中級 3384 タグ追加 保存
動画の字幕をクリックしてすぐ単語の意味を調べられます!
単語帳読み込み中…
字幕の修正報告
Caffeine a legal stimulant that most of us are pretty familiar with, many of us use every day,
and some of us are addicted to. If you are a caffeine user, you probably know your limits.
For me one small cup of coffee in the morning can help keep me alert and focused, whereas
two small cups of coffee in the morning can turn me into a cat on catnip.
Well for the purposes of this video and to best demonstrate the physical and mental effects of caffeine,
I'm going to get
very very caffeinated very very fast.
For science.
Go big or go home.
Caffeine is a stimulant drug that acts on your central nervous system.
Because caffeine is both lipid and water soluble
it can easily pass through the blood-brain barrier and act on the interior of your brain
Once there, caffeine works by diminishing the effect of a neurotransmitter called adenosine.
Adenosine acts as a suppressor for your nervous system,
reducing neural activity and slowing everything down.
Caffeine and adenosine have similar shapes so caffeine can bind to
the same neuroreceptors that adenosine does.
But because caffeine is not adenosine, it doesn't turn these neuroreceptors on.
This is called competitive inhibition.
Caffeine competes with adenosine to bind with the same receptors,
And because caffeine is bound, adenosine cannot bind and its effects are inhibited.
Long story short,
caffeine prevents adenosine from slowing down your nervous system.
So this explain part of why you feel more awake, alert and active with caffeine flowing through your veins.
But adenosine inhibition isn't the only thing that caffeine does.
Oh no.
Caffeine also stimulates the production of adrenaline or epinephrine.
Adrenaline is a pretty well known hormone involved in the fight-or-flight response.
It causes all sort of physiological reactions! It increases your heart rate,
increases the blood flow to your muscles,
opens up your airways, causes your blood pressure to rise, and also causes you're
your liver to release extra sugar into your blood stream for an added boost of energy.
It also causes your muscle to tighten up,
which would be useful if you were the lone human on the savannah,
deciding or not to fight or flee from that lion over the distance,
But as a modern twenty something sitting in from of my camera, it just give me the jitters.
Finally caffeine also plays with the dopamine levels in your brain.
Awesome, yeah.
Caffeine increases the amount of dopamine present in your brain by slowing down its reabsorption,
Much in the same way that cocaine increases the amount of dopamine present
by slowing down how quickly it can be sucked back into your brain tissue.
This means that caffeine also makes you feel good and this interaction with dopamine is how you can actually
build a caffeine addiction. So now you're a happy,
jittery, fight or flight ready bundle caffeine! Now what?
Well the now what really depends on how your specific body metabolizes caffeine.
The average half-life of caffeine in the human body is about six hours.
so this means that if you have two hundred milligrams of caffeine in your average cup of coffee at 9am in the morning,
then 6 hours later half of that will be left, so at 3pm
you will have a hundred milligrams of caffeine left, and then another 6 hours later you will have half of the hundred
you will have half of the hundred so you will have 50 milligrams of caffeine left at 9 o'clock at night.
But dude, who stops at just one cup of coffee?
Not this chick. So how much caffeine is too much caffeine?
A lethal dose of caffeine is about two hundred milligrams per kilogram
so it would take about nine thousand five hundred milligrams of caffeine to kill me.
Now, there are about two hundred milligrams of caffeine in a standard cup of coffee,
so that's about forty eight cups of coffee,
which is a surprisingly low number, but I would have to drink
all 48 of those before my body started to metabolize the caffeine,
which means I would literally have to chug 48 cups of coffee.
I literally wouldn't be able to drink that much coffee,
both because my stomach couldn't hold that volume of liquid and also because as every coffee drinker knows,
caffeine is a diuretic.
before I got to cup forty anyways, the stimulant effect of caffeine would be
jacked up so high that that the alertness and awakeness would be transformed into mania,
disorientation and hallucinations... great!
What would eventually kill you would be ventricular fibrillation, which basically means
that your heart would caffeine jitter itself to death.
So moral of the story, caffeine is a drug. It is a stimulant that has some pretty noticeable effects on your body,
can cause addiction, and, in high enough doses, can kill you.
So caffeinate wisely!
Go forth, do science!
My hand is actually not shaking too bad right now.
Don't try this at home, I know a lot of people do drink that much caffeine all on one day and
sometimes I approach it,
but I certainly don't do it over the span of 20 minutes.
I actually don't feel as terrible as I thought I would have after that amount, but I certainly don't feel good either.
コツ:単語をクリックしてすぐ意味を調べられます!

読み込み中…

Caffeine!! - Bite Sci-zed

3384 タグ追加 保存
VoiceTube 2013 年 3 月 20 日 に公開
お勧め動画

コメント

読み込み中…
  1. 1. クリック一つで単語を検索

    右側のスプリクトの単語をクリックするだけで即座に意味が検索できます。

  2. 2. リピート機能

    クリックするだけで同じフレーズを何回もリピート可能!

  3. 3. ショートカット

    キーボードショートカットを使うことによって勉強の効率を上げることが出来ます。

  4. 4. 字幕の表示/非表示

    日・英のボタンをクリックすることで自由に字幕のオンオフを切り替えられます。

  5. 5. 動画をブログ等でシェア

    コードを貼り付けてVoiceTubeの動画再生プレーヤーをブログ等でシェアすることが出来ます!

  6. 6. 全画面再生

    左側の矢印をクリックすることで全画面で再生できるようになります。

  1. クイズ付き動画

    リスニングクイズに挑戦!

  1. クリックしてメモを表示

  1. UrbanDictionary 俚語字典整合查詢。一般字典查詢不到你滿意的解譯,不妨使用「俚語字典」,或許會讓你有滿意的答案喔