Some Awesome People

Tuesday, July 17, 2012

How our bodies respond to heat


Why Is a 98.6-Degree Day So Miserable?

We can’t maintain a normal body temperature in air as warm as we are.

By Katy Waldman
Posted Wednesday, July 11, 2012



Whew, it's hot.
Photograph by Yana Paskova/Getty Images.

(...)  Because our bodies need to disperse heat, and they can’t do that effectively when the air temperature is close to our body temperature. Our muscles and metabolism generate heat continuously. We transfer that heat into our surroundings by sweating, exhaling warm air, and circulating blood near the surface of our skin to cool. When the temperature gradient (or difference) between the body and the air is high, heat flows easily from us into the environment, and we cool down. But when the weather hovers around our internal temperature, our inner swelter lingers, and we feel hot and uncomfortable. Humidity makes things worse by interfering with the vaporization of sweat, one of the human body’s main cooling mechanisms.

By the same token, frigid weather draws the heat from our bodies faster than we can produce it, and our core temperature falls. A person’s thermal comfort, or satisfaction with the temperature of the environment, depends on factors as varied as metabolic rate, body fat, and age. For instance, those with heavier builds have a lower ratio of skin surface area to mass—they evaporate heat less efficiently than the small-framed. And fat absorbs warmth readily, making the obese more susceptible to heat stress. Other groups shown to be especially sensitive to hot weather include pregnant women, the disabled, and people younger than 14 or older than 60. (The body’s effectiveness at thermoregulation declines with age.(...)

Full article: http://www.slate.com/articles/news_and_politics/explainer/2012/07/my_body_temperature_is_98_6_degrees_so_why_is_98_6_degree_air_unbearable.html

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