The endocrine system begins with glands which secrete regulatory chemicals known as hormones into the bloodstream. The bloodstream whisks the hormones to the intended target, supplying the necessary bodily function with an adequate supply of hormones. Target cell, the reception area of the appropriate reception of the hormones, give out feedback signals which explains to the endocrine glands how much hormone is necessary.

 The human body contains variable glands throughout the body. Each, however, is classified either as endocrine glands or exocrine glands. Exocrine glands are responsible for the production of mucous, sweat, saliva, and other bodily excretions. The endocrine glands produce enough variants within the entire system that they are worthy of an entire system devoted specifically to their responsibilities, thus the human body has an endocrine system.

 The endocrine glands secrete their product directly into the bloodstream, bypassing the need for a duct system that the exocrine glands require. Chemicals that can not be deposited into the blood are deposited into the interstitial fluid which surrounds the gland.