未登录,请登录后再发表信息
最新评论(0)
播放视频

这就是身体造血的机制

This Is How Your Body Makes New Blood

Say you’re feeling particularly kind one day,
假如有一天你心情不错
so you decide to make a donation to the local blood bank.
于是你决定去当地的血站献血
You come in, you fill out your paperwork,
你到了那里 填好表格
and you sit down for ten minutes
在你坐下来的十分钟里
while they take about a pint of blood out of your body.
他们从你身上抽走约一品脱的血
It’s all good though,
但这没什么
the boold is going to someone who really needs it.
你的血会留给真正需要它的人
Plus, they usually have free cookies of these things.
而且血站一般会在献血时提供免费饼干一类的东西
And while you’re noming on that little packet of treats,
而当你嚼着这些小饼干时
you can’t help but notice that
你肯定会留意到
there’s a lot of blood around you.
你身上有这么多血
Not in a creepy way,
先不说这是否可怕
but in a way that makes you wonder
但却让你不禁开始思考
If that just came out of me,
如果这些血从我身上抽出来
how is my body replenishing my own blood supply ?
那我的身体怎么补回抽出的血液呢
The fact that we can donate blood
我们之所以能够献血
is a really cool feature of our physiology,
是因为我们有一个超棒的生理学特征
in part because of how blood cells are made.
一部分来由是红细胞的产生方式
As I mentioned a few episodes ago,
前几期视频中我就提到过
red blood cell, or erythrocytes don’t have nucleus.
红细胞或红血球 它们没有细胞核
And without the genetic information inside of a nucleus,
也就没有核内的遗传物质
they have to come up with a different way
红细胞不得不用另一种方式
of making copies of themselves.
来进行自我复制
And then we have the task of cleaning and excreting all the old ones.
然后我们的身体负责清理并排出衰老的红细胞
The creation, maintenance, and filtration of blood
血液的制造 保存和过滤
is a unique process
有一个独特的过程
that’s different from other cells.
与其它细胞不同
Luckily, we’ve got some organs
还好 我们有专门的器官
and physiology up for the task.
和生理特征来完成这些工作
So what do I mean when I say that red blood cells
那我说 红细胞不能像其他细胞一样复制
don’t reproduce like normal cells?
到底是什么意思呢
Well, when our bodies want to create new skin or stomach cells,
当我们的身体要制造新的皮肤或胃细胞
old cells will duplicate their inner contents,
原细胞会复制细胞核内的物质
including their genetic information,
其中包括它们的遗传信息
and split into two new identical daughter cells.
然后分裂成两个相同的新子细胞
This is good old fashioned mitosis.
这就是经典的有丝分裂过程
But because red blood cells ditch their nuclei as mature cells,
但因为红细胞成熟时会失去细胞核
they can’t make direct copies of themselves.
所以它们无法直接自我复制
This means the body has to constantly manufacture and eject blood
这意味着身体必须一直制造输送新鲜血液
in order to keep the right number of cells in circulation
以保证血液循环中 稳定的红细胞数量
and function as a human.
并维持人体机能
It gets complicated,
这个过程很复杂
but too many red blood cells
但红细胞太多
can increase the thickness of blood to a dangerous amount,
会使血液粘稠度升高而产生危险
and too few red blood cells
而红细胞过少
and your tissues can’t get the oxygen they need.
会导致对组织供氧不足
To keep that balance,
为了保持这个平衡
we eliminate and restock our blood
身体以每秒生成几百万新红细胞的速度
with literally millions of new blood cells every second of our lives.
不断清理和补充血液
So yeah, the process is kind of important.
所以 这个过程相当重要
Our journey starts in the bone marrow,
红细胞的旅程从骨髓开始
the soft tissue inside of certain bones,
骨髓即为特定骨骼中的软组织
although similar processes are happening
不过淋巴结 脾 胸腺中
in the lymph nodes, spleen, and thymus as well.
也发生着类似的过程
That’s where we’ll find hematopoietic stem cells, or HSCs.
我们能在这些地方发现造血干细胞 或HSCs
