How stimuli can be detected by the tongue​

The chemical stimuli of special significance to taste are sugars (sweet), amino acids (umami), sodium chloride and other salts (salty), alkaloids (bitter) and acids (sour). Sugars and amino acids tend to be preferred, while alkaloids and acids tend to be avoided. Intake of salts depends on electrolyte balance. The gustatory system codes taste qualities and their associated hedonic attributes. The ability to distinguish foods from poisons is so important that it is hard-wired in the receptor cells themselves.