1. Stomach Anatomy and Activity
Control of Digestion
SI Anatomy
Macromolecule Digestion
Absorption .
Be able to discuss how the three stages of controlling the stomach including excitatory and inhibitory effects.
Be able to discuss the anatomy of the SI and accessory organs
Be able to discuss how proteins, carbohydrates and fats are digested and absorbed in the SI
Handout: Reflexes in the Stomach (in class)
Marieb: 23 1

2. The SI is the Main Digestive Organ
1” in diameter
6-7m in cadaver
2-4m in living person
Chemical Digestion
Absorption 2

3. Small Intestine: Gross Anatomy
Pyloric sphincter
Duodenum***
Jejunum
Illeum
Ileocecal Valve

4. Small Intestine is Specialized for Absorption
Mucosa has a huge surface area
Plicae circulars
(1cm) 4

5. Villi in the Small Intestine
Villus
(1mm)
Capillary bed
Lacteal
Intestinal Crypts

6. Microvilli in the Small Intestine
Brush Border
1/1000 of mm
Enzymes
Final protein and carbohydrate digestion

7. Cells of the Villi Enterocytes Goblet cells Enteroendocrine cells
Secretin
CCK

8. Cells of the Crypt Stem Cells Cells replaced every 3-6 days
Enzyme Production??? 8

9. Accessory Glands aide SI Digestion
Digestion in SI: 3-6 hours
Liver
Gall Bladder
Pancreas

10. Pancreas and Liver aid in Digestion10

11. Pancreas Aids in Digestion
Pancreatic juice:
ml/day
(pH ~8.5)
Pancreatic
Enzymes

12. Pancreatic Enzymes Amylases Zymogens Inactive in the pancreas
Activated in the small intestine 12

13. SI Digestion and Absorption
Pancreatic Enzymes
Brush Border
Transport into cell
Transport into capillary bed of villi 13

14. The Liver is a Versatile Organ
Detoxification
Activates Hormones and Vitamins
Stores Nutrients
Produces Bile

15. The Liver makes Bile Salts
Cholesterol Derivatives
Emulsifies Fat
Placed in Bile:
ml/day
Gall Bladder stores bile

16. CCK Triggers Bile Release
Low pH
Fat
Proteins
Cholecystokinin (CCK)
Gall bladder contracts

17. Absorption of Fats
Bile Salts + Fats= Micelles
Chylomicrons 17

18. Absorption of Fats Lacteals Chyle Fats broken down in blood or liver18

19. Secretin and CCK Regulate the Pancreas
HCl activates release
Pancreatic juice
CCK
Fat activation
Enzymes

20. Absorption in the SI 10-12L  1200ml 99% Nutrients
80% electrolytes and H2O 20

21. Small Intestine Motility: Segmentation
Duodenum 12-14/min
Ileum 8-9/min

22. Small Intestine Motility: Peristalsis
Migratory Mobility Model
Process repeats itself twice 22