你的大腦喝了咖啡後會怎樣：英語精讀講義

With its stimulating effects, 文法

由於它具有提神效果，

it's easy to understand why coffee is the second most traded commodity 文法

不難理解為什麼咖啡是全球交易量第二大的商品，

on Earth after oil.

僅次於石油。

For many,

對許多人來說，

it keeps us awake 文法

它能讓我們保持清醒，

and moving through our busy days.

撐過忙碌的每一天。

But how does it work?

但它究竟如何發揮作用？

What exactly does coffee do to your brain?

咖啡到底會對你的大腦做些什麼？

Whenever you're awake,

每當你醒著時，

a chemical called adenosine 文法

一種叫做腺苷的化學物質

slowly accumulates in your brain.

會在大腦中慢慢累積。

And this adenosine binds to receptors,

腺苷會與受體結合，

which slow down brain activity.

使大腦活動減緩。

Ultimately, the more adenosine there is, 文法

到頭來，腺苷越多，

the more tired your brain feels,

你的大腦就越覺得疲倦。

which makes sense as the longer you're awake,

這很合理，因為你醒著的時間越長，

the more fatigued you become.

就會變得越疲憊。

Conversely, while you sleep,

相反地，在你睡覺時，

the concentration of adenosine declines,

腺苷的濃度會下降，

gradually promoting wakefulness.

讓你逐漸恢復清醒。

But it turns out that the caffeine in your coffee 片語搭配

但原來，咖啡中的咖啡因

is incredibly similar to adenosine in structure. 片語搭配

在結構上和腺苷非常相似。

The caffeine works its way through your bloodstream 慣用語

咖啡因會隨著血液循環

and into your brain,

進入你的大腦，

where it starts to compete

並在那裡開始競爭，

and binds with the adenosine receptors.

與腺苷受體結合。

But because it's not adenosine,

但因為它不是腺苷，

the sleepiness effect isn't felt.

所以不會產生睡意。

Adenosine can no longer bind,

腺苷再也無法與受體結合，

meaning its calming properties are diminished, 文法

也就是說，它的鎮靜作用會減弱，

which is great for you when you're feeling tired.

這對疲倦時的你來說可是好事。

However, with long-term use of caffeine,

不過，長期攝取咖啡因後，

your brain responds by creating more adenosine receptors,

你的大腦會製造更多腺苷受體來因應，

which means more caffeine is required

也就是需要更多咖啡因，

to elicit the same response. 片語搭配

才能產生相同的反應。

It also means that when you try to quit drinking coffee 文法

這也代表，當你想戒掉咖啡

or miss your daily intake,

或漏掉每天那一杯時，

you might experience some withdrawal symptoms 用詞

你可能會出現一些戒斷症狀，

and feel more tired than you would have 文法

而且會覺得自己比

before you ever drank coffee.

從沒喝過咖啡時更疲倦。

But the caffeine doesn't stop there. 慣用語

但咖啡因的作用還不只如此。

It also stimulates the production of adrenaline,

它還會刺激腎上腺素的分泌，

you know, the fight or flight hormone. 用詞

就是那種引發「戰鬥或逃跑」反應的荷爾蒙。

This increases your heart rate,

這會讓你的心跳加快，

gets your blood pumping, 慣用語

促進血液循環，

and even opens up your airways. 片語動詞

甚至使呼吸道擴張。

Furthermore, it affects dopamine levels

此外，它也會影響多巴胺濃度，

by preventing its reabsorption in the brain,

阻止大腦重新吸收多巴胺，

which makes you feel happy.

讓你感到愉快。

In fact, this is the exact same thing

事實上，這正是

that cocaine does,

古柯鹼所做的事，

just to a lesser degree. 片語搭配

只不過程度輕一些。

It's a drug after all. 表達脈絡

畢竟，它也是一種藥物。

This dopamine stimulation

這種對多巴胺的刺激

is also the aspect of coffee

也正是咖啡

that makes it moderately addictive.

具有一定成癮性的原因。

So, can you drink too much coffee?

那麼，咖啡會不會喝太多呢？

It turns out there is a lethal dose of caffeine, 用詞

原來，咖啡因確實有致死劑量，

which is somewhere around 150 mg

大約是每公斤體重

of caffeine per kilogram of your body.

攝取150毫克咖啡因。

This means if you weigh 70 kg, 文法

也就是說，如果你重70公斤，

you would require 14,000 mg of caffeine

就要攝取14,000毫克咖啡因

to overdose.

才會過量中毒。

Put into perspective, 表達脈絡

換個方式來看，

an average cup of coffee

平均一杯咖啡

contains roughly 150 mg of caffeine,

大約含有150毫克咖啡因，

meaning if you're 70 kg,

也就是說，如果你重70公斤，

approximately 70 cups of coffee

大約70杯咖啡

would kill you.

就能要你的命。

However, you would have to drink those cups

不過，你必須把這些咖啡

all at once,

一次全部喝下，

making it effectively impossible 文法

因此實際上，

to overdose on caffeine from coffee,

幾乎不可能因喝咖啡而攝取過量咖啡因，

since you wouldn't be able to physically fit

因為你的胃根本不可能裝得下

that much in your stomach.

那麼多咖啡。

You would also start experiencing

你還會開始出現

mania and hallucinations

躁狂與幻覺，

before getting to this point.

而且是在達到這個程度之前。

Caffeine also has a half-life 用詞

咖啡因的半衰期

of around 6 hours,

也大約是6小時，

so if you drank a standard coffee

所以，如果你喝了一杯普通咖啡，

with around 150 mg of caffeine,

其中約含150毫克咖啡因，

after about 6 hours,

那麼大約6小時後，

there'll only be 75 mg left in your system

你體內就只會剩下75毫克，

and you'll be feeling half of the effect.

感受到的效果也會減半。

And 6 hours after that,

再過6小時，

you'll have 37.5 mg,

就只剩37.5毫克，

leaving more room for adenosine 片語搭配

讓腺苷有更多空間

to jump back into action, 慣用語

重新發揮作用。

which is why you may reach for another cup 片語搭配

這就是為什麼你可能會在

throughout the day

一天中再喝一杯咖啡，

to maintain that glorious alert

好維持那種美妙的清醒

and energetic feeling.

與精力充沛的感覺。

So, drink up and enjoy the buzz 用詞

所以，儘管喝吧，好好享受這股興奮感，

while it lasts. 片語搭配

趁它還沒消退。

And for all of you in school,

至於所有還在上學的同學，

while we know caffeine is key, 文法

我們知道咖啡因很重要，

so are good deals on textbooks.

教科書的優惠價格也一樣重要。

So, we've teamed up with slugbooks.com 片語動詞

因此，我們與slugbooks.com合作，

to get you the cheapest prices

幫你用最低的價格

for the books you need.

買到需要的書。

All you have to do is head to 文法

你只要前往

slugbooks.com/asapscience

slugbooks.com/asapscience，

and search the ISBN number

再搜尋ISBN編號，

of the books you're looking for.

也就是你正在找的書籍編號。

SlugBooks will then compare prices

接著，SlugBooks會比較

from all across the net.

全網各處的價格。

Seriously, we know how expensive 文法

說真的，我們知道

textbooks can be,

教科書有多昂貴，

so hopefully this will save you some money.

希望這能替你省下一些錢。

Got a burning question you want answered? 講解

有什麼迫切想知道答案的問題嗎？

Ask it in the comments

在留言區提出來，

or on Facebook and Twitter.

或到Facebook和Twitter上問我們。

And subscribe for more weekly science videos.

記得訂閱，每週觀看更多科學影片。