Gustatory system

The tongue is a muscular organ in the mouth of a typical tetrapod. It manipulates food for chewing and swallowing as part of the digestive process, and is the primary organ of taste. The tongue's upper surface (dorsum) is covered by taste buds housed in numerous lingual papillae. It is sensitive and kept moist by saliva and is richly supplied with nerves and blood vessels. The tongue also serves as a natural means of cleaning the teeth. A major function of the tongue is to enable speech in humans and vocalization in other animals.

thumb|right|Taste bud

tenth cranial nerve

scale for measuring heat of peppers

seventh cranial nerve

anatomical structure containing gustatory cells

9th cranial nerve, mixed nerve that carries afferent sensory and efferent motor information

Ageusia (from negative prefix a- and Ancient Greek γεῦσις geûsis 'taste') is the loss of taste functions of the tongue, particularly the inability to detect sweetness, sourness, bitterness, saltiness, and umami (meaning 'savory taste'). It is sometimes confused with anosmia – a loss of the sense of smell. True ageusia is relatively rare compared to hypogeusia – a partial loss of taste – and dysgeusia – a distortion or alteration of taste.

structure on the upper surface of the tongue

thumb|A child bites into a watermelon, experiencing mouthfeel sensations such as juiciness Mouthfeel refers to the physical sensations in the mouth caused by food or drink, making it distinct from taste. It is a fundamental sensory attribute which, along with taste and smell, determines the overall flavor of a food item. Mouthfeel is also sometimes referred to as texture.

Aftertaste is the taste intensity of a food or beverage that is perceived immediately after that food or beverage is removed from the mouth. The aftertastes of different foods and beverages can vary by intensity and over time, but the unifying feature of aftertaste is that it is perceived after a food or beverage is either swallowed or spat out. The neurobiological mechanisms of taste (and aftertaste) signal transduction from the taste receptors in the mouth to the brain have not yet been fully understood. However, the primary taste processing area located in the insula has been observed to be

branch of the mandibular nerve

L-shaped collection of fibers and sensory neurons of the facial nerve located in the facial canal of the head

thumb|Advertisement of castor oil as a medicine by Scott & Bowne company, 19th century Palatability (or palatableness) is the hedonic reward (which is pleasure of taste in this case) provided by foods or drinks that are agreeable to the "palate", which often varies relative to the homeostatic satisfaction of nutritional and/or water needs. The palatability of a dish or beverage, unlike its flavor or taste, varies with the state of an individual: it is lower after consumption and higher when deprived. It has increasingly been appreciated that this can create a hunger that is independent of home

brain structure responsible for perception of taste

Hypogeusia can be defined as the reduced ability to taste things. Due to a lack of stratification, the prevalence of hypogeusia, as well as hyposmia, may not be accurately known. Additionally, reviews do not always make distinctions between ageusia and hypogeusia, often classifying them as the same in certain circumstances and studies. The severity of the loss of taste from hypogeusia is not clearly outlined in current research due to these reasons.

fibre bundle at the base of the brain

Hypergeusia is a taste disorder where the sense is abnormally heightened. It can be associated with a lesion of the posterior fossa and Addison's disease; where a patient will crave for salty and sour taste due to the abnormal loss of ions with urine.