The collapse, David Kelly [best beach reads of all time .txt] 📗

Human bodies dissipate heat by varying the rate and depth of blood circulation,by losing water through the skin and sweat glands, and-as the last extremity is reached-by panting. The heart begins to pump more blood, blood vessels dilate to accommodate the increased flow, and the bundles of tiny capillaries threading through the upper layers of skin are put into operation. The body’s blood is circulated closer to the skin’s surface, and excess heat drains off into the cooler atmosphere. At the same time, water diffuses through the skin as perspiration. The skin handles the body’s heat dissipating function. Sweating, by itself, does nothing to cool the body, unless the water is removed by evaporation, and high relative humidity retards evaporation. The evaporation
process itself works this way: the heat energy required to evaporate the sweat is extracted from the body, thereby cooling it. Under conditions of high
temperature and high relative humidity, the body is doing everything . The heart is pumping a torrent of blood through dilated circulatory vessels; the
sweat glands are pouring liquid-including essential dissolved chemicals, like sodium and chloride onto the surface of the skin. Heat disorders generally have to do with a reduction or collapse of the body’s
ability to shed heat by circulatory changes and sweating, or a chemical imbalance caused by too much sweating. When heat gain exceeds the level the body
can remove, or when the body cannot compensate for fluids and salt lost through perspiration, the temperature of the body’s inner core begins to rise and heat-related illness may develop. Heat disorders share one common feature: the individual has overexposed or over exercised for his age and physical condition in the existing thermal
environment. Sunburn, with its ultraviolet radiation burns, can significantly retard the skin’s ability to shed excess heat. Studies indicate that, other things being equal, the severity of heat disorders tend to increase with age-heat cramps and heat stroke in a person . Acclimatization has to do with adjusting sweat-salt concentrations, among other things. The idea is to lose enough water to regulate body temperature, with the least possible chemical disturbance.

Publication Date: 02-18-2010

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