Some people are always suffering from heat, while others are freezing. What are these peculiarities connected with? And how can both adapt to the unloved seasons?
It’s freezing cold
Our thermoregulation, and therefore our well-being, depends mainly on air temperature. If we assume that the ice age has suddenly arrived and the temperature on the surface of the human skin has dropped to 29 ° C, he will start shivering from cold because of increased heat loss. It is urgently necessary to compensate for it, say, putting on a coat of natural fur. Otherwise, with further cooling of the skin to 27 ° C, coma will occur, and at 21 ° C – death.
However, not necessarily. In November 2004, a two-year-old boy was lost in the forest near Yakutsk and was found only three days later. And he didn’t even have a runny nose! This little boy, who had not yet realized himself as part of the human world, was probably helped to survive by the principle formulated by Gleb Travin: “I survive because I do not fight nature, but try to live according to its laws. For four years, from 1928 to 1931, Gleb Leontievich traveled 8.5 thousand kilometers by bicycle along the borders of the USSR. At one of the stages his way passed through the Arctic, on the ice of the Arctic Ocean, to Cape Dezhnev and to Petropavlovsk-Kamchatsky. He traveled this route of “white silence” in terrible frosts and storms with almost no food supplies and no sleeping bag – how much luggage can you put on a bicycle?
No less amazing adventures fell to the share of Frenchwoman Alexandra David-Neel, who lived 101 years and spent almost all her life traveling. In one of her books – “Mystics and Magicians of Tibet”, published in 1929, Alexandra wrote: “To live through the winter in a cave, often at an altitude of 4000 to 5000 meters, in a light dress or no dress and not to freeze is not so easy. However, many Tibetan hermits manage to do so.” Alexandra explained such an amazing record of the monks by the fact that they mastered the art of tumo – know how to stimulate the production of internal heat. This is achieved by training. Its first stage is breathing exercises. On the inhalation the Buddha spirit and all the nobility of the world are attracted into the body, and on the exhalation pride, anger and laziness are mentally expelled. Then the monks meditated, focusing on the fire that smolders somewhere inside, but flares brighter and brighter with each breath. In this way, a feeling of warmth emerged. To demonstrate their art, monks would gather on a winter night near an unfrozen river or ice-hole, strip naked, dip small sheets in the water and dry them on their bodies, sitting on the ground in the lotus position. The one who dried the sheets the most before dawn was recognized as the winner of this peculiar competition. Those initiated into the art of tumo are still called respa in Tibet. These people always, at any time of the year, wear only light cotton clothes.
In summer, the body’s main heat transfer is by evaporation of sweat (up to 80%), and in winter – by convection (up to 60%), i.e. cooling of the body by cold air or wind.
Terrible heat
Extreme heat is also a serious test for the body. If the outside temperature exceeds 30-33 ° C, i.e. the average values for the surface of clothing and areas of exposed skin, then, according to the laws of physics, the heat goes not from the person to the environment, but in the opposite direction. As a result, thermoregulation is disturbed, which can lead to overheating of the body – heat stroke. This condition is characterized by weakness, headache, reddening of the skin, possible fainting and a rise in body temperature to 40-42 ° C.
Such a body temperature is considered critical, but it is not always fatal. The record holder in this regard was a certain William Jones 52 years old. In July 1980, he went to a hospital in Atlanta with heat stroke. His body temperature turned out to be 46.5 ° C. To recover his health, it took him about three weeks to be under the control of doctors, but everything turned out fine. This “achievement” is recorded in the Guinness Book of Records.
“Steam does not break bones,” they say, meaning that it is easier to survive heat than frost. This is indeed true. But scientists have always been interested in the question: what is the maximum high temperature a person can withstand? In the 50s of last century, researchers in Belgium conducted experiments and recorded that a man five minutes could withstand in a thermal chamber at a temperature of 200 ° C.
Of course, such tests are fraught with dehydration, heart and vascular disorders. But no one would argue with the fact that sauna is useful for many people. There is also a more modern version of it – cryosauna, where “steamed” for five minutes at a temperature of -100 ° C. Dosed action of temperature stress – and it does not matter whether it is thermal or cold – contributes to health.
After heat stroke, antipyretics are not necessary. It is enough to move the person to a cool place. But if the severe increase in body temperature is caused by other reasons, such as infection, you can’t do without medication.
Amazing thermostat
The human body is arranged like a perfect thermostat: the production of necessary heat and the discharge of excess heat into the environment occur automatically, so that the body temperature always corresponds to the so-called set point +36.6 ° C. The hypothalamus directs the thermoregulation process. Directs the process of thermoregulation hypothalamus. This part of the brain receives signals from heat and cold receptors of the skin, its neurons respond to changes in blood temperature, and as a result, either heat production or heat dissipation increases.
