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, when blood is heated above 98.6 degrees. The heart
begins to pump more blood, blood vessels dilate to accommodate
the increased flow, and the bundles of tine 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 about 90 percent
of 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 form the body, thereby cooling it. Under
conditions of high temperature (above 90 degrees) and high
relative humidity, the body is doing everything it can to
maintain 98.6 degrees inside. 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 exceed the level the body
can remove, or when the body cannot compensate for the fluids
and salt lost through perspiration, the temperature of the
body's inner core begins to rise and heat-related illness
may develop.
Heat Disorder
Symptoms
First Aid
Sunburn
Redness and pain. Swelling of skin, blister, fever, and
headaches.
Ointments or a dry sterile dressing. Severe cases should
be seen by physician.
Heat Cramps
Painful spasms of muscles. Heavy sweating.
Firm pressure on muscles, or gentle massage. Give sips
of water. If nausea occurs, discontinue use.
Heat Exhaustion
Heavy sweating, weakness, skin cold, pale, and clammy.
Thready pulse. Fainting and vomiting.
Get victim out of sun. Lay down and loosen clothing. Apply
cool wet cloth. Give sips of water, unless nausea occurs.
If vomiting continues, seek medical attention.
Heat Stroke
High body temperature (106 or higher). Hot dry skin. Rapid
and strong pulse. Possible unconsciousness.
Summon emergency medical assistance immediately. Move victim
to a cooler environment and reduce body temperature with a
cool bath or sponging. Do not give fluids.
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