1. Anatomy of the Digestive System
The importance of sphincters!

2. Major Functions of the Digestive System
Excretion

3. Structure of the Gastrointestinal Tract Wall
Aka Enteroendocrine cells
Extramural glands

4. Liver, Gallbladder, and Associated Ducts
Main secretions of Liver: bile salts for emulsification of fats and bicarbonate

5. How are these exocrine secretions regulated?

6. Recall Components of a Reflex Arc
Stimulus
Receptors
Afferent Pathway
Integrator
Efferent Pathway
Effectors
Response
Enteroendocrine cells
Hormones
Glands, Smooth Muscles, Sphincters

7. Basic Principles of Control
Luminal stimuli:
Neural regulation comes through the CNS and ENS:
distension of the wall by the volume of luminal contents
Enteric nervous system
Chyme osmolarity
Submucosal plexus
Chyme acidity
Myenteric plexus
Chyme concentration of specific digestion products
CNS contributions to neural control of the GI system through regulation of the SNS and PSNS.
Hormonal regulation

8. Cholecystokinin

9. Stomach
AKA Cardiac Sphincter

10. Gastric Gland pH

11. Regulation of HCl Secretion

12. Pepsin Secretion
Why has natural selection resulted in the conversion of pepsinogen to pepsin in the lumen of the stomach?

13. Pancreas Exocrine cells here secrete
ZYMOGENS (which require modification to become enzymes!)
Why zymogens?

14. Trypsin Secretion Zymogens
What controls secretion of bicarbonate and zymogens from the pancreas?

15. Control of Pancreatic HCO3- Secretion

16. Control of Pancreatic Zymogen Secretion
What else does CCK do?

17. Regulation of Bile Flow

18. Large Intestine