5 - Thyroid gland Flashcards
hormone of thyoid galnd
t3 and t4
t3
triiodothyronine
t4
thyroxine
what are c clels
they secre calcitonin - the ca regulating hormone
what are follicular cells
they support the thryoid syntheis and surround the hollow cells, produng enzymes that make thyroid hores and thyroglobulin
concentrate iodide from the plasma and transport it to the colloid
what is in teh centre of the thyroid follicles
colloid - whihc has 2 - 3 months supply of th
thyroglobulin
a large protin rich in tyrosine resiules
what are tyrod hormes made from
tyrosine resius and iodide
how does iodien enter the follicular celsl
though the na+/I- tranpoerter symport, this takes up iodien against a conception gradient
how does iodien move form teh follicular cells to the colloid
thrugh the pendrin transpeorter
what happens in the thyroid due to tsh
parts of the colloid are taken to the follicular cell, where they are packaged into vesicules with proteolytic enzymes which cut the thryoglobuin and release thyroid hormoens
why do t3 and t4 need to be stored in vesicules
as they are lipid soluble so would be pass out of the foliuclar cell membrane
what to t3 and t4 bind to whwhen they leave the thyroid
thyroxine bind globulin
what is mit
onoiodotyrosine - addition of one iodine to tyrosine
what is dit
diiodotyrosine - adding a second iodine to mit
what is mit conguating with dit
t3
what is dit congulating with dit
t4
what turns iodide to iodine
enzyes exocytosed in the colloid
what percent of t3 and t4 are not plasma bound
0.2%
half life of t4 and t3
t4 - 6 day
t3 - 1 day
why is half life of t4 higher then t 3
as thyroxine bind globulin has a higher affinity for it prealiin git slowly into the plasma
what triggers tsh and trh, free hormones or hormone bound to thyroxine
only free hormones
is there more t4 or t3
about 50 times more t4 than t3
whihc binds to the cell more frequenly t3 or t4
t3
whch has a higher effect t3 or t4
t3 - 3 - 5 times the effect compared with t4
what happens to t4
it tunrs to t3 by deionisase enzymes in the plasma
or it is deiodnated inside targed cells also to t3
what causes realse of thryoid hormone
cold, exercise and pregnacny
why does pregancy cuase relase of thryoid hormoen
for the growth of the feautus
where is thryoid horme froeaed from
trh, form hypothal
cause tsh from pituratory in anteiro
what inhibtis tsh
somatosain and glucocoricoids
what inhibits t4 to t3
glucocoritisoids
what is the effect of thryoid hormone
it increase metabolic rate and theromoges though catbolism and anabolims
increases hepatic glucogenosis
proteolsysi
lipolysis
growth
gh receptor expression
brain development in utero
what is hyperthryoidsm diseases
graves
thyroid adenoma
what is a thryoid adenoma
hormone secreting thryoid tumour
what is graves disease
where auo anti bodies miminc tsh activating the thyroid gland
what happens to tsh realses in graves
swiches it off due to high level of thyroid hormone
why does thryoid gland grow in graves
due to hyperactivy of the thyroid gland due to antiboid that minci tsh
what is hyper thyroidsm symptons
increased metobolic rate - weight loss and heat production
increased protein break down - muscle weakness and weight loss
altered nervous system function - hyperexitable reflex and psycolical disturbances
elevated cardiovascular function 0 due to th permissues to adrenaline causing bh recpotes
what are causes of hypotherids
idopathic
deficenciy in dietary iodine
hashimotos disease
what is hashimoos diseaw
auto immune attack of thryoid gland
what is socures of diatary iodine
milk, fish,, seafood and seaweed
symptoms of hypothryoidsm
decreaed metabolic funciton - weiht gaain
disrupind protin synthesi - brittle nails and thin skin
alterd neou system - slow speech
reduced cardiocu function, slow heart rate and pulse
what is a goite
inlagement of thyrodi gland, vissible on neck
which condiion si gotire presnt in
both hypo and hyperthoids
why is gotire prent in hypothyoidms
due to no negative thead back to antieor peituratory ad hypoth, mean they increa smmount of trh and tsh
