Sometimes that's 30 seconds into a breath hold, sometimes a minute, sometimes multiple

有時是30秒進入憋氣狀態，有時是一分鐘，有時是多秒

minutes if the conditions are just right.

分鐘，如果條件正好。

Everyone's breakpoints are different, and individually, multiple factors influence our

每個人的斷點都是不一樣的，單獨來看，多種因素影響著我們的

time on the stopwatch.

秒錶上的時間。

But how does your body know that you're at your breaking point?

但是，你的身體怎麼知道你已經到了極限呢？

When do you know you've reached your absolute limit you know, before death?

你什麼時候知道你已經達到了你的絕對極限，你知道，在死亡之前？

As it turns out, it has to do with what's in our blood.

事實證明，這與我們血液中的東西有關。

In this video, we'll go over the physiology that monitors your blood chemistry and keeps

在這段視頻中，我們將介紹監測你的血液化學的生理學，並保持你的血液化學。

you breathing right.

你的呼吸正確。

Quick disclaimer, I'm going to talk about intentional breath holding in this video,

快速免責聲明，我在這個視頻中要講的是意念屏息。

not choking or airway obstruction which are emergencies.

而不是窒息或氣道阻塞，這些都是緊急情況。

Also, some young infants and toddlers experience involuntary breath holding spells, but this

另外，一些年幼的嬰幼兒也會出現不自主的憋氣現象，但這個

video is for curiosity and education, not medical advice.

視頻是為了好奇心和教育，不是醫療建議。

So please, please use common sense.

所以，請你用常識。

If you think something is wrong, get professional medical help.

如果你認為有什麼不對勁，請尋求專業的醫療幫助。

Okay, now we can get into the fun stuff.

好了，現在我們可以進入有趣的東西。

The whole point of breathing is so that our tissues can consume oxygen and glucose and

呼吸的全部意義是為了讓我們的組織能夠消耗氧氣和葡萄糖，並且...

turn them into energy, leaving water and carbon dioxide as waste products.

將它們轉化為能源，留下水和二氧化碳作為廢棄物。

This process called cellular respiration is essential to anything that breathes oxygen.

這個被稱為細胞呼吸的過程對任何呼吸氧氣的事物都是必不可少的。

And if our tissues don't get enough oxygen, or experience hypoxia, they can start to die

如果我們的組織得不到足夠的氧氣，或者缺氧，它們就會開始死亡。

off or see other problems.

關或看到其他問題。

There are a bunch of reasons that a tissue might not get enough oxygen — like an iron

有一大堆的原因，一個組織可能沒有得到足夠的氧氣 - 像一個鐵

deficiency might cause anemia, which means that less oxygen will be able to ride on each

缺少氧氣可能會導致貧血，也就是說，每一個人身上的氧氣會減少。

red blood cell and oxygenate your tissues.

紅血球和氧氣的組織。

Hypoxia can also happen if there's not enough blood flow to a tissue, like when an artery

如果沒有足夠的血液流向一個組織，也會發生缺氧，比如當一個動脈

is too narrow and doesn't deliver as much blood to its target tissue.

太窄了，不能將盡可能多的血液輸送到目標組織。

Then there's high altitude where oxygen isn't as easily available, but we'll come

還有高海拔地區，氧氣不容易獲得，但我們會來的

back to that later.

稍後再談。

Now, in a breath holding situation, it's pretty easy to see why you'd become hypoxic.

現在，在憋氣的情況下，很容易明白為什麼你會變得缺氧。

You're not breathing so you're not taking in any of that sweet sweet oxygen.

你沒有呼吸，所以你沒有吸收任何甜甜的氧氣。

But we have to keep another gas in mind during breath holding — carbon dioxide.

但是我們在憋氣的過程中還要注意另一種氣體--二氧化碳。

High CO2 levels in our blood, or hypercapnia, can cause symptoms like headaches and dizziness,

我們血液中的二氧化碳含量過高，也就是高碳酸血癥，會引起頭痛、頭暈等症狀。

but also more severe symptoms like paranoia, irregular heartbeats, and seizures.

但也有更嚴重的症狀，如妄想症、心跳不規律、癲癇發作。

Hypercapnia can happen without breath holding too, like if you're in a submarine or just

高碳酸血癥也可以在沒有屏氣的情況下發生，比如你在潛水艇裡或者只是

a stuffy room with the windows closed.

一個關著窗戶的悶熱的房間。

Since neither hypoxia or hypercapnia are ideal, our bodies are constantly measuring and reacting

由於缺氧或高碳酸血癥都不理想，我們的身體在不斷地測量和反應。

to oxygen and carbon dioxide in the blood.

到血液中的氧氣和二氧化碳。

That's where the carotid bodies come in, receptors embedded in the carotid artery in

這就是頸動脈體的作用，受體嵌在頸動脈中，在

your neck that are triggered by certain chemicals.

