Saliva 204420 223672330 2008-07-05T05:17:59Z Jimfbleak 7872 Reverted edits by [[Special:Contributions/68.127.229.2|68.127.229.2]] ([[User talk:68.127.229.2|talk]]) to last version by Numbo3-bot {{for|the band|Saliva (band)}}{{distinguish|Salvia}} {{wiktionary|saliva}} '''Saliva''' is the watery and usually frothy substance produced in the mouths of [[human]]s and most other [[animal]]s. Saliva is produced in and secreted from the [[salivary gland]]s. Human saliva is composed of 98% [[water]], the remainder of which includes [[electrolyte]]s, [[mucus]], [[antiseptic|antibacterial]] compounds, and various [[enzyme]]s. <ref>{{GeorgiaPhysiology|6/6ch4/s6ch4_6}}</ref> As part of the initial process of food digestion, the enzymes in the saliva break down some of the starch and fat in the food at the molecular level. Saliva also breaks down food caught in the teeth, protecting them from bacteria that cause decay. Furthermore, saliva lubricates and protects the teeth, the tongue, and the tender tissues inside the mouth. Various species have evolved special uses for saliva that go beyond predigestion. Some [[swift]]s use their gummy saliva to build their nests. Some ''[[Aerodramus]]'' [[swiftlet]] nests are made only from saliva and used to make [[bird's nest soup]].<ref name=Marcone>Marcone, M. F. (2005). "Characterization of the edible bird's nest the ''Caviar of the East''." ''Food Research International'' 38:1125–1134. doi:10.1016/j.foodres.2005.02.008 [http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T6V-4GHRBYJ-1&_user=10&_coverDate=12%2F31%2F2005&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=84ab2eeeba53cb499a10401f4d538cd9 Abstract retrieved 12 Nov 2007]</ref> Cobras, vipers, and certain other members of the [[venom clade]] hunt with venomous saliva injected by fangs. Some arthropods, such as spiders and caterpillars, create thread from salivary glands. ==Functions== ===Digestion=== The digestive functions of saliva include moistening food, and helping to create a food [[Bolus (digestion)|bolus]], so it can be swallowed easily. Saliva contains the [[enzyme]] [[amylase]] that breaks some [[starch]]es down into [[maltose]] and [[dextrin]]. Thus, digestion of food occurs within the mouth, even before food reaches the [[stomach]]. Salivary glands also secrete enzymes (salivary lipase) to start fat digestion.<ref>{{cite book | last = Maton | first = Anthea | authorlink = | coauthors = Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright | title = Human Biology and Health | publisher = Prentice Hall | date = 1993 | location = Englewood Cliffs, New Jersey, USA | pages = | url = | doi = | id = | isbn = 0-13-981176-1}}</ref> ===Disinfectants=== A common belief is that saliva contained in the mouth has natural [[disinfection|disinfectants]], which leads people to believe it is beneficial to "lick their wounds". Researchers at the [[University of Florida]] at [[Gainesville, Florida|Gainesville]] have discovered a [[protein]] called [[nerve growth factor]] (NGF) in the saliva of [[mouse|mice]]. Wounds doused with NGF healed twice as fast as untreated and unlicked wounds; therefore, saliva can help to heal wounds in some species. NGF has not been found in human saliva; however, researchers find human saliva contains such [[antibacterial]] agents as secretory [[IgA]], [[lactoferrin]], and [[lactoperoxidase]].<ref>[http://www.discover.com/issues/oct-05/departments/the-biology-of-saliva/ Discover Magazine, "The Biology of ...Saliva" October 2005]</ref> It has not been shown that human licking of wounds disinfects them, but licking is likely to help clean the wound by removing larger contaminants such as dirt and may help to directly remove infective bodies by brushing them away. Therefore, licking would be a way of washing, useful if purer water isn't available to the animal or person. The mouth of animals is the habitat of many bacteria, some [[pathogen]]ic. Some diseases, such as herpes, can be transmitted through the mouth. Animal (including human) bites are routinely treated with systemic [[antibiotics]] because of the risk of [[septicemia]]. Recent research suggests that the saliva of birds is a better indicator of [[avian influenza]] than are [[feces|faecal samples]]. <ref name = GPA> "Saliva swabs for bird flu virus more effective than faecal samples" German Press Agency December 11, 2006 [http://rawstory.com/news/2006/Saliva_swabs_for_bird_flu_virus_mor_12112006.html Retrieved 13 November 2007]</ref> ==Stimulation== The production of saliva is stimulated both by the [[sympathetic nervous system]] and the [[parasympathetic]].