Unit 2: The continuation of life

1. Higher Human Biology Unit 2: The continuation of life Chapter 22: Delivery of Materials to cells (NUTRIENTS) Mrs Smith Ch22 The delivery of nutrients to cells

2. Learning Intentions Success Criteria Mrs Smith Ch22 The delivery of nutrients to cells To understand how nutrients are delivered by the bloodstream to every living cell in the body.. • Explain how glucose and amino acids, the end products of digestion of carbohydrates and proteins, are absorbed into the blood stream. • Identify the parts of a villusand explain how it is adapted to its function. • Describe the role of the lacteal in transport of absorbed lipid.

3. large insoluble food molecules small soluble molecules Preparation for nutrient absorption Food is moved along the alimentary canal from the mouth, to the small intestine by peristalsis. As this happens digestive enzymes breakdown….. View the Peristalsis animation: http://www.westga.edu/~lkral/peristalsis/ Mrs Smith Ch22 The delivery of nutrients to cells

4. SG Revision: Labelling exercise Rectum Large intestine Gall bladder anus liver Oesophagus Salivary glands Small intestine stomach appendix mouth Mrs Smith Ch22 The delivery of nutrients to cells Pancreas

5. Enzymes: Scholar Activity http://courses.scholar.hw.ac.uk/vle/scholar/session.controller?action=viewContent&contentGUID=e6928e85-bb13-a0f0-102d-f1072a4fcd30 Mrs Smith Ch22 The delivery of nutrients to cells

6. Answers Scholar Activity http://courses.scholar.hw.ac.uk/vle/scholar/session.controller?action=viewContent&contentGUID=e6928e85-bb13-a0f0-102d-f1072a4fcd30 Mrs Smith Ch22 The delivery of nutrients to cells

7. Small Intestine Digestive Enzymes: revision Digestive enzymes at various parts of the digestive system act on different types of food molecule… Mrs Smith Ch22 The delivery of nutrients to cells

8. 1. Small Intestine Mrs Smith Ch22 The delivery of nutrients to cells

9. 1. It is long 2. It has a folded inner lining covered in villi …So has a large surface area for absorption 4. The lining of each villi is one cell thick – so nutrients can pass through easily 1. Small Intestine The small intestine is well suited to food absorption because: 3. Each villus has a lacteal & blood capillary network for efficient transport of absorbed substances

10. Epithelial cells, bearing microvilli, project into the lumen of the gut Intestinal gland between the villi; contains enzyme secreting cells and hormone releasing cells Mrs Smith Ch22 The delivery of nutrients to cells

11. 2. Absorption of nutrients • Glucose and amino acids, the soluble end products of carbohydrate and protein digestion, are absorbed into the epithelial cells from where the pass directly into the blood capillaries. • The products of lipid digestion also pass to epithelial cells but instead of blood capillaries enter the central lacteal. Mrs Smith Ch22 The delivery of nutrients to cells

12. 2. Absorption of nutrients • Nutrients requiring no digestion by enzymes are also absorbed by the lining of the small intestine. These include calcium, iron and many vitamins. • Remember Vit B12 can only be absorbed if intrinsic factor (a poly peptide made by the stomach) is present to stimulate endocytosis by the membrane of the epithelial cells. Mrs Smith Ch22 The delivery of nutrients to cells

13. digestion 2. Absorption of nutrients Absorbed into blood large insoluble food molecules small soluble molecules B L O O D Carbohydrates Glucose amino acids Proteins fatty acids and glycerol phosphates Lipids Absorbed into lacteal Nutrients that don’t need to be digested (e.g. calcium, iron & vitamins) by enzymes are also absorbed by the small intestine. Mrs Smith Ch22 The delivery of nutrients to cells

14. Learning Intentions Success Criteria Mrs Smith Ch22 The delivery of nutrients to cells To understand how nutrients are delivered by the bloodstream to every living cell in the body. • Carry out an experiment to examine the effects of bile salts i) as an emulsifier and ii) on the activity of lipase

