Monday 3 November 2014

Smell and Taste

I’ve been here before but when or how I cannot tell

I know the grass beyond the door / the sweet keen smell

Evolution has blunted some senses and sharpened others and there is every reason to suppose that our sense of smell is not what it once was. Animals live, communicate struggle and perish in a world of smell which marks territory, asserts dominance, deters rivals, attracts mates and distinguishes species from species, male from female and friend from foe. By comparison, our sense of smell is obtuse indeed.
 
How do we smell?

The human mechanism for picking up and differentiating smells is nevertheless, still remarkably delicate. Some 10 to 20 million olfactory receptor cells are situated in an area the size of a small coin in the roof of the nasal cavity just beneath the eye sockets. Not only can these cells detect as many as 4,000 separate and clearly identifiable odours but they also only require the tiniest fraction of the essence to do this. The smell of garlic for example becomes perceptible at a concentration of less than one millionth of a milligram in a liter of air and will also contribute very strongly to your appreciation of its taste.

Odours are created by moisture molecules evaporating into the air. All living and many inert things give off their separate, invisible and highly volatile essences whether it is the balmy fragrance of roses or the acrid fumes of car exhaust and, as long as the air temperature is just above freezing, will go on releasing them indefinitely. This is why leaving the stopper off a bottle of perfume or the petrol cap off a car will eventually cause perfume and petrol to evaporate entirely always.

Most smells have very distinct properties. We can say that they’re spicy, fragrant fruity, woody, aromatic, pungent or tarry, but our appreciation of them will be highly individual. Association, memory and even anticipation play an enormously important role in determining whether we respond positively or negatively to a certain smell. Smells, subconsciously catalogued away in the vast olfactory library of the brain, evoke strong association of events, people or places, once they’re reawakened. That unforgettable, unforgotten river smell was Grant-Chester to the poet Rupert Brooke, but the same smell might have carried someone else back to somewhere quite different. Some psychiatrists are now exploiting these strong associative qualities by using the smell of vanillin in breast milk to unlock early painful associations or memories when treating patients with certain types of psychological disorder.

There’s no doubt that scents and essences do exert a powerful psychological effect on the brain, influencing mood to calm and soother, invigorate or even stupefy, if arriving in large enough doses. They also play an important role in human communication and sexuality. However just how important to no one quite know. It does seem likely that human smell is a part of the highly complex body chemistry that sends out its signals of like and dislike, attraction and repulsion, excitement and fear. The ingredients thought to be responsible, known as pheromones, have now been isolated in the laboratory.
Receptivity to smell depends on several factors, such as the time of day (sensitivity increases as the day wears on), the stage of the menstrual cycle (women become between 100 and 5,000 times more receptive to smell over ovulation), and the length of exposure. Whether it is the smell of cabbage water or the exotic scent you have dabbed on your wrist, the nose soon tires of it. This is what makes people so impervious to their own body “odour”.
 
Human Smell

All body odour both the subtle odour that attracts and the stale odour that repels derivers from sweat. Sweating is an integral and essential part of the body’s internal temperature control mechanism. If exertion, fever or emotional tensions cause the body temperature to rise above 37.4’C (99.3’F) over 3,000,000 tiny sweat glands come into play. Known as eccrine glands, they release substance 99% water and 1% sodium chloride which exerts a cooling effect as it evaporates into the atmosphere. It is completely odourless. Emotional arousal, such as fear, embarrassment or sexual anticipation, steps up sweat production in the armpit, groin, hands and feet and brings a second set of glands, known as the apocrine glands, into action. Both types of sweat, however, are colorless adourless and totally inoffensive and it is only when they combine with bacteria living on the skin and body hair that odour is produced.
 
Controlling and Counteracting Odour

Stay clean. A daily bath or shower is the best way of guarding against odour, as it washes off the organic substances present in apocrine sweat. There’s no need to become obsessive about cleanliness. Not all bacteria are harmful and many serve to protect the body against infection. An over-enthusiastic use of anti-bacterial soap, together with more elaborate types of germ warfare, may contribute to rather than eliminate problems by washing away the essential bacteria that live on the skin and body hair and destroying the natural layer of fatty acids that acts as a barrier to invading germs.
 
Change your clothes frequently

Sweat clings to clothing preventing it from escaping into the atmosphere so that it becomes “stale”. Some synthetic fibres are particularly absorbent and you’ll perhaps find that it assist to wear natural fibers such as cotton or silk, next to the skin. To remove sweat stains from clothing rub on full strength liquid detergent and leave for about one hour before washing. One of the scourges that the woman of these days has completely eliminated from her path is that of the trying outcome of perspiration in any form said vogue in 1916. Had such a drastic measure been possible which thankfully, it was not. It’d have had dire consequences for the body. Perspiration is a natural healthy and important part of the body’s temperature control mechanism. It is also essentially odourless. Perspiration is only trying when it is excessive or stale. Staying clean and bathing daily should guard against both of these. If not, the use of an anti-perspirant or deodorant certainly will.

Use a deodorant or anti-perspirant regularly, as protection builds up over a period of days, even with regular bathing, and tapers off if use is discontinued. Roll-ons tend to be more efficient than aerosols, and both are considerably more effective if applied to clean, cool dry skin.

