The human body, in addition to endogenous heat produced by metabolic processes, can be obtained under certain conditions, is not only essential, but also the damaging the amount of heat from the environment. External heating significantly especially in direct sunlight, and in the presence of intense heat load from the fiery objects (that is observed in domestic and industrial conditions) or from the sun-warmed soil, stones and other (secondary radiation). In the same environmental conditions overheating much easier occurs when the physical work, than at the full rest. An important factor influencing the development of an over-temperature, high humidity. The intensity of evaporation from the surface of the body when the same external temperature is inversely depends on the humidity of the air. In the conditions of 100 % relative humidity, heat loss by evaporation practically stops. When the temperature of 28-30 C and 100% humidity can cause the overheating even at moderate physical activity. Factors that contribute to overheating, are the individual characteristics of the organism. Elderly people are more sensitive to high temperature.
Due to insufficient development of mechanisms of temperature regulation in the first months of life overheating particularly easy occur in children under the age of years. Overheating is promoted by such factors that increase thermogenesis, as hyperthyroidism, other violations of the endocrine regulation.
In conditions of a hot climate and intensive insolation phenomena overheating can occur by type thermal or heat stroke. The pathogenesis of these two different pathological conditions, there are a sufficient number of features which distinguish one from the other. The difference between heat and sunstroke is that at first there is a General overheating of the body, at the second - the overheating of the head. Heat stroke is a consequence of primary Central nervous system, caused by intense or prolonged exposure to direct rays on the head. Accompanied he headache, redness of the face, loss of strength. The victim appear nausea, vomiting, vision problems, General lethargy, increased heart rate and respiration, body temperature rises to 40 degrees C. In further loss of consciousness occurs, the body temperature reaches 42-44 °N Breath remains frequent, enters czenstochowa, and in severe cases terminated due to paralysis of the respiratory center. Pulse, first, fast, slow, becomes tense and waned because of the fall of cardiac activity, blood pressure decreases. Sweating stops. There are bleeding in the brain and internal organs. The defeat of the Central nervous system manifested in the development drowsiness, twilight state, the aberrations of consciousness, General arousal, hallucinations, fear, and often seizures.
In the development of thermal shock to distinguish several periods. Under the action of high temperatures or intense heat radiation, first there is a mobilization of regulatory mechanisms (increasing heat). At this time there is a short latent period, characterized by oppression CNS. The next period - the excitement is characterized by enabling and maximum voltage reactions increase of heat transfer, progressive fever and recurrent motor excitation, anxiety, increased irritability, outbursts of unmotivated anger, severe headache and dizziness, palpitations, shortness of breath and sometimes nausea and vomiting. The third period - exhaustion is characterized by weakness, moving into stuporous state, slower breathing, low blood pressure and in fact is Predgorny period. The transition stage of excitation in a coma can be very fast.
The overheating of the body is accompanied by serious violations of hemodynamics, one of the main components of pathogenetic links of heat stroke. Internal organs alone are the main sources of heat and need constant heat to the surface. The reduced blood flow through them exacerbates tissue hyperthermia, this raises hypoxia internal organs, which in turn stimulates the anaerobic oxidation with the accumulation of lactic acid in the tissues and offset active reaction to the side of the metabolic acidosis.
Under the action of high temperature develops non-specific stress reaction accompanied by the ejection of glucocorticoids and catecholamines and biogenic amines. Changes of microcirculation with the phenomena of stasis, violation of vascular tissue permeability worsens the condition of the body due to the difficulty of sharing water, metabolites and gases.
Death occurs usually from primary respiratory arrest at body temperature 42,5-43,5 °N the Immediate cause of death in acute overheating are deep circulation disorder, hypoxia, the damaging effect of heat and toxic products in the nerve centers. The weakening of the function of the myocardium by overheating due to a violation of the coronary circulation. In addition, what matters is the accumulation in the blood of biologically active substances that have toxic effects on the heart muscle. Finally comes the depletion of the reserve forces of the heart and cardio-vascular insufficiency.
When conducting a forensic examination of the corpses of people who have died from the General overheating of the body, macroscopically not identified any specific morphological changes, allowing to solve the question about the cause of death. Usually marked edema and hyperemia of the brain and its meninges, significant overflow blood veins and venous sinuses, minor bleeding in the brain, under the serous membrane, sharp and plethora of hemorrhage into the internal organs, the accumulation of mucus in the Airways. If it is assumed that the death was caused by thermal or heat stroke, it is necessary to exclude diseases and other external violent impacts. Essential for an expert opinion has a detailed introduction to the report of survey of a place of detection of a corpse, with the materials of the investigation and clinical symptoms prior to death.