Sweatology+HW+NLL

Sweatology

(1,) Why is sweat like your personal air-conditioner and why is that important? "Sweat is out interior coolant, part of a uniquely human biologic machine. The machine drips and occasionally stalls; long waits on torpid platforms can inspire glum reflections on how it will hold up as the planet heats up. But experts counsel optimism: the system is sturdy, adjustable and even reproducible by engineers working to make our future sweaty selves more comfortable."

(2.) The human body can tolerate cooling. How much? Give examples. "Humans operate in a tiny range of preferred internal temperatures. We can tolerate overcooling, routinely recovering from long periods of hypothermia with body temperatures diving 20 or more degrees below normal."

(3.) The human body can tolerate overheating. How much? Give examples. However we have "little tolerance for even brief overheating: the brain malfunctions with six or seven degrees of fever, and an internal temperature of 110, barely dozen degrees above normal, is often cited as the upper limit compatible with life. So good internal air-conditioner is essential, both to dissipate the heat generated by the body's metabolism and to relieve the heat absorbed from miserable summer weather."

(4.) Why do we think Humans evolved sweat glands? Give examples. "It is plain old unglamorous sweat that has made humans what they are today," writes the evolutionary anthropologist Nina G.Jablonski in her recent book "Skin." "Without plentiful sweat glands keeping us cool with copious sweat, we would still be clad in the thick hair of our ancestors, living largely apelike lives." "Fur inhibits sweat-induced cooling, and furry animals generally have other ways to lose heat. In humans, Dr. Jablonski argues, sweat glands evolved as body hair vanished, allowing optimal cooling of the enlarging hominid brain and an active lifestyle even in the blazing sun."

(5.) Describe some of the variation in the amount of sweat glands? "Some people have fewer than two million sweat glands; some have as many as four million. Heavy sweaters may have glands five times average size; their big glands are more sensitive to nerve stimuli and make more sweat.

(6.) What happens during menopause with respect to sweat? "Everyone's inner temperature cycles around a slightly different genetically determined version of 98.6 set by the hypothalamus, the brain region that serves as thermostat. We run a little cooler in the morning, a littler warmer in the late afternoon. Women run about half a degree higher after ovulation. With menopause the female thermostat becomes notoriously trigger-happy, imagining excess heat where none exists and generating unnecessary sweat."

(7.) What happens as we age? Why is that dangerous? "Men may be more thermally stable, but not for long: beginning about age 60 both sexes sweat less, even if they are in good physical condition, and even if they become seriously overheated. Thus the statistics that during heat waves the elderly are at higher risk of heat stroke."

(8.) Is clothing good or bad when it comes to sweat? "As for clothing, less is not always better. In studies during World War II, researchers sat volunteers on wooden boxes in the California desert, some wearing standard olive drab military fatigues, some in light tan summer uniforms, and some "near naked." The unclothed "soldier" sweated about 30 percent more than the others--an indication of how much heat their unprotected skin was absorbing from the environment.

(9.) Describe what happens during heat acclimation? "The process is called heat acclimation and is routinely seen in athletes training in hot weather. At first their internal temperatures climb, they sweat profusely, lose large quantities of salt in their sweat and feel miserable. But as the days pass they sweat even more, their salt loss diminishes, both skin and internal temperatures drop, and their endurance improves.

(10.) Who is "Adam"? Why is he being used for scientific experimentation? The United States Department of Energy's National Renewable Energy Laboratory in Colorado used Adam to complete work on a mannequin. "Adam who sweats like a human being and can complain like one." "Adams slim carbon frame is covered with 120 separate temperature sensing and sweating zones; water seeps from an interior two-quart reservoir out through his hypothalamus. "Adam was devised to help reduce automobile fuel consumption by evaluating ways to limit air-conditioner use. "Adam has helped evaluate clothes for astronauts to wear underneath their spacesuits, and devices to warm injured soldiers."