Editor-In-Chief: C. Michael Gibson, M.S., M.D. 
In biology, an organ (Latin: organum, "instrument, tool") is a group of tissues that perform a specific function or group of functions. Usually there is a main tissue and sporadic tissues. The main tissue is the one that is unique for the specific organ. For example, main tissue in the heart is the myocardium, while sporadic are the nervous, blood, connective etc.
Common animal (including human) organs include the heart, lungs, brain, eye, stomach, spleen, bones, pancreas, kidneys, liver, intestines, skin (the largest human organ), uterus, and bladder. Animal organs inside the body are often referred to as internal organs. The internal organs collectively are often called viscera, the plural of the rarely-used term viscus.
Plant organs can be divided into vegetative and reproductive. Vegetative plant organs are root, stem and leaf, while reproductive are flower, seed and fruit.
The vegetative organs are essential for maintaining the life of a plant (they do the vegetative, vital functions, like photosynthesis), while the reproductive are essential in the reproduction. But, if there is asexual vegetative reproduction, the vegetative organs are those which create the new generation of plants; therefore usually creating a clonal colony.
A group of related organs is an organ system. Organs within a system may be related in any number of ways, but relationships of function are most commonly used. For example the urinary system comprises organs that work together to produce, store, and carry urine.
The functions of organ systems often share significant overlap. For instance, the nervous and endocrine system both operate via a shared organ, the hypothalamus. For this reason, the two systems are combined and studied as the neuroendocrine system. The same is true for the musculoskeletal system, which involves the relationship between the muscular and the skeletal system.But with the help of the chloroplasts to turn the plant its green color.
Organs of the human body by region
Head and neck
- salivary glands
- parathyroid gland
Pelvis and perineum
- Fallopian tube
- urinary bladder
Upper limbs/Lower limbs
- Organ transplant
- Organelles, analogous sub-cellular structures
Template:Organ systems Template:Composition
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