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Chemistry of taste essay

Smell & Taste | American Academy of Otolaryngology-Head and

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sensitivity to these qualities is distributed differentially, with the tip of the tongue most sensitive to sweet, the back to bitter, the posterior portion of the sides to sour; the salty taste is perceived equally well in all receptive areas. papillae in different regions of the tongue have distinctive shapes and characteristic numbers of taste buds associated with them. it is the sense of touch that serves to localize taste perception, such that the taste is perceived to be coming from the area that is stimulated by touch. taste bud contains 50–150 neuroepithelial receptor cells arranged, like segments of an orange, to form a compact, pear-shaped structure, about 70 μm high and 40 μm in diameter. body’s ability to sense chemicals is another chemosensory mechanism that contributes to our senses of smell and taste. every schoolchild learns that it is one of the five senses, a partner of smell and sight and touch, a consequence of food flitting over taste buds that send important signals—sweet or bitter, nutrient or poison? enter the title keyword:Free Chemistry papers, essays, and research papers. the first, feast, celebrates our love for eating and our long-standing ingenuity in making food taste delicious. although certain medications can cause chemosensory problems, others—particularly anti-allergy drugs—seem to improve the senses of taste and smell. there is no area in the cerebral cortex uniquely associated with taste; rather, the incoming impulses are represented along with the sensory and motor mechanisms of the face area. very few studies measured salt taste perception, salt taste preference and actual salt consumption among the same respondents. in recent years scientists have found taste receptors all over the body, discoveries that have solved some long-standing mysteries. the nerve supply for most of the taste buds on the soft palate and towards the front of the tongue come from a division of the viith (facial) cranial nerve, called the chorda tympani, because its route to the brainstem passes close to the tympanic membrane in the ear. of smell and taste may result from polyps in the nasal or sinus cavities, hormonal disturbances, or dental problems. red drinks should taste like cherries, and purple drinks should taste like grapes. and smell when we eat or drink we perceive a sensation that most people call ‘taste’. five tastes are enough to help determine if the thing we just put into our mouth should go any farther—if it's sweet or savory and thus a probable source of nutrients or if it's bitter and potentially poisonous. (taste nerve) cells are clustered in the taste buds of the mouth and throat. each papilla houses onionlike structures of 50 to 100 taste cells folded together like the petals of a young flower about to bloom—taste buds, we call them. these cells transmit messages to the brain, where specific smells or tastes are identified. Smell and taste contribute to our enjoyment of life by stimulating a desire to eat – which not only nourishes our bodies, but also enhances our social activities. these cells have chemical receptors attuned to the five basic tastes—bitter, sweet, sour, salt and umami, the last a word borrowed from japanese that describes the savory flavors of roast meat or soy sauce. the primary qualities of taste are sour, sweet, salty, and bitter.

