Organ ( anatomy ) - wikipedia Organ ( anatomy ) `` Viscera '' redirects here. For other meanings, see Viscera ( disambiguation ). `` Organs '' redirects here. For other uses, see Organ. Organ Many of the internal organs of the human body Details Pronunciation awr - guh n System Organ systems Identifiers Latin organi Greek Οργανο FMA 67498 Anatomical terminology ( edit on Wikidata ) Organs are collections of tissues with a similar function. Plant and animal life relies on many organs that coexist in organ systems. Organs are composed of main tissue, parenchyma, and `` sporadic '' tissues, stroma. The main tissue is that which is unique for the specific organ, such as the myocardium, the main tissue of the heart, while sporadic tissues include the nerves, blood vessels, and connective tissues. The main tissues that make up an organ tend to have common embryologic origins, such as arising from the same germ layer. Functionally related organs often cooperate to form whole organ systems. Organs exist in all organisms. In single - celled organisms such as bacteria the functional analogue of an organ is known as an organelle. In plants there are three main organs. A hollow organ is a visceral organ that forms a hollow tube, or pouch such as the stomach, intestine, or bladder. In the study of anatomy, the term viscus is used to refer to an internal organ, and viscera is the plural form. By one widely used definition of the term organ, 80 organs have been scientifically validated in the human body. Contents 1 Structure 1.1 Tissue 1.2 Organ systems 2 Function 2.1 Mammals 2.2 Plants 3 Society and culture 4 History 4.1 Antiquity 4.2 Modern times 5 Origin and evolution 6 See also 7 References 8 External links Structure Tissue In biology, tissue is a cellular organizational level between cells and a complete organs. A tissue is an ensemble of similar cells and their extracellular matrix from the same origin that together carry out a specific function. Organs are then formed by the functional grouping together of multiple tissues. The study of human and animal tissues is known as histology or, in connection with disease, histopathology. For plants, the discipline is called plant anatomy. The classical tools for studying tissues are the paraffin block in which tissue is embedded and then sectioned, the histological stain, and the optical microscope. In the last couple of decades, developments in electron microscopy, immunofluorescence, and the use of frozen tissue sections have enhanced the detail that can be observed in tissues. With these tools, the classical appearances of tissues can be examined in health and disease, enabling considerable refinement of medical diagnosis and prognosis. Organ systems Main article : Biological system See also : List of organs of the human body Two or more organs working together in the execution of a specific body function form an organ system, also called a biological system or body system. 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 because of the relationship between the muscular and skeletal systems. Function Mammals The liver and gallbladder of a sheep Mammals such as humans have a variety of organ systems. These specific systems are also widely studied in human anatomy. Cardiovascular system : pumping and channeling blood to and from the body and lungs with heart, blood and blood vessels. Digestive system : digestion and processing food with salivary glands, esophagus, stomach, liver, gallbladder, pancreas, intestines, colon, rectum and anus. Endocrine system : communication within the body using hormones made by endocrine glands such as the hypothalamus, pituitary gland, pineal body or pineal gland, thyroid, parathyroids and adrenals, i.e., adrenal glands. Excretory system : kidneys, ureters, bladder and urethra involved in fluid balance, electrolyte balance and excretion of urine. Lymphatic system : structures involved in the transfer of lymph between tissues and the blood stream, the lymph and the nodes and vessels that transport it including the Immune system : defending against disease - causing agents with leukocytes, tonsils, adenoids, thymus and spleen. Integumentary system : skin, hair and nails. Muscular system : movement with muscles. Nervous system : collecting, transferring and processing information with brain, spinal cord and nerves. Reproductive system : the sex organs, such as ovaries, fallopian tubes, uterus, vulva, vagina, testes, vas deferens, seminal vesicles, prostate and penis. Respiratory system : the organs used for breathing, the pharynx, larynx, trachea, bronchi, lungs and diaphragm. Skeletal system : structural support and protection with bones, cartilage, ligaments and tendons. Plants See also : Plant anatomy The flower is the angiosperm 's reproductive organ. This Hibiscus flower is hermaphroditic, and it contains stamen and pistils. Strobilus of Equisetum telmateia The study of plant organs is referred to as plant morphology, rather than anatomy, as in animal systems. Organs of plants can be divided into vegetative and reproductive. Vegetative plant organs are roots, stems, and leaves. The reproductive organs are variable. In flowering plants, they are represented by the flower, seed and fruit. In conifers, the organ that bears the reproductive structures is called a cone. In other divisions ( phyla ) of plants, the reproductive organs are called strobili, in