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Digestive System

Digestive System. Part 2 Page 412-417 Practice problems page 420, #1,2,3,4a,5,7,8. Human digestive system. The Stomach. Muscular sac of acid Performs mechanical and chemical digestion Starts the breakdown of proteins. The Stomach. Sphincter : Know the sphincters of the stomach!.

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Digestive System

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  1. Digestive System Part 2 Page 412-417 Practice problems page 420, #1,2,3,4a,5,7,8

  2. Human digestive system

  3. The Stomach • Muscular sac of acid • Performs mechanical and chemical digestion • Starts the breakdown of proteins

  4. The Stomach • Sphincter: • Know the sphincters of the stomach!

  5. The Stomach • Layer to know: Muscularis • Chyme

  6. The Stomach • Mucosa: another layer to know • What is the function of the mucosa • Gastric juice: what is it and how does the mucosa protect itself from it?

  7. Pepsin • Catalyzes the breakdown of proteins into their amino acid subunits • Originally produced as pepsinogen • Page 411, #5

  8. Mucosa • Due to proximity to strong acid, must be constantly regenerated • Ulcer: • Heliobacter pylori: What role does this bacteri play in the production of ulcers?

  9. Human digestive system

  10. Small Intestine • Long (up to 7m), thin (2.5cm) tube • Site of the majority of digestion and absorption

  11. Small Intestine

  12. Small Intestine • Know these and what goes on at each! • Duodenum • Jejunum • Ileum

  13. Small Intestine • Pyloric sphincter:

  14. Pancreas • Bicarbonate ions (HCO3-) • Amylase: • Trypsinogen: • Trypsin: • Compare and contrast pepsin/pepsinogen with trypsin/trypsinogen.

  15. Pancreas • Carboxypeptidase and erepsin: • Lipases: • What difficulty do lipases encounter when digesting food?

  16. Liver • Produces bile • Stores it in the gall bladder • Bile emulsifies fats • What is this and why?

  17. Absorption • Once food is broken down into the smallest subunits, it is absorbed by the cells lining the small intestine and passed into the bloodstream • Occurs in the villi and microvilli

  18. Absorption – Surface area

  19. Absorption – Surface area • Ridges • Villi • Epithelial cells • Microvilli

  20. Absorption – Surface area

  21. Absorption - Transport • How do nutrients get absorbed? • Passive transport: • Diffusion • Osmosis • Facilitated diffusion • Know examples of molecules that get transported by these mechanisms!

  22. Absorption – Passive Transport

  23. Absorption – Active transport • Active transport: • Involves movement of molecules against a concentration gradient

  24. Absorption – Passive Transport

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