シャドーイング練習: Human digestive system - How it works! (Animation) - YouTubeで英語スピーキングを学ぶ
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The human digestive system is very complex and has evolved over millions of years.
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The human digestive system is very complex and has evolved over millions of years.
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It basically consists of the rectum,
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the large intestine, the small intestine,
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the pancreas, the stomach, also called gaster and ventriculus,
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and the liver with the gallbladder.
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The esophagus is also part of this system as well as various salivary glands near the mouth.
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First, the food is broken up in the mouth by the teeth
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and then mixed with saliva with the help of the salivary glands.
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Saliva contains a digestive enzyme called amylase that already begins to digest carbohydrates in the mouth.
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It splits carbohydrates into smaller units.
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The ball-like mixture of food with saliva,
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also known as bolus, is pushed into the throat by the tongue,
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and finally into the esophagus,
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which propels the bolus to the stomach.
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The esophageal lumen, that is,
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the opening inside the esophagus,
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is very flexible, which allows boluses of different sizes to be transported.
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The esophagus consists of several layers.
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These layers occur throughout the entire digestive tract.
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The two outer muscle layers are responsible for peristalsis.
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Through these two muscles, the bolus can be transported from the mouth to the stomach,
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even if the person is standing on his head.
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The stomach is often divided into six areas.
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The stomach is composed of a similar structure to the esophagus.
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It has a longitudinal muscle layer on the outside.
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Underneath, we can find circular muscle fibers.
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In addition to this, there is an oblique muscle layer overlaying the mucosa.
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On the inside, there are rugae that allow the stomach to enlarge when food is consumed.
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The stomach wall contains gastric glands.
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They produce mucus, which is able to protect the stomach wall from the secreted gastric acid.
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Gastric acid is produced by simply smelling or seeing food,
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but also spices, and the stretching of the stomach causes the secretion,
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that is, the release of gastric acid.
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About 1-2 liters of gastric juice are produced per day.
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Since the esophagus does not have a protective mucus layer like the stomach,
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stomach and esophagus are separated by a sphincter.
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It relaxes when a bolus is pushed from the esophagus into the stomach
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and then contracts to prevent acid and food from going back up.
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Gastric juice consists, among other things,
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of hydrochloric acid, the enzyme pepsin,
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the intrinsic factor, and lipase for the digestion of fat.
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In addition to nutrients, food also contains bacteria that can damage the body.
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The components of hydrochloric acid are able to destroy harmful bacteria.
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In addition, hydrochloric acid converts pepsinogen,
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also released by the gastric glands, into pepsin.
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is able to break down proteins in the stomach.
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For a vitamin B12 absorption in the small intestine,
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the intrinsic factor is needed,
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which is produced by the gastric glands.
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The vitamin must combine with intrinsic factor,
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then it can be absorbed later by the small intestine.
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Vitamin B12 helps keep the body's nerve and blood cells healthy and helps make DNA.
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It also contains gastric lipase,
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an acid-resistant enzyme for fat digestion.
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In the stomach, gastric lipase splits a triglyceride into a free fatty acid and a diglyceride,
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whereby only the free fatty acid can be absorbed by the body.
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More effective fat digestion takes place in the small intestine.
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Through gastric juice and stomach movements,
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which take place approximately every 20 seconds,
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the individual boluses are mixed to a semi-fluid mass of partly digested food, the so-called chime.
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The chime cannot enter the duodenum at first because there is a sphincter at the stomach exit.
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The pyloric sphincter resembles the esophageal sphincter.
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The pyloric sphincter opens only a few millimeters,
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so that larger pieces remain inside the stomach.
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In the first section of the small intestine,
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the duodenum, bile, and pancreatic secretions are mixed with the chyme via the ampulla of vader.
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Pancreatic juice contains numerous digestive proenzymes and enzymes.
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In order for these to do their job,
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a higher pH value than that in the stomach is necessary.
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For this reason, pancreatic juice contains sodium hydrogen carbonate.
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Hydrogen carbonate is able to neutralize the acid in the chyme and thus produce the optimum pH value of 7 or 8.
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Pancreatic juice also contains proenzymes.
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It is only through enterokinase,
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released by the duodenum wall,
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that the proenzyme trypsinogen becomes trypsin,
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which can split proteins and activate other trypsinogens.
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We also find alpha amylase,
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which we had already found in the mouth.
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It now does the rest regarding the splitting of carbohydrates,
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which it converts into maltose and isomaltose.
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Furthermore, pancreatic lipase is able to split triglycerides into two free fatty acids.
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The gastric lipase, as we have seen before,
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can produce only one free fatty acid.
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The pancreatic lipase can cleave triglycerides excellently because the bile breaks the fats down into tiny droplets.
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This is called emulsification.
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Numerous other enzymes are part of pancreatic juice,
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but these will not be explained in detail here.
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Bile is produced by the liver cells and transported to the gallbladder.
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The bile is stored in the gallbladder and finally added to the food in the duodenum via the ampulla of VATR.
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The pancreas also releases juice via the ampulla of VATR.
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The small intestine consists of three sections, duodenum, jejunum, and ileum.
