The thyroid gland , also called the thyroid gland , is a gland located at the border between the larynx and trachea , at the base of the front of the neck . The task of the thyroid gland, which is regulated by the pituitary gland , is to create and secrete thyroid hormones , which are essential for the growth and development of the human body.
What is the thyroid?
The thyroid gland is positioned at the border between the larynx and trachea. In physiological conditions the gland appears to be small in size. It has a variable weight, which can usually range between 10 and 50 grams . It is formed by two symmetrical lobes communicating in the front thanks to a small isthmus and placed behind against the cartilaginous rings that make up the trachea , and is characterized by a shape reminiscent of a butterfly . The position of the thyroid gland is rather superficial, and this feature allows this gland to be easily accessible on inspection and palpation. Inthe parathyroid or parathyroid glands are located posterior to the thyroid lobes .
The thyroid is a gland covered with a fibrous membrane . It is a highly vascularized gland , which internally contains two different types of cells : parafollicular cells, or C cells, and thyroid follicles . Parafollicular cells are responsible for secreting the hormone that regulates blood calcium levels – called calcitonin . Thyroid follicles are present in higher quantities, and have the role of collecting the iodine that circulates in the blood, and of reworking it in pre-thyroid hormone. This hormone will then be stored in the vesicles that the thyroid follicles have.
Thyroid follicles have a spheroidal or ellipsoidal shape and are equipped with a central cavity which houses a dense substance called the colloid . The colloid is the product of the secretion of the substances that form the wall of the follicles. Inside the colloid there are large quantities of thyroglobulin , an iodinated protein that constitutes the storage system of the main components of the thyroid hormones, T3 (triiodiothyronine) and T4 (tetraiodiothyronine or thyroxine) . The colloid substance, where the need arises , is broken down by the metabolic action of the follicular cells (through the intervention of a particular enzyme) obtaining triiodiothyronine(for about 20%) and tetraiodiothyronine (for 80%), which are introduced into the large blood network that supplies the gland. The cells that make up the thyroid follicles are called thyrocytes .
What is the thyroid for?
This gland is responsible for creating and controlling thyroid hormones , which are essential for the growth and development of the human body. Like all glands in the human body, the thyroid gland is controlled by the pituitary gland.