1. Stage 1 Digestion Molecular breakdown/absorption of Polysaccharides Lipids Proteins

3. General digestive events + Enzymes produced Mouth/teeth: reduce particle size/increase surface area, secretion of Amylase Stomach: production of HCl, acid-disinfection of food, secretion of Pepsin Pancreas: Bicarbonates (base) to neutralize stomach acid, Amylase, Trypsin, Chymotrypsin, Lipase Small intestine: Sucrase, Lactase, Maltase, high surface area (villi) absorption of monomers and water Large intestine: more water absorption, vitamin production by e-coli

4. Surface area of Stomach Small Intestine Villi

5. Digestion of Starches MOUTH: secretion of salivary amylase: hydrolyzes some glycosidic bonds Formation of dextrins: 3-8 glucose units STOMACH (pH 1) denatures salivary amylase –interruption of carb digestion DUODENUM/PANCREAS Secretion of pancreatic amylase completes digestion to maltose

6. Absorption of Carbs SMALL INTESTINE Mucosa cells lining Small intestine secrete enzymes to split disaccharides lactase Lactose → galactose + glucose sucrase Sucrose → fructose + glucose maltase Maltose → glucose + glucose Absorption of monosaccharides into blood stream

7. Digestion of Lipids Mouth- Stomach: no effect on lipids DUODENUM: bile salts from the gall bladder emulsify fat into tiny droplets called micelles

8. Lipids DUODENUM Pancreatic lipase hydrolyzes lipids lipase triglycerides → monoglycerides + 2 FA SMALL INTESTINE Absorption into lymphatic system which empties into blood stream (thoracic duct) Transport in the blood via lipoprotein vesicles (HDL, LDL)

9. Absorption of lipids SMALL INTESTINE Absorption into lymphatic system Rentry into the blood stream

10. Proteins MOUTH: no effect on proteins STOMACH contains HCl, pH 1 a. General acid denaturing of proteins b. Secretion of enzyme pepsin hydrolyzes peptide bonds, formation of small peptides pepsin Proteins → peptides

11. Proteins DUODENUM/PANCREAS Pancreatic enzymes Trypsin/ Chymotrypsin hydrolyze peptides into AA SMALL INTESTINE AA are absorbed into blood stream

12. The Food Machine The food machine