Air and human superpowers
Every day we pass through the lungs up to 40 kilograms of air. At the same time, we almost never think about what we breathe and where this air came from. Do you know, for example, is it possible to breathe through the skin? And why can’t you dry clothes in the apartment and use thermal water on the plane? Where did the Earth’s atmosphere come from and why is carbon dioxide needed? I told about all this in my book “Air. Unexpected facts about what you cannot live without.”
Before “entering IT” I designed ventilation. Now I am a Qa engineer, so I still have to think engineering. Whatever it is, it’s my favorite pastime. I am deeply convinced that before looking for bugs, you need to understand how the product works.
Air is a basic thing on Earth and we all use it. And is it well studied? Do we really know all its features? I want to share a fragment from my book and inspire you to study the world around you better 🙂
Chapter 12
Air not only gives us the opportunity to live, but also adds pleasure to this life. It fills our everyday life with sounds, music, various aromas. We can communicate with other people, read poetry, sing. Imagine, for all this, too, we must say thank you to the air!
The rustle of dry leaves. The sound of raindrops on the umbrella. Dog’s bark. Here, somewhere, a tram passed with a roar, and a mosquito flew over my ear with a characteristic squeak. By the way, about the mosquito. I wonder how he manages to squeak so disgustingly? Perhaps the mosquito has a special “squeaker” to make this sound? It turns out not: it’s all the fault of his small wings, with which he very often hits the air during the flight. It is these sounds that we perceive as a squeak.
Sound
Sound is mechanical vibrations that propagate in solids, liquids and gases. Air is an excellent medium for transmitting sound. He, like all vibrations, has a frequency (height) and an amplitude (loudness). The oscillation frequency is measured in hertz (Hz). The range that the human ear can hear is between 16 Hz and 20 kHz. The loudness of sound is measured in logarithmic units – decibels (dB). The study of sound deals with a special branch of physics, acoustics.
A person can interact with sound in different ways, perceive it and produce sounds independently. Let’s see how this happens.
Hearing is the ability to hear sound. The organ for capturing sound is the ear. The sound wave enters and causes the eardrum to vibrate. You have probably heard that there is one in our ear. From it along the chain, vibrations reach the ends of the auditory nerve, which, in turn, transmits a signal to the brain. That’s exactly what we hear.
The human voice is nothing more than sound vibrations that create the vocal cords located in the larynx. Air passes through them as if through an obstacle, from which they vibrate and generate a sound wave. The degree of tension of the ligaments determines the pitch of the sound that a person reproduces. With the help of the vocal cords, we can speak, sing, shout and whisper. By the way, the vocal cords can only vibrate when you exhale.
The vocal cords are very delicate and vulnerable. They are sensitive to colds and overexertion. During an illness, a person may become hoarse and even lose his voice – this is due to inflammation of the ligaments. They swell, lose their elasticity, which means they cannot vibrate freely from the air flow. A similar thing happens if they are overstrained, or, as they say, “break your voice.” When you scream very hard, the air flow in the bundles can reach speeds of 30km / h, this is a real hurricane that damages them and makes it impossible to vibrate as before. A phoniatrist deals with the issue of voice and the treatment of ligaments. This is a rather rare specialist whose main patients are artists and singers.
Unusual about sound
Probably, each of us at least once put a shell to his ear and heard the sound of the sea in it. However, that noise is not the sea at all, but the sound of blood flowing in your own vessels.
We can hear with bones. This happens because sound is a wave that can also propagate in a solid medium. According to this principle, for example, headphones with bone conduction of sound work.
Many people don’t like the sound of their own voice on recordings, and sometimes they don’t even recognize it. The fact is that when we hear ourselves in life, we catch the sound of our own voice also through the tissues of the head, but when we listen to a recording, then perception goes only with the help of the ear.
Thunder and lightning always have an interval because the speed of sound is almost a million times lower than the speed of light. I love the joke that advice given by parents in childhood doesn’t reach us until we’re in our thirties, because the speed of sound is so damn slow.
Humidity affects hearing. The less moisture is contained in the air, the easier the sound wave propagates, because there are fewer obstacles in its path. The amount of moisture in the air is affected by temperature, so we can safely say that hearing is better in winter, because the air is drier.
The sound wave is able to bounce off the obstacles that it meets on its way, sometimes even several times, returning to them. This is called an echo. In the mountains it is generated by the sound reflected from the rocks, in the forest – from the trunks of trees, in your own apartment, if all the furniture is taken out of it – from the walls. The loudspeaker works on the principle of echo: it reflects the sound wave from its walls and concentrates it, so the sound is more powerful and can spread over long distances.
