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Your brain works together with the rest of your body in lots of different ways.
你的大脑和身体的其他部位有很多不同的协作方式。
If things go wrong with some organs, like if your heart stops pumping,
如果某些器官出了问题，比如心脏停止跳动，
your brain's obviously going to have a bad time.
显然，你的大脑也不会好过。
But sometimes the connection is a little less straightforward.
但有时这种联系不那么直接。
Take the liver, for example: you need it for things
以肝脏为例，你需要它做的工作是
like filtering blood, storing vitamins, and lots of other processes that keep you alive.
过滤血液、储存维生素以及许多其它维持生存的过程等。
So, basically, what happens in the liver doesn't stay in the liver.
所以，基本上，肝脏的毛病不会只停留在肝脏处。
And an issue there can cause a chain reaction across your body that seriously affects your brain.
一个身体问题会引起它的连锁反应并严重影响大脑。
Patients with many kinds of liver damage or disease
病人的多种肝脏损伤或疾病
can develop a condition called hepatic encephalopathy or HE.
可以发展成一种叫做肝性脑病（HE）的疾病。
Hepatic refers to the liver, and encephalopathy means brain disease, damage or malfunction.
“Hepatic”是指肝脏，“encephalopathy”是指脑部疾病、脑损伤或脑故障。
Physicians think of HE as a spectrum of symptoms
医生认为肝性脑病有一系列的症状，
that can affect personality, movement, cognition, and even levels of consciousness.
可以影响性格、运动、认知甚至意识水平。
They can range from mild, like mood swings, to severe, like a coma.
它们的范围可以从情绪波动等轻微症状到昏迷等严重症状。
And HE is mainly caused by substances that build up when the liver stops working as well as it should.
肝性脑病主要是由肝脏停止正常工作时积累的物质引起的。
In a healthy liver, chemicals from the rest of the body are filtered out of the blood
在健康的肝脏中，身体其余部位的化学物质会从血液中过滤出来，
and broken down by specialized cells and enzymes.
并被特殊的细胞和酶分解。
If the liver becomes damaged, like from certain drugs, a bad diet,
如果因为某些药物、糟糕的饮食、
or some other kind of injury or disease, the tissue changes structure and gets all scarred.
或者其他伤害或疾病等引起肝脏受损，肝组织就会改变结构并受到创伤。
This scar tissue isn't able to function like normal liver cells.
这种疤痕组织不能像正常肝细胞那样运转。
Plus, all those structural changes make it harder for blood to get in for detoxification.
此外，所有这些结构上的变化使血液更难进入其中排毒。
And in really severe cases, a lot of blood may bypass the liver entirely.
在肝脏受损非常严重的情况下，大量血液可能直接绕过肝脏。
One important toxin your liver deals with is ammonia,
肝脏处理的一种重要毒素是氨。
which mostly comes from the digestion of proteins in your gut.
它主要来自于肠道内蛋白质的消化。
Ammonia gets turned into urea, which is excreted in pee.
氨转变成尿素，后者从尿中排泄出去。
So a damaged liver can lead to a buildup of ammonia in the bloodstream, which is bad news for the brain.
因此，肝脏受损会导致血液中的氨堆积，这对大脑来说是个坏消息。
Ammonia can cross the blood-brain barrier,
氨可以穿过血脑屏障，
which is a membrane that blocks a lot of molecules in your bloodstream from circulating around your brain,
后者是一种膜，可以阻止血流中大量的分子在大脑周围循环，
to protect it from potential damage.
保护它免受潜在伤害。
Once ammonia slips past, it's mostly taken up by astrocytes,
一旦氨滑过血脑屏障，就会被星形胶质细胞占用，
which are brain cells that help out neurons in a lot of different ways.
星形胶质细胞是一种脑细胞，可以通过不同的方式帮助神经元。
And astrocytes have enzymes that convert ammonia into the amino acid glutamine to help protect the neurons.
它拥有把氨转化成氨基酸的酶来帮助保护神经元。
If they do this too much, though, studies have found that their structure gets messed up.
但是，研究发现，如果它们的工作量过大，就会导致结构混乱。
Cell-damaging molecules called free radicals get produced,
被称为自由基的细胞破坏分子由此产生，
and their mitochondria stop working as efficiently, which means they can't make as much energy.
而且它们的线粒体会停止高效工作，这意味着它们不能产生尽可能多的能量。
As the astrocytes lose function, they stop getting rid of ammonia,
当它们失去功能时，就会停止去除氨，
and everything gets even more messed up.
一切变得更加混乱。
Too much ammonia can affect the storage, production, and use of neurotransmitters across the whole brain.
过多的氨会影响整个大脑中神经递质的储存、生产以及使用。
In other words, your neurons can't really communicate,
换句话说，你的神经元无法真正交流，
which can cause a whole range of problems with mood, movement ... pretty much anything.
这可能会导致情绪、运动等一系列问题，几乎是所有问题。
Even though ammonia is a significant part of HE, other toxins might be involved too.
即使氨是HE的重要组成部分，但其他的毒素也可能参与其中。
And researchers are still figuring out exactly what they are and how they might make HE worse.
