If you've had surgery, you might remember starting to count backwards from ten, nine, eight,
如果你做过手术，你也许会记得，开始从10倒数，9，8，
and then waking up with the surgery already over before you even got to five.
在你还没数到5的时候，你就苏醒过来，发现手术已完成了。
And it might seem like you were asleep, but you weren't.
也许看起来像是你睡着了，可事实并非如此。
You were under anesthesia, which is much more complicated.
你被麻醉了，这更为复杂。
You were unconscious, but you also couldn't move, form memories, or, hopefully, feel pain.
你不仅陷入了昏迷状态，而且你也动不了，不能形成记忆，当然，你也感觉不到疼痛。
Without being able to block all those processes at once, many surgeries would be way too traumatic to perform.
如果不能在同一时间阻止上述的发生，许多手术会十分痛苦而难以进行下去。
Ancient medical texts from Egypt, Asia and the Middle East
来自埃及，亚洲和中东的古代医学书籍，
all describe early anesthetics containing things like opium poppy, mandrake fruit, and alcohol.
都有描述早期的麻醉药，包括罂粟、曼德拉草果以及酒精。
Today, anesthesiologists often combine regional, inhalational and intravenous agents to get the right balance for a surgery.
如今，麻醉师通常会结合局部麻醉、吸入麻醉和静脉注射麻醉的方法，在手术中获得合适的平衡点。
Regional anesthesia blocks pain signals from a specific part of the body from getting to the brain.
局部麻醉可以阻止从身体某一部位发出的疼痛信号传输到脑部。
Pain and other messages travel through the nervous system as electrical impulses.
疼痛感与其它感觉在神经系统中就好像电脉冲一样传输。
Regional anesthetics work by setting up an electrical barricade.
局部性麻醉剂可以设立一个电子路障。
They bind to the proteins in neurons' cell membranes that let charged particles in and out,
它们结合到神经元细胞膜的蛋白质上，这些蛋白质让粒子进出，
and lock out positively charged particles.
并保持正电荷的粒子不能进入细胞。
One compound that does this is cocaine,
可卡因是这种类型的化合物的一个例子，
whose painkilling effects were discovered by accident when an ophthalmology intern got some on his tongue.
当一位眼科实习生不小心把它弄到舌头上，它的止痛效果被偶然发现。
It's still occasionally used as an anesthetic,
它仍然偶尔被用作麻醉剂，
but many of the more common regional anesthetics have a similar chemical structure and work the same way.
但许多更常见的局部麻醉剂具有类似的化学结构和工作方式。
But for major surgeries where you need to be unconscious,
但对于大部分需要昏迷的手术，
you'll want something that acts on the entire nervous system, including the brain.
你要的是可以针对整个神经系统的药物，包括大脑。
That's what inhalational anesthetics do.
这就是吸入麻醉药的用处。
In Western medicine, diethyl ether was the first common one.
西药里，乙醚是最先常见的一种。
It was best known as a recreational drug
它以前是以娱乐性药物而闻名，
until doctors started to realize that people sometimes didn't notice injuries they received under the influence.
直到医生开始认识到人们有时没注意到他们在乙醚的影响下受的伤。

In the 1840s, they started sedating patients with ether during dental extractions and surgeries.
在19世纪40年代，他们开始将乙醚麻醉用在拔牙和手术中。
Nitrous oxide became popular in the decades that followed and is still used today,
几十年后，一氧化二氮开始变得普遍，一直沿用到今天，
although ether derivatives, like sevoflurane, are more common.
虽然醚衍生物，像七氟醚，更常见。
Inhalational anesthesia is usually supplemented with intravenous anesthesia, which was developed in the 1870s.
吸入式麻醉剂通常在静脉麻醉的补充下运作，它源于19世纪70年代。
Common intravenous agents include sedatives, like propofol, which induce unconsciousness,
常见的静脉注射剂包括镇静剂，比如异丙酚，可以导致昏迷状态，
and opioids, like fentanyl, which reduce pain.
以及阿片类药物，可以减轻疼痛的芬太尼。
These general anesthetics also seem to work by affecting electrical signals in the nervous system.
这些普遍麻醉药似乎也能影响神经系统的电信号工作。
Normally, the brain's electrical signals are a chaotic chorus as different parts of the brain communicate with each other.
通常情况下，大脑的电信号是一个混乱的大合唱，因为大脑的不同部位会互相通信。
That connectivity keeps you awake and aware.
那种连接使你保持清醒。
But as someone becomes anesthetized, those signals become calmer and more organized,
但当一个人被麻醉，这些信号变得平静、更有条理，
suggesting that different parts of the brain aren't talking to each other anymore.
这表明大脑的某些部分不能互相交谈了。
There's a lot we still don't know about exactly how this happens.
关于麻醉，仍有有很多我们不清楚的地方。
Several common anesthetics bind to the GABA-A receptor in the brain's neurons.
几种常见的麻醉药绑定到大脑的神经元GABA-A受体。
They hold the gateway open, letting negatively charged particles flow into the cell.
它们开着大门，让着带负电荷的粒子进入细胞。
Negative charge builds up and acts like a log jam, keeping the neuron from transmitting electrical signals.
负电荷积聚和作用就像一个塞子，不让神经元传输电信号。
The nervous system has lots of these gated channels, controlling pathways for movement, memory, and consciousness.
神经系统有很多门控通道，它们控制运动通道、记忆以及意识。
Most anesthetics probably act on more than one, and they don't act on just the nervous system.
大多数麻醉剂可能作用于不止一个，而且不只作用于神经系统。
Many anesthetics also affect the heart, lungs, and other vital organs.
许多麻醉药也影响心脏、肺以及其它重要器官。
Just like early anesthetics, which included familiar poisons like hemlock and aconite, modern drugs can have serious side effects.
就像早期的麻醉剂，其中包括熟悉的毒药，比如铁杉和附子，现代药可能有严重的副作用。
So an anesthesiologist has to mix just the right balance of drugs to create all the features of anesthesia,
因此，一个麻醉师必须搭配好药物之间的平衡，才能发挥出麻醉的所有功能，
while carefully monitoring the patient's vital signs, and adjusting the drug mixture as needed.
同时密切监测患者的生命体征，并根据需要调整药物。
Anesthesia is complicated, but figuring out how to use it allowed for the development of new and better surgical techniques.
麻醉是复杂的，但是弄清楚如何使用它为开发新的更好的外科技术创造了条件。
Surgeons could learn how to routinely and safely perform C-sections, reopen blocked arteries,
外科医生可以学习如何系统化地和安全地进行剖腹产，打开阻塞的动脉，
replace damaged livers and kidneys, and many other life-saving operations.
替换受损的肝脏和肾脏，以及许多其它可以拯救生命的手术。
And each year, new anesthesia techniques are developed that will ensure more and more patients survive the trauma of surgery.
而且每年，新的麻醉技术都在被开发，这将确保越来越多的患者经受得住痛苦的手术过程。