15. Bile salts Bile salts are…. Produced in the liver Stored in the gall bladder. Pass into the small intestine via the bile duct Mrs Smith Ch22 The delivery of nutrients to cells

16. Bile salts help us break down fat • Bile is necessary for efficient digestion of lipids. During a meal, bile is secreted from the gallbladder into the small intestine. In the small intestine, bile helps to break dietary fat into smaller particles, a process called emulsification. Emulsified fat can be more easily acted upon by digestive enzymes. Without bile, digestion and absorption of fat is incomplete. Mrs Smith Ch22 The delivery of nutrients to cells

17. A B A B A B Olive oil Olive oil Bile salts act as an emulsifier so oil still emulsified Bile salts solution Emulsification – oil droplets in water Water Water Investigating the effect of bile salts as an emulsifier Lipids are, insoluble in water and less dense than water (so float). Shaken Emulsifier = a substance that preserves emulsion. Mrs Smith Ch22 The delivery of nutrients to cells

18. Discussion • In test tube A, when the layers are shaken vigorously, the become mixed forming an EMUSION of tiny oil droplets. • This does not last long the oil droplets settle to the top into two distinct layers again. • In test tube B, when the layers are shaken vigorously, they again form EMUSION. • However in this case the emuslsuin does not separate into two separate layers. Mrs Smith Ch22 The delivery of nutrients to cells

19. Conclusion • An EMULSIFYER is an agent which reserves an emulsion. From this experiment it can be concluded that bile salts act as an emulsifier. Mrs Smith Ch22 The delivery of nutrients to cells

20. Droplet of lipid Bile salt molecule acting as an emulsifier Action of Bile Salts Bile salt molecule: • Head • water soluble • hyrdophilic (water-loving) • Tail • lipid soluble • hyrdophobic (water-hating) When shaken, with a lipid, the bile salt molecule becomes attached to the lipid with the lipid soluble tails pointing in to the centre. The heads are negatively charged so the lipid droplets repel each other and don’t rejoin. This is emulsification. Mrs Smith Ch22 The delivery of nutrients to cells

21. FYI: What are Gallstones • Gallstones form when bile hardens into a small pebble-like substance that can grow as big as a golf ball due to high cholesterol, too much bilirubin, or inadequate bile salts. In the event, when gallstones clog these ducts, it causes inflammation to the gallbladder wherein if it stays there for a longer period of time, it can result to a severe damage or infection to the gallbladdder, liver or pancreas. Mrs Smith Ch22 The delivery of nutrients to cells

22. Lipase • A digestive enzyme made in the pancreas • Active in the small intestine where it catalyses the breakdown of lipid molecules by cleaving off the first and third fatty acid molecules. Mrs Smith Ch22 The delivery of nutrients to cells

23. LIPASE Free fatty acids Lipid molecule (triglyceride) monoglyceride Lipase SUBSTRATE END PRODUCTS + Mrs Smith Ch22 The delivery of nutrients to cells

24. Universal indicator A B C A B C Olive oil Lipase Bile salts Bile salts Water No digestion from bile salts alone Lower pH shows bile salts aid digestion of lipid to fatty acid Acid conditions due to breakdown of lipids to fatty acids by lipase Investigating the effect of bile salts on the action of lipase Shaken + alkali added to make pH 7 then left for 30 mins in water bath at 37˚C pH 4 pH 5 pH 7 Mrs Smith Ch22 The delivery of nutrients to cells

25. Investigating the effect of bile salts on the action of lipase • Here the lipid substrate is being used in olive oil. • After 30 minutes the contents of tubes A and B are found to show a drop in pH indicating the presence of acidic conditions. • It is therefore concluded that lipase has promoted the breakdown of lipid to fatty acids in tubes A and B. Mrs Smith Ch22 The delivery of nutrients to cells

