thyroid function 2
Card Set Information
thyroid function 2
thyroid function #2
What two hormones play an important role during pregnancy?
hCG & estrogen
Reasons thyroid function tests during pregnancy could be difficult to interpret?
hcg & estrogen can cause increased thyroid hormone levels in the blood.
The function of the thyroid gland is to what?
synthesize thyroxine (T4) and triiodothyronine (T3)
Thyroid cells are the only cells in the body that can absorb this element?
Where is iodine found?
in many foods
Thyroid cells combine iodine and the amino acid, tyrosine to produce?
T3 and T4
The T3 and T4 hormones are then released into the bloodstream and are transported thru the body where they play an important role in what?
The thyroid gland is controlled by the __________________ gland.
When levels of T3 and T4 drop too low, what produces the thyrotropin releasing hormone (TRH)?
hypothalamus stimulates the pituitary gland to produce?
TSH in turn stimulates the thyroid gland to produce more?
Under the influence of ____, the thyroid will manufacture and secrete ________, thereby raising their blood levels.
TSH; T3 & T4
The hypothalamus senses the rise in T3 and T4 and responds by what?
decreasing its TRH production Thyroid Hormones
Thyroid hormones are present in the circulation but are mainly bound to what?
Approximately 75% to 80% are bound to ______________ (inactive), and about 20% are bound to _________ (less active).
thyroxine binding globulin(TBG); albumin
Why is measuring free thyroid hormones generally the most useful in determining thyroid function?
Because only a small fraction of thyroid hormones is unbound and biologically active,
The TBG protein is generally increased by ___________, and rises especially during _________.
Growing levels of estrogen leads to an increase in ?
thyroid hormone binding
Less free hormones lead to the stimulation of ________ and further production of _________________.
TSH ; thyroid hormones
A normally functioning thyroid is able to adapt to changes of TSH and thyroid hormones, and the level of _________________ is not altered.
Free thyroid hormone
What is Thyroxine?
hormone referred to as T4 because it contains four iodine atoms.
The normal thyroid gland produces about 80 percent of ____ and is its primary secretory product.
How is T4 converted to T3?
by the removal of an iodine atom.
What is predominantly bound by proteins?
T4 and is prevented from entering tissues.
What makes free T4 the most effective way to determine thyroid function?
ability to enter tissues