Thyroid Gland

• Is a butterfly-shaped mass of tissues located in the anterior part of the neck.

• It is about 2 inches long, with two lobes joined by strands of thyroid tissues called the isthmus.

• Thyroid gland has a rich blood supply. It fact, it has been estimated that about 4 to 5 liter (some 8.5 to 10.5 pints) of blood pass through the gland every hour.

• Thyroid gland secretes three hormones: thyroxine, triiodothyronine and calcitonin.

• The function of thyroxin (T4) and triiodothyronine (T3) are as follows:

1. Controls the rate of metabolism in the body: how cell use glucose and oxygen to
produce heat and energy.
2. Stimulates protein synthesis and thus helps in tissue growth.
3. Stimulates the breakdown of liver glycogen

• Calcitonin controls the calcium ion concentration in the body by maintaining a proper calcium level in the bloodstream.

• Approximately 99% of calcium stored in bones. Calcium is necessary for blood clotting, holding cell together and neuromuscular functions.

• Proper secretion of calcitonin into the bloodstream prevents hypercalcemia, a harmful rise in the blood calcium level.