How the Digestive System Works | 3D Animation · Dr. Paulien Moyaert
通过3D动画展示消化系统的运作过程，涵盖从口腔到大肠的各个阶段。适合练习英语词汇和科学类表达。
Digestion begins the moment you take a bite.
消化过程从你咬下一口食物的那一刻就开始了。
Food is shuttled from the mouth to the stomach via the esophagus, a ride that will take about 5-8 seconds.
食物通过食管从口腔输送到胃部，这一过程大约需要5到8秒的时间。
The peristalsis is the involuntary muscular force that propels food through the digestive tract.
蠕动是一种无意识的肌肉运动，它将食物推进消化道中。
It almost looks like an ocean wave pushing food from one organ to the next.
这几乎就像海浪一样，将营养物质从一个器官输送到另一个器官。
When food reaches the end of your esophagus, a ringlike muscle called the lower esophageal sphincter relaxes and lets the food pass into your stomach.
当食物到达食道的末端时，一种被称为“下食道括约肌”的环形肌肉会放松，从而让食物进入胃中。
Weakness of this sphincter causes a back-flux of stomach acid and heartburn.
这个括约肌的功能减弱会导致胃酸倒流，从而引发烧心症状。
The stomach is where the real action begins.
胃才是真正开始消化食物的地方。
Digestive juices and enzymes break down the food that you swallowed.
消化液和酶会分解你吞下的食物。
This helps make nutrients available for absorption later in the small intestine.
这有助于使营养物质在小肠的后期阶段被吸收。
The digestive juices are powerful hydrochloric acids that kill pathogens in food and give the stomach the low pH digestive enzymes need.
消化液是一种强效的盐酸，能够杀死食物中的病原体，并为胃创造适宜的低pH值环境，从而使消化酶能够正常发挥作用。
This acid could literally dissolve most of the other organs in your body.
这种酸确实能够溶解你身体里的大部分其他器官。
Luckily, your stomach contains a thick mucous lining.
幸运的是，你的胃内部有一层厚厚的黏液。
However, when there’s too much acid in the stomach, it can eat away the inner surface of the stomach,
然而，当胃中的酸性物质过多时，这些酸性物质会侵蚀胃的内壁。
causing an ulcer.
这可能会导致溃疡的发生。
The process of digestion takes longer for some types of foods than others.
对于某些类型的食物来说，消化过程所需的时间比其他食物更长。
Simple carbohydrates such as an energy drink break down the fastest.
简单的碳水化合物（比如能量饮料中的成分）分解速度最快。
This explains why many recommend energy drinks for a quick energy boost.
这就解释了为什么很多人推荐饮用能量饮料来快速补充能量。
Proteins take longer to digest, and fats take the longest time of all.
蛋白质需要更长的时间才能被消化，而脂肪则是所有食物中消化所需时间最长的。
The stomach slowly empties its contents – which now has the consistency of oatmeal – into your small intestine.
胃会慢慢将其中的内容物（此时内容物的质地已类似于燕麦粥）排入小肠。
The muscles of the small intestine mix food with digestive juices from the pancreas, liver, and intestine and push the mixture forward for further digestion.
小肠的肌肉将食物与来自胰腺、肝脏和小肠的消化液混合在一起，然后将这种混合物推向前方，以便进一步消化。
The walls of the small intestine are covered by tiny finger-like projections called villi.
小肠的肠壁表面布满了细小的、呈手指状的突起结构，这些突起被称为绒毛。
These projections increase the surface area through which nutrients can be absorbed into your bloodstream.
这些结构的变化增加了营养物质被吸收到血液中的表面积。
As peristalsis continues, the waste products of the digestive process move into the large intestine.
随着蠕动作用的持续进行，消化过程中产生的废物会进入大肠。
The large intestine is named for the diameter of the cavity, not for its length.
大肠的名称是根据其肠腔的直径来命名的，而不是根据其长度。
It is actually much shorter than the small intestine.
实际上，它的长度比小肠要短得多。
Its role is to absorb any extra water from the digested material before it is finally excreted.
它的作用是在消化后的物质最终被排出体外之前，吸收其中多余的水分。
If food passes through too quickly, too little water is absorbed, and you might have diarrhea.
如果食物通过消化系统的速度过快，那么吸收的水分就会很少，从而导致腹泻。
If it passes too slowly, your body absorbs too much water, and you may become constipated.
如果这个过程进行得太慢，你的身体会吸收过多的水分，从而导致便秘。
It takes about 30 hours for food to move through the large intestine.
食物通过大肠大约需要30个小时的时间。
All in all, the whole process —
总而言之，整个过程……
from the time you swallow food to the time it leaves your body as feces — takes about two to four days.
从你吞下食物到食物以粪便的形式排出体外，大约需要两到四天的时间。
Solid waste is characteristically brown and stinky.
固体废物的典型特征是呈棕色且具有异味。
Do you know what causes its odor?
你知道是什么导致了这种气味吗？
If you guessed that bacteria are involved, you’d be right.
如果你猜到细菌参与了这个过程，那么你猜对了。
Microbes that reside in the large intestine make a meal of the leftovers from the small intestine.
栖息在大肠中的微生物会以小肠中未被吸收的食物残渣为食。
The smell associated with stool comes from the gases released by bacteria.
粪便散发出的气味，其实来源于细菌释放出的气体。
The large intestine then empties its contents into the rectum.
大肠随后将其内容物排入直肠。
Its job is to let you know that there is a stool to be evacuated and to hold the stool until that evacuation happens.
它的作用是提醒你有一块粪便需要被排出体外，并在粪便真正被排出之前将其“固定”在体内（即防止其过早移动或泄漏）。
Thank you for watching this video.
感谢您观看这个视频。
If you want to learn more about how our heart or lungs work, please take a look at my next video.
如果您想了解更多关于我们心脏或肺部的工作原理，请观看我的下一个视频。