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为什么河獭的心脏有骨头

Why River Otters Have Bones… In Their Hearts

At first glance,
乍一看
river otters’ hearts don’t look too different from ours.
河獭的心脏和我们的没什么不同
But if you look at enough of them, especially older ones,
但是如果你看得足够多 尤其是年龄较大的
you might find patches of bone
你可能会在一些心脏内壁
around some of the internal walls of the heart
和主要的心脏瓣膜周围
and around the major heart valves.
发现一块块的骨头
It’s a structure called the os cordis.
这是一个叫做os cordis的结构
Os for bone, and cordis for heart.
Os代表骨头 cordis代表心脏
Literally the heart bone.
也就是心脏骨
Now river otters aren’t the only creatures to grow brone tissue in their hearts.
河獭并不是唯一心脏中长有骨组织的动物
But their aquatic lifestyle can help us understand why they do.
但是它们水生的生活方式可以帮助我们理解它们为什么会如此
And it seems like a healthy response to stress.
这似乎是对压力的健康反应
So first of all, why would hearts need bones?
首先 为什么心脏会需要骨头
Our human hearts actually do have a structure called the cardiac skeleton.
人类的心脏实际上有一个叫做心脏骨架的结构
But despite its name,
虽然叫做骨架
It’s made of tough connective tissue,including cartilage,
但它是由结实的结缔组织组成的 包括软骨
not actual bone.
而不是真正的骨头
Its job is to help anchor certain soft parts of the heart together,
它的作用是帮助固定心脏的某些柔软部分
like the valves between the upper and lower chambers.
像心脏上下腔之间的瓣膜
Plus, it helps keep the heart’s electrical signals
此外 它还有助于保持心电信号
flowing in the right direction.
沿着正确的方向流动
And it’s a good thing that it’s made of cartilage
它由软骨组成 这是件好事
since we want our cardiac skeletons
因为我们希望我们的心脏骨架
to be at least a little soft and forgiving.
至少有一点韧性和承受能力
When we do see calsium deposits, which are precursed bone,
当我们在心脏骨骼中看到钙沉积
show up in our cardiac skeletons,
这是预先坏死的骨头
those otherwise soft structures turn stiff.
那些原本柔软的结构会变僵硬
So bone in our hearts is considered a sign of heart disease.
所以我们的心脏骨骼被认为是心脏病的征兆
And the same thing may be true for other primates.
其他灵长类动物可能也是如此
A study published in 2020 showed that
2020年发表的一项研究表明
chimpanzees developed os cordis alongside certain heart disease,
黑猩猩在患上心脏病的同时也长出了心脏骨
which made the researchers think that
这让研究人员认为
the bone might be a sign of chronic heart stress.
这块骨头可能是慢性心脏压力的迹象
But what’s dangerous in our hearts is the feature for other animals.
我们心脏的骨骼是危险的 但其他动物则未必
Over the twentieth century,
在二十世纪
we’ve learned that certain animals especially ruminants like sheep and goats
我们已经了解到某些动物 特别是反刍动物 如绵羊和山羊
may have some bone tissue here and there throughout their cardiac skeletons.
它们的心脏骨骼中可能到处都有一些骨组织
In the year 2000, researchers publishing in the Journal of Anatomy found that
2000年 研究人员在《解剖学杂志》上发表文章称
otters often had heart bones as well,
河獭通常也有心脏骨
especially older individuals.
尤其是年龄大的
They think that over the otters’ lives,
他们认为 在水獭的一生中
bony tissues would begin to develop in the cartilaginous parts of their hearts,
由于一种叫做软骨骨化的过程
thanks to a process called endochondral ossification.
骨组织会在它们心脏的软骨部分开始发育
That’s the formation of bony tissues out of cartilage.
这是由软骨形成的骨组织
It happens in humans as our bones are forming in the womb,
当骨头在子宫里形成 或者骨折被修复时
but also when broken bones are repaired.
我们人类也会出现这样的情况
See, as far connective tissue goes, cartilage is a pretty tough material.
看 就结缔组织而言 软骨是一个很坚硬的东西
But if the body finds itself constantly under physical stressors strain,
但是如果身体发现自己一直处于压力之下
it can reinforce itself further.
它可以进一步加强自己
If the area in question already has some cartilage,
如果有问题的区域已经有一些软骨
it would add more cartilage on top of that.
它会在上面增加更多的软骨
If that doesn’t do the trick,
如果这样还不行
it can add a bone.
它就会增加一块骨头
And this process happens in pretty much
这一过程几乎发生在任何一种
any skeleton-having animal you’d care to name,
