How Humans' Taste Buds Work

Tasting The Difference Between Sweet, Sour, Salty and Bitter Flavors

Jun 15, 2009

Taste buds are located on the tongue, palate and throat and provide sense of taste. The nerves in the tongue send signals to the brain to interpret flavors.

Taste buds contain papillae. Within these papillae are chemoreceptor cells designed to detect taste. Food and drink combine with saliva in the mouth and send information to the taste buds via taste pores. This triggers nerve activity in the taste bud, which then sends a message to the brain.

The Different Taste Buds Of The Tongue

Receptor cells for taste are modified epithelial cells. These are organized as taste buds and are located in several areas of the tongue. Humans recognize four basic flavors. These are:

Sweet
Sour
Salty
Bitter

Author, science graduate and ex-BBC radio manager, Michael Quinion states, “In recent years some workers have added a fifth taste, umami, to the other four, though western food scientists are divided about whether it really exists or not. Both the word and the concept are Japanese, It is also said to involve all the senses, not just that of taste. To read more, visit World Wide Words or The Fifth Tastebud.

Different taste buds are receptive to specific flavors.

Taste buds at the front of the tongue are more sensitive to sweet flavors.
Taste buds along the side of the tongue are more sensitive to salt or sour flavors.
Taste buds at the back of the tongue, and the throat and palate, are more sensitive to bitter flavors.

The Nerves Of The Tongue

There are three different nerves of the tongue that transmit information about taste. These are:

The facial nerve
The glossopharyngeal nerve
The vagus nerve

The facial nerve sends information from the taste buds situated at the front of the tongue.
The glossopharyngeal nerve sends information from the taste buds located at the back of the tongue.
The vagus nerve conveys information from taste buds located in the throat.

The information from these nerves is sent to the medulla oblongata in the brain stem. Next it relays the message to the thalamus and then to processing centers in the parietal lobe of the brain to be identified.

Taste And Smell Are Interrelated

Both taste and smell rely on chemoreceptors to detect chemicals present in food, drink or the environment. Human and mammal taste and smell are interrelated with smell thought to determine a large proportion of what humans taste.

Compare the taste and smell senses of humans, dogs and cats. Smell is the sense that dogs and cats use most and is much more effective in them than in humans. A dog’s sense of smell is approximately 13 times better then a human’s and approximately 3 times more effective then a cat’s sense of smell. It is the first sense dogs and cats use when eating, which is why good quality kibble is designed for taste and smell rather than visual appeal.

Taste sense in dogs and cats however, is far less developed than in humans. It is not nearly as refined as in humans, and dogs and cats can barely detect sweet flavors. Humans have approximately 9,000 taste buds with dogs having approximately 1,700 and cats having about 500 taste buds. It is curious as to why pets want to taste human treats, as they can't appreciate them nearly as much as humans do.