This chapter discusses getting introduced to the endocrines, where hormones transmit messages from endocrine glands to target organs, and hence may be referred to as chemical messengers. Substances which are secreted from endocrine cells of the gut are also secreted at several nerve endings. There are several meeting points between the two major regulatory systems of the body such as the endocrine system and the nervous system. All vital functions of the body such as temperature regulation, energy balance, growth, development and reproduction depend upon integrated neuroendocrine activity. The endocrine glands are scattered throughout the body. The quantity of hormones secreted is regulated in accordance with their requirement. Endocrine glands pour their secretions directly into the bloodstream. A receptor is a molecular assembly, which recognizes a specific hormone. The receptors for steroid hormones are located within the cell whereas the receptors for peptide and related hormones are located on the cell membrane.