mnsr 37 Flashcards
thyroid gland is attached to the — and downgrowth is from the floor of the — and it weighs — and its highly —
- larynx
- pharynx
- 25 grams
- vascularised ( which has greater blood supply than kidney and is 2nd only to adrenal gland in blood flow )
a — is a bi-lobed structure with one love either side of the trachea
thyroid gland
each follicle consist of fluid filed spaces surrounded by a layer of — and these spaces are filled with jelly like substance called —- and it consist of — , surrounded by highly vascularised connective tissue lightly stained with — , they are held together by — which is a connective tissue supporting the follicles
follicular cells , colloid ,thryoglubin which is a protein prosecutor to the thyroid hormone , follicular cells , stroma
TRS is released by —
TSH is released by —
hypothalamus
anterior pituitary which promotes the release of T3 , T4
T3 + T4 :
has +ve effect on :
-ve effect on :
- +ve on the target organ and -ve on hypothalamus and pituitary
Acumalation and storage of — is essential for the production of thyroid hormone .
Active — are located — membrane of the —
- iodine and its ingested in small quantities in our diet ( 150 ug is suffiencet in diet )
- idoine pump is located outside the membrane of the follicular cells
the uptake of iodine is partially under the control of the —-
pituitry hormone TSH ( thyroid stores 4,000 ug of iodine )
– stimulates follicular cells to increase the uptake of — from the bloodstream , the follicular cells pumps the iodide into the —-
TSH , idoide , follicular spaces
Iodide (I -) is oxidised by — to from —
TPO ( thyroid peroxidase ) , Iodine (I2)
— is a prosecutor to thyroid hormone and produced within the follicular cells and forms —
thyroglobulin (Tg) , homodimers
( each thryroglobulin has 140 tyrosine amino acids)
hormone formation process :
1- the oxidation of iodide to iodine by the enzyme TPO
2- after they get released into the follicular cells they iodine binds to tyrosine amino acid residue of the thryoglibulin folicule
3- each tyrosine has two or one iodine attached to form MIT ( monoiodotyroxine ) or DIT ( diiodotrysoine ) , these remain attache to the Tg protein
4- peroxide combines 2 DIT and produce T4 more than T3
5- throyglobin remains in the colloid until TSH stimulates the endocytosis of the colloid back to the follicular cells
5- protease will cleave T3 and T4 and hormones will be released into the bloodstream
5- the rest of Tg protein will be degraded and any iodinated tyrosine not incorporated in T3 or T4 is recycled
Peroxide is more efficient at combining — which makes — generation more easily thus the thyroid gland produces more – -than —
- 2 DIT
- T4 more readily
- T4 more than T3
thyroid also contains smaller amount of — which are also called – and they produce —
- parafollicular , c-cells , calcitonin
peroxidase will form — between iodanated tysoine
covelant bonds
2 DITS forms
T4