SLICEsweatology

Sweatology Article (1) Why is sweat like your personal air-conditioner and why is that important?

(2) The human body can tolerate cooling. How much? Give examples. Who would believe that every sufferer had the same model of personal air-conditioner operating at full blast?

Sweat is our 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.

(3) The human body can not tolerate over heating. How much? Give examples. But 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 a dozen degrees above normal, is often cited as the upper limit compatible with life. So a good internal air-conditioner is essential, (4) Why do we think humans evolved sweat glands? Give examples. 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. Give examples. 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? Give examples. 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 dangeous? Give examples. 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 highest risk of heat stroke.

(8) Is clothing good or bad when it comes to sweat? Why? Give examples. And 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 “soldiers” 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. Give examples. 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? Adam’s slim carbon frame is covered with 120 separate temperature-sensing and sweating zones; water seeps from an interior two-quart reservoir out through his porous skin. He is wirelessly connected to a computer whose software forms his hypothalamus. Other software based on human reactions to a range of temperatures provides estimates of his comfort in various situations.

Adam was devised to help reduce automobile fuel consumption by evaluating ways to limit air-conditioner use. Fully dressed in a car parked in the hot sun, he gets as wet on his back and rear end as any human driver, and just as irritable. Programmers can also rev up his metabolic rate to provide a good, sweaty simulation of road rage, said one of his creators, John Rugh, a senior mechanical engineer.

Adam has helped evaluate clothes for astronauts to wear underneath their spacesuits, and devices to warm injured soldiers. Currently unemployed, he is looking for other work mimicking the human experience in temperature extremes, Mr. Rugh said.