Internal secretion is secretion into the bloodstream. External secretion may be into the intestinal canal or other organs or on to the skin. Compare EXCRETION. secretion. the process by which a useful substance produced in a cell is passed through the plasma membrane to the outside. the substance itself. read more
Secretion, in biology, production and release of a useful substance by a gland or cell; also, the substance produced. In addition to the enzymes and hormones that facilitate and regulate complex biochemical processes, body tissues also secrete a variety of substances that provide lubrication and moisture. read more