Deodorants contain perfume that masks odour by over powering it. They’re made more effective by the addition of an anti-bacterial agent. Anti-perspirant contains metal salts, usually aluminum compounds, which restrict the secretion of sweat from the eccrine and apocrine glands by as much as 50%. They’ll not actually stop you perspiring altogether, nor will they adversely affect the body’s thermostat as there’re more than sufficient sweat glands in the rest of the body to compensate. However you cannot become “immune” to a brand of roll-on or aerosol, it does take a certain amount of trial and error to find the best for you.

If you’re already using a strong anti-perspirant and you continue to sweat copiously, see a doctor or dermatologist, who’ll be able to make up a special prescription for you. The same can be done for sweaty palms and soles; if you’re regular anti-perspirant does not work.

Avoid using the so-called “feminine” deodorant sprays. The healthy vagina keeps itself clean and does not need deodorizing. Straightforward washing with soap and water should constitute your first line of defense and should you smell something abnormal, do not disguise it with a deodorant go to see your doctor.

It is a myth, too that menstrual blood smells. Like any other type of blood, it only begins to smell when it decomposes and that can only happen when it comes into contact with the air. Use an ordinary unscented, cotton or natural fiber tampon while menstruating and change it regularly at least every six hours and preferably more often.

Cut down foot odour by washing socks and stockings frequently. Wear wool and cotton rather than synthetics, and shoes that enable your feet to “breath” by allowing air to circulate freely around them.  A liberal application of surgical spirit or a foot spray can be helpful in counteracting odour when applied to clean dry skin. While foot sprays do not entirely prevent perspiration, they do contain alcohol, which exerts cooling and drying effect and an anti-bacterial agent which inhibits the action of the naturally occurring bacteria that mingle with the sweat to produce the odour. A second line of defense is to buy medicated insoles which combat odour through absorption or through the slow release of a deodorant.

Eliminate bad breath at source not necessarily the mouth. The most common sources of bad breath are the throat particularly if you have a throat infection, the stomach particularly if you’ve not eaten for some hours and the lungs particularly if you smoke or drink. Because bad breath emanates largely from the digestive and respiratory systems and not from the mouth, the usefulness of mouth washes is limited. They may give the impression of fresh smelling breath but it is only a temporary one.

Overcome or guard against bad breath by having regular dental checkups stopping smoking cutting down the amount of coffee you drink and eating frequently. If you’re fasting or crash dieting, you’ll become aware of an unpleasant taste in the mouth. Crunching an apple or a carrot should make it disappear.

Garlic one of the strongest known smells which has an unpleasant way of lingering on the breath for hours, and sometimes even for days, has no really effective “antidote” of the several old folk remedies, the only one that really appears to work is that of eating large amounts of parsley with the garlic. Alternatively, make sure that those you live with have eaten it too so you’re all oblivious of the smell.

Use scent judiciously to enhance your own natural smell, not to kill it. Using a cloying, heavy scent or excessive amounts of a lighter one will actually make you smell worse than if you had left it off entirely.

Taste

 If you blindfold people and offer alternate glasses of red and white wine, both at room temperature, you’ll find that find that they have the greatest difficulty in distinguishing between them. An appreciation of the differences in flavor depends first on color, second on temperature, third on smell or bouquet and only fourth on the sensation of taste. The same thing can be repeated with a large number of foods. Even onion, which most of us think of as having a very distinctive flavor, will taste exactly like a strawberry if you are not allowed to see or smell it first. This is because all these foods have considerably more smell than taste and your preference for one over the other originates, not from the sensations they produce in the mouth, but from the sensations they produce in the nose.

Unlike the appreciation of color sound, touch or smell, the appreciation of flavor arrives from a combination of senses, particularly the sense of smell, which is why nothing impairs your taste like a heavy cold. Even when certain types of food have arrived in the mouth, your appreciation of them may have more to do with sense receptors other than the taste buds. Mustard, peppers and spices are irritants that trigger the pain and touch receptors in the mouth, while smooth and crisp foods are more likely to be distinguished by virtue of their textures rather than their tastes.
 
How do we Taste.
Taste buds do not have anything like the extensive repertoire of smell receptor cells. They’re capable of distinguishing four qualities. These’re sweet (sugar) salt, sour (acidic juices, such as lemon) and bitter (coffee). It is the balance between these qualities that determines exactly how a food will taste. Although no food can stimulate all four types buds at once, most foods stimulate at least two, and often three of them.

Your taste “threshold” or ability to taste certain foods depends on three factors. The first of these is how acute your other senses are. Smoking, contrary to popular opinion, does not affect the transmission of taste impulses, but perhaps does undermine the sense of smell. The second factor is age. The number of taste buds in the mouth decreases s you grow older and, with them, your sensitivity to the tastes of various foods. The third factor is the intensity and duration of the taste stimulus. Taste buds tire very quickly. It is not flavor that makes you reach for a second helping but unsatisfied appetite.


The appetite, a still little understood control mechanism situated in the hypothalamus in the brain, is influenced by a number of factors of which conditioning is perhaps greatest and taste probably least. Appetite may be stimulated by taste sensations but it seems to “free run” after that. In fact, experiments have shown that there’s a lag of about 20 minutes between the stomach feeling full and sending its messages of satiation to the brain and appetite responding to them and switching off. Put this observation to practical use. A failsafe way of regulating what you eat is to concentrate on sensations of taste rather than appetite and to stop when they. The taste buds are responsible for transmitting one of four basic taste “sensation” to the brain. Sweet is detected at the tip to the tongue sour and salt along the edges and bitter right at the back of the mouth, which is why some foods are said to have bitter aftertaste. There’re no taste buds in the center of the tongue.

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