Heat or cold: what is more dangerous for the body?
Some do not tolerate heat, some cold, and you never asked this question - which of them is more dangerous? It would seem that there is no salvation from the heat, at least you can wrap up and warm up from the cold. But in fact, everything is completely different ...
Scientists to this question give a definite answer - the greatest harm entails being in extreme cold than in the heat. Death from extreme cold comes 17 times more often than from extreme heat. Experts have found that the cause of death in 0.86% of people are sudden changes in temperature.
How does death from hypothermia
So, you find yourself in cold conditions, without any hope of sheltering and warming. What will happen to you.
36.6 - 35 degrees
When the body temperature reaches 36 degrees, the muscles around your neck and shoulders will begin to contract - this is called pre-convulsive muscle tone. Receptors send a signal to the hypothalamus, which, in turn, gives the command to narrow the entire network of capillaries on the surface of your body and therefore the arms and legs begin to ache from the cold.After about 45 minutes, the body temperature will drop to 35 degrees - the body begins to shake violently due to the natural reaction of the muscles, which, by rapid compression and unclenching, give the body heat.
35 - 32 degrees
With each degree that the body temperature drops to after 35, the metabolic rate in the body drops by 3-5%, and after 34 degrees a person loses memory and mind - you no longer understand where you are and what you are doing. Most often at this moment a person falls into the snow and convulsively freezes. Below 33 degrees comes apathy, and below 32 - a stupor.
32 - 30.5 degrees
This is a zone of extreme hypothermia in which the body finishes attempts to warm itself with a shiver. Blood thickens, oxygen consumption drops. The constricted vessels of the extremities squeeze out a huge amount of fluid that the kidneys are trying to handle. At this moment, a person ceases to recognize everything around him - between 31 and 30 degrees he does not even recognize his own person.
30.5 - 29.5 degrees
In this state, the electrical impulses that send chilled nerve endings to your heart become arrhythmic, the heart pumps only 2/3 of the total volume, and the lack of oxygen causes hallucinations. Death occurs around 29.5 degrees.
At extremely low temperatures, the human body is preserved as it were, greatly slowing down the internal processes. Many people found supercooled seem dead only at first glance. The body can exist in such a state for hours, and it should be very carefully and gradually removed from it.
An interesting moment - in a painful attack, at a body temperature of 30-29.5 degrees, a phenomenon called “paradoxical undressing” occurs. Very often, criminologists, finding the naked body of a frozen person, think that they have been robbed or left without clothes. In fact, it is at this peak that people themselves take off their clothes. There is no exact explanation for this phenomenon, but the most logical explanation is that as the body cools the body turns on a protective function - vasoconstriction, which results in the involuntary constriction of the blood vessels of the outer skin integument, which reduces heat loss. However, for the compression of these muscle cells, energy and glucose consumption are required, therefore, with further cooling, the compressive vessels of the muscle relax at a certain point.This causes the warm blood washing the internal organs to rush to the peripheral tissues, and the person feels a “hot flash” - a powerful surge of heat. Without giving a report on what he is doing, a person frantically pulls off his clothes, which further aggravates his position.
However, paradoxical undressing is not the only thing that happens to dying from hypothermia. Often the bodies of people who died from hypothermia have wounds, scratches, abrasions on the hands, knees and elbows, and the corpses themselves are found in "a pose that indicates desperate attempts to defend themselves - for example, under the bed, behind the closet, in the recess." Scientists explain this by the example of the behavior of animals, which, before falling into hibernation, dig holes. In the same way, when a person overcools, he prevents heat losses and buries as deep as possible - into the ground, under branches, into foliage, etc. This phenomenon is called “terminal digging”.
Another fact about frost
It is believed that cold air is extremely harmful to health, but in fact this is not true. Of course, it all depends on how much you are in the cold and in what conditions, but due to the fact that in the winter the air contains 30% more oxygen, it has a positive effect on human skin.Moreover, the frosty air can alleviate the condition of patients with bronchitis and even pneumonia - but only if the frost is dry, that is, it is not damp outside.
Also, the frosty air helps people who suffer from cardiovascular diseases and helps to stop migraine attacks.
Do you know that there is also a physiological adaptation to cold?
Some peoples who constantly live in cold climates, such as the Chukchi and Eskimos, metabolism 25-50% more intense than the inhabitants of the temperate zone.
Australian aborigines and Tibetan monks can spend the whole night almost naked at air temperatures around zero and not even experience shivering.
Korean and Japanese women pearl catchers, who spend several hours a day in the water, whose temperature is only about + 10 ° C, are also insensitive to cold.
As death comes from the heat
Body temperature in excess of 43 ° C is fatal for humans. Changes in the properties of proteins and irreversible cell damage already begin at 41 ° C, and exposure to temperatures above 50 ° C for several minutes leads to the death of all cells.
Heat stroke occurs when the internal temperature crosses the 41 ° C boundary and the body's thermoregulation system is disturbed. The first warning signs are a burning face, hot, dry skin, headache, dizziness, fatigue and irritability. Next come confusion and lack of coordination.
With further increase in body temperature, above 42 degrees, a person dies from brain damage. It is our brain — the internal thermostat and the normal human hypothalamus thermostat is set at 37 ° C, but during fever it can switch to 2–3 degrees higher and the temperature with the same sensitivity will be adjusted to a new level. The signals from the thermal and cold skin sensors cause a local reaction by sending signals to the brain, where, based on information compared with the data of central thermoreceptors in the hypothalamus, the total heat production and heat loss of the body is regulated. The surface of the skin is cooled to a temperature significantly lower than ambient air due to sweating, which is controlled by the hormone adrenaline, released into the blood when the body temperature rises.
In humans, there are about 3 million sweat glands, which play a major role in thermoregulation. Human skin receives heat, which is produced by muscles and internal organs and gives it to the environment. When the external temperature rises, the vessels expand, increasing heat transfer, which takes place in four stages — radiation, thermal conductivity, convection, and sweating.
With a significant increase in external temperature, the body increases sweating - cooling the skin afterwards (evaporating 1 ml of sweat from the surface of the skin, the body spends about 2,400 calories), which, in turn, cools the nearby blood vessels.
Sweating can increase the heat output by almost 20 times, but there is a significant loss of fluid (about 3 l / h). Of course, such intense perspiration cannot last for a long time, so a person who is in the heat loses about 10–12 liters of water per day, along with which salt from the body leaves and the salt necessary for its functioning, the lack of which leads to painful spasms of the limbs. The man stops moving. With prolonged exposure to high temperatures, there is a breakdown of adaptive mechanisms, a so-called heat stroke occurs — the person begins to experience nausea,dizziness or weakness (or all at once). Dark spots will appear before your eyes, making it difficult to see, muscle spasm or swelling of the legs may occur.
If the body continues to be exposed to heat, ultimately there will be a risk of terminal organ damage - a condition where they are almost “welded”. From this point on, a person is at risk of lifelong disability or even death.
Why do people, while in the sauna, not die at high temperatures?
Most people find it difficult to tolerate a temperature of 50 ° C at high humidity, but in a dry 90-degree heat, it is quite comfortable for a person for some time. Saves all the same sweating. Dry air with a temperature of up to 127 ° C (for example, in a sauna) can be kept up to 20 minutes, and for some even this is not the limit. The temperature in the bath is always lower than in the sauna, although both are perceived as equally hot. However, this endurance is not infinite. Brain cells are extremely sensitive to heat, their limit is 42 ° C, so an increase in body temperature of just a few degrees has a huge impact on brain function.