hormone

n. a substance secreted into the bloodstream by an endocrine gland or other tissue or organ to regulate processes in distant target organs and tissues. These secretions include those from the anterior and posterior pituitary gland; the corticosteroids and epinephrine, secreted by the adrenal glands; and the sex hormones released by the reproductive glands. Other organs that secrete hormones include the hypothalamus (see hypothalamic hormone) and the stomach, which emits at least five: cholecystokinin, enterogastrone, gastrin, ghrelin, and secretin. —hormonal adj.