Literally meaning: “affecting within ”
Origin: Anc Greek
ενδο-/endo-(= compining form for “inside”, “internal”, “within”)
+εκκρίνω/ecrino(=to secrete)>εκ/ec>(=prefix meaning “out”, “ from”) + κρίνω/crino(=to judge, to separate)
Claude Bernard, in 1855 was first who used for the term ‘internal secretion’ in order to describe the release of glucose from liver glycogen. Ernest Starling (1866–1927) who coined the term “hormone” defined also the term of “endocrine” to contrast the actions of hormones secreted internally (endocrine) with those secreted externally (exocrine) or into a lumen, such as the gastrointestinal tract.
Endocrine is the type of signaling in which a hormone secreted by a cell into the blood and carried by blood and tissue fluids to the cells they act upon.