The primary organ which deals with taste perception is the tongue. The tongue uses the sensory receptors of taste buds to transform the chemicophysical stimulus of food into neural signals. The taste buds, also called taste onions, were first described over one hundred years ago. Taste receptor binding sites exhibit a range of specificity, from highly specific to relatively non-specific. Taste buds contain the taste receptor cells, which sense the presence of chemicals in the mouth.
Afferent axons relay the information to the brain via the cranial nerves.
The taste cells are not really neurons, but do synapse upon the axons that relay information to the brain. Some taste receptors directly activate ion channels, while others are similar to G protein-coupled receptors in structure. For example, small molecules such as NaCl and HCl can directly pass through ion channels. Increases in sodium concentrations can lead to increased sodium conductance through an amiloride-sensitive sodium channel. Other chemicals may activate or block ion channels directly, or bind to receptors similar to G protein-coupled receptors.