고등학교 공통영어1 (NE능률 민병천) 연계 글

On a hot August afternoon, Yunseo and her volunteer club spent two hours picking up trash along a river trail. Near the end, she felt dizzy and had a headache, and her arms were wet with sweat but cool to the touch. The club leader suggested that she sit in the shade, loosen her collar, and sip cool water. Within half an hour, Yunseo felt much better, but she began to wonder what had happened inside her body.

The human body regulates its temperature and keeps it close to 37°C, even when the air around it is much hotter. Normally, the body cools itself by sweating. To understand why sweat cools us, we need to know what happens to it on the skin. As sweat evaporates, it carries heat away from the body. In humid air, however, sweat evaporates slowly, so the body cannot release heat as quickly.

The blood also plays a part in keeping the body cool. When the body grows warm, blood vessels near the skin become wider. More blood then flows close to the surface, where it can pass heat out of the body.

Sometimes, though, the body gains more heat than it can remove, and its temperature begins to rise. Heat exhaustion is the body's response to losing too much water and salt, usually through heavy sweating. Its symptoms include heavy sweating, dizziness, a headache, and nausea. The skin may also look pale and feel cool and moist. Heat stroke is far more severe because the body can no longer control its temperature. The skin may feel hot and dry because sweating has stopped, and the person may become confused. Heat stroke is a medical emergency, so experts insist that someone call 119 right away.

Fortunately, a few simple habits can lower the risk of heat illness. Health experts recommend that a person drink water regularly on hot days, even before thirst sets in. They also suggest that everyone wear loose, light-colored clothing and take frequent breaks in the shade. It is also wise to check on older neighbors during a heat wave.

Now Yunseo carries a water bottle whenever she volunteers outdoors in summer. She also knows which warning signs mean that someone needs emergency help.