These things are a cool type of cell
这种细胞可厉害了
that can become any of our blood cells —
它们可以变成我们的任何一种血细胞
red blood cell, leukocyte, or platelet-producing cell
红细胞 白细胞或者血小板生成细胞
it doesn’t matter, they all start as an HSC.
无论哪种 它们都来源于造血干细胞
It can also make copies of itself,
这种细胞还可以自我复制
which is awesome
这一点非常赞
because you never wanna run out of a cell that can become anything.
你能永远拥有这种可以任意分化的细胞
it’s just like getting a magic genie.
就像得到许愿精灵
The first thing you do is wish for more wishes.
第一个愿望就是可以许更多的愿望
it’s the exact same thing with stem cells,
这和干细胞一样
you make more stem cells
你先制造更多干细胞
from there, the HSCs are differentiating into
然后 这些干细胞又分化成
more specialized types of cells.
更多不同类型的细胞
At this point, the cell has a few different options:
到这一步 干细胞有几种分化选择
it can either become a common myeloid progenitor,
它可以变成普通的骨髓祖细胞
and have the option of turning into a platelet-producing cell,
也可以分化成一个血小板生成细胞
a red blood cell, or certain types of white blood cell.
一个红细胞 或者特定种类的白细胞
Or it can become a common lymphoid progenitor
或者发育成骨髓淋巴样祖细胞
where it can become a natural killer cell
然后变成一种自然杀伤细胞
or lymphocyte like a B or T cell.
或者淋巴细胞 比如B或是T细胞
These progenitor cells are kind of an in between step in cell differentiation.
这些祖细胞是细胞分化的一个中间步骤
They’re not full blown stem cells where
它们不像全能干细胞那样
they can become anything,
可以发育成任何细胞
but they still have options.
但它们还是有选择
kind of like in the wizarding world
有点像魔法世界里
when you turn eleven, say you get your letter to Hogwarts
你在11岁的时候被霍格沃茨录取了
Now you know you’re not going to Ilvermorny or Beauxbatons,
现在你不能去伊法魔尼或布斯巴顿了
but you still need to get sorted into your house.
但你仍然会被划分到不同的学院
That’s what it’s like to be a progenitor cell.
祖细胞就是这种情况
The future identity of the cell is starting to take shape
然后开始分化成其他细胞类型
And depending on what kind of chemical environment the cell is exposed to
而祖细胞所处的化学环境
will determine what type of cell these multipotent cells become.
决定了它们最终会变成哪一种细胞
Take the red blood cell for example.
以红细胞为例
A common myeloid progenitor has a few options in front of it.
一个普通的骨髓祖细胞有几个选择
Not infinite options, but it still has options.
不是无限的选择 但依然有选择
It can become a myeloblast
骨髓祖细胞能发育为成髓细胞
and turn into a number of white blood cells,
然后变为许多白细胞
or turn into megakaryoblast and produce platelets.
或者变成原巨核细胞并制造血小板
Also megakaryoblast is the coolest cell name of all time.
原巨核细胞是有史以来最酷的细胞名字
I stand behind this claim a thousand percent —
我1000%坚持我的观点
if you have any challengers for that title,
如果有人不同意
tell me in the comments.
留言告诉我
But I’m letting you know ahead of time. you are wrong.
但我要提前告诉你 你错了
Now, the progenitor could turn into a proerythroblast.
祖细胞可以变成原红细胞
The Erthryo- part tells us that it’s a red blood cell,
其中“红”表示它是红色血细胞
and -blast tells us that it’s a cell that creates a certain cell type.
“原”表示它可以制造特定类型的细胞
You can see more examples of that in the hematopoietic family tree.
在造血细胞家族中 你可以找到更多例子
A lymphoblast turns into a lymphocyte
淋巴母细胞能变成淋巴细胞
and a monoblast turns into a monocyte
而原单核细胞能变成单核细胞
At this point, the erythrocyte-in-the-making still has a nucleus,
这时 分化过程中的细胞仍然有细胞核
albeit, one that’s condensing over time.
尽管这个核正渐渐缩小
From there, it keeps condensing down and loses its nucleus
