Page 302 - Color_Atlas_of_Physiology_5th_Ed._-_A._Despopoulos_2003

C. Synthesis, storage and mobilization of the thyroid hormones
I
Exocytosis
OH OH
Thyro- Tyrosyl residue
globulin Monoiodotyrosyl
residue (MIT)
I – I 0 Iodination
Thyroid peroxidase
I
OH
TSH I
Stored form
Diiodotyrosyl
I I residue (DIT) Thyroid Hormones II
3 O 3’ OH
Endocytosis 5 5’
I
T 3
See B.3 T 3 Triiodothyronyl residue Coupling
T 4
T 4
I I
O OH Plate 11.12
I I
Follicular cell Colloid Tetraiodothyronyl residue
D. Iodine balance
Blood Extracellular
fluid (ECF)
Iodine intake
150µg/day 2–10µg/L I – T 4
(varies greatly) T 4 stores
1–2µg/L T 3 500µg
I –
35–80µg/L T 4
Thyroid gland
T 3
I –
T 4
10–15µg/day
T 4 glucuronide, I – I – Total iodine content
T 3 sulfates 5000–7000µg
I –
Liver I loss increases
–
I – when breast-feeding
(milk contains iodine)
I –
I – I – Kidney
Urinary excretion
Fecal excretion I – I – (increases with
(increases with diarrhea) proteinuria)
10µg/day 150µg/day 289

Despopoulos, Color Atlas of Physiology © 2003 Thieme
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