你的脖子會被某些化學物質觸發。

Since they measure our blood's chemistry, we call them chemoreceptors. 

由於它們能測量我們血液的化學成分，我們稱它們為化學感受器。

Their positioning in the neck lets them sample arterial blood before it gets into the brain,

他們在頸部的定位讓他們在動脈血進入大腦之前就能取樣。

which consumes a bunch of oxygen.

其中消耗了一堆氧氣。

These bodies take information about CO2, pH, temperature and oxygen to give your body an

這些機構獲取二氧化碳、酸鹼度、溫度和氧氣的資訊，給你的身體一個

idea of what's happening in your blood.

血液中發生的事情的想法。

And their structure at the tissue level supports that.

而它們在組織層面的結構也支持這一點。

The carotid body itself is made of glial cells to give it some shape, which are hooked up

頸動脈體本身是由膠質細胞組成的，使其具有一定的形狀，這些膠質細胞被勾住了

to neurons that communicate information about the blood to the brain.

到神經元，將血液的資訊傳達給大腦。

When they detect hypoxia or hypercapnia, they'll kick off some kind of response in the cardiorespiratory system.

當它們檢測到缺氧或高碳酸血癥時，它們會啟動心肺系統的某種反應。

And they work fast.

而且他們的工作速度很快。

They can detect hypoxia in just a few seconds. 

它們可以在幾秒鐘內檢測到缺氧。

When the carotid bodies detect hypoxia, they communicate with parts of your body that slow

當頸動脈體檢測到缺氧時，它們會與你身體的部分進行溝通，以減緩

down heart rate.

下心率。

The blood vessels of the skin, muscles, and most organs constrict in order to conserve

皮膚、肌肉和大多數器官的血管收縮，以保存。

oxygen rich blood for the brain.

大腦的富氧血液。

A few studies have looked into how competitive breath holders delay their breakpoint, the

一些研究考察了競爭性氣息持有者如何延遲他們的斷點，即

time at which someone takes a breath after trying to hold it as long as they can.

一個人在盡力屏住呼吸後的時間。

Their carotid bodies still work just fine.

他們的頸動脈體還是很好用的。

Their bodies still know they're hypoxic, but they're able to brute force their way

他們的身體仍然知道自己缺氧，但他們能夠用蠻力來解決。

to a longer hold. 

到較長的保持。

Sometimes the studies will look at how to delay breakpoint with some kind of distraction

有時候，研究會研究如何用某種分心的方式來延遲斷點的時間

like squeezing a rubber ball.

就像擠橡皮球一樣。

But if these pro-breath holders are able suppress every last urge to breathe, they ultimately

但是，如果這些支持呼吸的人能夠壓制住每一個呼吸的衝動，他們最終會

pass out and reflexive breathing takes over again. 

昏迷，反射性呼吸又開始了。

In fact, loss of consciousness is fairly common among competitive breath-holding athletes

事實上，意識喪失在競技憋氣運動員中相當常見。

which, ehh, “athlete” is used loosely.

其中，誒，"運動員 "用得很寬泛。

As interesting as voluntary breath holding is, other low-oxygen situations work differently.

雖然自願憋氣很有趣，但其他低氧情況下的工作方式也不一樣。

High altitude creates hypoxia because less oxygen is available for our bodies to grab onto.

高海拔會造成缺氧，因為可供我們身體抓住的氧氣少了。

Our bodies react by breathing more and more, but after a while of living in high altitude,

我們的身體反應是呼吸越來越多，但在高海拔地區生活一段時間後。

our bodies acclimatize by making more red blood cells.

我們的身體通過製造更多的紅血球來適應。

That's a different situation entirely from being hypoxic because you're underwater.

這和因為在水下而缺氧的情況完全不同。

Breath-holding underwater causes something called the mammalian dive reflex — our heart

在水下憋氣會引起一種叫做哺乳動物潛水反射的東西--我們的心臟。

rate slows down even more in an effort to conserve oxygen.

為了節約氧氣，速度更慢。

That's what I find so fascinating about this phenomenon.

這就是我覺得這種現象的魅力所在。

Hypoxia from diving is different from visiting Denver.

潛水缺氧與參觀丹佛不同。

So while I'm definitely not telling you to hold your breath until you lose consciousness,

所以，雖然我絕對不是叫你屏住呼吸直到失去意識。

I'm confident knowing that our bodies can use our blood chemistry to keep us in check.

我知道我們的身體可以利用血液化學來控制我們，我很有信心。

Here's a pro tip: Instead of holding your breath until the next episode of Human, just

這裡有一個專業的提示：與其屏住呼吸等待下一集的人類，不如直接

subscribe and hit the notification bell so you never miss an upload from us.

訂閱並按下通知鈴，這樣你就不會錯過我們的上傳。

Thanks for watching Seeker, I'll see you next week.

謝謝你的觀看《探尋者》，下週見。