| Sweating - an overlooked but natural way
of beating the heat
By Eric Adler
Knight Ridder News Service
You know what a heat wave means. Dripping,
beading, and vastly under appreciated sweat.
Yes, under appreciated. Because while
sweat may seem bothersome, without it every one of us would
be melting like a Salvador Dali pocket watch.
In fact, if sweating doesn't do it's
job and your core body temperature rises beyond 105 degrees,
you're talking kidney dysfunction, muscle breakdown, disruption
of brain functions, and even death.
Which is why the human body employs
all the processes at it's disposal to stay close to the temperature
at which it best runs: 98.6 degrees.
Exercise, contract a fever, stand
in the summer sun, do anything to increase the body's temperature
just a fraction, and you'll quickly appreciate how reliable
the body's five million sweat glands are.
In more detail, here's how our bodies
handle the heat:
Nerves called thermoreceptors inside the body
and on the skin signal the brain to a rise in temperature.
In the brain, the hypothalamus is the body's
thermostat. When body temperature rises above 98.6 degrees,
the nervous system reacts to get rid of the heat.
Flushed skin: Blood vessels dilate, opening up
like big pipes, rushing more blood to the skin's surface,
causing more heat to escape.
Sweat glands pump perspiration through pores.
Cooling occurs when body heat is transferred to the sweat,
causing it to evaporate and carry heat away, cooling the skin.
Dripping sweat means perspiration can't evaporate fast enough.
Sweat is 99 percent water and 1 percent dissolved
substances such as salt.
About a pint of water is lost through the skin
in normal conditions, although as much as three gallons can
be lost in a day because of exercise or hot weather. That's
why staying hydrated is vital.
The body's five million sweat glands are packed
so tight that a green pea placed on the skins surface would
cover more than 100.
Sweat itself is odorless. A reaction with bacteria
Aluminum and zirconium salts in antiperspirants
react with sweat to create a plug that stops up the sweat
gland. They also contain some anti-bacterial agents, as do
deodorants, which are mostly perfume. The best roll-on and
soft-solid antiperspirants reduce sweat output by about 50
percent; sticks 25 to 45 percent; aerosols 25 to 35 percent.
Facial sweating from spicy foods comes from capsaicin,
a component in the food that stimulates nerves in the mouth
that usually respond to rises in temperature.
When comfortable and at rest, the body typically
gets rid of about 60 percent of excess heat via infrared radiation.
Heat travels from the skin to cooler surrounding objects.
It's when the body heats up that sweat and evaporation become
Humidity: The body stays hot because the air
is already thick with water vapor. There's little place for
evaporated sweat to go, so the rate of evaporation slows.
Since it's evaporation and not sweat, per se, that cools the
skin, the skin stays hot and wet.
Danger is at hand if someone suddenly stops sweating
in hot weather. That means the body is in shock, preserving
water and going into possibly fatal heart stroke.
Some people are born without working sweat glands.
The condition, hypohidrotic ectodermal dysplasia, is rare,
inherited and incurable. It also produces dry skin, wrinkled
skin, sparse dry hair, small brittle nails and cone-shaped
teeth. Reduced activity is the most common treatment.
Hyperhidrosis is a socially embarrassing disorder
that causes people to sweat excessively, especially from the
arms, feet and hands, even in normal conditions. The use of
botulism toxin, or Botox, to paralyze the sweat gland is the
most recent effective treatment, lasting up to six months,
after which new nerve endings grow and the treatment must
Reprinted with permission of Knight Ridder/Tribune Information
From the Philadelphia Inquirer - Monday, August