How Sunburns Work追根究底談曬傷

Enjoy the sun this summer by Marshall Brain / (c) 2007, How Stuff Works Inc

Now that we are getting into the thick of summertime activities, sunburn is something that you have to think about. How is it that light can cause such intense pain?
Getting sunburn 曬傷了!
The easiest way to get sunburn is to stay inside for a month or two and then spend a day outside. When you go out in the sun, ultraviolet light penetrates into living skin cells, and it starts damaging and killing those cells.
The repair process starts when damaged cells release chemicals. The first thing the chemicals do is set off pain signals in your skin’s pain sensors. Those same chemicals also tell your body to send in white blood cells to eat all the damaged and dead cells. Your body dilates all the capillaries in the damaged area to increase blood flow. Sunburned skin turns red and hot because of all of those dilated capillaries bringing in the white blood cells. And your skin stings because every pain sensor in your sunburned skin is sounding the, “Hey, there is damage here!” alarm. 當受損的細胞釋放化學物質,修復的過程開始。最開始的時候,化學物質會對你皮膚的痛感應器官引發疼痛信號。這些相同的化學物質,也會告訴你的身體把白血球送過來,吃掉那些受損或死亡的細胞。你的身體會膨脹曬傷區域的所有微血管,增加血流順暢。曬傷的皮膚變紅、變熱,因為所有這些擴張的微血管流入了白血球,而且你的皮膚刺痛,因為你曬傷的皮膚的每個痛感應器都發出了『嘿!我這受傷了。』的信號。
Avoiding sunburn 避免曬傷
There are three ways you can avoid sunburn. One is to stay inside or cover all your skin with clothing. The second way is to use a sunscreen.
Sunscreen contains chemicals that absorb ultraviolet light. The third way is to go out in the sun a little bit each day and get a tan. The tan will protect your skin from sunburn.

More about tans 更多關於古酮色
Here’s how a tan works. If you look at a cross section of your skin, you have the outer layer called the stratum corneum.
This layer contains the dead skin cells that you actually see covering your body. Below the stratum corneum is the granular layer, and below that is the basal layer. Tanning happens in the basal layer, which contains special cells called melanocytes. When a melanocyte detects ultraviolet light, it creates a brown pigment called melanin. Melanin, like sunscreen, absorbs ultraviolet light and protects your skin from damage. If people spent all their time outdoors, their skin would naturally tan and “untan” with the seasons. You would never get a sunburn.
More INFO更多資訊
Your skin is one of the most amazing organs in your body. The skin of a typical adult weighs about 3.5kilograms and covers about 1.8 square meters. Skin is loaded with sensors, blood vessels, sweat glands, hair follicles and muscles (one tiny muscle for each hair) and it has a very tough design so that it can handle things like abrasion and sunlight.
你的皮膚是你身體上最另人驚訝的器官之一。一個典型成人的皮膚,總重約3.5公斤。覆蓋的面績是1.8平方公尺。皮膚內有感應器、血管、汗腺、毛曩和肌肉(每根頭髮包有一小單位的肌肉) 。而且它也是非常強韌的設計,它可以應付擦傷和陽光。