Lycopodiophyta, or simply gametophores in mosses. The vegetative organs are essential for maintaining the life of a plant. While there can be 11 organ systems in animals, there are far fewer in plants, where some perform the vital functions, such as photosynthesis, while the reproductive organs are essential in reproduction. However, if there is asexual vegetative reproduction, the vegetative organs are those that create the new generation of plants ( see clonal colony ). Society and culture Many societies have a system for Organ donation, in which a living or deceased donor 's organ is transplanted into a person with a failing organ. The transplantation of larger solid organs often requires immunosuppression to prevent organ rejection or graft vs host disease. There is considerable interest throughout the world in creating laboratory - grown or artificial organs. History Human viscera This section needs expansion. You can help by adding to it. ( February 2018 ) The English word `` organism '' is a neologism coined in the 17th century, probably formed from the verb to organize. At first the word referred to an organization or social system. The meaning of a living animal or plant is first recorded in 1842. Plant organs are made from tissue built up from different types of tissue. When there are three or more organs it is called an organ system. The adjective visceral, also splanchnic, is used for anything pertaining to the internal organs. Historically, viscera of animals were examined by Roman pagan priests like the haruspices or the augurs in order to divine the future by their shape, dimensions or other factors. This practice remains an important ritual in some remote, tribal societies. The term `` visceral '' is contrasted with the term `` parietal '', meaning `` of or relating to the wall of a body part, organ or cavity '' The two terms are often used in describing a membrane or piece of connective tissue, referring to the opposing sides. Antiquity Aristotle used the word frequently in his philosophy, both to describe the organs of plants or animals ( e.g. the roots of a tree, the heart or liver of an animal ), and to describe more abstract `` parts '' of an interconnected whole ( e.g. his philosophical works, taken as a whole, are referred to as the `` organon '' ). Some alchemists ( e.g. Paracelsus ) adopted the Hermetic Qabalah assignment between the seven vital organs and the seven classical planets as follows : Planet Organ Sun Heart Moon Brain Mercury Lungs Venus Kidneys Mars Gall bladder Jupiter Liver Saturn Spleen Modern times The variations in natural language definitions of what constitutes an organ, their degree of precision, and the variations in how they map to ontologies and taxonomies in information science ( for example, to count how many organs exist in a typical human body ) are topics explored by writer Carl Engelking of Discover magazine in 2017 as he analyzed the science journalism coverage of the evolving scientific understanding of the mesentery. He explored a challenge now faced by anatomists : as human understanding of ontology generally ( that is, how things are defined, and how the relationship of one thing to another is defined ) meets applied ontology and ontology engineering, unification of varying views is in higher demand. However, such unification always faces epistemologic frontiers, as humans can only declare computer ontologies with certainty and finality to the extent that their own cognitive taxonomy ( that is, science 's understanding of the universe ) is certain and final. For example, the fact that the tissues of the mesentery are continuous was something that was simply not known for sure until it was demonstrated with microscopy. Because humans can not predict all future scientific discoveries, they can not build a unified ontology that is totally certain and will never again change. However, one of the points made by an anatomist interviewed by Engelking is that, finality aside, much more could be done even now to represent existing human knowledge more clearly for computing purposes. Origin and evolution Relationship of major animal lineages with indication of how long ago these animals shared a common ancestor. On the left, important organs are shown, which allows us to determine how long ago these may have evolved. The organ level of organisation in animals can be first detected in flatworms and the more derived phyla. The less - advanced taxa ( like Placozoa, Sponges and Radiata ) do not show consolidation of their tissues into organs. Complex animals are composed of organs and many of these organs evolved a very long time ago. For example, the liver evolved in the stem vertebrates more than 500 million years ago, while the gut and brain are even more ancient, arising in the ancestor of vertebrates, insects, and worms more than 600 million years ago. Given the ancient origin of most vertebrate organs, researchers have looked for model systems, where organs have evolved more recently, and ideally have evolved multiple times independently. An outstanding model for this kind of research is the placenta, which has evolved more than 100 times independently in vertebrates, has evolved relatively recently in some lineages, and exists in intermediate forms in extant taxa. Studies on the evolution of the placenta have identified a variety of genetic and physiological processes