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The Digestive System

The Digestive System. Objectives. Students will be able to: Outline the journey of a meal through the digestive system Identify the functions of the digestive organs Know the function and location of the digestive enzymes. Functions.

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The Digestive System

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  1. The Digestive System

  2. Objectives • Students will be able to: • Outline the journey of a meal through the digestive system • Identify the functions of the digestive organs • Know the function and location of the digestive enzymes

  3. Functions • Digestion - breaks food down into molecules the body can use • Absorption - molecules are absorbed into the blood and carried to different cells in the body. • Elimination - wastes are removed from the body

  4. What your digestive system DOESN’T do…

  5. Digest safety pins…

  6. Absorb car keys…

  7. Eliminate forks…

  8. Man swallows scissors that he was using to clean his teeth

  9. Digestive System • 30 feet long • Disassembly line • Mouth  Anus • Entire process takes 24 to 36 hours

  10. Digestion • Where does digestion begin? • In the mouth • Mechanical Digestion is: • Physical break-down of food into smaller pieces • Chemical Digestion is: • Breaking down macromolecules into their subunits

  11. Digestive Enzymes • Are proteins • Facilitate the breakdown of chemical bonds in macromolecules • Work like a lock and key (they are specific) • Different enzymes break down different macromolecules

  12. Mouth • Mechanical digestion • Chewing • Chemical digestion • Saliva • Moisture (Bolus) • Cleansing • Tasting • Starch digestion • Salivary Amylase

  13. Esophagus • Lined with mucus • Epiglottis • Food remains for 10 seconds • Fluids remain 1-2 sec

  14. Esophagus • Contractions of muscle push food toward the stomach • Collapsed when not in use

  15. From mouth To stomach Food mass Contraction Peristalsis

  16. Heartburn • Burning radiating pain • Symptoms very similar to heart attack • Occurs when the acidic gastric juice regurgitates into the esophagus • Over eat • Pregnancy • Running

  17. Heartburn

  18. Stomach • J-shaped muscular pouch • Expands to hold food • Empty = 50 ml • Hold up to 4000 ml • Performs mostly mechanical digestion • Churning Why does the inside of the stomach look like this?

  19. Why does the inside of the stomach look like this? Stomach • Chemical Digestion • Protein • Hydrochloric Acid • Pepsinogen  Pepsin • Why doesn’t it digest itself?

  20. Stomach • Food remains until all solid material has been broken down • 3 to 4 hours • Thick liquid called chyme exits the stomach. • (tomato soup texture)

  21. What is digestive juice? • Composed of hydrochloric acid and the enzyme Pepsin • Pepsin only breaks down proteins • What are proteins broken down into? • Amino Acids • Why is it important for your stomach to be acidic? • Because Pepsin only works at an acidic pH!

  22. Ulcer

  23. Peptic Ulcers

  24. Small Intestine

  25. Small Intestine • 20 feet long • As tall as a two-story building • Slow process of digestion • Food stays for 3 to 5 hours • Chemical digestion and absorption of nutrients.

  26. Small Intestine • Chemical Digestion • Carbohydrates • Maltase, sucrase, and lactase • Disaccharides  monosaccharides • Proteins • Peptidase • Dipeptides  amino acids

  27. Organs that are crucial to the function of the digestive system, but food never enters them. Liver Produces Bile – separates (emulsifies) fat molecules Gallbladder Stores bile Accessory Organs

  28. Pancreas Neutralize acids Sodium Bicarbonate Accessory Organs

  29. Pancreas Amylase breakdown of starch Trypsin breakdown of protein Lipase breakdown of fat Accessory Organs

  30. Gallstones

  31. Gallstones

  32. What is digested in the small intestine? • Lipids • digestive enzyme Lipase • Leftover carbohydrates • broken down by pancreatic amylase • Leftover proteins • broken down by pancreatic protease

  33. Columnar epithelium Villi - AbsorptionConnection between Digestive and Circulatory Systems Blood vessel network Fatty acids Amino acids Monosaccharide

  34. VilliConnection between Digestive and Circulatory Systems

  35. Large Intestine (Colon) • 5 feet long • length of bathtub • 12 to 24 hours • Water re-absorption from food occurs here, so that excess water is not lost in the waste. • Many bacteria live in the colon, some secrete– Vitamin K

  36. What if…. • Your large intestine does not reabsorb enough water? • You get diarrhea • Your large intestine reabsorbs too much water? • Constipation

  37. Human vs. Horse • Horse intestines are 89 feet long! • 70 feet small intestine, Why? • Plant materials are very difficult to digest, so the digestive system must be longer. • Cecum: an extension of the large intestine that is greatly reduced in carnivores and omnivores.

  38. 1 5 2 8 4 3 6 9 7 Review

  39. Review • Salivary Amylase • Pepsinogen • HCl (chemical) • Maltase • Sucrase • Lactase • Peptidase • Amylase • Trypsin • Lipase • Bile (chemical) • Stores bile

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