Taste Buds

Taste Buds by Elizabeth Feins

I. Intro

Fig. 1: The Five Senses

Of the five senses, taste is often the most overlooked (look—in Fig. 1, it’s the last one listed!). Historically, it’s the most mysterious sense, as well as the sensation we use least often. When we’re taking a walk in the park, for example, we can see the trees, hear the birds, feel the breeze, and smell the barbecue going on in a neighbor’s backyard—but we don’t taste anything. It seems to be the least important sense. In actuality, however, taste plays a huge role in the daily lives of humans. Our sense of taste affects the foods we choose to eat, and, consequentially, our lifestyle.

II. Background

Fig 2: Diagram of a Taste Bud

Taste buds are small bumps that coat the tongue, soft palate, epiglottis, and, according to recent studies, the lungs. Each bump contains a cluster of taste cells (as seen in Fig. 2), which enable humans to taste the foods they eat. Taste buds have the ability to detect chemical messages in food, and then translate the messages into electrical signals called action potentials. The action potentials then travel via nerve fibers to the brain, which translates them into the tastes we experience daily. Taste buds are considered chemoreceptors—sense organs that respond to a chemical stimulus. Some chemoreceptors, such as the organs that sense smells, do not need to make direct contact with chemicals; taste buds, however, must physically touch the chemical in order to send the message to the brain.

Taste buds can recognize five distinct tastes: salty, sweet, bitter, sour, and umami (“savory”). Rotten foods tend to taste bitter or sour, while nutritious, high-calorie foods trigger the other three tastes; because of this, humans have evolved to prefer salty, sweet, and savory flavors over bitter or sour.

Fig. 3: An Outdated “Tongue Map”

In the past, scientists believed each region of the tongue could sense a specific taste (Fig. 3). This theory has since been disproven; any taste bud can detect any flavor using ion channels. Salty foods, for example, contain sodium chloride. Each molecule of sodium chloride contains one positively charged sodium ion and one negatively charged chlorine ion. The sodium ions affect the electrical charge of the taste bud cells. Similarly, sour foods contain acids, which are made up of positively charged hydrogen ions. The hydrogen ions affect the taste buds differently than the sodium ions. Bitter, sweet, and savory flavors are sensed in a parallel manner using proteins instead of ions.

III. Biography of Investigator

Fig. 3: Marcello Malpighi, Discoverer of Taste Buds

Born in 1628, Marcello Malpighi was an Italian physician and biologist who studied the anatomy using microscopes. As the first scientist to employ microscopes to analyze physical composition of humans, Malpighi is considered the “Father of Histology” (the microscopic study of tissues). He helped change many outdated concepts of medicine and biology—his discovery of the capillary demonstrated that blood moved between veins and arteries, proving the existence of the circulatory system. He also also studied microscopic subdivisions of organs such as the liver, spleen, kidneys, bones, and the deeper layer of the skin that is now named after him: the Malpighian layer.

In 1662, Malpighi became a professor of medicine at the University of Messina in Sicily. During this period, he discovered the minute structures of the brain and optic nerve, in addition to identifying taste buds. However, Malphighi’s work was very controversial; in 1684 his home was burned, his microscopes shattered, and his research papers destroyed. In spite of this, Malpighi was invited to be the personal physician for Pope Innocent XII. He held this position until his death in 1694.

IV. Impact on Humanity

Restaurants add extra salt to stimulate taste buds.

Taste buds greatly impact humanity. Each human has individual taste preferences, but for the most part, people tend to prefer sweet, salty, and savory over bitter and sour. Food manufacturers take this into consideration when creating new recopies; restaurants such as McDonald’s incorporate extra salt into their trademark French fries in order to stimulate the taste buds and keep customers coming back for more.

Recent studies regarding taste include the discovery of taste buds lining the walls of the lungs. These taste buds respond to bitter tastes by expanding the airways significantly. This new information could lead to new asthma treatments.

V. Journal Article Review: Making Sense of Taste

The article follows the history of human knowledge of taste buds. Beginning in the 1940s, scientists have done tests on taste cells, trying to determine how they communicated with the brain. Up until recently, it was thought that each region of the tongue could only experience one flavor. For example, the taste buds at the tip of the tongue could supposedly only detect sweetness; everything else would seem tasteless. Similarly, the back of the tongue would only react to bitter tastes. However, later discoveries showed that the same taste bud could detect more than one flavor—it simply reacted more strongly to one flavor in particular.

Works Cited

Foster, Niki. "How Do Taste Buds Work?." wiseGEEK: clear answers for common questions. Bronwyn Harris, n.d. Web. 1 May 2011. .

"Marcello Malpighi Summary BookRags.com." BookRags.com Study Guides, Lesson Plans, Book Summaries and more. N.p., n.d. Web. 1 May 2011. .

McMaster, Nick. " Your Lungs Have Their Own Taste Buds - Scientists find bitter tastes open airways, could treat asthma." Newser Headline News Summaries, World News, Breaking News, and Local News. N.p., n.d. Web. 1 May 2011. .

Smith, David , and Robert Margolskee. "Making Sense of Taste." Making Sense of Taste. N.p., 18 Mar. 2001. Web. 1 May 2011.