研究人员仍在研究它们到底是什么，以及它们如何让肝性脑病变得更糟。
Besides waste products like ammonia,
除了氨这样的废物，
your liver also has a huge impact on how long lots of drugs, from aspirin to LSD,
肝脏也会对从阿斯匹林到麦角酸二乙基酰胺（LSD）等很多药物的时效产生巨大影响，
stay in your system before they're flushed out.
它们在被排出前都会待在你体内。
A healthy liver takes drug molecules from your bloodstream and converts them into different chemicals.
健康的肝脏从血液中提取药物分子，并将其转化为不同的化学物质。
Sometimes they're the active form of a drug,
这些化学物质有时是药物的活性形式，
but eventually they become more water-soluble compounds that can be peed out.
但最终它们大多会变成可以被排出体外的水溶性化合物。
To do this, it mostly uses a system of enzymes known as the cytochrome p450 family,
为了做到这一点，肝脏主要使用一种酶系统，即细胞色素p450家族，
which may be responsible for up to 75% of drug metabolism.
它们可能负责多达75%的药物代谢。
So if a disease damages liver cells or directly interferes with these enzymes, things can go sour.
所以，如果一种疾病损害了肝细胞或者直接干扰了这些酶，事情就会变糟。
Even just as we age naturally, the activity of cytochrome p450 enzymes seems to dip.
我们自然衰老的时候，细胞色素p450的酶活性似乎也在下降。
Slower drug metabolism can mean a normally fine painkiller,
缓慢的药物代谢意味着正常的止痛药，
like acetaminophen, may build up until it hits toxic levels.
如扑热息痛，可以累积到有毒水平。
This can lead to more damage, and eventually we're right back to hepatic encephalopathy.
这会导致更多的损伤，最终会导致肝性脑病。
Now some brain diseases are linked to toxic substances that some people intentionally put in their bodies,
现在一些脑部疾病与人们故意注入体内的有毒物质有关，
which their livers have to process, like ethanol from alcoholic drinks.
因此他们的肝脏需要处理它们，如酒精饮料中的乙醇等。
Basically, in the process of breaking down ethanol,
基本上，在乙醇分解的过程中，
the byproducts can cause tissue damage and trigger inflammation.
它的副产物可以引起组织损伤并引发炎症。
And if your liver keeps getting damaged, it won't be able to handle ethanol as well.
如果你的肝脏继续受损，就不能处理乙醇了。
It's a vicious cycle.
这是一个恶性循环。
It turns out that too much ethanol can affect your cells' ability to take up,
事实证明，过量乙醇会影响细胞从饮食中吸收、
store and use thiamine, also known as vitamin B1, from your diet.
存储以及使用硫胺素（维生素B1）的能力。
Some enzymes that depend on thiamine are a key part of glycolysis,
一些依赖硫胺素的酶是糖酵解的关键，
a process your body uses to break down glucose molecules and make energy.
糖酵解是指你的身体分解葡萄糖分子和制造能量的过程。
So a lack of thiamine can limit the amount of energy your body can get from food.
因此，缺乏硫胺素可能限制你的身体从食物中获得能量。
And since the brain is basically an energy-hungry monster, that is a recipe for disaster.
因为大脑基本上是一个能量饥渴的怪物，是灾难之源。
And it can lead to Korsakoff syndrome, one of the lesser-known diseases that affects memory.
它还会导致柯萨可夫综合症，一种不太为人所知的影响记忆的疾病。
Patients find themselves basically frozen in time, with retrograde and anterograde amnesia.
患者会感到时间冻结，有逆行性和顺行性遗忘。
So they can't recall large chunks of their past, or form new memories going forward.
所以他们不能回忆起大部分过去，也不能形成新的记忆。
Specifically, in patients' MRIs, we've seen shrinking in the medial thalamus,
具体来说，在病人的核磁共振成像中，我们看到他们的内侧丘脑、
mammillary bodies and nearby areas, which are all linked with memory.
乳头体及附近区域萎缩了，这些部位都与记忆有关。
With treatments aimed at getting thiamine and other nutrient levels back to normal,
利用让硫胺素和其他营养水平恢复正常的治疗，
many Korsakoff's patients can at least partly recover.
许多科萨科夫患者至少可以部分恢复。
But, basically, if you want to keep your brain in tip-top condition,
但是从根本上说，如果你想让自己的大脑保持最佳状态，
remember to take good care of the rest of you as well.
记住要好好照顾身体的其他部位。
And take special care of your liver, just a good ol'...wherever it is.
还要特别照顾你的肝脏，它是一个好的ol……无论是哪儿都要照顾好。
Thanks for watching this episode of SciShow Psych!
感谢您收看本期的心理科学秀！
If you want to keep learning about the human brain with us,
如果你想和我们继续学习人类大脑，
from questions about behavior to more deep dives into disease,
了解更多从行为问题到更深入疾病的内容，
you can go to youtube.com/scishowpsych to subscribe!
可以登录youtube.com/scishowpsych点击订阅！