<ref>{{GeorgiaPhysiology|6/6ch4/s6ch4_7}}</ref> The saliva stimulated by sympathetic innervation is thicker, and saliva stimulated parasympathetically is more watery. ==Daily salivary output== There has been some disagreement regarding the daily salivary output in a healthy individual. Today, it is believed that the average person produces approximately 0.75 l of saliva per day, less than half of the output originally thought produced. It is produced at a rate of 1-1.5 l/day. 20ml/hr at rest, 250 ml/hr under stimulated conditions. While sleeping, salivary flow drops to almost zero. == Contents == Produced in [[salivary gland]]s, human saliva is 98% [[water]], but it contains many important substances, including [[electrolyte]]s, [[mucus]], [[antiseptic|antibacterial]] compounds and various [[enzyme]]s. <ref>{{GeorgiaPhysiology|6/6ch4/s6ch4_6}}</ref> It is a [[fluid]] containing: * [[Water]] * [[Electrolyte]]s: ** 2-21 mmol/L [[sodium]] (lower than [[blood plasma]]) ** 10-36 mmol/L [[potassium]] (higher than plasma) ** 1.2-2.8 mmol/L [[calcium]] ** 0.08-0.5 mmol/L [[magnesium]] ** 5-40 mmol/L [[chloride]] (lower than plasma) ** 25 mmol/L [[bicarbonate]] (higher than plasma) ** 1.4-39 mmol/L [[phosphate]] * [[Mucus]]. Mucus in saliva mainly consists of [[glycosaminoglycan|mucopolysaccharides]] and [[glycoprotein]]s; * Antibacterial compounds ([[thiocyanate]], [[hydrogen peroxide]], and secretory [[immunoglobulin A]]) * Various [[enzyme]]s. There are three major enzymes found in saliva. ** α-[[amylase]] (EC3.2.1.1). Amylase starts the digestion of starch and lipase fat before the food is even swallowed. It has a [[pH]] optima of 7.4. ** [[lysozyme]] (EC3.2.1.17). [[Lysozyme]] acts to cause [[lysis]] in bacteria. ** [[lingual lipase]] (EC3.1.1.3). Lingual lipase has a [[pH]] optimum ~4.0 so it is not activated till entering an acidic environment. ** Minor enzymes include salivary acid phosphatases A+B (EC3.1.3.2), N-acetylmuramyl-L-alanine amidase (EC3.5.1.28), NAD(P)H dehydrogenase-quinone (EC1.6.99.2), salivary lactoperoxidase (EC1.11.1.7), [[superoxide dismutase]] (EC1.15.1.1), glutathione transferase (EC2.5.1.18), class 3 aldehyde dehydrogenase (EC1.2.1.3), glucose-6-phosphate isomerase (EC5.3.1.9), and tissue kallikrein (EC3.4.21.35). * Cells: Possibly as much as 8 million human and 500 million bacterial cells per mL. The presence of bacterial products (small organic acids, amines, and thiols) causes saliva to sometimes exhibit [[Halitosis | foul odor]]. * [[Opiorphin]], a newly researched pain-killing substance found in human saliva. Different reagents used to determine the content of saliva \1. Molisch test gives a positive result of purple color that is costituent to the presence of carbohydrates ==References== {{reflist}} ==External links== * {{MeshName|Saliva}} {{Gastrointestinal physiology}} [[Category:Body fluids]] [[Category:Digestive system]] [[ar:لعاب]] [[zh-min-nan:Chhùi-noā]] [[bg:Слюнка]] [[ca:Saliva]] [[cv:Сĕлеке]] [[cs:Slina]] [[da:Spyt]] [[de:Speichel]] [[dv:ކުޅު]] [[et:Sülg]] [[el:Σάλιο]] [[es:Saliva]] [[eu:Listu]] [[fa:بزاق]] [[fr:Salive]] [[hr:Slina]] [[io:Salivo]] [[id:Air liur]] [[is:Munnvatn]] [[it:Saliva]] [[he:רוק (ביולוגיה)]] [[la:Saliva]] [[lv:Siekalas]] [[lt:Seilės]] [[hu:Nyál]] [[nl:Speeksel]] [[ja:唾液]] [[no:Spytt]] [[pl:Ślina]] [[pt:Saliva]] [[ksh:Seiver]] [[ru:Слюна]] [[scn:Sputazza]] [[simple:Saliva]] [[sk:Slina]] [[sl:Slina]] [[sr:Пљувачка]] [[fi:Sylki]] [[sv:Saliv]] [[ta:உமிழ்நீர்]] [[th:น้ำลาย]] [[vi:Nước miếng]] [[uk:Слина]] [[fiu-vro:Sülg]] [[yi:שפייאכץ]] [[zh-yue:口水]] [[zh:唾液]]