Why Does Food Taste So Delicious? - Scientific American

it turns out that strains of mice that lack sweet taste (they don't prefer sweet food to non-sweet) have a mutation of this gene. smell and taste warn us of dangers, such as fire, poisonous fumes, and spoiled food. the salty taste is associated with both the anión and cation of soluble salts. specific ageusias (absences of taste) have been discovered in man; one of them, to phenyl thiocarbimide (ptc), is especially interesting to geneticists, for it is inherited as a simple mendelian recessive and can be used as an aid in classifying ethnic groups. eight to 12 larger mushroom shaped (circumvallate) papillae, each surrounded by a circular trough, lie at the back of the tongue in a v-shaped formation; these have on average 250 taste buds each. a layer of saliva extends into the taste pores and constantly bathes the receptors. both taste and smell have been restored in some patients by oral zinc supplementation. taste losses, if present, are often localized and whole mouth taste sensation is often not affected. the essential process depends on specific interactions between taste substances and specialized protein receptor molecules embedded in the membrane of the receptor cell, which trigger a series of chemical reactions, leading to a change in the flow of ions through pores in the membrane, and hence a change in the electrical potential inside the cell. there is no evidence that taste cells are no longer regenerated or that the structure of taste buds changes in healthy older adults. they consist of up to nine folds of epithelium and have as many as 600 taste buds each. white wine with a drop of red food coloring tastes like red wine—even to experienced wine tasters. individual taste cells live for only ten to twelve days, and new cells below them evolve to replace them as they die. beidler (1961) has suggested that the adsorption of the stimulus onto the surface of the taste cell may result in a change in the membrane potential of the cell such that a nervous impulse can be generated. potato chips taste crisper if you hear a crunch over headphones. radiation treatment for oral cancer frequently directly damages salivary glands and thus can reduce taste function. penicillamine, sometimes used to treat rheumatoid arthritis, also binds metals and interferes with taste perception. phlogiston was a fire-like substance without color, odor, taste or mass that every combustible substance was in part composed of, and it was released during combustion (bowler 56). patients with disruption in zinc metabolism often experience loss of both taste and smell. three cranial nerves (the seventh, ninth, and tenth) are involved in the transmission of nerve impulses from the taste cells to the brain. that slurpee would not taste the same if it did not dye your tongue an electric blue., yngve (editor) 1963 olfaction and taste: proceedings of the first international symposium held at the wenner-gren center, stockholm, september, 1962. when smell and taste become impaired, we eat poorly, socialize less, and feel worse.

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some scientists count the taste of monosodium glutamate (msg) as a fifth basic taste quality known as umami. a patient may also be asked to compare the smells or tastes of different chemicals, and how the intensities of smells and tastes grow when a chemical concentration is increased. more rarely, head trauma may damage nerves involved in taste perception. in humans each fungiform papilla contains a number of taste buds, each one opening to the outside through a tiny taste pore. taste cells require the presence of gustin, a compound in saliva, in order to develop normally. it impairs the ability to identify odors and diminishes the sense of taste. signals from the taste buds are relayed, via a chain of nerve cells and fibres, at various cell stations in the brainstem and thalamus, up to the cerebral cortex. studies show that food choices are very largely determined by how foods taste. however, there is still controversy as to whether combination of these four primary tastes adequately describes all gustatory experiences. he was not only a chemist and a physicist as we know him to be, but also an avid theologian, a philanthropist, an essayist, and a beginner in medicine. is no dramatic decline in taste or smell function in healthy aging. saliva is essential for normal taste because it acts as both a solvent for the chemicals as well as a transport medium for those chemicals to reach the receptors. information about taste in the rear of the tongue is carried to the brain by the glossopharyngeal nerve. when people describe how food tastes, they are actually talking about food flavor, and not just the basic tastes of sweet, sour, salty and bitter. in many cases, nasal obstructions, such as polyps, can be removed to restore airflow to the receptor area and can correct the loss of smell and taste. circumvallate papillae of such patients show a disruption of taste buds and taste pores, with obvious cell death. however, there does not appear to be a unique mechanism for each of the basic tastes: each seems to use several different mechanisms. the ixth (glossopharyngeal) and xth (vagus) nerves innervate taste buds in the back of the mouth and the pharynx respectively. both food scientists and chefs will tell you that the smell, sound, feel, and, yes, the sight of your food are just as important as taste to fully appreciate what you eat. a lessening of nerve input from one area of the tongue may cause another area to take over and thus maintain the level of taste sensation. surgery to repair the nerve increases taste pore density and partially restores taste function. some experiments in monkeys suggest that nerve cells at higher levels in the taste pathway respond more selectively, with a larger proportion of them essentially responding to only one basic taste. dietary deficiencies in man may result in changes in food preferences without affecting taste thresholds.

