Anatomy
The thyroid is an organ located in the neck region that is part of the endocrine system. It is shaped like a butterfly (see below on why this description makes me cringe) and it has two lobes (think: the wings) and connected by the isthmus (think: the "butterfly's" body). The thyroid lies against the larynx and near the trachea (see the image below from the Mayo Clinic). The parathyroid glands (four small glands) are located on the "back side" of the thyroid gland. I will explain more about the parathyroids in another blog post at a later date.
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| Photo Credit: http://www.mayoclinic.com/health/medical/IM01872 |
The primary function of the thyroid gland is to produce and excrete hormones. The thyroid hormones are triiodothyronine (T3) and thyroxine (T4) and calcitonin. Most of the T4 is converted to T3 by peripheral organs (the liver, kidney and spleen) because T3 is the more active form of the hormones. Within the thyroid both T3 and T4 are synthesized using iodine and tyrosine, thus iodine is important in proper thyroid tissue functioning (this is why a lack of iodine is bad for thyroid function and also why radioactive iodine is perfect for treatment). Thus, by using iodine and the amino acid tyrosine, thyroid tissue synthesizes T3 and T4 and then excretes the hormones into the body. The hormones are involved in the control of metabolism, growth and development and so much more. To see a list of what T3 and T4 are involved in see The Endocrine Surgeon.
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| Photo Credit: http://www.endocrineweb.com/conditions/thyroid/how-your-thyroid-works |
The thyroid is regulated by thyroid-stimulating hormone (TSH) which is produced and excreted by the pituitary gland. The pituitary gland is regulated by the hypothalamus which releases thyrotropin-releasing hormone (TRH). These hormones regulate by a negative feedback loop. When there is not enough T3 and T4 in the blood stream, the pituitary will release more TSH to signal to the thyroid to produce and release more hormone. But when there is enough hormone, TSH will not be released.
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| Photo Credit: http://en.wikipedia.org/wiki/File:Thyroid_system.png |
There is a basics of the anatomy and physiology (structure and function) of the thyroid gland. To learn more please see the references cited at the end of this blog post. These resources have MUCH more detail about the thyroid... I just wanted to give a basic overview about this tremendous little organ.
In closing, I have to admit -- As someone who studied neuroendocrinology I started to get peeved when a doctor told me basics, such as "Well you see your thyroid is this butterfly shaped organ..." Grrr dude! I KNOW! Many have suggested that as one lives with a condition, you actually become an "unprofessional expert" on the topic. I think with my previous research experience I jumped to this status quickly. As such I became frustrated with physicians who talked down to me about my condition and what was next in the procedures. So this is my backwards way of apologizing to those who have stumbled onto this blog post and see that this is a simplistic explanation of the thyroid. But you have to start somewhere... and because this is the start of My ThyLife, the beginning is a good place to start.
References
Endocrine Surgeon. (nd). What does the thyroid gland do? Retrieved from: http://www.endocrinesurgeon.co.uk/index.php/what-does-the-thyroid-gland-do
Endocrine Web. (October 13, 2010). How your thyroid works. Retrieved from: http://www.endocrineweb.com/conditions/thyroid/how-your-thyroid-works
Mayo Clinic. (April 10, 2009). Thyroid cancer. Retrieved from: http://www.mayoclinic.com/health/thyroid-cancer/DS00492.
MedLine Plus. (March 15, 2011). Thyroid diseases. Retrieved from: http://www.nlm.nih.gov/medlineplus/thyroiddiseases.html
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