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The ileum continues into the large intestine in the right lower abdomen.
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The duodenum and the jejunum have circular folds to increase the contact surface with the food.
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These circular folds extend about 1 cm into the lumen of the small intestine.
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These folds are covered with small finger-like projections called villi.
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Villi increase the surface considerably.
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Villi are about 1 mm long.
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Each villus contains blood capillaries and a lymphatic capillary called lacteal,
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which we will see later.
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The nutrients, marked green here,
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are absorbed by the villus and transferred to the blood capillaries.
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Some nutrients, such as glucose,
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do not require a carrier.
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They are transported freely in the bloodstream.
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Other nutrients, such as iron,
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require transport proteins like transferrin.
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Fats are transported by chylomicrons, which are lipoproteins.
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The triglycerides to be transported are virtually enclosed in the lipoprotein.
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Chylomicrons and triglycerides are then transported through the lacteal of the villus.
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Each villus is covered by even smaller microvilli.
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They multiply the intestinal surface considerably.
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The microvilli absorb nutrients and transport them to the inside.
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The last part of the small intestine is the ileum.
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It does not have, unlike the duodenum and jejunum, circular folds.
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The ileum absorbs electrolytes such as calcium for building bones, hair and teeth.
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Trace elements such as zinc for sperm production and the immune system.
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such as B12 for the formation and maturation of red blood cells
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and remaining bile acid which is transported back to the liver via the bloodstream
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as with the esophagus the food is transported by peristalsis in contrast segmentation contractions serve to mix the chime,
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which is shown here in yellow and red to make it easier to see the mixing process.
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The large intestine is thicker than the small intestine.
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It is about one meter long and surrounds the small intestine.
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The small intestine is connected to the large intestine via the Bauheims valve.
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It opens when Chime is to pass from the small intestine to the large intestine.
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The large intestine does not have any villi like the small intestine
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because most digestible substances have already been absorbed in the small intestine.
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However, the large intestine has an estimated 100 billion bacteria inside.
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They are important for many other tasks,
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such as the production of vitamins and the decomposition of fiber for the body's energy production.
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Many of these bacteria are an important part of the immune system by killing harmful germs.
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Through peristalsis, the chime is transported from the ascending colon to the transverse colon to the descending colon.
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On its way through the large intestine,
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water is removed from the chyme.
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Furthermore, mucus is added for proper excretion of waste.
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Substances that cannot be absorbed through the small intestine or the large intestine remain in the rectum
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and are finally excreted through the anus.
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この動画で話す練習をする理由
この動画では、人間の消化システムの複雑さとその機能について詳細に説明されています。英語での会話力を向上させるためには、実際の文脈に基づいた練習が効果的です。このような内容を使用して英語シャドーイングを行うことで、リアルな発音、イントネーション、リズムを学ぶことができます。さらに、健康や生理学に関する専門用語も同時に学ぶことができ、IELTSスピーキング対策として役立つでしょう。動画の内容を真似しながら話すことで、自信を持って英語を話す能力が向上します。
文法と表現の文脈
以下は、この動画で使用されている重要な構造の分析です：
- 過去形の使用：「evolved over millions of years」というフレーズから、過去の出来事を表現するための過去形の使用方法を学ぶことができます。
- 受動態：「are produced」という表現に見るように、受動態は生理学の説明でよく使用され、特にプロセスや結果を強調するときに便利です。
- 条件文：「if the person is standing on his head」という条件文は、状況に応じた事例を説明する際に役立ちます。
- 比較級：「more effective fat digestion」に見られるように、何かが他のものよりも効果的であることを述べるときに使います。
これらの構文を使用しながら会話を構築することは、shadowspeakの技術を磨くためにも効果的です。
発音上の注意点
この動画で注意すべき発音のポイント：
- "esophagus"のような専門用語は特に発音が難しいです。正しいアクセントをつけて練習することで、正確な発音が身につきます。
- "intrinsic factor"の発音もトラップになります。「intrinsic」は「インストリンシック」と発音される部分に注意が必要です。
- 動画に登場する「胃酸」や「消化酵素」といった単語も、繰り返しの発音練習を通じて流暢さが向上します。
これらの発音を正確にすることは、YouTubeで英語学習の一環として非常に重要です。動画を見ながら真似することで、会話力と発音を同時に鍛えることができます。
シャドーイングとは？英語上達に効果的な理由
シャドーイング（Shadowing）は、もともとプロの通訳者養成プログラムで開発された言語学習法で、多言語習得者として知られるDr. Alexander Arguelles によって広く普及されました。方法はシンプルですが非常に効果的：ネイティブスピーカーの英語を聞きながら、1〜2秒の遅延で声に出してすぐに繰り返す——まるで「影（shadow）」のように話者を追いかけます。文法ドリルや受動的なリスニングと異なり、シャドーイングは脳と口の筋肉が同時にリアルタイムで英語を処理・再現することを強制します。研究により、発音精度、抑揚、リズム、連音、リスニング力、そして会話の流暢さが大幅に向上することが確認されています。IELTSスピーキング対策や自然な英語コミュニケーションを目指す方に特におすすめです。