The Chemistry of Food Colorings - American Chemical Society

and smellbibliographythe topics of taste and smell are frequently combined for discussion because the nature of the stimulus in each case is defined in chemical terms. bitter and sweet tastes occur for representatives of many chemical classes whose essential characteristics are not yet recognized.'s not all from our mouth, or our mouth and the back of our nose, or our mouth, and nose, and taste cells in the intestine. for example, drugs that interfere with cell division or growth, such as cancer chemotherapy agents, can disrupt both taste and smell. introduction: the short stories i have chosen to focus on for this essay are ‘flight’ by doris lessing and ‘your shoes’ by michele roberts. stimulus substances possessing hydrogen ions taste sour, although hydrogen-ion concentration is not the only determining factor. a branch of the facial nerve innervates the fungiform papillae, and carries information about taste on the front of the tongue to the brain. rats hate the taste of cocoa, yet some enterprising scientists recently separated a rat from its brood and coaxed it to eat some anyway. smelling chocolate odor while chewing on tasteless gum is interpreted by the brain as eating chocolate. in 2007 they discovered that cells lining the small intestine also contain taste receptors. burning mouth syndrome is one of the very few conditions that affect taste response to sweet. in humans, the number of taste buds varies considerably from person to person, with the majority having 2000 to 5000, distributed over the various regions. in everyday experience they are typically so intermingled that a large part of sensations commonly called taste are actually olfactory sensations arising from odorous molecules from ingested material in the mouth reaching the olfactory epithelium by way of the posterior nares . at some point the brain must perform a comparison between the activity in several different nerve fibres in order to decide what the taste actually is. for instance, after eating a west african fruit called miracle fruit, even quite acidic substances (such as lemon juice), which would normally be sour, taste extraordinarily sweet. hunger, this quest for deliciousness, has effects that reach far beyond our taste buds (and our waistlines). nerve damage during the extraction of wisdom teeth has been found to reduce taste pore density (and presumably taste bud density) in the front of the tongue. the life of an individual taste cell may be as short as one week, which raises some provocative questions concerning the neural organization of a continuously shifting population that provides constant patterns of information. remember, many types of smell and taste disorders are reversible. highly preferred tastes may cause us to overeat to the point of discomfort, and almost everyone has experienced the arousal of appetite by the smell of desirable food as well as the analogous loss of appetite produced by objectionable odors. has always been assumed that the number of taste buds declines with age but that does not appear to be the case. an unpleasant taste in the mouth is one of the main factors limiting use of the ace-inhibitor captopril. two subjective intensity scales have been devised for taste (geldard 1953, pp.

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    for example, what you may think is a taste problem could actually be a smell problem, because much of what you taste is really caused by smell. this may explain why older people often do not perceive a loss in taste, even when damage to taste nerves is readily apparent to a medical professional. certain medications are the cause of smell or taste disorders, and improvement occurs when that medicine is stopped or changed. patients with burning mouth syndrome report a persistent burning sensation, usually localized to the front of the tongue, as well as distorted and persistent bad tastes. if the nerves are damaged the taste buds degenerate and slough off, and following regeneration of the nerves, the taste buds reappear. upper respiratory infections are blamed for some losses, and injury to the head can also cause smell or taste problems. smell and taste contribute to our enjoyment of life by stimulating a desire to eat – which not only nourishes our bodies, but also enhances our social activities. among the known side effects of antiglaucoma agents are changes in taste. damage from bacterial or viral infection may result in an enhanced perception of bitter taste or in taste phantoms. at any one time less than a third of the cells in the taste bud are innervated.-related taste deficits are most pronounced when testing is localized to specific areas on the tongue. some patients, notably those with serious respiratory infections or seasonal allergies, regain their smell or taste simply by waiting for their illness to run its course. therefore low dietary levels of zinc, disruption of salivation, or drugs that bind zinc and prevent its use by the body may contribute to taste loss. who have lost their larynx (voice box) commonly complain of poor ability to smell and taste. these taste fibres belong to three different cranial nerves, connected to the brain. in fact cilia is the only part of the brain that is visible outside of the skull(the science of taste and smell). moreover, very few studies have examined taste or smell function, dietary intakes, and nutritional status in the same persons. inasmuch as all taste receptors appear to be responsive to stimuli of more than one quality, the mechanism underlying the distinctiveness of the different qualities must, be sought in some aspect of the patterning of the afferent neural signals. a block of cheese with sharp edges tastes sharper than one with round corners. taste buds are made up of thirty to fifty individual cells, which are organized into an oblong sphere, much like the segments of an orange. fungiform papillae on the tip of the tongue have more taste buds than do those in the middle region of the tongue. smell losses may lead people to select foods that are sweet or rich in fat, such that the taste and texture will contribute to sensory appeal. one might have expected that each fibre would respond, with a burst of impulses, when a solution of just one of the primary taste substances was dripped on to the appropriate taste bud or buds.

