Excretion - wikipedia Excretion Excretion is the process by which metabolic waste is eliminated from an organism. In vertebrates this is primarily carried out by the lungs, kidneys and skin. This is in contrast with secretion, where the substance may have specific tasks after leaving the cell. Excretion is an essential process in all forms of life. For example, in mammals urine is expelled through the urethra, which is part of the excretory system. In unicellular organisms, waste products are discharged directly through the surface of the cell. Green plants produce carbon dioxide and water as respiratory products. In green plants, the carbon dioxide released during respiration gets utilized during photosynthesis. Oxygen is a by product generated during photosynthesis, and exits through stomata, root cell walls, and other routes. Plants can get rid of excess water by transpiration and guttation. It has been shown that the leaf acts as an ' excretophore ' and, in addition to being a primary organ of photosynthesis, is also used as a method of excreting toxic wastes via diffusion. Other waste materials that are exuded by some plants -- resin, saps, latex, etc. are forced from the interior of the plant by hydrostatic pressures inside the plant and by absorptive forces of plant cells. These latter processes do not need added energy, they act passively. However, during the pre-abscission phase, the metabolic levels of a leaf are high. Plants also excrete some waste substances into the soil around them. Chemical structure of uric acid. In animals, the main excretory products are carbon dioxide, ammonia ( in ammoniotelics ), urea ( in ureotelics ), uric acid ( in uricotelics ), guanine ( in Arachnida ) and creatine. The liver and kidneys clear many substances from the blood ( for example, in renal excretion ), and the cleared substances are then excreted from the body in the urine and feces. Aquatic animals usually excrete ammonia directly into the external environment, as this compound has high solubility and there is ample water available for dilution. In terrestrial animals ammonia - like compounds are converted into other nitrogenous materials as there is less water in the environment and ammonia itself is toxic. White cast of uric acid defecated with the dark feces from a lizard. Insects, birds and some other reptiles also undergo a similar mechanism. Birds excrete their nitrogenous wastes as uric acid in the form of a paste. Although this process is metabolically more expensive, it allows more efficient water retention and it can be stored more easily in the egg. Many avian species, especially seabirds, can also excrete salt via specialized nasal salt glands, the saline solution leaving through nostrils in the beak. In insects, a system involving Malpighian tubules is utilized to excrete metabolic waste. Metabolic waste diffuses or is actively transported into the tubule, which transports the wastes to the intestines. The metabolic waste is then released from the body along with fecal matter. The excreted material may be called ejecta. In pathology the word ejecta is more commonly used. See also Burping Countercurrent exchange Defecation Homeostasis Human excreta Osmoregulation Respiration ( physiology ) Urination References Wikimedia Commons has media related to Excretion. Jump up ^ Beckett, B.S. ( 1987 ). Biology : A Modern Introduction. Oxford University Press. p. 110. ISBN 0 - 19 - 914260 - 2. Jump up ^ Ford BJ, Even Plants Excrete, Nature 323 p763, 1986 Jump up ^ `` excretion. '' Encyclopædia Britannica. Encyclopædia Britannica Ultimate Reference Suite. Chicago : Encyclopædia Britannica, 2010 Jump up ^ http://www.tutorvista.com/content/science/science-ii/excretion/excretion-plants Jump up ^ Oliver and Boyd ( 1887 ) The Transactions of the Edinburgh Obstetrical Society, Volume 12, p. 169 Jump up ^ ejecta. Oxford English Dictionary. Oxford University Press. 2nd ed. 1989. External links Look up excretion in Wiktionary, the free dictionary. UAlberta.ca, Animation of excretion Brian J Ford on leaf fall in Nature NDL : 00562817 Concepts in pharmacology Pharmacokinetics ( L ) ADME : ( Liberation ) Absorption Distribution Metabolism Excretion ( Clearance ) Loading dose Volume of distribution ( Initial ) Rate of infusion Compartment Bioequivalence Bioavailability Onset of action Biological half - life Plasma protein binding Pharmacodynamics Mechanism of action Mode of action Toxicity ( Neurotoxicology ) Dose -- response relationship ( Efficacy, Potency ) Therapeutic index ( Median lethal dose, Effective dose ) Antimicrobial pharmacodynamics : Minimum inhibitory concentration ( Bacteriostatic ) Minimum bactericidal concentration ( Bactericide ) Agonism and antagonism Agonist : Inverse agonist Irreversible agonist Partial agonist Superagonist Physiological agonist Antagonist : Competitive antagonist Irreversible antagonist Physiological antagonist Other : Binding Affinity Binding selectivity Functional selectivity Other Drug tolerance : Tachyphylaxis Drug resistance : Antibiotic resistance Multiple drug resistance Drug discovery strategies Classical pharmacology Reverse pharmacology Related fields / subfields Pharmacogenetics Pharmacogenomics Neuropsychopharmacology ( Neuropharmacology, Psychopharmacology ) Pharmacy and pharmacology portal Metabolism portal Retrieved from `` https://en.wikipedia.org/w/index.php?title=Excretion&oldid=843552063 '' Categories : Pharmacology Digestive system Metabolism Excretion Hidden categories : All articles with dead external links Articles with dead external links from November 2016 Articles with dead external links from December 2013 Talk About Wikipedia Asturianu বাংলা Bân - lâm - gú Български Bosanski Català Čeština Cymraeg Deutsch Ελληνικά Español Euskara فارسی Français Galego 한국어 हिन्दी Hrvatski Bahasa Indonesia Íslenska Italiano עברית Basa Jawa Kapampangan Kiswahili Македонски Bahasa Melayu Nederlands नेपाली 日本 語 Norsk Oʻzbekcha / ўзбекча Polski Português Română Русский Scots Simple English Slovenčina Српски / srpski Srpskohrvatski / српскохрватски Suomi Svenska Tagalog தமிழ் తెలుగు ไทย Türkçe Українська 中文 42 more Edit links This page was last edited on 29 May 2018, at 21 : 51. 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Question: removal of excretory products from the human body
Answer: Excretion