Shadowing Practice: Human digestive system - How it works! (Animation) - Learn English Speaking with YouTube

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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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About This Lesson

In this lesson, you will learn about the intricate details of the human digestive system as presented in the animated YouTube video titled "Human digestive system - How it works!" This fascinating topic not only helps you to understand how our body processes food but also enriches your English vocabulary. By engaging with the video, you will be practicing your listening and speaking skills, promoting improved English pronunciation. As you repeat phrases and sentences from the video, you will effectively engage in shadowing, a technique that enhances your fluency and comprehension.

Key Vocabulary & Phrases

  • Digestive system - The complex system responsible for breaking down food in the body.
  • Bolus - The ball-like mixture of food and saliva that is swallowed.
  • Peristalsis - The wave-like muscle contractions that move food through the digestive tract.
  • Gastric juice - A digestive fluid produced by the stomach, containing enzymes and acids.
  • Intristic factor - A protein necessary for the absorption of vitamin B12 in the small intestine.
  • Chyme - The semi-fluid mass of partially digested food found in the stomach.
  • Pyloric sphincter - The valve that controls the passage of chyme from the stomach to the small intestine.
  • Pancreatic juice - A fluid containing enzymes that aid in digestion in the small intestine.

Practice Tips

To make the most out of this lesson, try to incorporate shadow speak techniques while watching the video. The speed of the narration offers a balanced tempo – not too fast, allowing for clear pronunciation. This is an ideal pace for learners. Repeat phrases aloud immediately after the speaker to engage in shadow speech. This practice helps you not only to improve English pronunciation but also to enhance your ability to recall and use new vocabulary in context. Focus on mimicking the tone and intonation of the speaker, which will make your language learning experience dynamic and enjoyable. Remember to take breaks to review difficult segments and reinforce your learning. By combining these strategies, you will effectively learn English with YouTube, making your study sessions both productive and fun!

What is the Shadowing Technique?

Shadowing is a science-backed language learning technique originally developed for professional interpreter training and popularized by polyglot Dr. Alexander Arguelles. The method is simple but powerful: you listen to native English audio and immediately repeat it out loud — like a shadow following the speaker with just a 1–2 second delay. Unlike passive listening or grammar drills, shadowing forces your brain and mouth muscles to simultaneously process and reproduce real speech patterns. Research shows it significantly improves pronunciation accuracy, intonation, rhythm, connected speech, listening comprehension, and speaking fluency — making it one of the most effective methods for IELTS Speaking preparation and real-world English communication.

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