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Say you're at the beach, and you get sand in your eyes.
How do you know the sand is there?
You obviously can't see it, but if you are a normal, healthy human,
you can feel it,
that sensation of extreme discomfort, also known as pain.
Now pain makes you do something,
in this case, rinse your eyes until the sand is gone.
And how do you know the sand is gone? Exactly. Because there's no more pain.
There are people who don't feel pain.
Now, that might sound cool, but it's not.
If you can't feel pain, you could get hurt, or even hurt yourself
and never know it.
Pain is your body's early warning system.
It protects you from the world around you, and from yourself.
As we grow, we install pain detectors in most areas of our body.
These detectors are specialized nerve cells
called nociceptors.
that stretch from your spinal cord to your skin, your muscles, your joints,
your teeth and some of your internal organs.
Just like all nerve cells, they conduct electrical signals,
sending information from wherever they're located back to your brain.
But, unlike other nerve cells,
nociceptors only fire if something happens that could cause or is causing damage.
So, gently touch the tip of a needle.
You'll feel the metal, and those are your regular nerve cells.
But you won't feel any pain.
Now, the harder you push against the needle,
the closer you get to the nociceptor threshold.
Push hard enough, and you'll cross that threshold
and the nociceptors fire, telling your body to stop doing whatever you're doing.
But the pain threshold isn't set in stone.
Certain chemicals can tune nociceptors,
lowering their threshold for pain.
And when cells are damaged, they and other nearby cells
start producing these tuning chemicals like crazy,
lowering the nociceptors' threshold to the point where just touch can cause pain.
And this is where over-the-counter painkillers come in.
Aspirin and ibuprofen
block production of one class of these tuning chemicals,
called prostaglandins.
Let's take a look at how they do that.
When cells are damaged, they release a chemical called arachidonic acid.
Now, two enzymes called COX-1 and COX-2
convert this arachidonic acid into prostaglandin H2,
which is then converted into a bunch of other chemicals that do a bunch of things,
including raise your body temperature, cause inflammation
and lower the pain threshold.
Now, all enzymes have an active side.
That's the place in the enzyme where the reaction happens.
The active sites of COX-1 and COX-2
fit arachidonic acid very cozily.
As you can see, there is no room to spare.
Now, it's in this active site that aspirin and ibuprofen do their work.
So, they work differently -- aspirin acts like a spine from a porcupine.
It enters the active site and then breaks off,
leaving half of itself in there,
totally blocking that channel and making it impossible for the arachidonic acid to fit.
This permanently deactivates COX-1 and COX-2.
Ibuprofen, on the other hand,
enters the active site, but doesn't break apart or change the enzyme.
COX-1 and COX-2 are free to spit it out again,
but for the time that ibuprofen is in there,
the enzyme can't bind arachidonic acid,
and can't do its normal chemistry.
But how do aspirin and ibuprofen know where the pain is?
Well, they don't.
Once the drugs are in your bloodstream,
they are carried throughout your body,
and they go to painful areas just the same as normal ones.
So that's how aspirin and ibuprofen work.
But there are other dimensions to pain.
Neuropathic pain, for example,
is pain caused by damage to our nervous system itself;
there doesn't need to be any sort of outside stimulus.
And scientists are discovering that the brain controls how we respond to pain signals.
For example, how much pain you feel can depend on
whether you're paying attention to the pain, or even your mood.
Pain is an area of active research.
If we can understand it better, maybe we can help people manage it better.
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【TED-Ed】止痛藥如何發揮作用?How do pain relievers work? - George Zaidan (How do pain relievers work? - George Zaidan)

37238 分類 收藏
Ashley Chen 發佈於 2018 年 3 月 25 日

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疼痛是身體的預警系統,會感到痛其實對人體有益,讓我們能夠提防危險,來看看疼痛的生理機制吧!

1rinse0:30
rinse 的意思為「沖洗」,而在飯店常見的 rinse 則是「潤髮乳」,台灣直翻「潤絲」,跟 conditioner 一樣都是用來保養頭髮。
Rinse your fruits and veggies with baking soda. Make sure you rinse them well.
用小蘇打來清洗水果和蔬菜,要確保你洗得很乾凈。


*同場加映:
正妹的日常肌膚保養 My Skincare Routine


2threshold1:32
threshold 的意思為「門檻」,可以用來表示實際 bedroom threshold「房間門檻」,亦可表達較抽象的界線,例如 tax threshold 「稅金門檻」,賺多少錢以上就必須繳稅。
Once your income passes a certain threshold, you have to start paying taxes.
一旦你的收入超過一定門檻,你必須開始繳稅。


3over-the-counter1:59
over-the-counter 在醫學上的意思是「非處方」,又簡稱 OTC,因此 over-the-counter medicine 即為「非處方藥」,也就是一般說的「成藥」,不需要醫生證明即可在藥局購買服用。
Stop taking over-the-counter medicine and go see a doctor!
不要再吃成藥了,去看醫生吧!


4inflammation2:26
inflammation 的意思為「發炎」、「炎症」,例如受傷時紅腫就是發炎的一種,另外 acute inflammation 是表示「急性發炎」,而 acute 這個字本身就有「急性」的含義。
Aspirin helps reduce inflammation while antibiotics help cure infections.
阿斯匹靈幫助減緩發炎症狀,而抗生素能治療感染。


5spare2:42
spare 有眾多解釋,比較常見的作為動詞「分讓」以及「省去」,例如 I spared you some tea 我幫你留了一些茶,另外作為形容詞「多餘的」、還有名詞「備用」。
Oh I forgot to bring pen! Do you have a spare?
噢我忘記帶筆了,你有多的嗎?


*同場加映:
不想跟陌生人講話時的私藏大絕招! How To Avoid Talking To People You Don't Want To Talk To


原來阿斯匹靈跟布洛芬減緩疼痛的作用原理不一樣呢!長知識了!

文/ Carol Chen

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