The endocrine glands, the products which, are called hormones, located in parts of the body that are generally hidden from view. This system is closely related to the nervous system and the secretions are effective on top of each other and have direct interactions. Various secretions that are secreted in small amounts from cells, sacs and glands are able to affect large areas of membership in a short time. The endocrine glands, together with the nervous system, coordinate the actions and activities of different parts of the body. The endocrine glands are usually classified into three groups. The main endocrine glands, their role is to secrete hormones, including the epiphyseal, adrenal, thyroid, parathyroid, and pituitary glands. Mixed glands - where cells, sacs, and endocrine tissue are located within the exocrine tissue. Such as pancreas, ovaries, testicles, kidneys, thymus, and placenta. Diffuse endocrine system - in which hormone-producing cells are widely distributed in the digestive and respiratory systems. In terms of effectiveness, its amount is related to the anatomical and physiological needs of the body. Internal disorders of the body and the external environment can cause changes in the number of secretions, which appear as a result of irregularities in the body, which can often be treated by timely diagnosis of the complication; Because the endocrine glands control the body's metabolic rate; Participates in the metabolism of organ materials.