Thyroid Hormone, Thyroid Stimulating Hormone, and More...

I am particularly interested in the thyroid gland, since I have been diagnosed with hypothyroidism, which means my body is not making enough thyroid hormone. In Anatomy & Physiology, we have identified the thyroid gland on various models in lab, and we have also learned about the physiology of the thyroid gland. I am surprised to find out that many people I talk to are either being treated for hypothyroidism, or think they have it, so I thought I would share what I know here.

The first picture is a model of the larynx. The thyroid gland is the big yellow blob in the lower left corner of the picture. The second picture is the neck and chest of a torso model. The thyroid gland is the big yellow blob attached to the larynx!



Hormones made by the Thyroid Gland
Calcitonin works with Parathyroid Hormone (which is made by the Parathyroid Glands) to regulate calcium in the bloodstream and calcium in the bones. Calcitonin stimulates osteoblasts (causing bone formation by increasing calcium in the bone matrix and removing calcium from the bloodstream). In other words, irregular levels of these hormones could lead to osteoporosis.

What about other hormones made by the thyroid gland?
At the microscopic level, the thyroid gland has Thyroid Follicles surrounded by Follicular Cells. The Follicular Cells make Triiodothyronine (T3) and Tetraiodothyronine, also known as Thyroxine (T4). Together these 2 hormones are referred to as “Thyroid Hormone”.

These thyroid hormones are mainly regulated by Thyroid Stimulating Hormone (TSH), which is produced at the Anterior Pituitary Gland. In my case, my TSH was recently at 6.69, which is considered elevated. According to Medline, normal TSH values are .4 to 4.0. If your TSH is high, it means your thyroid hormones are low. Your doctor may prescribe a synthetic thyroid hormone known as Synthroid, which I had a bad reaction to, or a natural (but less used) thyroid hormone known as Armour Thyroid.

What do increases in “Thyroid Hormone” cause?
1. Nervous System – Increases activity and necessary also for proper fetal development of the nervous system (also necessary after birth for normal nervous system)

2. Skeletal System – Promotes normal bone growth while growing in height AND promotes remodeling of bone after a fracture or as a result of change in weight, etc.

3. Cardiovascular System - Increases Heart Rate, Force of contraction of cardiac muscle and blood pressure

4. Respiratory System – Increases respiratory rate and depth of respiration

5. Increases Metabolic Rate – Increases heat production AND Increases rate of catabolism of carbohydrates, proteins and lipids