Digestion of a Meal

1. Digestion of a Meal

2. time taken for food to pass through the digestive system depends on: • type of diet • amount of fibre present Digestion of a Meal

3. carbohydrases: • general name for all enzymes that break down carbohydrates stored in: • various glands ex. • salivary • pancreas • small intestine • liver and muscles to: • break down glycogen Digestion of Carbohydrates

4. starch maltase → → amylase glycogen …..1000’s polysaccharides → disaccharides → monosaccharides Glu Glu maltose glucose Digestion of Carbohydrates - made in salivary glands & pancreas - works in mouth & duodenum • made in duodenum • work in duodenum

5. Digestion of Carbohydrates sucrase → F Glu lactase → Gal Glu Note: Other disaccharides are also chemically digested into monosaccharides in the duodenum. sucrose fructose glucose lactose galactose glucose

6. proteases: • general name for all enzymes that break down proteins • cannot be stored in active form because: • it would digest organ parts • therefore stored as inactive enzymes • when secreted into the digestive tract, chemicals present activate enzyme Digestion of Proteins

7. Example: Stomach: + → (inactive enzyme) (active enzyme) pepsinogen HCl pepsin Digestion of Proteins

8. pepsin trypsin 100’s …. protein peptides amino acids Digestion of Proteins • made in stomach • works in stomach • made by pancreas • works in small intestine

9. lipases: • general name for all enzymes that break down lipids stored in: • various glands: ex. • pancreas • small intestine • fatty tissue under the skin Digestion of Lipids

10. smaller fat globule glycerol & 3 fatty acids fat globule bile lipase glycerol fatty acid • made by pancreas • works in duodenum • made by liver • works in duodenum Digestion of Lipids (physical digestion) (chemical digestion) emulsification

11. gland: • organ that produces & releases a secretion exocrine gland: • organs that release their secretions into ducts (tubes) such as: • sweat glands Exocrine vs. Endocrine Glands

12. exocrine glands: (continued) • mammary glands • digestive organs: ex. • salivary glands • pancreas • liver Exocrine vs. Endocrine Glands

13. endocrine gland: • organs that release hormones directly into the blood (not through ducts) examples: • testes → testosterone • ovaries → estrogen • pancreas → insulin Endocrine vs. Exocrine Glands

14. important so that secretions are only released when the appropriate food is present • hormones (chemicals that control metabolic pathways) get to their target tissue via the blood stream • stimulus: • target tissue: • response: action that triggers a response tissue that is affected by hormone action tissue produces as a result of hormone binding Hormonal Control of Digestion

15. duodenal gland cells cardiac sphincter cells protein in food acidic chyme stomach lining pancreas cells • Release: • HCl • pepsinogen Release: sodium bicarbonate activates pepsin digest amino acid chains neutralizes acidity in chyme Hormonal Control of Protein Digestion

16. Complete ‘Chemical Digestion of Nutrients’ Handout Homework