Organ (biology)

from Wikipedia, the free encyclopedia
Scheme: anatomy of a snake:
1 esophagus
2 trachea
3 tracheal lung
4 rudimentary left lung
5 right lung
6 heart
7 liver
8 stomach
9 air sac
10 gall bladder
11 pancreas
12 spleen
13 intestine
14 testes / ovaries
15 kidneys

An organ (from ancient Greek ὄργανον órganon , German 'tool, sensory tool' ) is a specialized part of the body made up of different cells and tissues . An organ is a separate functional unit in a multicellular living being. An organ goes back to its own organ structure and goes through a specific organogenesis . The interaction of the organs realizes the organism . Organs are functionally connected directly to one another through organ systems . Organs are based on the biological differentiation (“division of tasks”) of the cells of real multicellular cells .


Even single-celled organisms have structurally definable areas with higher-level functional units organelles ( "Orgänchen") are called. Eusocial animals form associations of individuals who perform different tasks in a socially differentiated way (“division of labor”) and form 'social organs' in the homologous sense. Societal, social differentiation leads to the organization of social or socio-technical systems .

Functional classification

A uniform assignment of certain functions to organs is often problematic, since many organs in different multicellular living beings can take on different tasks that are distributed over several organs in other living beings. An example of this is the gill of fish , which is used for both breathing and excretion of substances and thus partially replaces the function of a kidney.

Organs in humans

The internal organs of women in the thorax and abdomen (drawing by Leonardo da Vinci around 1507)

Data based on the following comparative values: age: 20–30 years, lifespan: 70 years, height: 170 cm, weight: 70 kg and a body area of ​​1.8 square meters. (The sensory organs and the genital organs were not taken into account here .)

body part Weight proportion of
Muscles 30.0 kg 43.0%
Skeleton without bone marrow 7.0 kg 10.0%
Skin and subcutaneous tissue 6.1 kg 8.7%
Digestive tract 2.0 kg 2.9%
liver 1.7 kg 2.4%
red bone marrow 1.5 kg 2.1%
brain 1.3 kg 1.8%
both lungs 1.0 kg 1.4%
heart 0.3 kg 0.43%
both kidneys 0.3 kg 0.43%
spleen 0.18 kg 0.26%
thyroid 0.02 kg 0.03%
total 70 kg 100%

Plant organs

The term plant organs is understood to mean the individual functional, but not purely morphologically classifiable parts of a plant . Essentially, these are the various shoot , leaf and root types and their individual parts, as well as metamorphoses of the same.

Analogous to the functions of animal organs, the plant organs serve the main tasks

Stem axis



See also


  • Jörn Henning Wolf: The term “organ” in medicine. Broad history of its development. Munich 1971 (= New Munich Contributions to the History of Medicine and Natural Sciences, Medical History Series. Volume 3).

Web links

Commons : Organs  - collection of images, videos and audio files

Individual evidence

  1. ^ Wilhelm Gemoll : Greek-German school and hand dictionary. Munich / Vienna 1965.