時(shí)差N小時(shí):被燒傷的假象

You're on the deck catching rays, and even thoughyou know you aren't supposed to tan withoutsunblock, you figure you'll be able to tell if you startto get really burned. Sure enough, after a little whileyou can see a redness coloring your skin, but itdoesn't look too bad. Five or six hours later, the realburn begins appearing, and it's too late now to stopit.

你在甲板上沐浴陽光，即使你能看到，不涂防曬霜時(shí)你沒被曬黑，但你不會(huì)覺察到皮膚從何時(shí)起被曬傷。果然，過一會(huì)你的皮膚開始變紅，但是看起來紅得并不厲害。五六個(gè)小時(shí)候，你感到皮膚在灼燒，但為時(shí)已晚。

What just happened is a kind of pump-fake from the system that runs temperature-balance inyour body. People often assume it's possible to watch sunburn mounting on your skin, but thisis a serious mistake. The red coloration that comes after an hour or so is not the first signs oftanning at all; that redness is caused by an increased flow of blood toward the skin due toexcess body heat.

剛發(fā)生的現(xiàn)象是一種假象，與你身體內(nèi)維持體溫恒定的系統(tǒng)有關(guān)。通常人們誤以為皮膚燒傷時(shí)會(huì)有看得見的痕跡。但這種想法大錯(cuò)特錯(cuò)。一小時(shí)左右后皮膚泛紅，這根本不是皮膚被曬黑的第一個(gè)跡象：皮膚呈現(xiàn)紅色是因?yàn)樯眢w過熱致使流向皮膚的血液增多。

It's the same effect that gives people a ruddy glow after exercise: the over-heated bodyattempts to read just its temperature by directing more blood toward its surfaces, which hasthe effect of radiating away heat. This "flush" will disappear as soon as you cool down.Therefore, it's no indication as to whether the skin itself is becoming burned.

這跟運(yùn)動(dòng)之后人們滿面紅光是同一個(gè)道理：身體過熱，血液流向表面的皮膚以保證體溫恒定，同時(shí)放出熱量。在身體涼快之后臉上的紅光立刻褪去。因此，沒有跡象表明皮膚自身是否在灼燒。

The redness of a burn looks the same because it's also caused in part by increased blood flow——but with an actual burn, the blood is being shunted outward much more rapidly in an effortto repair already damaged cells. By the time the blood starts being sent to the aid of yourtraumatized skin, several hours have elapsed since that deceptive "first blush" has faded. It'sonly then that you can start to feel how much or how little burn you actually received.

曬傷的紅色跟這看起來很像，因?yàn)闀駛笃つw呈現(xiàn)紅色部分是因?yàn)檠髁吭龆?，但真正燒傷時(shí)，會(huì)有更多的血液快速分流到體表，以修復(fù)已經(jīng)損傷的細(xì)胞。然而，“第一次泛紅”的假象消失了好幾個(gè)小時(shí)之后，血液才開始修復(fù)損傷的皮膚。直到這時(shí)你才能感覺到皮膚燒傷的程度。