-
The receptors to taste in humans, called taste buds, are small chemosensory receptor cells. They are sensitive to sweet, salty, bitter, sour and umami (MSG) tastes. Spicy food is a small pain in the tongue. Taste buds are located on the tongue, hard and soft palates, larynx, pharynx, epiglottis and the tonsils; essentially throughout your mouth and top of your throat. However most taste buds are located on the tongue within different types of papillae. The bumps you see on your tongue are the papillae, not the taste buds.
These papillae have taste buds on the outer surface (fungiform papilla) or in the troughs of the papilla (foliate, vallate and filliform papilla). A papillae has anywhere from a couple to 15 taste buds on it. Taste buds regenerate every 10 days.
To see your papillae well - drink some milk and look at your tongue in a mirror. -
Taste bud receptor cells are stimulated by chemicals in solution along with the thermal and tactile information as well. This information gets to the brain via three different nerves: the facial nerve (VII), the glossopharyngeal (IX) and the vagus nerve (X). Since there are three different information pathways to the brain through these three nerves, the sense of taste integrates mulitple forms of stimuli. If damage occurs to one of these nerves, the other two nerves are strengthened through inhibitory reduction.
-
The sense of taste is strongly connected to the sense of smell (olfaction). Many of the supposed taste problems are due to a decreased ability to smell many foods. It has been shown that age related decreases in taste are not due to taste buds and the taste receptors but to olfactory reductions (Cowart, Mistretta, Murphy). Like when we get sick and food doesn't have the same strength of taste, the elderly often have decreased olfaction that affects taste. For more information on the role of olfaction in taste, check out some of these links.
Image appears with permission from http://www.bioanim.com/CellTissueHumanBody3/jezik1lgws.html