?
globulin
albumin
transthyretin
lipoproteins
which carrier protein has a high affinity for T4?
globulin
metabolism of T3 and T4 are catalyzed by what enzymes?
type I-III deiodinases
type I deiodinase: function, locations, products
- function: outer and inner rings activity toward T4
- location: liver, kidney, thyroid
- products: T3 or rT3
type II deiodinase: function, locations, products
- function: outer ring activity toward T4 (INACTIVATES)
- location: vast tissue distribution
- products: intracellular T3
type III deiodinase: function, locations, products
- function: inner ring activity toward T4 and T3
- location: brain, placenta
- products: rT3, T2
