Human digestive system - How it works! (Animation) · Thomas Schwenke
视频详细讲解人体消化系统的各个器官及其功能，适合练习生物相关词汇和句子结构。
[MUSIC PLAYING] The human digestive system is very complex and has evolved over millions of years.
[音乐播放中] 人类的消化系统非常复杂，是经过数百万年的进化才形成的。
It basically consists of the rectum, the large intestine, the small intestine, the pancreas, the stomach, also called gaster and ventriculus,
它主要包括直肠、大肠、小肠、胰腺以及胃（也称为“gaster”或“ventriculus”）。
and the liver with the gallbladder.
以及肝脏和胆囊。
The esophagus is also part of this system, as well as various salivary glands near the mouth.
食管也是该系统的一部分，此外还包括口腔附近的各种唾液腺。
First the food is broken up in the mouth by the teeth, and then mixed with saliva with the help of the salivary glands.
首先，食物在口腔中通过牙齿被咀嚼碎裂，随后在唾液腺的分泌作用下与唾液混合在一起。
Saliva contains a digestive enzyme called amylase that already begins to digest carbohydrates in the mouth.
唾液中含有一种名为“淀粉酶”的消化酶，这种酶会在口腔中就开始分解碳水化合物。
It splits carbohydrates into smaller units.
它将碳水化合物分解成更小的单位。
The ball like mixture of food with
这种混合物就像是将食物与某种物质混合在一起形成的球状物……
saliva, also known as bolus, is pushed into the throat by the tongue and finally into the esophagus which propels the bolus to the stomach.
唾液（也被称为“食团”）由舌头推送至咽喉，随后进入食道，最终被送入胃中。
The esophageal lumen, that is the opening inside the esophagus, is very flexible, which allows boluses of different sizes to be transported.
食管腔（即食管内部的通道）具有极高的柔韧性，这使得各种大小的食物块都能够被顺利输送。
The esophagus consists of several layers.
食管由多层结构组成。
These layers occur throughout the interdigestive tract.
这些层结构存在于整个消化间期（即食物消化完成后到下一次进食之前的时间段）的消化道中。
The two outer muscle layers are responsible for peristalsis.
最外层的这两层肌肉负责蠕动（即食物在消化道内的移动）。
Through these two muscles the bolus can be transported from the mouth to the stomach, even if the person is standing on his head.
通过这两块肌肉，食物团可以从口腔被输送到胃部——即使这个人是倒立着的。
The stomach is often divided into six areas.
胃通常被划分为六个区域。
The stomach is composed of a similar structure to the esophagus.
胃的结构与食道类似。
It has a longitudinal muscle layer on the outside.
它的外层有一层纵向排列的肌肉。
Underneath we can find circular muscle fibers.
在下方，我们可以看到环状肌纤维。
In addition to this, there is an oblique muscle layer overlaying the mucosa.
除此之外，黏膜表面还覆盖着一层斜肌。
On the inside there are rugae that allow the stomach to enlarge when food is consumed.
胃的内部有特殊的皱褶结构，当食物进入胃部时，这些皱褶会扩张，从而使胃的容积增大。
The stomach wall contains gastric glands.
胃壁内含有胃腺。
They produce mucus, which is able to protect the stomach wall from the secreted gastric acid.
它们会分泌黏液，这种黏液能够保护胃壁免受胃酸的侵蚀。
Gastric acid is produced by simply smelling or seeing food, but also spices, and the stretching of the stomach causes the secretion.
胃酸的分泌不仅会因闻到或看到食物而发生，也会因食物的味道（尤其是香料）以及胃部的扩张而引发。
That is, the release of gastric acid.
也就是说，胃酸的分泌。
About one to two liters of gastric juice are produced per day.
每天大约会产生1到2升的胃液。
Since the esophagus does not have a protective mucus layer, like the stomach, stomach and esophagus are separated by a sphincter.
由于食道没有像胃那样的保护性黏液层，因此胃和食道之间通过一个括约肌来分隔开来。
It relaxes when a bolus is pushed from the esophagus into the stomach, and then contracts to prevent acid and food from going back up.
当食物从食道被推入胃部时，这个结构会放松；随后它会收缩，以防止胃酸和食物倒流回去。
Gastric juice consists, among other things, of hydrochloric acid, the enzyme pepsin, the intrinsic factor, and lipase for the digestion of fats.
胃液中含有多种成分，其中包括盐酸、消化酶胃蛋白酶、用于帮助铁质吸收的“内因子”，以及用于分解脂肪的脂肪酶。
In addition to nutrients, food also contains bacteria that can damage the body.
除了营养成分外，食物中还含有可能对人体造成伤害的细菌。
The components of hydrochloric acid are able to destroy harmful bacteria.
盐酸的成分能够消灭有害细菌。
In addition, hydrochloric acid converts pepsinogen also released by the gastric glands into pepsin.
此外，盐酸还能将胃腺分泌的胃蛋白酶原转化为胃蛋白酶。
Pepsin is able to break down proteins in the stomach.
胃蛋白酶能够在胃中分解蛋白质。
For a vitamin B12 absorption in the small intestine, the intrinsic factor is needed, which is produced by the gastric glands.
为了在小肠中吸收维生素B12，需要一种名为“内因子”的物质，这种物质由胃腺分泌产生。
The vitamin must combine with intrinsic factor, then it can be absorbed later by the small intestine.
这种维生素必须与“内因子”结合后，才能被小肠吸收。
Vitamin B12 helps keep the body's nerve and blood cells healthy, and helps make DNA.
维生素B12有助于维持人体神经细胞和血细胞的健康，并参与DNA的合成过程。
It also contains gastric lipase, an acid resistant enzyme for fat digestion.
其中还含有胃脂肪酶（gastric lipase），这是一种耐酸的酶，专门用于脂肪的消化。
In the stomach, gastric lipase splits a
在胃中，胃脂肪酶会分解某种物质（具体是什么物质未在原文中明确）。
triglyceride into a free fatty acid, and a diglyceride whereby only the free fatty acid can be absorbed by the body.
甘油三酯会被分解成游离脂肪酸和甘油二酯；只有游离脂肪酸才能被人体吸收。
More effective fat digestion takes place in the small intestine.
更有效的脂肪消化过程发生在小肠中。
Through gastric juice and stomach movements, which
通过胃液和胃部的运动，这些……