Taste

This is a function of a healthy human body.

The primary taste sensations

• Sweetness
• Sugars (sweet carbohydrates): glucose, fructose, galactose
• Sourness
• Acidity
• Saltiness
• Cations (positive ions): Sodium, potassium, lithium, ammonium (NH4+), calcium
• Bitterness 
• TAS2Rs (taste receptors, type 2)
• Most sensitive taste
• Bitterness is associated with many toxic substances

 

Other taste sensations and taste modifiers

• Savoriness (umami)
• Glutamate
• Oleogustus (pinguis)
• Fatty acids
• Heartiness (kokumi)
• Tasteless substances which alter the sensation of other tastes
• Pungency (spiciness, hotness)
• Capsaicin
• Coolness 
• Menthol
• Numbness 
• Hydroxy alpha sanshool 
• Astringency (dryness) 
• Tannin
• Calcium oxalate
• Chalkiness
• Calcium
• Metallicness 
• Iron / blood

 

Physiology

• The surface of the tongue and the epiglottis are coated with taste buds. These structures express receptors which are capable of detecting each taste.
• Taste signals from the anterior 2/3 of the tongue are carried by the facial nerve (cranial nerve VII).
• Taste signals from the posterior third of the tongue are carried by the glossopharyngeal nerve (cranial nerve IX).
• The gustatory cortex is responsible for processing taste perception. It consists of two substructures: the anterior insula on the insular lobe and the frontal operculum on the inferior frontal gyrus of the frontal lobe. 
• The sensations of taste and smell are synergistic. When one is removed, the other is diminished.

Purpose

• Taste sensations invoke a pleasure response in humans. This reinforces the vital behaviour of food consumption.
• It allows humans to detect abnormalities in substances before they are ingested. The vomiting centres in the brain may become activated by taste, promoting the expulsion of noxious substances. This protects against infections and poisoning.
• Taste discrimination is a useful source of information for tracking predators, prey and rivals.

 

Pathology

• Taste disorders

 

Common misconceptions

• In international education systems, it was often taught that the tongue has a "taste map" of specialised taste regions. This has long since been proven false. All areas of the tongue should have taste buds which are capable of all taste sensations.