Anatomy and Physiology: Sense of Taste

The typical map of an "average" person's tongue.

For your sense of taste, there are taste bus, which are specific receptors that are scattered in the mouth.  Most are on the tongue, but there are some on the soft palate and inner surface of the cheeks.  There are five basic taste sensations and five major types of taste buds, which match each other.  There are sweet receptors believed by some to respond to the hydroxyl (OH-) group, sour receptors to respond to hydrogen ions (H+), bitter receptors to respond to alkaloids, salty receptor to respond to metal ions in solution, and umami (discovered by the Japanese) appearing to respond to the "beef taste" (292) of meat and the food additive monosodium glutamate.  The tongue tip is usually sensitive to sweet and salty substances, the sides to sour, the back to bitter, and the pharynx to umami.


Taste is affected is heavily affected by olfactory (smell) receptors, which stimulate our sense of taste.  This is why food tastes bland when you have a cold and your nasal passages are congested.  Also, the temperature and texture of food can affect taste of food.  For instance some people do not eat foods with a pasty texture or hot, spicy foods that stimulate the mouth's pain receptors.


Sources:
information from: Essentials of Human Anatomy & Physiology, Eighth Edition by Elaine N. Marieb
tongue mapping picture from: http://misconceptions.us/taste-buds-and-the-tongue/