1. Biology 212 Anatomy & Physiology I Dr. Thompson Digestive System

2. Functions:

3. Organs Two functional groups: 1. Alimentary Canal or Gastrointestinal tract 2. Accessory Digestive Organs

4. Organs:

5. Oral Cavity:

6. Paired Salivary Glands:

7. Saliva: 97% - 99% water Solutes:

8. Swallowing

9. From esophagus to anus: 4 concentric layers or tunics Alimentary Canal:

10. Esophagus: Propels food from pharynx to stomach Posterior to trachea & heart Mucosa: Submucosa: Muscularis Externa: Adventitia:

11. Esophagus: Passes from thorax to abdomen through diaphragm, enters stomach (left of midline).

12. Stomach: Storage: Highly distensible Delivers slowly to duodenum Secretion of mucous, hydrochloric acid Secretion of enzyme - Digestion of proteins Secretion of enzyme - Digestion of lipids Secretion of enzyme - Absorption of B 12

13. Stomach:

15. Small Intestine:Total length: 6 to 7 meters Diameter: 2.5 to 3 centimeters

16. Small Intestine: Duodenum Jejunum Ileum

17. Small Intestine: DUODENUM: Receives Secretes JEJUNUM: ILEUM:

18. Small Intestine:

19. Mucosa specialized three ways to increase surface area for absorption

20. Large Intestine (colon): From ileocecal junction to anus ~ 2 meters long ~ 5 to 8 cm diameter

22. Abdominal Accessory Organs:

23. Liver

24. Digestive functions:

25. Liver:

26. Pancreas:

27. Produces many different digestive enzymes: Amylases: starches & monosaccharides glycogen & disaccharides Proteases: proteins amino acids Lipases: diglycerides & fatty acids triglycerides & glycerol Nucleases: nucleic acids nucleotides

28. The abdominal cavity is lined by a double-layered serous membrane

29. More terminology:

31. Intraperitoneal Retroperitoneal

32. Intestinal Motility: Moves liquid distally

33. Digestion: Breakdown of food into molecules small enough to be absorbed from the lumen of the intestine into its blood vessels. Four types of molecules = more than 95% of total: Also: Nucleic acids Ions (electrolytes, minerals) Vitamins ? Others ?

34. Mechanical digestion Chemical digestion Absorption of nutrients electrolytes vitamins Absorption of water

35. All absorbed molecules

36. Since contents include many foreign substances, including microorganisms, your immune system considers it “outside” so Lined by many lymphatic and immune tissues in lamina propria and submucosa Alimentary Canal: