How does hypothermia affect a person?

Instruction
The effect of hypothermia on a person will depend on the general condition of the body and on environmental conditions. The cooling capacity of the environment increases with decreasing air temperature, increasing humidity and wind speed. Strong wind and high humidity can lead to hypothermia, even at +8 .. + 10 ° C. Influence and time of exposure to cold on the human body. At a temperature of 0 ° C fatal cooling occurs in 10-12 hours. In water, it occurs much earlier due to the fact that its thermal conductivity is 25 r. higher than air. In icy water, a person dies within 5-10 minutes. Strongly weaken the body's resistance to cold fatigue and alcohol.
There are the following phases of hypothermia of the human body. In the first phase, there is a mobilization of physiological mechanisms to maintain a constant body temperature. This is achieved by reducing heat transfer and stimulation of heat production.In the brain, the cerebral cortex inhibition occurs and pathological excitation of subcortical centers occurs. The sympatho-adrenal system responds to the effect of cold: the content of catecholamines increases in the blood, the arterial vessels narrow, and the cardiac output increases.
Prolonged exposure to cold depletes energy, causes hypoxia (oxygen deprivation) of tissues. Pathological changes further inhibit the thermostatic functions of the central nervous system. As a result, the moment comes when the ability to maintain body temperature at a constant level is lost, the next freezing phase begins. Decrease in body temperature progresses, vital functions die out. A “biological zero” of vital activity appears - this is the temperature of the tissue at which its activity reversibly stops. The value of "biological zero" is not the same for different organs and tissues.
When freezing stops breathing in humans occurs when the body temperature drops to + 15 .. + 20 ° C. After that, cardiac activity is maintained for a few more minutes.Distinctive features of a lethal outcome with general cooling: the length of the process of dying and the absence of irreversible changes in the tissues with a short cooling. They determine the successful outcome of timely and properly implemented resuscitation measures.

Date: 12.10.2018, 04:58 / Views: 55492

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