此后 它不断地缩小 直到最终失去细胞核
to become a reticulocyte,
从而成为网状细胞
and after ditching even more of its contents
然后 它丢掉细胞内甚至更多的结构
and slipping into the bloodstream
并汇入血流之中
becomes mature red blood cells.
这便是成熟的红细胞了
This process of going from proerythroblast to mature erythrocyte
原红细胞变成成熟红细胞的过程
takes up to 5 days
最多需要5天
although your body can speed it up
不过 如果机体需要更多红细胞
if it needs more of them.
身体可以加速这个过程
A few different factors can bump up the production rate,
有几个因素会影响红细胞生产速度
like a lack of oxygen for example.
比如缺氧
And if your tissues detect that your blood is running low on oxygen,
如果你的组织察觉血液含氧量在降低
your kidneys will crank out a hormone
你的肾脏会分泌一种激素
called erythropoietin, or EPO,
叫促红细胞生成素或EPO
which tells the bone marrow to get busy making red blood cells.
它促使骨髓去生产红细胞
Then as the kidneys detect that oxygen levels are back to normal,
然后 当肾脏感觉含氧量回到正常水平时
they’ll back off the EPO production
就会停止分泌EPO
which brings our bodies back to homeostasis.
使机体回到稳态
If you’ve ever traveled somewhere at a high altitude,
如果你曾去过高海拔地方旅游
your body needs to get used to the new oxygen situation
你的身体需要适应新的氧环境
and can adjust EPO accordingly.
并据此调节EPO的分泌
Likewise, other events like infection
另外 如感染等其他因素
will trigger your body to make more white blood cells,
会促使机体产生更多的白细胞
and bleeding will trigger the creation of more platelets to plug up that new cut.
而流血将促使更多血小板产生 以堵塞伤口
So at this point,
这个时候
you’ve got a certain amount of red blood cells floating through circulation.
你的血液中含有一定量的红细胞
They’ll live their lives for about a hundred and twenty days
它们在被清理和替换之前
before being cleaned out and replaced.
有大约120天的寿命
Now, this process is different from when you’re making your very first blood cells
这个过程和你在子宫中
when you’re still in the womb.
开始自主造血的过程不同
After all, you have to make your very first stem cells
毕竟 你必须在细胞开始分化之前
before they can start differentiating.
制造自己的干细胞
Unfortunately, we know much less about the embryonic version
不幸的是 相对于成年时期
than we know about the adult version.
我们对胚胎时期的认识还太少
And as an adult, since you’re constantly making new blood cells,
作为成年人 从你完全开始制造新血细胞
you’ve also got to get rid of old cells
同时你也要清理衰老细胞
to maintain a consistent blood volume and thickness.
去维持一定的血量和血粘度
That’s where a few important organs come in,
这一过程需要一些重要器官的参与
namely the liver and the spleen.
分别是肝脏和脾脏
For such a useful,
对于一个有用的
and you know what, I’ll say it, underrated organ,
被小看的器官
the spleen itself is pretty tiny.
脾脏本身非常小
It’s about the size of an old Gameboy Color
大概是旧版任天堂游戏机的大小
and only weighs on average up to 200 grams.
平均仅重200克
Although scientists would never shame a spleen for its small stature.
然而 科学家不会因为它小而忽略它
In fact, an enlarged spleen,
实际上 脾脏的肿大
a condition called splenomegaly,
称为脾肿大症状
is a sign that something bad is happening.
这是机体正发生不良反应的信号
It can happen when someone has liver disease,
患有肝脏疾病的人
or other chronic illnesses,
或患有其它慢性疾病
like the classic virus mononucleosis, or mono.
如患有传统单核细胞增多症的人 就有这种症状
But when it’s healthy,
但在健康状态下
the spleen works as a lymphatic and immune center
脾脏是淋巴和免疫中心
while also picking off old red blood cells
同时会筛选出衰老红细胞
and preparing them for excretion.
并准备产生新的红细胞
And if you were to slice it open,
如果你切开它
