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For other uses, see Organ (disambiguation)

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.

Contents 1 Animal organs 2 Plant organs 3 Organ systems 3.1 List of major human organ systems 4 Organs of the human body by region 4.1 Head and neck 4.2 Back 4.3 Abdomen 4.4 Pelvis and perineum 4.5 Upper limbs/Lower limbs 5 See also

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.Asexual reproduction is usually done by single celled organisms.

Main article: Biological system

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 the skeletal system and the digestive system.

There are typically considered to be eleven major organ systems of the human body.

• Digestive system - Absorption of nutrients and excretion of waste.
• Skeletal system - Support and movement, lymphocyte production
• Muscular system - Support and movement, production of heat
• Nervous system - Integration and coordination through electrochemical signals
• Endocrine system - Integration and coordination through hormones
• Cardiovascular system - Internal transport
• Respiratory system - Elimination of CO₂ and absorption of O₂
• Reproductive system - Production of offspring.
• Integumentary system - Body covering
• Lymphatic system - Regulate fluids and immunity
• Urinary system - Excretion of nitrogenous waste, and maintain homeostasis of electrolytes

• brain
• face
• ears
• orbit
• eye
• mouth
• tongue
• teeth
• lips
• nose
• scalp
• larynx
• pharynx
• salivary glands
• meninges
• thyroid
• parathyroid gland

• vertebra
• spinal cord
• ribs

• peritoneum
• stomach
• duodenum
• intestine
• colon
• liver
• spleen
• pancreas
• kidney
• adrenal gland
• appendix
• skin
• gall bladder

• pelvis
• sacrum
• coccyx
• ovaries
• Fallopian tube
• uterus
• vulva
• clitoris
• perineum
• urinary bladder
• testicles
• rectum
• penis

• muscle
• skeleton
• nerves
• hand
• wrist
• elbow
• shoulder
• hip
• knee
• ankle

• Fascia
• Organ transplant
• Organelles, analogous sub-cellular structures

v • d • e Human organ systems
Cardiovascular system • Digestive system • Endocrine system • Immune system • Integumentary system • Lymphatic system • Muscular system • Nervous system • Reproductive system • Respiratory system • Skeletal system • Urinary system

v • d • e Into Matter
Organism → System → Organ → Tissue → Cell → Organelle → Molecule → Atom → Subatomic particle  (Composite particle . Elementary particle)