that contribute to the origin and evolution of organs, these include the re-purposing of existing animal tissues, the acquisition of new functional properties by these tissues, and novel interactions of distinct tissue types. See also Biology portal Medicine portal Organoid References Jump up ^ `` Definition of Organ ''. Dictionary.com. Dictionary Group ( likely Random House ). Jump up ^ Widmaier EP ; Raff H ; Strang KT ( 2014 ). Vander 's Human Physiology ( 12th ed. ). ISBN 978 - 0 - 07 - 128366 - 3. Jump up ^ `` Botany / Plant structure - Wikibooks, open books for an open world ''. en.wikibooks.org. Jump up ^ `` Viscus - Definition ''. Merriam - Webster Online Dictionary. Retrieved 14 December 2009. Jump up ^ `` Viscera ''. MeSH. Retrieved 14 December 2009. Jump up ^ `` New organ named in digestive system ''. BBC News. 2017. Retrieved 2018 - 02 - 05. Jump up ^ `` '' It was astonishing, almost too good to be true. `` ''. metafilter. Retrieved 28 March 2018. Jump up ^ Barnhart 's Concise Dictionary of Etymology Jump up ^ `` Organ System - Definition and Examples Biology Dictionary ''. Biology Dictionary. 2016 - 10 - 31. Retrieved 2018 - 02 - 10. Jump up ^ `` Parietal -- Learning brain structure, function and variability from neuroimaging data ''. team.inria.fr. Retrieved 2018 - 02 - 10. Jump up ^ Philip Ball, The Devil 's Doctor : Paracelsus and the World of Renaissance Magic and Science, ISBN 978 - 0 - 09 - 945787 - 9 ^ Jump up to : Engelking, Carl ( 2017 - 01 - 06 ), `` We got the mesentery news all wrong '', The Crux ( a group blog by Discover writers ). Jump up ^ Coffey, J Calvin ; O'Leary, D Peter ( 2016 ). `` The mesentery : structure, function, and role in disease ''. The Lancet Gastroenterology & Hepatology. 1 ( 3 ) : 238 -- 247. doi : 10.1016 / S2468 - 1253 ( 16 ) 30026 - 7. ^ Jump up to : Griffith, Oliver W. ; Wagner, G ? nter P. ( 23 March 2017 ). `` The placenta as a model for understanding the origin and evolution of vertebrate organs ''. Nature Ecology & Evolution. 1 ( 4 ) : 0072. doi : 10.1038 / s41559 - 017 - 0072. External links Media related to Organs ( anatomy ) at Wikimedia Commons Human systems and organs Musculoskeletal Skeletal system Bone Carpus Collar bone ( clavicle ) Thigh bone ( femur ) Fibula Humerus Mandible Metacarpus Metatarsus Ossicles Patella Phalanges Radius Skull Tarsus Tibia Ulna Rib Vertebra Pelvis Sternum Cartilage Joints Fibrous joint Cartilaginous joint Synovial joint Muscular system Muscle Tendon Diaphragm Circulatory system Cardiovascular system peripheral Artery Vein Lymphatic vessel Heart Lymphatic system primary Bone marrow Thymus secondary Spleen Lymph node CNS equivalent Glymphatic system Nervous system Brain Spinal cord Nerve Sensory system Ear Eye Integumentary system Skin Subcutaneous tissue Breast Mammary gland Immune system Myeloid Myeloid immune system Lymphoid Lymphoid immune system Respiratory system Upper Nose Nasopharynx Larynx Lower Trachea Bronchus Lung Digestive system Mouth Salivary gland Tongue upper GI Oropharynx Laryngopharynx Esophagus Stomach lower GI Small intestine Appendix Colon Rectum Anus accessory Liver Biliary tract Pancreas Urinary system Genitourinary system Kidney Ureter Bladder Urethra Reproductive system Female Uterus Vagina Vulva Ovary Placenta Male Scrotum Penis Prostate Testicle Seminal vesicle Endocrine system Pituitary Pineal Thyroid Parathyroid Adrenal Islets of Langerhans Hierarchy of life Biosphere > Ecosystem > Biocoenosis > Population > Organism > Organ system > Organ > Tissue > Cell > Organelle > Biomolecular complex > Macromolecule > Biomolecule GND : 4043769 - 3 Retrieved from `` https://en.wikipedia.org/w/index.php?title=Organ_(anatomy)&oldid=832991692 '' Categories : Organ systems Organs ( anatomy ) Hidden categories : Pages with unresolved properties Wikipedia articles needing page number citations from May 2015 All articles with unsourced statements Articles with unsourced statements from February 2018 Articles to be expanded from February 2018 All articles to be expanded Articles using small message boxes Articles with unsourced statements from May 2015 Commons category with local link different than on Wikidata Wikipedia articles with GND identifiers Talk Contents About Wikipedia Afrikaans Aragonés ܐܪܡܝܐ Asturianu Avañe'ẽ Авар বাংলা Bân - lâm - gú Башҡортса Беларуская Беларуская ( тарашкевіца ) ‎ Български Bosanski Brezhoneg Català Čeština Chavacano de Zamboanga Cymraeg Dansk Deutsch Eesti Ελληνικά Español Esperanto Euskara فارسی Français Frysk Gaeilge Gaelg Galego 한국어 Հայերեն हिन्दी Hrvatski Ido Bahasa Indonesia Interlingua Íslenska Italiano עברית Basa Jawa ಕನ್ನಡ Kapampangan ქართული Kiswahili Kreyòl ayisyen Лакку Latina Latviešu Lietuvių Limburgs Magyar Македонски മലയാളം მარგალური Bahasa Melayu Nederlands नेपाल भाषा 日本 語 Napulitano Norsk Norsk nynorsk Occitan Олык марий ਪੰਜਾਬੀ Plattdüütsch Polski Português Română Runa Simi Русиньскый Русский Саха тыла Scots Shqip Sicilianu Simple English سنڌي Slovenčina Slovenščina کوردی Српски / srpski Srpskohrvatski / српскохрватски Basa Sunda Suomi Svenska Tagalog தமிழ் Татарча / tatarça ไทย Türkçe Українська اردو Vèneto Tiếng Việt Võro Winaray ייִדיש 粵語 中文 93 more Edit links This page was last edited on 29 March 2018, at 02 : 19. 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Question: what is the definition of a human organ
Answer: collections of tissues with a similar function