Name the four principal tastes and the respective regions of the tongue concerned with their perception.

Sweet, sour, salty and bitter tastes can actually be sensed by all parts of the tongue. Thus, these are known as the four fundamental tastes. Only the sides of the tongue are more sensitive than the middle overall. This is true of all tastes – with one exception: the back of our tongue is very sensitive to bitter tastes. This is apparently to protect us so that we can spit out poisonous or spoiled foods or substances before they enter the throat and are swallowed.