endocrine

The body's glands remove specific substances from the blood and alter them for rerelease into the blood or removal. Glands such as those that produce saliva and sweat secrete their products through tiny ducts or tubes on or near the body's surface. The glands without ducts, called the endocrine glands, instead secrete their products into the bloodstream; the endo- root indicates that the secretions are internal rather than on the surface. The endocrine system includes such glands as the pituitary (which controls growth, regulates the other endocrines, and performs many other tasks), the thyroid (another growth gland that also influences metabolism), the adrenals (which secrete adrenaline and steroids), the hypothalamus (which influences sleep and weight regulation), and the ovaries (which produce eggs). Endocrine problems are treated by endocrinologists.