    Chemistry Is Everywhere - American Chemical Society

    scattered taste buds are also found in the epithelium of the soft palate, pharynx, larynx and epiglottis. nicotine patches may interfere with taste perception, perhaps because they reduce salivary flow. because of the very slow progression of sensory losses, an older person may not even be aware that a decline in taste or smell acuity has occurred. these surface cells send taste information to nearby nerve fibers, which send messages to the brain. the senses, taste and smell have been relatively neglected as areas of research. taste buds in the soft palate are innervated by a branch of the facial nerve, and taste buds in the throat are innervated by the glossopharyngeal nerve and the vagus nerve. there have been valiant attempts to classify these into a smaller number (usually 10–20) basic or primary smells, comparable to the four or so primary tastes, but no scheme is universally accepted. scattered over the main body of the tongue are approximately 200, small, mushroom-shaped (fungiform) papillae, which have, on average, only three taste buds each. are harder to convince—they have to try an unfamiliar food about nine times, on average, before they begin to like the taste. some researchers have argued that irreversible changes in taste and smell lead directly to altered food preferences, reduced food consumption, and poor nutrition. therapy patients with cancers of the head and neck often complain of lost smell and taste. have recorded with tiny electrodes from individual nerve fibres innervating the taste buds, in anaesthetized animals. the enhanced air flow through the nose helps smell and taste sensations to be re-established. the absence of these sensations is recognized during periods of nasal congestion that result in the so-called flat taste of foods. very recently, a gene called t1r2 has been identified in mice, which is selectively switched on in taste bud receptor cells. although many hundreds of different chemicals can stimulate activity in taste receptor cells, the four basic taste qualities of salt, sour, sweet and bitter have stood the test of time. a history of middle ear infections has been associated with taste abnormalities. there is a small 2–10 μm opening in the epithelial surface called the taste pore, which allows direct contact between chemicals dissolved in the saliva and the tips of the receptor cells. scientists believe that whole mouth perception may compensate for some of the regional losses of taste function with age.., enjoying cooking, eating a wide variety of foods); lower preference for foods with sour/bitter taste, such as citrus fruits; higher intake of sweets; and higher intake of fats. taste phantoms are a taste sensation in the absence of a stimulus. commonly identified taste sensations:sweetsourbittersaltycertain tastes combine with texture, temperature, and odor to produce a flavor that allows us to identify what we are eating. people are born with a poor sense of smell or taste.
    • What Is Taste Essay - 1603 Words -

