时差N小时 为什么嘴唇会干呢?

Let's start by reviewing the ways in which the surface of ourlips is different from the surface of the skin on the rest of ourbodies.

首先，我们需要知道嘴唇的表皮有别于身体其他部位的。

Basically, our lips are made of the same mucusmembrane that coats the inside of our mouths.

基本而言，嘴唇有相同的粘液膜组成，保护我们的嘴巴。

This means two things.

这就说明了两件事首先。

First, our lips don't have the same protective outer layer as the skin elsewhere on our bodies.

第一，我们身体其他部位的肌肤有一层“保护层”，这是嘴唇所没有的。

This layer is part of the barrier to evaporation¹, and its absence means our lip skin retains less fluid.

“保护层”能有效保湿，嘴唇因为没有而不易保湿。

Second, our lips don't have the same glands² and pigments⁴ as ordinary skin.

第二，嘴唇不像其他肌肤有腺体和色素。

For example, lipsdon't have oil glands, which also help keep moisture from evaporating, and they contain lessmelanin, the pigment³ that helps protect our skin from sunburn.

比如，嘴唇不能分泌油脂，不易保湿。此外，嘴唇缺少黑色素等色素保护皮肤免受太阳灼伤。

What this means is that our lips have little to no protection from the environment, and their mainsource of moisture is the saliva⁵ that comes from our mouths.

这就说明嘴唇易受环境影响，而嘴唇水分大多来源于嘴里的唾液。

What's more, unlike much of therest of our body, our lips are almost always on display, and rarely covered by clothing.

此外，嘴唇有别于身体其他部位的皮肤，嘴唇经常暴露在外面。

As a result,the moisture on our lips is continually evaporating.

这样一来，嘴唇的水分一直在蒸发，

And that's before we take into account exposure to sun, wind, cold, and air-conditioning.

这还不算阳光、大风、天冷、空调的“摧残”。

Plus, if you're sick or have allergies⁶, and your nose is congested, your lips end up drying more quickly because you tend to breathe through your mouth.

此外，如果你生病了或者过敏而鼻塞，不得不用嘴巴呼吸，嘴唇会干得更快！

1 evaporation   

n.蒸发，消失

参考例句：

• Be careful not to lose too much liquid by evaporation.小心不要因蒸发失去太多水分。
• Our bodies can sweat,thereby losing heat by evaporation.我们的身体能出汗，由此可以蒸发散热。

2 glands   

n.腺( gland的名词复数 )

参考例句：

• a snake's poison glands 蛇的毒腺
• the sebaceous glands in the skin 皮脂腺

3 pigment   

n.天然色素，干粉颜料

参考例句：

• The Romans used natural pigments on their fabrics and walls.古罗马人在织物和墙壁上使用天然颜料。
• Who thought he might know what the skin pigment phenomenon meant.他自认为可能知道皮肤色素出现这种现象到底是怎么回事。

4 pigments   

n.（粉状）颜料( pigment的名词复数 )；天然色素

参考例句：

• The Romans used natural pigments on their fabrics and walls. 古罗马人在织物和墙壁上使用天然颜料。 来自辞典例句
• The original white lead pigments have oxidized and turned black. 最初的白色铅质颜料氧化后变成了黑色。 来自辞典例句

5 saliva   

n.唾液，口水

参考例句：

• He wiped a dribble of saliva from his chin.他擦掉了下巴上的几滴口水。
• Saliva dribbled from the baby's mouth.唾液从婴儿的嘴里流了出来。

6 allergies   

n.[医]过敏症；[口]厌恶，反感；（对食物、花粉、虫咬等的）过敏症( allergy的名词复数 )；变态反应，变应性

参考例句：

• Food allergies can result in an enormous variety of different symptoms. 食物过敏会引发很多不同的症状。 来自辞典例句
• Let us, however, examine one of the most common allergies; hayfever. 现在让我们来看看最常见的变态反应的一种--枯草热。 来自辞典例句