Thyroid is one of the largest among the glands that constitute the endocrine system. The endocrine system regulates various bodily functions, like metabolism, growth, and sexual development. Such regulation is achieved through the hormones produced by the glands, that form the system.
One such gland is the thyroid, that is located below the Adam's apple in the neck. Like other endocrine glands, the thyroid too produces hormones that are very important for the body.
This butterfly-shaped gland has two lobes, that are located on the left and right sides of the trachea (windpipe). It consists of two types of cells called follicular cells and parafollicular cells. While the follicular cells secrete hormones called thyroxine (T4) and triiodothyronine (T3); the parafollicular cells secrete the hormone called calcitonin.
In order to produce these hormones, the thyroid gland needs iodine and tyrosine (an amino acid). It is also noted that thyroid cells are the only cells in the human body, that can absorb iodine.
The main function of the thyroid gland is to produce these hormones, that are directly released into the blood. The thyroid gland is controlled by the hypothalamus and the pituitary gland. The latter is located at the base of the hypothalamus.
The thyrotropin releasing hormone (TRH) released by the hypothalamus stimulates the pituitary to produce thyroid stimulating hormone (TSH). The TSH stimulates the thyroid gland to produce T4 and T3 hormones, which are released into the blood stream. It is the hypothalamus and the pituitary gland, that regulate the levels of thyroid hormones in the blood.
What is the primary function of the thyroid gland? Of course, it is the production of hormones called T3, T4, and calcitonin. The hormones (T3 and T4) are released directly into the bloodstream, which transports them to every part of the body. These hormones enter the body cells, and control the metabolism that takes place in those cells.
In fact, the metabolism that happens in each and every cell is controlled by the thyroid hormones called T3 and T4. These hormones stimulate the metabolism in the cells, where oxygen and nutrients are converted to energy. As cells work efficiently, it reflects in the functions of the organ too.
So, it is also partly responsible for the healthy functioning of the organs. Thyroid has an important role in regulating body temperature too. The hormone calcitonin is associated with regulation of calcium level in the body.
Any abnormality of the thyroid gland and the level of hormones produced by it, can lead to various health problems. The most common thyroid problems are hyperthyroidism, hypothyroidism, goiter, and thyroid cancer. In short, a healthy thyroid is very much necessary for a healthy body.