The control systems in the body of the animal and human being represented by endocrinology and nervous system, and the growth processes in the animal are under the endocrine glands beside that the changes are largely under the control of the glands despite the fact that hormonal control are slow in their work, compared with the rapid neurological control. The endocrine system control many functions such as growth, reproduction, metabolism as well as regulation of the b internal temperature and others, such as secretion an chemicals from endocrine cells in small quantities up to pico grams, that called hormones and accomplish specialized task in other cells "target cells." Hormones being known as chemical messengers, that perform important roles in the control of the vital actions that occur in living organisms and excreted in mammals by endocrine glands to move to various parts of the body by the blood. The hormones are divided in mammals to three groups, the first group contains peptide hormones that include the hypothalamus and pituitary as well as insulin and glucagon. The second group is called steroidal hormones, which includes hormones of the adrenal cortex and the sex glands, such as androgens and estrogens and the third group include amino derivative hormones such as adrenaline and hormones of the thyroid hormones. The hormones are synthesized in endocrine gland, which has no channels "Ductless." It can be defined as chemicals that appear as a result of its composition in the endocrine gland of the human body excreted directly into the blood and transported to other organs of the body by the blood streams directly affecting the effectiveness of the body's life. This definition could be applied to non-hormonal substances such as carbon dioxide, which can be transferred to various organs of the body during breathing and neurological process such as acetyl choline, synthesized by the nerve tissue and transported to other locations in the body.