noun, plural: secretions
(1) The physiological process of synthesizing and eventually releasing substances from the interior of a cell to its exterior
(2) The substance secreted
In eukaryotes, cells primarily involved in secretion have well-developed endoplasmic reticulum and Golgi apparatus. Secretion may also occur without involving the classical ER-Golgi pathway. Examples are blebbing, lysosomal secretions, etc.
In humans, the glands comprised mainly of secretory cells are responsible for the production and release of substances essential to different bodily functions. The glands can be classified into two kinds:
- endocrine glands (glands secreting substances into the bloodstream or to adjacent target cells)
- exocrine glands (glands secreting substances onto the surface or exterior through a duct)
In prokaryotes, such as bacteria, secretion occurs by releasing substances from the bacterial cell interior to its external environment.
Word origin: Latin secretio, from secernere (to secrete)