function taste receptors are present on the human tongue in papillae taste main articles: taste, taste receptor, and supertaster chemicals that stimulate taste receptor cells are known as tastants. once a tastant is dissolved in saliva, it can make contact with the plasma membrane of the gustatory hairs, which are the sites of taste transduction. the tongue is equipped with many taste buds on its dorsal surface, and each taste bud is equipped with taste receptor cells that can sense particular classes of tastes. distinct types of taste receptor cells respectively detect substances that are sweet, bitter, salty, sour, spicy, or taste of umami. umami receptor cells are the least understood and accordingly are the type most intensively under research. there is a common misconception that different sections of the tongue are exclusively responsible for different basic tastes. although widely taught in schools in the form of the tongue map, this is incorrect; all taste sensations come from all regions of the tongue, although certain parts are more sensitive to certain tastes. mastication the tongue is an important accessory organ in the digestive system. the tongue is used for crushing food against the hard palate, during mastication and manipulation of food for softening prior to swallowing. the epithelium on the tongue's upper, or dorsal surface is keratinised. consequently, the tongue can grind against the hard palate without being itself damaged or irritated. speech the tongue is one of the primary articulators in the production of speech, and this is facilitated by both the extrinsic muscles that move the tongue and the intrinsic muscles that change its shape. specifically, different vowels are articulated by changing the tongue's height and retraction to alter the resonant properties of the vocal tract. these resonant properties amplify specific harmonic frequencies (formants) that are different for each vowel, while attenuating other harmonics. for example, is produced with the tongue lowered and centered and is produced with the tongue raised and fronted. consonants are articulated by constricting airflow through the vocal tract, and many consonants feature a constriction between the tongue and some other part of the vocal tract. for example alveolar consonants like and are articulated with the tongue against the alveolar ridge, while velar consonants like and are articulated with the tongue dorsum against the soft palate (velum). tongue shape is also relevant to speech articulation, for example in retroflex consonants, where the tip of the tongue is curved backward. intimacy the tongue plays a role in physical intimacy and sexuality. the tongue is part of the erogenous zone of the mouth and can be used in intimate contact, as in the french kiss and in oral sex. the tongue can be used for stimulating the clitoris and other areas of the vulva. disease main article: tongue disease a congenital disorder of the tongue is that of ankyloglossia also known as tongue-tie. the tongue is tied to the floor of the mouth by a very short and thickened frenulum and this affects speech, eating, and swallowing. the tongue is prone to several pathologies including glossitis and other inflammations such as geographic tongue, and median rhomboid glossitis; burning mouth syndrome, oral hairy leukoplakia, oral candidiasis (thrush), black hairy tongue , bifid tongue (due to failure in fusion of two lingual swellings of first pharyngeal arch) and fissured tongue. there are several types of oral cancer that mainly affect the tongue. mostly these are squamous cell carcinomas. food debris, desquamated epithelial cells and bacteria often form a visible tongue coating. this coating has been identified as a major factor contributing to bad breath (halitosis), which can be managed by using a tongue cleaner. medication delivery the sublingual region underneath the front of the tongue is an ideal location for the administration of certain medications into the body. the oral mucosa is very thin underneath the tongue, and is underlain by a plexus of veins. the sublingual route takes advantage of the highly vascular quality of the oral cavity, and allows for the speedy application of medication into the cardiovascular system, bypassing the gastrointestinal tract. this is the only convenient and efficacious route of administration (apart from intravenous therapy) of nitroglycerin to a patient suffering chest pain from angina pectoris. other animals giraffe's tongue extended proboscis of a long tongued macroglossum moth the muscles of the tongue evolved in amphibians from occipital somites. most amphibians show a proper tongue after their metamorphosis. as a consequence most vertebrate animals—amphibians, reptiles, birds, and mammals—have tongues (the frog family of pipids lack tongue). in mammals such as dogs and cats, the tongue is often used to clean the fur and body by licking. the tongues of these species have a very rough texture which allows them to remove oils and parasites. some dogs have a tendency to consistently lick a part of their foreleg which can result in a skin condition known as a lick granuloma. a dog's tongue also acts as a heat regulator. as a dog increases its exercise the tongue will increase in size due