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**"Digestive Mechanisms in Stomach: Roles & Function of Small Intestine"**

Explore the roles of mouth, stomach, small & large intestine in digestion. Covers functions of pepsin, villi, microvilli, cecum, cellulose, and cellulase in animal nutrition. Learn about digestive mechanisms like mechanical mixing, chemical breakdown, and enzymatic digestion. Discover why certain enzymes like pepsin are crucial for protein breakdown. Delve into the structure and function of the small intestine and large intestine, emphasizing nutrient absorption and water reabsorption. Review key questions on defects in enzyme production and variations in vertebrate digestive systems.

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**"Digestive Mechanisms in Stomach: Roles & Function of Small Intestine"**

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  1. Animal Nutrition II (Ch. 41)

  2. Roles of mouth, stomach, sm.&lg. Intestine in digestion Pepsin, pepsinogen Villi, microvilli Cecum Cellulose Cellulase Keywords

  3. Stomach

  4. Digestive mechanisms in stomach • Mechanical • Chemical • enzymatic

  5. Mechanical • Mixing and churning

  6. Chemical • pH around 2 • Also breaks food down

  7. Enzymatic • Pepsin • Breaks down proteins

  8. Why doesn’t pepsin digest stomach?

  9. Activation of pepsin

  10. Small intestine • Most of the enzymatic digestion occurs here

  11. Table 41.13 p. 803 in Campbell

  12. Why doesn’t the small intestine digest itself? Fig. 37.13

  13. Most nutrient absorption takes place in small intestine • Structure: another example of increasing surface area

  14. Structure of small intestine

  15. Microvilli

  16. Large intestine (colon) • Major function is to reabsorb water

  17. Here are a few review questions

  18. What would happen if you had a defect in pepsin production?

  19. What would happen if you had a defect in pepsin production? • A. carbohydrate would not be digested well • B. meat would not be digested at all • C. perhaps decreased absorption of protein

  20. What would happen if you had a defect in salivary amylase production?

  21. What would happen if you had a defect in salivary amylase production? • A. You would die • B. You would be unable to digest starch • C. The pH of the stomach would be affected • D. None of the above

  22. Which of the following would you least like to donate to science while you are still alive? • A. Cecum • B. Pancreas • C. Reproductive organs

  23. What would happen if you had a defect in small intestine enteropeptidase?

  24. Variations of vertebrate digestive system • Herbivorous mammals • Specialized fermentation chambers

  25. Coyote vs. Koala

  26. Why does herbivory require specializations? • Plant tissue • Harder to break up • Contains cellulose • Nutrients less concentrated than meat

  27. Structure of cellulose

  28. Only bacteria and protozoa can break down cellulose Via the enzyme cellulase

  29. Cecum • Pouch at junction between lg and sm intestine • Large cecum in rabbits, some rodents, koala, horses • Full of symbiotic bacteria

  30. Symbiosis • “living together”

  31. Cecum function • Fermentation chamber • Bacteria breakdown cellulose • Feces must be reingested

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