What are the five unknown facts about 'smell'?

We sniff a variety of things on a daily basis and are getting a lot of information. Alice Bartlett who works for the customer product team of the UK daily newspaper Financial Times on the "unfamiliar five facts" on such a smell is summarized.

Five facts about smell writeup
http://alicebartlett.co.uk/blog/five-facts-about-smell

◆ 1: Olfactory is one of the three chemistry of human beings
According to Bartlett, humans sense chemical substances in three areas of taste, skin sensation, and olfaction. Taste senses several heavy compounds, the skin sensation that the trigeminal nerve carries reacts to irritants such as capsaicin , menthol , and carbonated gas of carbonated drinks, and olfactory senses volatile compounds. Taste is sensed in the tongue and throat, skin sensation is sensed in the whole body, and olfactory sensation sensory cells in the nasal cavity detect odors.

by Barney Moss

◆ 2: 1.5% of people can not feel the smell <br> There are many people who think that it is natural for people to feel smell, but in fact one or two people smell to 100 people It is Anosmia (olfactory loss) which you can not feel. Anosmia is not only congenital but also acquired after accidents, but according to the 1987 study conducted on 1.5 million people, he smelled six smells to the participants Where 1.2% answered that I can not feel any smell. Also, some people said that they can not feel a certain smell.

It seems that Bartlett himself is also Anosmia, he says it can not smell any smell. Bartlett seems to have thought that "smelling a smell is a skill to be worn by effort" until he was 7 years old, he thought that it is embarrassing that the smell can not be smelled and he could not tell anyone Thing. In the end, Bartlett said that by asking other people "How can you smell the smell", you do not have yourself acquiring skills, and that there is no sense of olfactory in the first place It was.

◆ 3: There is a smell more easily detectable by humans than some other smell <br> <br> The reason is unknown, but it is said that a specific smell is much easier to detect than other odors. Five kinds of smells such as "grapefruit" " cork " "butter" " peperoni " "strawberry" can smell even human concentration close to zero. I am not sensitive to these scents, so it is not clear what kind of merit is for human beings, so it has not been given a scientific explanation yet.

The fact that humans are sensitive about these smells can be confirmed by obtaining a compound that smells, diluting it with water and asking "whether this smells out of this water". If you say "smell", add water further to dilute the compound, and measure how much you do not smell at how thin it is. For example, the compound citral contained in lemon smells quite intensely, but the thioterpineol contained in grapefruit is 3.2 million times more odorful.

◆ 4: There are seven kinds of smells in general. There seems to be roughly classified into seven types of odors in the classification of perfume, classification is not scientific, but the compounds contained in each category are somewhat It is said that chemical shapes are consistent. The scent is "smell of camphor " " floral smell" "smell of peppermint series" " ether odor (smell of solution used for dry cleaning)" "irritating smell (vinegar like smell)" "Severe odor (smell of rotten egg)" and "odor of musk ". Unfortunately Bartlett himself can not smell these smells, although I got this knowledge in the process of examining the smell.

◆ 5: I do not yet know how olfactory works ... Surprisingly, it is surprising that there are still many things left unknown about human olfaction even in the modern era of the 21st century. For example, humans encode 347 kinds of odor receptors by the human genome, and these receptors are located in the nasal epithelium of about 5 square cm, but if the number of receptors is small due to mutation, You can not smell the smell. " However, in fact, it is not clearly understood how much smell human beings can sniff, and according to research in recent years it is said that approximately 1 trillion smells can be divided into sniffs.

There are also two competing theories as to what kind of work is done in epithelial cells when people smell the smell. One is said to be "chemical theory" or "keyhole and key story", and it is not only the three-dimensional shape that the molecule has but also that it smells it by chemistry and physical properties. The other is "oscillation theory", which means that each molecule can be perceived as a different smell by the vibration pattern of the molecule.

Although the chemical theory was proposed in 1949 and it is said that the oscillation theory was proposed in 1938, there are also many points that can not be fully explained by either the chemical theory or the oscillation theory, and yet the researchers are still thinking which theory is correct Bartlett said he could not decide whether it was.