The production of internal heat depends, first of all, on the metabolic rate. In children under 7 years of age, this rate is higher than in adults, and heat production is stronger than heat output, so kids can play in the cold for hours and not get cold. Depends on the metabolism and hormonal background: we “warm” the glands of internal secretion, mainly thyroid and adrenal glands. Thus, with an excess of thyroid hormones, heat production is increased, so a person can be hot all the time. Conversely, when there is a deficiency of these hormones, people complain that they get chilly and their fingers and toes are cold all the time.
Our sensations also depend on the work of the autonomic nervous system. It is in charge of the receptors that send signals to the hypothalamus, it determines the vascular reactions of the body to heat and cold. For example, on a hot summer day, our peripheral vessels dilate, and the blood, which has a very high heat capacity, carries excess heat from the inside to the surface of the body. As a result, the excess heat is dissipated through the emission of infrared rays, as well as air movement (convection) and evaporation of sweat from the skin. If we are cold, the surface vessels constrict, blood flows to the internal organs, heat dissipation decreases, and the body uses energy more sparingly.
If the autonomic nervous system malfunctions, these processes, and therefore thermoregulation, can be disturbed. Then doctors say that there is a vegetative vascular dystonia. It may be the reason that a person does not tolerate heat or cold. If you establish what causes dystonia, and then eliminate the effect of this factor, then seasonal changes in weather will not be so unpleasant. The root cause of dystonia, as a rule, are neurosis, diseases of the spine, endocrine glands, gastrointestinal tract, allergies and chronic infections.
Tricking “tricky” receptors
However, it is not only the external temperature that affects human sensations. The humidity of the air and the strength of the wind can greatly “trick” our heat and cold receptors. If for the duration of the heat wave you move to an area where there is a strong wind, say, to the sea, it will be much easier to survive it than in the city. It is because of the immobility of the air, the asphalt on the streets of the “stone jungle” in especially hot days becomes soft. And if the relative humidity instead of the normal 40-60% is close to 85-100%, the heat transfer becomes even worse. Evaporation becomes problematic, sweat condenses into droplets and runs off the skin. In this case, we estimate the heat almost ten degrees more than it is in reality, and literally “die”. Meanwhile, it is experimentally established that our margin of safety in this regard is very significant. At zero humidity, a healthy person is able to endure a truly hellish heat without damage to the body: the temperature of 70 ° C he can tolerate for an hour.
The same is true for the perception of cold. In a penetrating icy wind, skin receptors will certainly “lie” to us, informing us that the frost reaches somewhere 15-20 °C, although it will be only 10 °C. The same thing will happen at high humidity, because moisture dispersed in the air has a higher thermal conductivity, or rather, “cold conductivity”, which increases unpleasant sensations. But at zero humidity and windlessness one can stay for hours in winter “in nature” in Yakutia at -50 °С, as locals do, of course, warmly dressed. In Antarctica, such “feats” are usually impossible due to strong winds.
For an adult, the comfort temperature at rest is +28-30 degrees Celsius, i.e. he/she is neither cold nor hot and does not need clothes. For people who have received a severe burn (on average 37% of the skin surface), the comfort temperature is higher, approximately +32-33 °C. The same values of comfort temperature should be provided for newborns; for lightly clothed children at the age of one month its values are lower: +22-25 °C, for half-year olds – 19-23 °C.
Hardening training
There is no doubt that the human body can adapt to very serious temperatures. And even in everyday life there is evidence of this, although we do not think about it. For example, everyone knows the feeling that the “cold” water in the river or lake after a few minutes of being in it becomes warm, like steamed milk. In fact, its temperature does not change, just turns on the center of thermoregulation and provides adaptation to new temperature conditions. The effect of this mechanism can be judged by the familiar to all the paradoxical reaction: when a person is immersed in a warm bath, in the first moment he may have a “gooseflesh”. The fact is that cold receptors react to the temperature effect, transmitting an impulse to the nervous system, before the thermal ones, and then “realize” their mistake, and the person feels the true temperature of the water.
The mechanism of thermoregulation always works – better or worse. And to keep it running like clockwork, it is necessary to train it and eliminate pathologies interfering with it, if any. To increase “heat resistance” are suitable well-known and simple ways: visiting a sauna, swimming pool, swimming in open water, and finally, walrus bathing. And those who like exotics can try the Tibetan method of warming up in the cold.
Alternating exposure to heat and cold is an excellent workout to increase adaptation to changing external temperatures. Cool water increases heat generation, while hot water stimulates heat release. The main thing in this training is the gradual increase in the contrast of temperatures and persistence (the method of “drive a wedge out of the wedge” is not suitable!). But if you take yourself seriously, then after a year or two you will be surprised to note that the change of seasons no longer causes any discomfort.
Shutterstock/FOTODOM UKRAINE photos were used
