Endocrine glands

Article title:

Endocrine glands

Article text:

Hormones cannot be classified into any one class of chemical compounds. All hormones are organic substances, but some of them are proteins, others are simpler compounds, such as amino acids or steroids. The distinctive feature of all hormones is that they are secreted by cells in one part of the body and carried by the blood to some other part, where they act in very small concentrations, regulating and coordinating the activity of cells.

All hormones (and, of course, the glands that secrete them) are necessary for the normal functioning of the body; deficiency or excess secretion of any of them leads to a characteristic pathological condition. These conditions are often called functional diseases, in contrast to diseases caused by vitamin deficiencies, and from infectious diseases caused by the presence of some pathogenic agents, such as bacteria. Endocrine glands are characterized by the fact that they secrete substances not into a duct leading to the surface of the body or to one of the internal organs, but directly into the blood. For this reason, they are sometimes called ductless glands or endocrine glands.

Some of them - the thyroid gland, parathyroid glands, pituitary gland and adrenal glands - secrete only hormones and are indeed completely devoid of excretory ducts. Others, such as the pancreas, ovaries and testes, carry out both external secretion (through ducts) and internal secretion, that is, they secrete hormones carried by the blood.

Hormones regulate many processes in the body - metabolism, the functioning of internal organs, growth, development and functioning of the reproductive system. Disturbances in the functioning of the endocrine glands can lead to serious diseases.