Thyroid Hormones Flashcards
How many mg of iodine are required each year?
50
Where is iodine absorbed?
from gut tract in same manner as chlorides
What is the ratio for the sodium-iodine symporter?
2:1 in basal membane of thyroid
Where does the engery for the sodium-iodine pump come from?
sodium-potassium ATPase pump
How is iodide transported?
across apical membrane into follicle via chloride iodide counter-trasporter = pendrin
KNOW IGURE 76.2 on IODINE TRANSPORT
look now plz look now`
Where is thyroglobulin secreted?>
thyroid cells
How many tyrosine amino acids are for each thyroglobulin?
70 which bind to iodine
T/F Iodine ions can bind directly to tyrosine
T
What is the major hormonal product in iodine metabolism?
thyroxine (T4) which can be converted to T3
How is thyroxine formed?
two molecules of diiodotyrosine are joined
How is triiodothyronine (T3) formed?
one monoiodotyrosine with one diiodotyrosine
How many molecules of thyroxine are in a thyroglobulin?
30
How are thyroid hormones released?
Form pinocytic vesicles
Fuse with lysosomes that break down thyroglobulin to release T3 and T4
Diffuse into blood
Most released as T4 but can be converted to T3
Most are immediately bound to plasma protein
Once bound released slowly into tissue
What does most of the iodinated tyrosine in the thyroglobulin do?
recycled using deiodinase enzyme
What are the physiological functions of thyroid hormones?
increaed transcription increased cellular metabolic activity Effects growth Effects metablosm of carbs and fats Increase BMR Decrease body weight Increased GI Excitatory on CNS Trouble Sleepings Effect sexual function
What effect does TSH have on thyroid secretion?
increase release from thyroid
What effect does cAMP have on thyroid secretion?
decrease thyroid releasing
What effect does TRH have on thyroid secretion?
increase release of thyroid hormones
What effect does cold have on thyroid secretion?
increase release of thyroid hormones
What are the two causes of Hyperthyroidism
Grave’s Disease, Adenoma
What are the symptoms of hyperthyroidism?
Excitability, intolerance to head, sweating, weight loss, diarrhea, muscle weakness, trouble seeing, hand tremors
What is exophthalmos and when does it occur
eyes appear as they are bulging out because skin around it is retracting
occurs during hyperthyroidism
What is the treatment for hyperthyroidism?
surgical removal of thyroid, or treat with radioactive iodine
What are the causes of hypothyroidism?
Hashimoto disease (autoimmunity)
Endemic goiter
Cretinism
What are the symptoms of hypothyroidism?
Opposite of hyperthyroidism
Myxedema
Atherosclerosis
What is the treatment for hypothyroidism?
oral medication
What are three types of antithyroid drugs?
Thiocyanate ions
Propylthiouracil
Iodides
One of the best known stimuli for increasing the rate of thyroid releasing hormone is
cold
Which of the following is a common cause of hyperthyroidism?
Grave’s Disease
The basal membranes of thyroid cells contain symporters for iodine. What ion is cotransported with iodine by these symporters?
Sodium
Down regulation of receptor may occur as a result of which of the following
Inactivation of some of the intracellular proton signaling molecules.
