endocrine system [Gk, endon + krinein, to secrete; systema] , the network of ductless glands and other structures that elaborate and secrete hormones directly into the bloodstream, affecting various processes throughout the body, such as metabolism, growth, and secretions from other organs. Glands of the endocrine system include the thyroid, the parathyroid, the anterior pituitary, the posterior pituitary, the pancreas, the suprarenal glands, and the gonads. The pineal gland is also considered an endocrine gland because it is ductless, although its precise endocrine function is not established beyond its involvement in daily, monthly, and annual rhythms. Various other organs have some endocrinological function. See also the Color Atlas of Human Anatomy, pp. A18-A19. Compare exocrine.
