If you look at the thyroid gland with the naked eye, you will notice that it resembles a butterfly (or it can be compared to the letter “H”). It consists of two lobules – right and left. And between them, like a bridge, an isthmus. On average, the thyroid gland of an adult weighs 12-25 g and 2-3 g in a newborn. The dimensions of each lobe are 2.5-4 cm in length, 1.5-2 cm in width and 1-1.5 cm in thickness. A volume of up to 18 ml for women and up to 25 ml for men is considered normal. The weight and size of the thyroid gland varies from person to person.

The thyroid gland is covered with a fibrous capsule on the outside . The capsule is a thin plate, which, growing together with the tissue of the gland, sends processes into the thickness of the organ and divides the gland into separate lobules . It is in the thickness of these processes of the capsule that the smallest blood vessels, lymphatic vessels and nerve endings are located.  

The thyroid gland is an important and intensively working organ. Therefore, it is very well supplied with blood. By the amount of blood that passes through the gland in one minute, it is second only to the kidneys (not even to the heart and brain).

In addition, a large number of nerve endings are laid in the thickness of the gland, which regulate its work (sympathetic and parasympathetic). It is along these fibers that command signals from the central nervous system go , which enhance or inhibit its work.

Structural and functional units, that is, a complex of “working” cells of the thyroid gland, are follicles – closed spherical or slightly elongated vesicular formations. In the lumen of the follicle, a colloid , thyroglobulin, accumulates . From which, in the future, thyroid hormones are formed.   

The thyroid gland is a very important, one of the most important organs of the human endocrine system, because the effects of the action of thyroid hormones are very diverse and affect almost all organs and organ systems of the human body.