      the taste buds on the tongue are associated with characteristic ‘papillae’ (from the latin for pimples), whereas those in the other regions are found on the smooth epithelial surface. have always assumed that taste and smell would undergo dramatic declines with age, much as vision and hearing do. some studies on salt taste preferences reported that older subjects preferred saltier mashed potatoes and chicken broth than did young people, while others found no age-related increase in preference for salt in soup or in tomato juice. some people may have twenty-five or more taste buds per papilla. losses in taste might be expected, given the anatomy of the taste system., we use our friends and loved ones in much the same way that medieval monarchs used food tasters—let them try it first, then let's see how they are doing in 20 minutes. extent of loss of smell or taste can be tested using the lowest concentration of a chemical that a person can detect and recognize. diuretics, which reduce blood pressure by increasing urine output, have occasionally been associated with a loss of taste. most nerve fibres respond to two or more of the basic taste stimuli, the magnitude of the response varying from one taste substance to another. intact nerve supply is necessary for the normal function of taste buds. the receptor cells for taste are known as taste buds and, in mammals, are distributed throughout the oral cavity, including the larynx and pharynx, with the major concentration on the papillae of the upper and lateral surfaces of the tongue. the sensations that result from individual stimulation of these two types of chemoreceptors are respectively taste and smell. there may even be similarities of mechanism for different basic tastes. retronasal olfaction produces a completely unique sense—neither smell nor taste alone but a hybrid that we call flavor. taste buds are found all over the oral cavity, the perceived taste of food appears to come from the entire mouth and not from isolated patches on the tongue, throat, and roof of the mouth. taste and smell participate in the regulation of feeding activities of animals, including man. taste buds are located in tissue folds on the sides of the tongue, just in front of the circumvallate. when it comes to food choices, deficits in taste and smell, if present, can be compensated for by prior learning and experience. it is difficult to taste food with a dry mouth. for purposes of scientific discussion, taste refers to those sensations arising from stimulation of specialized receptors in the mouth, primarily on the tongue, while smell refers to those sensations arising from the stimulation of receptors in the upper portion of the nasal cavity. ‘‘salt taste perceptions and preferences are unrelated to sodium consumption in healthy older adults. these studies did not speak to the key question of whether changes in salt taste perception affect intake of saltier foods on a regular basis. and in the case of the latter, it ropes them together with the signals from the taste buds.
    • Flavor Chemistry Research at the USDA National Historic Chemical

      at the first relay in the brainstem almost no neurons respond to one taste, yet in the taste area of the cortex, about 75% of neurons respond to a single taste. each taste bud is innervated by more than one nerve fibre and each single nerve fibre can connect to a number of receptor cells, taste buds and even papillae. the deficit was related to smell as opposed to taste. in one experiment, researchers connected volunteers' tongues to a low-voltage electrical device, showed them pictures of food items and then sent a mild shock across their taste buds—a sensation not unlike licking a battery. taste bud is contacted, at its base, by the terminals of sensory nerve fibres. reflex secretion of saliva from the salivary glands under the tongue and in the cheeks is stimulated by chewing, taste and smell, to varying degrees. this suggests a high degree of convergence of input from taste buds on to the sensory nerve fibres. generally, age-related deficits in the sense of smell are more dramatic than taste deficits. tastes are detected in the mouth by specialized receptor cells located in the upper part of taste buds and near the taste pore. although normal caged rats maintain their caloric intake in the absence of taste and smell sensations, rats with dietary deficiencies or with reduced hunger and thirst induced by brain lesions are highly dependent on these sensations for regulation of intake., if not all, of the observed taste losses with age may be caused by a cumulative history of disease or by the chronic use of medications. taste buds are located not only on the tongue but also in the throat and on the roof of the mouth (soft palate). taste bud complex is a dynamic system in which the receptor cells are rapidly turning over. many of the small bumps that can be seen on the tongue contain taste buds. the past decade our understanding of taste and flavor has exploded with revelations of the myriad and complex ways that food messes with our consciousness—and of all the ways that our biases filter the taste experience. the time of aristotle (384–322 bc) there have been attempts to categorize taste into primary or basic tastes. both taste and pain pathways may contribute to burning mouth syndrome. the measurements so far suggest that differential sensitivity to the salty taste is slightly greater than that to sweet and sour, and sensitivity to biter is slightly less. receptorsthe receptors involved in gustation are found in specialized ‘end-organs’ called taste buds, embedded in the epithelium that covers the surface of the tongue, soft palate, pharynx, larynx and epiglottis. the four taste qualities are perceived through receptors located on the tongue and elsewhere in the oral cavity.—patients react to different chemical concentrations in taste testing; this may involve a simple “sip, spit, and rinse” test, or chemicals may be applied directly to specific areas of the tongue. the wayin which we can perceive many subtle tastes and distinguish between different compounds of the same basic taste category might be explained by the multiplicity and specificity of these mechanisms. metallic and astringent tastes have, in the past, been suggested as primaries, and more recently japanese researchers have proposed that the characteristic taste of monosodium glutamate (used as a taste enhancer by the food industry) is also a basic taste, with its own receptive mechanism.
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