Thyroid, T3, T4, Hypothalmous and the Pituitary gland...

[Jack Tragic]

 
How Your Thyroid Works

"A delicate Feedback Mechanism" 

 Your thyroid gland is a small gland, normally weighing less than one ounce, located in the front of the neck. It is made up of two halves, called lobes, that lie along the windpipe (trachea) and are joined together by a narrow band of thyroid tissue, known as the isthmus. 

The thyroid is situated just below your "Adams apple" or larynx. During development (inside the womb) the thyroid gland originates in the back of the tongue, but it normally migrates to the front of the neck before birth. Sometimes it fails to migrate properly and is located high in the neck or even in the back of the tongue (lingual thyroid) This is very rare. At other times it may migrate too far and ends up in the chest (this is also rare).

The function of the thyroid gland is to take iodine, found in many foods, and convert it into thyroid hormones: thyroxine (T4) and triiodothyronine (T3). Thyroid cells are the only cells in the body which can absorb iodine. These cells combine iodine and the amino acid tyrosine to make T3 and T4. T3 and T4 are then released into the blood stream and are transported throughout the body where they control metabolism (conversion of oxygen and calories to energy). Every cell in the body depends upon thyroid hormones for regulation of their metabolism. The normal thyroid gland produces about 80% T4 and about 20% T3, however, T3 possesses about four times the hormone "strength" as T4.

The thyroid gland is under the control of the pituitary gland, a small gland the size of a peanut at the base of the brain. When the level of thyroid hormones (T3 & T4) drops too low, the pituitary gland produces Thyroid Stimulating Hormone (TSH) which stimulates the thyroid gland to produce more hormones. Under the influence of TSH, the thyroid will manufacture and secrete T3 and T4 thereby raising their blood levels. The pituitary senses this and responds by decreasing its TSH production. One can imagine the thyroid gland as a furnace and the pituitary gland as the thermostat. Thyroid hormones are like heat. When the heat gets back to the thermostat, it turns the thermostat off. As the room cools (the thyroid hormone levels drop), the thermostat turns back on (TSH increases) and the furnace produces more heat (thyroid hormones).

The pituitary gland itself is regulated by another gland, known as the hypothalamus (shown in our picture in light blue). The hypothalamus is part of the brain and produces TSH Releasing Hormone (TRH) which tells the pituitary gland to stimulate the thyroid gland (release TSH). One might imagine the hypothalamus as the person who regulates the thermostat since it tells the pituitary gland at what level the thyroid should be set.



 
 
 

[p.s.]

Now that was a very well written explanation of thyroid and I would think that most anyone would be able to fully understand the basics of thyroid output from the body with this little article.

[queenofthedamned]

do women have thyroids too?

i thought t-3 was a movie.....geeze, learn something everyday

im such a sarcastic bitch....great post Jacky, thanx for posting

[southernmommie]

I also read an article in my research on thyroids, that because of the meat industry today and what all they inject in their meat, that they don't use iodine anymore and that is partially the cause of higher rates of Americans having thyroid problems. I wish I bookmarked that article. It also said that the synthetic thyroid that is prescribed is faulty and will constantly have to be raised the longer you are on it. Please someone post what you think.

[Camilo]

I also read an article in my research on thyroids, that because of the meat industry today and what all they inject in their meat, that they don't use iodine anymore and that is partially the cause of higher rates of Americans having thyroid problems. I wish I bookmarked that article. It also said that the synthetic thyroid that is prescribed is faulty and will constantly have to be raised the longer you are on it. Please someone post what you think.

Most table salt in the world contains iodine as a regulation, so hypothyroidism due to lack of this mineral is almost extinct through the world.  For what I know, thyroxin works perfectly well, and it tends to be raised in some hypothyroid patients because their "working" gland tends to damage through time, not because of the synthetic drug, but because most people with this disease have an intrinsic glandular problem (we already made clear its not common to have a normal gland and just have lack of iodine).

Cheers,

Camilo

[p.s.]

It's great that you're doing such research (god only knows that more people should), but when doing any research remember if one particular "paper" seems to refute what most other peer reviewed studies are stating then there may be a bit of a glitch in how the study was conducted. IMO always question what you're reading and never take anything totally at face value.