Smell
Odor is the presence of volatile odorants in the air. Thanks to special receptors on the inner lining of the nose, we can perceive and distinguish between these substances. The ability to smell is called the sense of smell. Let’s see how it works.
Molecules of substances enter the nose through the nostrils and fall on the olfactory epithelium, located deep in the nose. Previously, it was believed that the area of the human olfactory epithelium is about 10 cm2, but in later studies it turned out that only 2-4 cm2*. But in animals, for example, in dogs, it can be 200 cm2, by the way, which is why they smell much more sharply than people.
The olfactory epithelium, like any mucous membrane, is covered with a thin layer of moist mucus, in which molecules of odorous substances accumulate and dissolve, activating special olfactory receptors. They, in turn, transmit signals to the brain. Olfactory receptors are cells of the nervous system, which is why they are sometimes called olfactory neurons.
You’ve probably heard the phrase that “nerve cells don’t regenerate.” This is not entirely true, and it would be more correct to replace it with “not all nerve cells are restored.” Because just the olfactory neurons belong to those cells of the nervous system that are constantly updated. They live on average for about a month, and after this time, new ones appear in place of the old ones.
The sense of smell is an area in which many mysteries and theories remain. Until now, no one can accurately answer why each person smells slightly differently and what set of aromas is “basic”. What is the maximum number of odors that a person can distinguish is also unknown.
By the way, the sense of smell is closely related to the taste perception of products. When chewing food, particles of aromatic substances enter the nasopharynx, and then on the olfactory receptors. It enhances and brings out the taste. If you don’t believe that without smell there is practically no taste, think about yourself during a cold. When a person suffers from a runny nose, the cells of his olfactory epithelium swell, the smells around seem muffled or disappear altogether, so the usual food loses its taste.
Try a taste experiment right now. Take, for example, a banana and before taking a bite, hold your nose tightly. You will see that the taste is practically not felt in this way, to the point that it is generally difficult to understand what exactly you are eating.
Loss of smell is called anosmia. It can be temporary and permanent, partial and total, congenital and acquired: for example, after a nose injury or illness.
Smell is the first sense that a person develops. It is most pronounced in infants and worsens with age. By the way, usually women are more sensitive to aromas than men.
Unusual flavors
Radiation smells like ozone. Although it is believed that it is absolutely imperceptible to the human senses, workers at the Chernobyl nuclear power plant noted that when the radioactive background increased to critical, the air began to smell like after a thunderstorm. This is because intense ionizing radiation splits the oxygen molecules in the air, which leads to the formation of ozone with its specific smell.
We choose the one we like by smell. Studies show that a person can use the sense of smell to read the genetic compatibility with a partner, as well as the compatibility of immune systems. The experiments sometimes looked comical: for example, scientists from Scotland invited a group of men not to bathe, not to use hygiene products and not to take off T-shirts for several days, and then a group of women sniffed at these worn clothes. They chose the most attractive smell and decided what kind of man they like.
There are olfactory trainings, the purpose of which is to “teach” the olfactory receptors to distinguish smells. They are widely practiced by perfumers, winemakers and tasters. However, such training has recently begun to be used to treat patients with anosmia, including those caused by COVID-19. To do this, you need to use four strong odors and inhale them several times a day. It is best to use essential oils such as clove, cinnamon, star anise, eucalyptus, lemon, vanilla or other intense fragrances.
For special connoisseurs, there are perfumes with atypical smells, such as blue cheese, garage scents, fresh books, dust, washing powder, and even a funeral home.
The worst-smelling fruit on the planet is the durian. Its smell is very corrosive and consists of many components: sweet, garlicky, putrid, rotten. Despite this, Air and man it is considered very tasty. In Southeast Asia, in its homeland, there is a law according to which it is forbidden to bring durian into public places and enclosed spaces.
The aroma of baking, vanilla and cinnamon is considered one of the most pleasant for humans. They are often used as bait to attract customers to a coffee shop or store and increase sales. One realtor told me that before showing an apartment, he always puts vanilla sugar and cinnamon on the hot stove in the kitchen. A pleasant smell fills the rooms, and the apartment seems more comfortable to the buyer.
Favorite music, the voice of a loved one, the smell of the forest after the rain, the scent of freshly cut grass… The air definitely gives us something more in life than just the ability to breathe.
