Thyroid Gland
At the picture illustrates, the thyroid is a small butterfly-shaped gland that lies along the trachea (the windpipe) in the front of the neck. It is made up of two lobes, connected by the “isthmus”, a narrow band of tissue. In most people the thyroid is located below the larynx (voice box), but some peoples’ thyroids may be located higher in the neck or even at the back of the tongue  and are referred to as a lingual (near the tongue) thyroid

A normal thyroid gland weighs only 20 grams–less than the 28 grams in an ounce.

The thyroid hormones:
• Regulate the body’s metabolism (conversion of oxygen and calories into energy)
• Affect brain development
• Affect breathing
• Affect heart and nervous system functions
• Affect blood cell formation
• Affect body temperature
• Affect muscle strength
• Affect bone health
• Affect skin dryness
• Affect menstrual cycles
• Affect body weight
• Affect cholesterol levels

HOW DOES THE THYROID WORK?

Iodine is necessary to the proper functioning of the body. The thyroid absorbs iodine and combines the iodine with tyrosine, an amino acid, to produce triiodothyronine (T3) and thyroxine (T4) hormones. (T3 has three iodine molecules and T4 has four iodine molecules.) If your thyroid is working properly, it will produce about four T4 hormones for each T3 hormone, but each T3 hormone is about four times as strong as each T4 hormone. It is the action of T4 and T3 that causes the regulation of the various activities of the body set forth above.
One interesting point is that the T3 created in the thyroid is almost always not the T3 found in our cells. The cells absorb T4 from the bloodstream and convert it into T3 by removing one iodine molecule.