你说得出名字的有骨骼的动物身上
from cows to hamsters.
从奶牛到仓鼠
But as to why this would happen,
但至于这个为什么会发生
it usually comes back to reducing physical stress.
它通常可以归结为减轻身体压力
So what does reducing stress do for the otters?
那么减轻压力对河獭有什么作用呢?
Scientists still aren’t totally sure, but they have some ideas.
科学家们还不能完全确定 但是他们有一些想法
For starters, river otters have huge hearts compared to their body size.
首先 与体型相比 河獭的心脏很大
Our human hearts are around six ten
我们人类的心脏大约占
ths of a percent of our body weight.
我们体重的百分之六十
While most aquatic mammals’ hearts
而大多数水生动物的心脏
are closer to nine tenths of a percent.
占体重的近0.9%
And river otter hearts in particular
尤其是河獭的心脏
are on the upper end of that,
占比是其中最高的
coming in at nearly a full percent of their body weight.
心脏几乎占它们体重的百分之一
And they need those big hearts
它们需要大的心脏
since they are constantly swimming and swimming fast.
因为它们一直在游 而且游得很快
If you have ever been to a zoo that has these little guys,
如果你去过有河獭的动物园
you know what impressive athletes they are.
你就会知道它们是多么令人印象深刻的运动员了
Not only are they always moving,
它们不仅一直在动
but they are doing it in fresh water,
而且是在淡水中移动
which is less buoyant and supportive than salty ocean water.
淡水的浮力和支持性都不如咸的海水
Not coincidentally, river otters have bigger hearts than their salt water counterparts.
并非巧合的是 河獭的心脏比它们在咸水中的同类更大
Now some scientists think that the increased stress from their high-performance hearts
一些科学家认为 由于提高供能而增加的压力
gets distributed across the fibrous parts of the cardiac skeleton.
分布在心脏骨架的纤维部分
Heart muscle cells anchor into this structure.
心肌细胞固定在这个结构中
So stiff bone might provide them more support.
所以坚硬的骨头可能会提供更多的支撑
Plus their hearts are more cone shaped than ours,
另外 它们的心脏比我们的更像圆锥形
which contributes to more stress in the exact area that they have heart bones.
这就增加了它们心脏骨骼的额外区域的压力
That leaves us with the question though.
这给我们留下一个问题
Is this just the side effect of aging when you are an otter,
对河獭来说 这仅仅是衰老的副作用
or is it a benefitial adaptation to swimming?
还是对游泳有益的适应?
Calcium deposits show up in the heart cartilage alongside healthy, living cartilage cells,
钙沉积在心脏软骨和健康的 鲜活的软骨细胞一起出现
which makes it seem like this ossification is a healthy process of reinforcing that tissue,
这使得软骨化似乎是一种加强组织的健康过程
not a sign that things are breaking down.
而不是物质正在分解的迹象
But the placement of the bits of bone is somewhat random,
但是骨头的位置是随机的
They’re not consistently found on the same side, for instance,
比如 它们并不总是在同一边
which means scientists haven’t found a brand new bone
也就是说 科学家们还没有找到
that all otters will always have in the future.
所有河獭在未来都会有的全新骨骼
Instead they are more common in older otters,
相反 它们在年老的河獭身上更长见
which suggests that they grow in response to stress over time.
这表明 随着时间的推移 河獭会对压力做出反应
But regardless of exactly why river otters develop these bony hearts,
但是不管河獭为何会长出这些骨质心脏
it shows us how the body isn’t a static thing.
它都向我们展示了身体并不是静止的
It’s constantly adapting to the stresses placed on it,
身体会不断地适应施加在它身上的压力
to the point where entirely new anatomy might emerge.
到一定程度时 可能会出现全新的骨骼
Thanks for watching this episode of SciShow
感谢收看本期科学秀
and thank you to our patrons for your patronage.
感谢赞助人对我们的赞助
In addition to helping us make great videos,
除了帮助我们制作精彩的视频
patrons get acess to various perks like Bluebers and our patron-only discord.
赞助人还可以获得各种特权 比如Bluebers和我们的顾客专属折扣
If that sounds like fun to you, you can check out patreon.com/scishow.
如果你感兴趣的话 可以访问patron.com/scishow

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视频概述

河濑心脏的骨头是它身体对压力的反应,从而告诉我们身体并非静止的,它会在适应中发生改变。

听录译者

牧神PAN

翻译译者

Song

审核员

审核员DY

视频来源

https://www.youtube.com/watch?v=MBQCfjQuIV4

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