Taste buds are located on the upper surface of the tongue. They provide information to the brain about the taste of food being eaten by contact. There are 4 types of taste buds: -Fungiform papillae - located on the tongue tip. -Filiform papillae - the most numerous. -Foliate papillae - in the posterior part of the tongue. -Vallate papillae - most people have only 3-14 of these. An average human tongue has about 10,000 taste buds. Taste buds interpret the different flavors (or tastes), decodifying information present on the food, by two types of signals: -G-protein coupled receptors (for Sweet, Bitter and Umami) -Ion channels (for Salty and Sour) Umami is the fifth taste. The most familiar example of this, now widely accepted new taste, is that of the food additive called MSG (monosodic glutamate). Is popular understanding that taste is experienced on different parts of the tongue, but this is only a myth. Even though there are small differences in sensation, all taste buds can respond to all types of taste. In conclusion, they work exactly as any other sense: interpreting and decodifying signals from the surrounding environment. The eyes do it with light, the skin with surfaces and temperatures, and so on.

Taste is the ability to respond to dissolved molecules and ions called tastants. Humans detect taste with taste receptor cells. These are clustered in taste buds. Each taste bud has a pore that opens out to the surface of the tongue enabling molecules and ions taken into the mouth to reach the receptor cells inside. There are five primary taste sensations: salty, sour, sweet, bitter and umami. A single taste bud contains 50–100 taste cells representing all 5 taste sensations (so the classic textbook pictures showing separate taste areas on the tongue are wrong). Each taste cell has receptors on its apical surface. These are transmembrane proteins which bind to the molecules and ions that give rise to the 5 taste sensations. Although a single taste cell may have representatives of several types of receptor, one type may be more active than the others on that cell. And, no single taste cell contains receptors for both bitter and sweet tastants. Each taste receptor cell is connected, through a synapse, to a sensory neuron leading back to the brain. However, a single sensory neuron can be connected to several taste cells in each of several different taste buds. The sensation of taste — like all sensations — resides in the brain . http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/Taste.html The average person has about 10,000 taste buds and they're replaced every 2 weeks or so. But as a person ages, some of those taste cells don't get replaced. An older person may only have 5,000 working taste buds. That's why certain foods may taste stronger to a child than an adult. Smoking ("they say") also can reduce the number of taste buds a person has.

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