Learn the Human Digestive System: Functions, Enzymes, and Absorption

1. Glenlola Collegiate School excellence through commitment, contribution and caring DIGESTION

2. LEARNINGOUTCOMES ALL MUST… Know that enzymes are used in the digestion of food in the body, which can then be absorbed into the bloodstream

3. LEARNINGOUTCOMES ALL MUST… Know that enzymes are needed to break down (digest) large, insoluble molecules into small, soluble ones:

4. View the photograph on the next slide and jot down Where you would find it What produced it What it is starter activity

6. The Human Digestive System The process of digestion has 5 functions: Ingestion: taking food into the body Digestion: breakdown of insoluble substances into soluble ones Absorption: uptake of soluble substances into cells Assimilation: how cells use food Egestion: removal of undigested waste

7. Digestion Egestion faeces Ingestion Absorption

8. Food is broken down into smaller pieces by biting, chewing, churning, bile action. These pieces are not solublebut have a large surface area for enzymes to work on.

9. 1cm 1cm 1cm 2cm Surface area = 24 cm2 Volume = 8 cm3 SA : V ratio = 24:8 = 3:1 2cm 2cm Surface area = 6 cm2 Volume = 1 cm3 SA : V ratio = 6:1

10. Digestive enzymes break chemical bonds to make insoluble food particles soluble. Carbohydrases break down carbohydrates into sugars Proteases break down proteins into aminoacids Lipases break down fats (lipids) into fatty acids and glycerol

11. model gut experiment boiling tube

12. LEARNINGOUTCOMES ALL MUST… Label a diagram of the component parts of the digestive system and identify their function.

13. LEARNINGOUTCOMES to include: buccal cavity - the mechanical digestion by teeth and the chemical digestion of starch by amylase;

14. LEARNINGOUTCOMES to include: stomach - the production of gastric juice containing protease enzyme and acid, and the digestion of proteins;

15. Pin the pancreas on the body starter activity

16. What do you remember

17. Add gall bladder, bile duct, sphincter Buccal cavity Salivary gland Oesophagus Liver Stomach Duodenum Pancreas Ileum Colon Appendix Rectum Anus

18. The Buccal cavity (mouth) Mechanical: chewing, biting Chemical: Saliva from the salivaryglands contains the enzyme CARBOHYDRASE. Starch + carbohydrase  sugar (maltose) The ball of food is called a bolus

19. The oesophagus NO FOOD IS BROKEN DOWN HERE Muscles in the wall of the oesophagus contract, pushing food down to the stomach. This is called PERISTALSIS

20. peristalsis

22. Oesophagus wall Muscles in wall contract FOOD Food moves forwards PERISTALSIS

23. The stomach The strong muscle walls contract to churn and mix food with stomach juices called GASTRIC JUICES. Cells in the stomach wall produce a protease enzyme that digests proteins, breaking them down into amino acids.

24. The stomach cells also produce hydrochloric acid HCl, which • Lowers the pH for the protease enzyme to work • Kills bacteria • Stops salivary amylase from working A circular, sphinctermuscle at the exit of the stomach opens to allow food into the small intestine. It controls release of food from the stomach.

25. LEARNINGOUTCOMES to include: liver - the production of bile, its storage in the gall bladder and its actions in the duodenum in neutralisation of acids and emulsification of fats

26. LEARNINGOUTCOMES to include: duodenum - enzyme production by the pancreas and the duodenal wall to include carbohydrases, lipases and proteases

27. LEARNINGOUTCOMES to include: ileum - relate its structure to its function of absorption of digested food molecules and the ways it is adapted: large surface area (length, folds and villi), good blood supply, and thin and permeable membranes;

28. LEARNINGOUTCOMES SOME MAY… explain how the structure of a villus (finger-like shape, single layer of surface cells, capillary network and lacteal) is adapted for the efficient absorption of digested food molecules. HIGHER TIER

29. The liver Bile, made in the liver and stored in the gallbladder passes along the bile duct into the duodenum. Bile breaks fats into very small droplets, increasing the surface area for enzymes to work on. This is called emulsification. Bile is alkaline and therefore also neutralises acid from the stomach.

30. bile made in the liver passes into the gall bladder gall bladder digestive enzymes produced in pancreas pancreatic duct bile duct duodenum

31. The duodenum ENZYMES are added to the duodenum from: • The pancreas • The wall of the duodenum Carbohydrasesbreak down starch to sugars Proteases break down protein to amino acids Lipase breaks down fat to fatty acids and glycerol

32. The ileum Main function is absorption. The walls are adapted for efficient diffusion of the soluble products of digestion.

33. ridge covered with villi network of blood capillaries lacteal absorbs fatty acids single layer of epithelial cells villus muscle layer arteriole venuole

34. A villus sugar ileum wall Made of epithelial cells amino acids blood capillaries fatty acids lacteal to liver

35. how the ileum is adapted for absorption • Long length (5m), folds and villi increase the surface area for absorption • Villi contain blood vessels to carry away absorbed nutrients • Villi contain lacteals to carry away absorbed fats • The walls are thin, one cell thick, and permeable to form a short diffusion distance

36. The absorbed nutrients, amino acids and sugars are carried in the blood to the liver in the HEPATIC PORTAL VEIN.

37. LEARNINGOUTCOMES to include: colon - large surface area for water absorption; rectum & anus - storage and removal of faeces.

38. the colon NO DIGESTION OCCURS HERE The colon has a large surface area for the absorption of water from the fluid we drink, food we eat, mucus and digestive juices. It also absorbs mineral salts.

39. the rectum & anus Solid waste made up of undigested food, bacteria and cells from the gut forms faeces, which is stored in the rectum before passing out of the body through the anus.

40. transverse colon descending colon ascending colon rectum appendix anus

41. Summarybbc learning zoneclip 4180

42. dvd

43. Cut & stick activity