Biochemistry in Taste

Taste: You and Your Buds

Taste is one of our five senses, also referred to as gestation. Smell and taste are so complex they require special neurons sensitive to chemical substances to facilitate the senses. Although we are born with the ability to taste, the sense develops as we age, therefore babies and young children tend to dislike strong flavors such as onions and mustard. Taste buds are nerve endings on the tongue that sense only four sensations: bitter, salty, sour, and sweet (some scientist also believe there to be a fifth sensation; umami - savory). Texture, temperature, smell, and combinations of these sensations allow us to detect differences in the foods we eat. Taste is so influenced by smell that it is very important to our sense of taste to inhale and exhale as we eat or drink. Also, the sense of taste can be hindered by things such as zinc deficiency, smoking, a head cold or sinus problems, deficient sense of smell, or damage to certain parts of the brain. My dad was involved in a car crash as a teenager in which he suffered a laceration across his nose and mouth, severing the nerves to his nose. His injury made him unable to smell for a long time and even now, his sense of smell is limited. He is able to smell today because the only cells in the nervous system to be replaced when old ones are damaged or die are the neurons associated with smell and taste. Since his recovery my dad has developed a taste for strong flavors such as vinegar, citrus, and peppers. Texture is also a big factor for my dad now, he explains, "because there is not a lot of nuance in my taste, I'm very focused on the textures of the food I eat". For example (and much to my dismay) he does not like avocados but chocolate is his favorite food. 

The Wolrd of Biology states, "taste begins when food or drink mix with saliva in the mouth and stimulate taste buds on the surface of the tongue, soft palate, pharynx, larynx, and epiglottis". I remember growing up believing the falsehood that specific areas of the tongue were designated for specific tastes. For instance, the taste buds receptive to sweetness were supposedly at the front, along the front sides were the taste buds receptive to salt, those further back were for sour flavors, and bitterness was detected by the far back taste buds. In 1901, D.P. Hanig, a German scientist, published the first "tongue map". Then in 1974 one of the first breakthroughs in taste research surfaced, and at this time scientists realized that the tongue map was a century old understanding that no one challenged. This breakthrough was realized by Virginia Collins. His research stated that individual taste buds are not even specifically sensitive to individual taste, instead "there are variations in sensitivity to the four basic tastes around the tongue" and he found that there are receptors that are sensitive to all tastes located around the tongue, on the soft palate, and in the epiglottis. These receptors have a neuronal response to combinations of bitterness, saltiness, sourness, and sweetness which are decoded in the brain, not in the mouth. Each one of us has 2,000-5,000 taste buds, which each contain 50-150 neuroepithelial cells. An action potential is initiated in these cells when a chemical stimulation occurs. These cells "interact through a complex system of electrical and synaptic responses with fibers within the central nervous system". Then these responses synapse to the medulla, the thalamus, and the postcentral gyrus.

Work Cited:
http://ic.galegroup.com/ic/scic/ReferenceDetailsPage/ReferenceDetailsWindow?disableHighlighting=&displayGroupName=Reference&currPage=&dviSelectedPage=&scanId=&query=&source=&prodId=&search_within_results=&p=SCIC&mode=view&catId=&u=dc_demo&limiter=&display-query=&displayGroups=&contentModules=&action=e&sortBy=&documentId=GALE%7CCV2431500598&windowstate=normal&activityType=&failOverType=&commentary=

http://www.livescience.com/7113-tongue-map-tasteless-myth-debunked.html