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At some point, you've probably heard of someone who supposedly "died of old age."
你可能听说过有人“老死”。
Usually, that just means they died of complications related to getting older,
通常这指的是他们死于衰老的并发症，
or from something a younger person might have survived, like pneumonia.
或者是死于肺炎等年轻人易于幸存的疾病。
Because, even though age can contribute to someone's death, it almost definitely won't be the direct cause.
因为，虽然老化会触发死亡，但大部分情况下，这绝不是导致死亡的直接原因。
The cells in our bodies do have a set lifespan -- or a point at which they quit dividing
我们体内的细胞确实有设定的生命周期-或者是细胞停止分裂的某个零界点
but you'll never find that written on a death certificate.
但你绝不会在死亡证明中找到这个。
It's called cellular senescence,
这被称为细胞衰老，
and scientists think it's mostly because of little structures on the end of your chromosomes called telomeres.
科学家认为这主要是因为你的染色体末端，即染色体终端上的小结构。
Telomeres are stretches of repeating nucleotides, the compounds that make up DNA.
染色体终端是核酸重复组成的延伸，核酸重复组成是形成DNA的化合物。
And they act as caps to protect the genetic material in your chromosomes during cellular reproduction.
它们充当盖子的角色，在细胞繁殖过程中保护染色体中的遗传物质。
Each time a cell divides, those telomeres get a little shorter, thanks to the mechanics of how chromosomes are copied.
每当一个细胞分裂时，这些染色体终端就会变短，这多亏了染色体复制的机制。
And when they get short enough, senescence sets in, and the cell can't duplicate itself anymore.
当它们足够短时，衰老就到来了，而细胞就再也无法自我复制了。
But other factors also contribute to cell aging.
但其他因素也会促进细胞衰老。
One is oxidative stress, or damage done to your DNA by highly reactive molecules that contain oxygen.
一个是氧化应激，即含氧的高度反应分子对你的DNA所造成的损害。
Another is glycation, which is when sugar molecules bind to key parts of your cells and prevent them from functioning.
另一个是糖化，即糖分子附在你的细胞的主要部位并阻止它们的运转。
Unfortunately, all of these things are pretty much inevitable over time.
不幸的是，随着时间流逝，所有这些都是不可避免的。
You can take some actions to combat them like,
你可以采取些行动来对抗他们，比如
you might've heard how antioxidants in certain foods can fight the effects of oxidation but you can't stop them completely.
你可能听过，一些含抗氧化剂的食物能够对抗氧化作用，但却不能完全阻止它们。
Scientists aren't sure how old you'd have to be before your cells just couldn't duplicate anymore,
科学家们并不确定，当细胞无法复制时，你会是多少岁，
but that's because age-related diseases and injuries will catch up with someone
但这是因为年龄相关的疾病和伤害会赶在人类
long before they can die directly of cellular senescence.
直接死于细胞衰老之前。
As someone gets older and damage from all these sources pile up,
年龄流逝，各方面损伤累积，
their cells are more likely to have problems working correctly and fixing themselves when something goes wrong.
出错时，细胞无法正常工作也无法正常修复。
That means their immune system gets weaker, and they become more susceptible to all kinds of injuries and diseases,
这意味着免疫系统变得脆弱，更易于受到各种损伤和疾病的影响，
like heart and blood pressure problems, and Alzheimer's.
比如，心脏病、高血压和阿兹海默氏症。
When these diseases appear, they can affect someone's ability to get around and take care of themselves,
当出现这些疾病时，疾病会影响人们对抗疾病和自我照顾的能力，
and can also cause problems in their organ systems.
这也可能造成器官系统问题。
And those will be the direct causes of death, even though age may be a contributing factor.
这些都有可能是造成死亡的直接原因，虽然年纪或许是影响因素之一。
Thanks to Patreon patron Tommy Boyer for asking,
感谢Patreon观众Tommy Boyer的提问，
and thanks to all of our patrons who voted on our poll to help us choose this question to be answered.
谢谢所有投票的观众，谢谢你们帮助我们选择需要回答的问题。
If you'd like to submit your questions and help SciShow keep existing, go to patron.com/scishow.
如果你想要提问并帮助科学秀，请登录patron.com/scishow