you’d find two main units, red pulp and white pulp.
你会发现两部分 红浆和白浆
Yep! The same colors as our blood cells.
是的 和我们的血细胞颜色一样
And lucky for you,
巧合的是
the colors roughly match up with the cell type.
这些颜色和血细胞类型匹配
The white pulp is built around a central blood vessel
白浆包裹着中央血管构造
and stacks a bunch of B cells and T cells
白浆中储存着一些B细胞和T细胞
so it can be ready to pump those cells into the bloodstream
因此 在免疫应答过程中
during an immune response.
白浆能将细胞泵入血液中
All in all, about a quarter of all the body’s lymphocytes live in the spleen
总之 全身淋巴细胞约有四分之一驻于脾脏
and at most, about a cup of blood.
最多为约一杯的血液
And that blood is found in the other segments of the spleen known as red pulp,
这些血液在脾脏内流动的部分叫红浆
which is where the heavy duty blood filtration happens.
这里是血液过滤工作量最大的地方
When blood first comes into the spleen,
当原血流入脾脏
it fills into empty space that surrounds the white pulp,
会填满白浆周围的空白
eventually, collecting into little empty pockets within the red pulp.
最终 会被收集到红浆的空腔中
In particular,
实际上
all red blood cells have to pass through the narrow splenic cords,
所有的红细胞必须通过狭窄的脾索
also known as the Cords of Billroth.
也称红髓索
Sounds a DnD character.
听起来像是龙与地下城里的人物似的
And remember how red blood cells are ridiculously tiny?
还记得红细胞有多小吗
Only six thousands of a millimeter across?
仅有六千毫米
Well, in order to pass through those splenic cords
红细胞为了能通过脾索
and stay in circulation,
并在血液中循环流动
they have to contort themselves into an even smaller shape.
它们必须扭曲成更小的形状
When they’re young and flexible,
当红细胞还很新鲜 灵活时
red blood cells slip through without any trouble.
它们可以毫不费力地通过
But as they get older,
但当红细胞越来越老
they also get bigger and stiffer,
它们会变得越来越大 越来越硬
so they get trapped at this step,
因此 它们就卡在了这一步
which is when they start the process of getting recycled.
这时就进入循环利用的过程了
The hemoglobin in those old red blood cells
那些衰老红细胞的血红蛋白
is still a valuable resource for future cell material.
是生成新红细胞的重要的来源
So immune cells in the red pulp
因此 红浆中的免疫细胞
recycle the hemoglobin’s iron molecules
循环利用血红蛋白的铁原子
and either store them in the liver or spleen,
要么将铁原子储存在肝脏或脾脏中
or send them back to the bone marrow
要么将原子送回骨髓
to make more hemoglobin for new red blood cells.
为新红细胞制造更多的血红蛋白
And all those globin proteins get broken down into smaller amino acids
所有这些球蛋白被分解成小的氨基酸
and recycled for new red blood cells as well.
也在制造新红细胞中被循环利用
Meanwhile, all the non useful material from those dead cells
同时 这些死细胞里没用的物质
gets transformed into bile and then ends up in your poop.
会转化成胆汁 然后随粪便排出
Now clearly, there’s more in your blood
显然 在你的血液中还有更多
that your body might want to clean out
机体可能想要清除的物质
than just blood cells.
不仅仅只是血细胞
When people are looking to “detox”,
当人们想到“排毒”时
they’re probably thinking about this part.
也许指的就是这些要清除的物质
That’s what we have a liver and kidney for.
所以我们才有肝脏和肾脏
Well, hopefully two kidneys.
但愿能有两个肝脏吧
But, you don’t need to buy a charcoal drink
但是 你不用买碳酸饮料
or a special juice or eat anything special.
或果汁 或吃任何特殊的东西
your body’s built to clean its own blood.
你的身体会自己清理血液
Thanks for watching this episode of Seeker Human.
感谢观看本期《探索新闻台》
I’m Patrick Kelly.
我是Patrick Kelly

发表评论

译制信息
视频概述

讲解血细胞生产的过程、储存位置及与之相关的器官

听录译者

收集自网络

翻译译者

YXG-90743

审核员

审核员LG

视频来源

https://www.youtube.com/watch?v=8cCgBp8DAb8

相关推荐