to greater blood flow. the tongue hangs out of the dog's mouth and the moisture on the tongue will work to cool the bloodflow. some animals have tongues that are specially adapted for catching prey. for example, chameleons, frogs, pangolins and anteaters have prehensile tongues. other animals may have organs that are analogous to tongues, such as a butterfly's proboscis or a radula on a mollusc, but these are not homologous with the tongues found in vertebrates and often have little resemblance in function. for example, butterflies do not lick with their proboscides; they suck through them, and the proboscis is not a single organ, but two jaws held together to form a tube. many species of fish have small folds at the base of their mouths that might informally be called tongues, but they lack a muscular structure like the true tongues found in most tetrapods. society and culture figures of speech the tongue can be used as a metonym for language. for example, the new testament of the bible, in the book of acts of the apostles, jesus' disciples on the day of pentecost received a type of spiritual gift: "there appeared unto them cloven tongues like as of fire, and it sat upon each of them. and they were all filled with the holy ghost, and began to speak with other tongues ....", which amazed the crowd of jewish people in jerusalem, who were from various parts of the roman empire but could now understand what was being preached. the phrase mother tongue is used as a child's first language. many languages have the same word for "tongue" and "language", as did the english language before the middle ages. a common temporary failure in word retrieval from memory is referred to as the tip-of-the-tongue phenomenon. the expression tongue in cheek refers to a statement that is not to be taken entirely seriously – something said or done with subtle ironic or sarcastic humour. a tongue twister is a phrase made specifically to be very difficult to pronounce. aside from being a medical condition, "tongue-tied" means being unable to say what you want due to confusion or restriction. the phrase "cat got your tongue" refers to when a person is speechless. to "bite one's tongue" is a phrase which describes holding back an opinion to avoid causing offence. a "slip of the tongue" refers to an unintentional utterance, such as a freudian slip. the "gift of tongues" refers to when one is uncommonly gifted to be able to speak in a foreign language, often as a type of spiritual gift. speaking in tongues is a common phrase used to describe glossolalia, which is to make smooth, language-resembling sounds that is no true spoken language itself. a deceptive person is said to have a forked tongue, and a smooth-talking person said to have a silver tongue. gestures sticking one's tongue out at someone is considered a childish gesture of rudeness or defiance in many countries; the act may also have sexual connotations, depending on the way in which it is done. however, in tibet it is considered a greeting. in 2009, a farmer from fabriano, italy, was convicted and fined by the country's highest court for sticking his tongue out at a neighbor with whom he had been arguing. proof of the affront had been captured with a cell phone camera. body art tongue piercing and splitting have become more common in western countries in recent decades. in one study, one-fifth of young adults were found to have at least one type of oral piercing, most commonly the tongue. as food the tongues of some animals are consumed and sometimes considered delicacies. hot tongue sandwiches are frequently found on menus in kosher delicatessens in america. taco de lengua (lengua being spanish for tongue) is a taco filled with beef tongue, and is especially popular in mexican cuisine. as part of colombian gastronomy, tongue in sauce (lengua en salsa), is a dish prepared by frying the tongue, adding tomato sauce, onions and salt. tongue can also be prepared as birria. pig and beef tongue are consumed in chinese cuisine. duck tongues are sometimes employed in sichuan dishes, while lamb's tongue is occasionally employed in continental and contemporary american cooking. fried cod "tongue" is a relatively common part of fish meals in norway and newfoundland. in argentina and uruguay cow tongue is cooked and served in vinegar (lengua a la vinagreta). in the czech republic and poland, a pork tongue is considered a delicacy, and there are many ways of preparing it. in eastern slavic countries, pork and beef tongues are commonly consumed, boiled and garnished with horseradish or jelled; beef tongues fetch a significantly higher price and are considered more of a delicacy. in alaska, cow tongues are among the more common. both cow and moose tongues are popular toppings on open-top-sandwiches in norway, the latter usually amongst hunters. tongues of seals and whales have been eaten, sometimes in large quantities, by sealers and whalers, and in various times and places have been sold for food on shore. additional images the human tongue spots on the tongue exclusive lines on the tongue an okapi cleaning its muzzle with its tongue. a yawning cat's tongue is comb-like. medical illustration of a human mouth by duncan kenneth winter distended dog tongue acting as a heat regulator