Taste buds

Taste buds are small structures on the upper surface of the tongue, soft palate, and epiglottis that provide information about the taste of food being eaten.

The human tongue has about 10,000 taste buds. The majority of taste buds on the tongue sit on raised protrusions of the tongue surface called papillae. There are four types of papillae present in the human tongue:
 * Fungiform papillae - as the name suggests, these are slightly mushroom shaped if looked at in section. These are present mostly at the apex (tip) of the tongue.
 * Filiform papillae - these are thin, longer papillae that don't contain taste buds but are the most numerous. These papillae are mechanical and not involved in gustation.
 * Foliate papillae - these are ridges and grooves towards the posterior part of the tongue.
 * Vallate papillae - there are only about 3-14 of these papillae on most people, and they are present at the back of the oral part of the tongue. They are arranged in a V-shaped row just in front of the sulcus terminalis of the tongue.

It is known that there are five taste sensations:
 * Sweet, Bitter, and Umami, which work with a signal through a G-protein coupled receptor.
 * Salty and Sour, which work with ion channels.

Contrary to popular understanding, taste is not experienced on different parts of the tongue. The "tongue map myth" was based on a mistranslation of a German paper that was written in 1901 by a Harvard psychologist. Though there are small differences in sensation, which can be measured with highly specific instruments, all taste buds can respond to all types of taste.