時差N小時:寒冷的曬傷 A Cool Sunburn

A listener from Ontario, California wrote to AMoment of Science with a question her sonshadasked her.

一位來自加利福尼亞安大略的聽眾我們給寫信詢問她兒子們遇到的問題。

The boys wondered why is it that when you getsunburned you often feel chilled.

這些小男孩想知道為什么人曬傷的時候會覺得冷。

It really doesseem like a contradiction: you've beenburned, but you feel cold.

這簡直就是矛盾至極:你明明曬傷了，卻覺得冷。

The answer to this seeming contradiction is in your blood.

這個看上去自相矛盾的問題的答案就在你的血液當(dāng)中。Sunburn is an injury to your skin, and yourbody's usual reaction to being injured is to enlarge theblood vessels in the damaged area.

曬傷表明你的皮膚受到了損傷，而通常人體應(yīng)對損傷的辦法就是使受創(chuàng)的血管擴(kuò)張。

This allows more blood to be circulated near the injury, whereit can deliver cells to help heal thewound.

這使得更多的血液在傷口附近循環(huán)，同時血液中的一些細(xì)胞也會被輸送到傷口附近，幫助傷口愈合。

Since sunburn is usually damage to the surface of your skin, the blood vessels in the area oftheburned skin enlarge so that more blood is circulated there; this is where the redness comesfrom.

由于曬傷通常會損害你的皮膚表面，而曬傷部位的血管會擴(kuò)張，使更多的血液在附近循環(huán)。這就是為什么曬傷部位會變紅。

When you're sunburned a large area of your body is usually involved, so a result of somuchblood being near the surface of your skin is that you lose more than a normal amount ofbodyheat through it.

曬傷通常會波及到人體的大部分區(qū)域。而大量血液聚集在皮膚表面附近的結(jié)果就是:你會散失比平時更多的熱量。

Your brain tries to balance this loss of heat by activating reactions which attempt toconserveheat.

為了平衡損失，大腦嘗試通過刺激人體作出某種反應(yīng)來保存熱量。

A common reaction is shivering, which is the body trying to generate heat in an efforttocompensate for the heat that is being lost.

該反應(yīng)通常表現(xiàn)為顫抖，這一動作表明人體正試圖產(chǎn)生熱量來補(bǔ)充正在散失的那一部分。

So, even when your skin feels hot to the touch, you shiver and feel chilled as your body triestomake up for the extra heat loss.

因此，即使你的皮膚摸一下都覺得發(fā)燙，但你還是會顫抖，覺得冷，因?yàn)檫@是人體正設(shè)法補(bǔ)充額外散失的熱量。