1. Part 2 Page 412-417 Practice problems page 420, #1,2,3,4a,5,7,8
Digestive System
Part 2
Page
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
Involves movement of molecules against a concentration gradient

24. Absorption – Passive Transport