Organ

from greek: organon - body part
German: Organ

The term organ designates a part of a body consisting of different tissues in the form a functional unit of a whole organism.

Frequently, organs are summarized according to functional criteria like respiratory organs, excretory organs, sexual organs, digestion organs etc.

A more physiologically oriented summarization according to criteria of mutual interaction marks organ systems like cardiovascular system, respiratory system, gastrointestinal system, endocrine system or nervous system.