时差N小时 痒痒（在线收听）

When you have an itch, you scratch it.

痒痒就挠挠。

What could be more simple than that?

还有什么比这更简单的吗?

Scratching itches is one of our most basic instincts, one which we share with many other animals.

挠痒是我们与许多其他动物共同具有的最基本的本能之一。

Have you ever stopped to wonder, mid-scratch, exactly why scratching is so effective against itching?

但你是否在挠舒服的同时停下来想过,为什么抓挠能治痒?

We'll learn the itchy truth, on today's Moment of Science.

我们将在今天的《科学一刻》节目中了解有关发痒的事实,。

On the most basic level, scratching is a way to remove whatever irritant might be causing the itch in the first place.

从最基本的角度上看, 抓挠首先是一种去除任何可能会导致瘙痒刺激的方式。

If an insect is biting you, or you have a patch of dead, flaking skin, scratching has a good chance of getting rid of it.

如果一只昆虫咬了你,或者你有一块死皮,皮肤剥落,抓挠很有可能将它弄掉。

In this case, it's pretty obvious why the scratching works.

这样的情况很明显说明了为什么抓挠会有效。

Much of the time we scratch, however, it seems to be somewhat after the fact.

大部分时间我们总是在真正痒了之后才会去抓挠。

Perhaps the mosquito has already bitten us and flown away, and we are left scratching at the swelling bite.

也许蚊子已经吸完血飞走了我们才会抓挠被叮咬的肿胀部分。

Clearly this won't get rid of the mosquito.

很明显,这不会摆脱蚊子。

Is there any good reason for this kind of scratching, or is this just an over-zealous instinct that doesn't realize it's too late?

但这种抓挠有什么好的理由,或者只是一种不知道太晚的过度本能吗?

Actually, this kind of scratching can serve two additional functions.

实际上,这样的抓挠可以起到两个额外的作用。

First, it can stimulate the irritated tissues and cause extra blood to flow to them.

首先可以刺激激扩张组织,使额外的血液流动。

This can help your immune system remove whatever itchy substances might be below your skin.

这可以帮助你的免疫系统清理在你皮肤下任何可能发痒的物质。

Second, it can trick your brain into ignoring the annoying itch.

其次是可能会欺骗你的大脑忽略这恼人的痒痒。

Your nervous system can generally process only one stimulus from a given area of your skin at a time.

你的神经系统通常只能处理一次皮肤特定区域的刺激。

If you scratch at an area that itches, this new, greater stimulus can override the itching, effectively blocking it out.

如果你抓挠很痒的部位,这种新的、更大的刺激可以覆盖瘙痒,有效地阻止它。