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1.8. EXCESSIVE INCREASE IN BODY TEMPERATURE AND ITS CONSEQUENCES
The danger of overheating of the body is connected, in particular, with the fact that not all people recognize the approach of overheating of the body well enough, and do not assess the degree of danger of this condition. Nevertheless, the first subjective signs of overheating of the body include such as a feeling of pulse in the temples, chills of the upper torso, muscle weakness, discoordination, imbalance. There may be a violation of sweating. People who perform physical exercises in conditions of high ambient temperature should be aware of the symptoms mentioned above and stop active muscle activity if these symptoms occur.
Let's consider the most frequent pathological phenomena that occur due to overheating of the body.
Heat fainting. Heat fainting is probably the most common pathological reaction in response to an increase in internal body temperature. The mechanism of thermal fainting is usually described as follows. In this case, the venous return to the heart decreases, blood pressure drops, which leads to insufficient blood supply to the brain. At the same time, the body temperature is slightly increased, but intense sweating is observed.
Factors contributing to the occurrence of thermal fainting are the vertical position of the body at work, hearty and plentiful food, and the intake of alcoholic beverages. From a physiological point of view, heat fainting is initiated by a decrease in the central volume of blood due to fluid loss as a result of active sweating and blood deposition in relaxed peripheral muscles, as well as in the extracellular space. Competition between working muscles and subcutaneous tissues leads to the fact that the return of blood to the heart decreases. As a result, blood pressure drops.
Moderate heat exhaustion. This term refers to phenomena observed in humans as a result of overheating for several hours. For example, phenomena observed in the evening after staying all day in conditions of high external temperature. The symptoms that are observed here usually include a feeling of fatigue, agitation, deterioration of mechanical efficiency of work, an increase in accidents.
If we ignore such phenomena, then over time they accumulate and lead to chronic neurotic reactions ("thermal neurasthenia"). Such phenomena are sometimes observed in people who have moved to regions with a hot climate.
Heat stroke. The term "heat stroke" refers to a set of phenomena associated with a dangerous and potentially irreparable violation of thermoregulatory mechanisms. Heat stroke is associated with a fairly high mortality rate. The most common victims are overweight, physically ill-prepared and unlemmatized people who perform active physical work in conditions of high ambient temperature.
In a state of heat stroke, an increase in body temperature is accompanied by dehydration, a decrease in sweating and a decrease in subcutaneous blood flow. The combination of high body temperature and "adequate blood flow to brain structures can cause hallucinations, coma and irreversible brain damage. It may have a negative effect on the kidneys and adrenal cortex.
Heat cramps. A person performing physical work in conditions of high external air temperature sweats profusely and loses about 2 g of salt per hour, which significantly reduces the total supply of salt in the body. Usually, the physiological manifestation of salt deficiency consists in the appearance of painful muscle cramps. This symptom is also often observed when moving to the tropics, when the body has not yet adapted to these new conditions, and the "novice" is not used to adding salt supplements to his usual diet. The appearance of salt deficiency leads to increased dehydration (as a result of increased renal clearance and sweating), since there is a tendency to maintain constant osmotic blood pressure due to the elimination of "excess" fluid.
Such thermal cramps pass relatively easily and quickly if the salt deficiency is replenished with salt solutions or special "sports mixtures". This must be done necessarily, since if the body does not receive the necessary amount of salt additives and trace elements, thermal convulsions can become only the first link in the chain of subsequent pathological processes. In particular, vomiting is possible, which leads to an increase in salt loss and the subsequent development of events in an unfavorable direction.
Heat rash. The literature describes skin diseases associated with prolonged exposure to high ambient temperatures, the so-called "heat rash". The pathology is based on the blockade of sweat glands, which is a consequence of excessive sweating and maceration of the skin. In advanced cases, the situation is complicated by secondary infections. Such phenomena require the intervention of a dermatologist.
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