Your thyroid works in concert with a whole team of glands to keep your body running smoothly. Like mailmen, they deliver messages (hormones) between themselves and other parts of your body so all those tiny cells are regulated and functioning at the proper levels.
The thyroid's main job is to produce two very special hormones. They both have deliciously unpronounceable names, but luckily, they also have abbreviations if you're not in the mood for a tongue twister. The first one is triiodothyronine and the second one is thyroxine (or tetraiodothyronine) -- but to their friends, they're known respectively as T3 and T4. The method behind the moniker madness stems from the fact that T3 gets three atoms of iodine, while T4 gets -- ready for this? -- four atoms of iodine. Take a couple tyrosine amino acids, slap on a few other ingredients and you've got yourself some hormones ready to hit the town.
After they're released by the thyroid, these little guys hitch a ride in the bloodstream and get to work. Like door-to-door salesmen or restaurant flyer distributors, the hormones stop at each and every cell, knock on the door and tell the cell if it needs to be consuming more oxygen and nutrients -- thereby stepping up its rate of metabolism -- or vice versa. The hormones also have a hand in stimulating heart muscle contraction and nerve function, increasing the utilization of cholesterol and nutrients, ensuring normal growth and brain development -- some pretty important stuff!
Most of the cells in the thyroid are called follicular cells, but there are others calledparafollicular cells (or C cells) which produce another important hormone called calcitonin. The thyroid also has four teensy glands called the parathyroid glands, which are embedded in the back of the thyroid and produce the hormone creatively called parathyroid hormone. These two hormones, calcitonin and parathyroid hormone, work in tandem to keep your body's calcium level in check. We all know how important calcium is to prevent diseases like osteoporosis, but too much of a good thing isn't ideal either. That's where calcitonin comes in; it decreases how much calcium is in your blood, while parathyroid hormone works to beef those levels up.
Ready to find out how these microscopic masterminds impact you in the bigger scheme of things? On the next page, we'll learn what an unruly thyroid affects and what you can do to turn it around.