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There are generally thousands of taste buds scattered in the tongue. Each taste bud has about 50 to 150 taste receptors that usually perform a selective taste function. Taste receptors are cells responsible for allowing individuals to evaluate the saltiness, sweetness, and bitterness of the food and beverages they are eating and drinking. Other taste sensations that can also be detected by the taste receptors include sourness and umami.
Umami is a taste sensation the brain recognizes when individuals consume food containing glutamate, which is usually in the form of monosodium glutamate (MSG). MSG is an ingredient frequently added to many processed foods, like cheese and meat, to enhance their flavor. An example of a bitter tasting food is lettuce. Sweet foods include milk and sugar. Lemon and mango are sour, while salt and seaweed are salty.
The interpretation of taste is often made possible due to the interactions between the food molecules and the taste receptors in the tongue. For example, when a person takes a gulp from a glass of milk, the taste buds for the sense of sweet taste often undergo several chemical reactions. These reactions then result in the release of nerve signals to the brain, which in turn, interprets or acknowledges the sweet taste of milk. This is also what occurs whenever other foods with different tastes are placed in the mouth.
Not everyone has the same number of taste receptors, however, and taste sensitivity may also differ among individuals. Some people have more sensitive taste receptors than others. The number of taste receptors is often inherited by children from their parents. Taste sensitivity is also often influenced by a person's sense of smell.
Many elderly individuals experience changes in their sense of taste. This is mostly due to the decreasing number of taste receptor cells in the tongue as one gets older. The taste buds may also be reduced in number in most individuals who smoke.
Several factors can affect the functions of the taste receptors, thus leading to the development of taste disorders. These include infections in the ears and the upper respiratory tract, and injury to the nerves caused by head trauma, or surgical procedures. Some medications may also have side effects that alter the taste sensation of patients. Ingestion of harmful chemicals like insecticides may also cause some serious damage to the taste buds. Tooth problems, as well as poor oral hygiene, can also contribute to the development of taste disorders.