1. Digestive System

2. introduction

3. Overview Gastrointestinal Tract (GI Tract) – from mouth to anus
Accessory organs – teeth, tongue, salivary glands, liver, gallbladder, pancrea s

4. Functions Ingestion Secretion – H20, enzymes, acid, buffers
Mixing and propulsion – peristalsis
Digestion – mechanical and chemical breakdown
Absorption
Defecation

5. structures

6. Mouth, Pharynx & Esophagus
Mouth includes teeth, tongue, salivary glands
Pharynx – throat; swallowing reflex
Esophagus – muscular tube; transports food to the stomach; some absorption

7. Stomach J-shaped enlargement of the GI tract Gastric Juice:
Mucus
Pepsinogen
HCl
Intrinsic factor
Chyme: thick liquid of gastric juice and food

9. Stomach 4 Layers of stomach wall Mucosa Secretory Cells
Rugae – folds of stomach wall
Columnar epithelium – secretes mucus
Secretory Cells
Mucus cells
Parietal Cells – HCl and Intrinsic factor (vit. B12 absorption)
Chief cells – secrete pepsinogen
G cells – secrete gastrin

10. Stomach Muscularis 3 layers of muscle Serous Membrane
Forms the greater omentum and mesentery

12. Small Intestine 3 sections: duodenum, jejunum, ileum
Most of digestion and absorption takes place here
Absorptive cells in the microvilli
Absorption of sugars, amino acids, H2O, lipids, vitamins
Digestive enzymes come from pancreas and small intestine

13. Small Intestine Digestive enzymes: Maltase, sucrase, lactase Lipase
Absorption:
Simple sugars, amino acids, ions, H2O, lipids, and vitamins

15. Large Intestine
1st section at opening of ileum – cecum; appendix attached
4 regions: ascending, transverse, descending, and sigmoid colon
Final stage of digestion (work of bacteria)
Absorption of H2O, vitamins
Chyme → feces → defecation (elimination)

17. Pancreas Pancreatic juice: H2O, salts, HCO3-, enzymes Enzymes:
Amylase; breaks down starches
Trypsin; breaks down proteins (inactive form)
Lipase; breaks down fats

19. Liver & Gallbladder
Bile: emulsifies large lipid globules; stored in gallbladder
Functions:
Carbohydrate metabolism – blood glucose levels
Lipid metabolism – cholesterol production, etc.
Protein metabolism – ATP production, converting ammonia into urea, plasma protein production

20. Liver & Gallbladder Functions (continued)
Processes drugs and hormones; detox center
Stores minerals and vitamins
Activates vitamin D