5 Senses
Chemical Which Triggers Taste
Sweet
Hydroxyl (OH-)
Sour
Acidic (H+)
Bitter
Alkaloids
Salty
Sodium (Na+)
Umami (Delicious)
Glutamates (amino acid)
Each gustatory cell in the taste bud is surrounded with microvilli. When the food comes in contact with the tongue these microvilli are stimulated, giving sending the impulse to the cranial nerves (discussed on the other page). 

To look at this more in depth:
Taste will occur when the specific protein binds to the receptors on the taste bud. Each taste is stimulated by the shape of the respective chemical (see chart above), which needs to fit the shape of the receptor inside of the cell. The action potential then needs to be created. This happens when:
  1. The molecules dissolve in saliva.
  2. They go into the taste pore and bind to the receptor.
  3. A receptor potential is then created because the potassium ions (K+) are reduced in the cell membrane.
  4. This triggers the Calcium channels (Ca+) to open, creating the action potential, through the diffusion of neurotransmitters throughout the synapse.

Once there, the chemical signal is transitted through the cranial nerves, and decoded and given to the thalamus and later the hypothalamus, giving the sensation of taste.

The placement of the taste buds also play a role in detecting the taste. For example, the density of the bitter taste buds is higher toward the dorsal side of the tongue. This is the last resort of rejecting a food which could be potentially dangerous to the body, and will typically cause a gag.


File:Kieli kaikki en.svg
File:Kieli kaikki en.svg
http://commons.wikimedia.org/wiki/File:Kieli_kaikki_en.svg