Tongue facts for kids
|The human tongue|
|System||Alimentary tract, gustatory system|
|Artery||lingual, tonsillar branch, ascending pharyngeal|
Anterior two-thirds: Lingual (sensation) and chorda tympani (taste)
Posterior one-third: Glossopharyngeal (IX)
Hypoglossal (XII), except palatoglossus muscle supplied by the pharyngeal plexus via vagus (X)
|Lymph||Deep cervical, submandibular, submental|
|Precursor||pharyngeal arches, lateral lingual swelling, tuberculum impar|
The tongue is the fleshy muscle inside the mouth. A tongue lets us taste because the top of the tongue is made mostly of taste buds. It also helps the process of mastication by mixing food with saliva. It is very flexible, so it also helps us eat and talk.
The human tongue is divided into two parts, an oral part at the front and a pharyngeal part at the back. The left and right sides are also separated along most of its length by a vertical section of fibrous tissue (the lingual septum) that results in a groove, the median sulcus, on the tongue's surface.
There are two groups of muscles of the tongue. The four intrinsic muscles alter the shape of the tongue and are not attached to bone. The four paired extrinsic muscles change the position of the tongue and are anchored to bone.
The tongue is the strongest muscle in the human body.
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.
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.
The intrinsic muscles of the tongue enable the shaping of the tongue which facilitates speech.
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. 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.
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.
Some people can roll their tongue into a tube. The reason why some people are able to and some are not is because of genetic inheritance, meaning that it is based on whether their parents are able to do it. Many schools use tongue rolling as an example of a genetic trait.
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Tongue Facts for Kids. Kiddle Encyclopedia.