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That's where the carotid bodies come in, receptors embedded in the carotid artery in your neck that are triggered by certain chemicals.
这就是颈动脉体，颈动脉中的受体是由某些化学物质触发的。
Since they measure our blood's chemistry, we call them chemoreceptors.
因为它们测量我们血液的化学成分，所以我们称之为化学感受器。
Their positioning in the neck lets them sample arterial blood before it gets into the brain, which consumes a bunch of oxygen.
它们在颈部的位置可以让它们在动脉血进入大脑之前采集样本，这消耗了大量氧气。
These bodies take information about CO2, pH, temperature and oxygen to give your body an idea of what's happening in your blood.
它们获取有关二氧化碳、酸碱度、温度和氧气的信息，让你的身体了解血液中发生了什么。
And their structure at the tissue level supports that.
它们在组织层面的结构支持了这一点。
The carotid body itself is made of glial cells to give it some shape, which are hooked up to neurons that communicate information about the blood to the brain.
颈动脉体本身是由胶质细胞组成的，胶质细胞赋予它一定的形状，它们与神经元相连，神经元将血液的信息传递给大脑。
When they detect hypoxia or hypercapnia, they'll kick off some kind of response in the cardiorespiratory system. And they work fast.
当他们检测到缺氧或高碳酸血症时，他们会在心肺系统引起某种反应，它们运行的速度很快。
They can detect hypoxia in just a few seconds.
它们能在几秒钟内发现缺氧。
When the carotid bodies detect hypoxia, they communicate with parts of your body that slow down heart rate.
当颈动脉体检测到缺氧时，它们会与减慢心率的身体部位进行交流。
The blood vessels of the skin, muscles, and most organs constrict in order to conserve oxygen rich blood for the brain.
皮肤、肌肉和大多数器官的血管收缩，以便为大脑保存富氧的血液。
A few studies have looked into how competitive breath holders delay their breakpoint, the time at which someone takes a breath after trying to hold it as long as they can.
一些研究调查了憋气能力强的人是如何延迟他们的憋气临界点的，也就是一个人憋不了气的时候。
Their carotid bodies still work just fine.
他们的颈动脉还可以正常工作。
Their bodies still know they're hypoxic, but they're able to brute force their way to a longer hold.
他们的身体仍然知道自己缺氧，但他们能逼迫自己憋气更长时间。
Sometimes the studies will look at how to delay breakpoint with some kind of distraction like squeezing a rubber ball.
有时，研究会着眼于如何通过挤压橡皮球之类的干扰来延迟临界点。
But if these pro-breath holders are able suppress every last urge to breathe, they ultimately pass out and reflexive breathing takes over again.
但是，如果这些专业憋气者能够抑制每一个最后的呼吸冲动，他们最终会昏过去，再次进行反射性呼吸。
In fact, loss of consciousness is fairly common among competitive breath-holding athletes which, ehh, "athlete" is used loosely.
事实上，意识丧失在竞技性屏气运动员中是相当普遍的，“运动员”这个词算是滥用了。
As interesting as voluntary breath holding is, other low-oxygen situations work differently.
与自愿屏气一样有趣的是，其他低氧情况的运行方式也不同。
High altitude creates hypoxia because less oxygen is available for our bodies to grab onto.
高海拔会造成缺氧，因为我们身体所能获得的氧气较少。
Our bodies react by breathing more and more, but after a while of living in high altitude, our bodies acclimatize by making more red blood cells.
为了适应这种状况，我们会更频繁地呼吸，但在高海拔地区生活一段时间后，我们的身体会通过制造更多的红细胞来适应。
That's a different situation entirely from being hypoxic because you're underwater.
这与缺氧完全不同，因为你在水下。
Breath-holding underwater causes something called the mammalian dive reflex - our heart rate slows down even more in an effort to conserve oxygen.
在水下屏住呼吸会引起一种叫做哺乳动物潜水反射的现象——我们的心率会更慢，以保存氧气。
That's what I find so fascinating about this phenomenon.
这就是我发现这个现象如此有趣的原因。
Hypoxia from diving is different from visiting Denver.
潜水造成的缺氧与去丹佛是不同的。
So while I'm definitely not telling you to hold your breath until you lose consciousness, I'm confident knowing that our bodies can use our blood chemistry to keep us in check.
所以，虽然我绝对不会在你失去意识之后才告诉你不要屏住呼吸，但我确信，我们的身体可以利用我们的血液化学来控制我们。
Here's a pro tip: Instead of holding your breath until the next episode of Human, just subscribe and hit the notification bell so you never miss an upload from us.
这里有一个专业提示：不要傻傻地等着下一集《人类》，只需订阅并点击通知铃，你将永远不会错过我们的更新。
Thanks for watching Seeker, I'll see you next week.
感谢收看《科学探秘之旅》，下周见。
