Secretion

Secretion, complex substance produced in certain cells or glands in the body and discharged into or expelled from the body; also, the process of forming and discharging the substance. External secretions, those released through ducts from the exocrine glands onto an internal or external surface of the body, include tears, mucous, sweat, bile, saliva, and pancreatic juice. Internal secretions, or hormones, are released from the endocrine glands directly into the blood or lymph and effect processes distant from the point of origin. These include thyroxine, insulin, epinephrine, androgens, and estrogens.