26. Significance of the control tube • Since no change in pH is found to occur in tube C, it is concluded that lipase is required to catalase the digestion of lipid and that bile salts alone are unable to bring about the digestive reaction Comparing tube A and B • A has undergone a greater drop in pH than B. It is therefore concluded that more digestion of lipid to fatty acids occurs when bile salts are present. Mrs Smith Ch22 The delivery of nutrients to cells

27. Droplet of lipid Bile salt molecule acting as an emulsifier Why do bile salts aid digestion by lipase? Bile salt molecules maintain an emulsion of lipid droplets. This increases the relative surface area of the lipid exposed to the lipase enzyme, so increases the number of substrate molecules that the enzyme can act on, thus aiding digestion. Mrs Smith Ch22 The delivery of nutrients to cells

28. Absorption of the end products of lipid digestion Following digestion, monoglyceridesand fatty acids, the end products of lipid digestion, combine with bile salts to form tiny water-soluble particles called micelles. Micelles move to the surface of the intestinal epithelium, which has microvilli. Fatty acids and monoglyceride molecules leave the micelles and diffuse through the cell membrane into the epithelium.

29. Video: Micelles Mrs Smith Ch22 The delivery of nutrients to cells

30. E.R. fatty acids Lipid molecule (triglyceride) monoglyceride Exocytosis Lipoprotein coat Absorbed by lacteal Absorption of the end products of digestion After passing through the epithelium of the microvilli, the monoglycerides & fatty acids pass into the cell’s endoplasmic reticulum to be built back intolipidmolecules (triglycerides). + They are then coated with lipoprotein and move out of the cell by exocytosis. They get absorbed by the lacteal and are transported via the lymphatic system to the blood. Mrs Smith Ch22 The delivery of nutrients to cells

31. Task: Torrance-TYK pg169 Qu 1-3 Mrs Smith Ch22 The delivery of nutrients to cells

32. Learning Intentions Success Criteria Mrs Smith Ch22 The delivery of nutrients to cells To understand how nutrients are delivered by the bloodstream to every living cell in the body. • Explain why the liver needs a dual blood supply • Analyse data on the composition of plasma of hepatic artery, hepatic vein and hepatic portal vein.

33. 4. The Liver Hepatic vein carries deoxygenatedblood from the liver to the vena cava Hepatic artery carries oxygenated blood to liver Hepatic portal vein carries deoxygenatedblood to the liver directly from the gut Mrs Smith Ch22 The delivery of nutrients to cells

34. Portal System • The portal system is circulation where blood in a capillary bed (e.g. gut) passes through a vein (e.g. hepatic portal vein) and into a second capillary bed(e.g. liver) before returning the normal circulation system. • This prevents the end products of digestion entering directly into the circulation system. They are passed through the liver instead, which removes anything toxic by metabolism or excretion and converts nutrients into useable or stored forms . Mrs Smith Ch22 The delivery of nutrients to cells

35. Composition of plasma Try the scholar activity: http://courses.scholar.hw.ac.uk/vle/scholar/session.controller?action=viewContent&contentGUID=8f30977c-4cb9-fe59-4dfa-86bf98b62bdd Hepatic vein contains normal blood plasma concentrations of glucose & amino acids + high urea concentration Hepatic artery contains blood with all essential nutrients + normal urea concentration Hepatic portal vein contains blood plasma with high concentrations of the end products of digestion + normal urea concentration • In liver: • excess glucose stored as glycogen • excess amino acid converted to urea Mrs Smith Ch22 The delivery of nutrients to cells

36. Scholar Activity Try the scholar activity: http://courses.scholar.hw.ac.uk/vle/scholar/session.controller?action=viewContent&contentGUID=ae01a001-7a3a-b119-c268-9aa0c7ae8160 Mrs Smith Ch22 The delivery of nutrients to cells

37. Answers: Scholar Activity Try the scholar activity: http://courses.scholar.hw.ac.uk/vle/scholar/session.controller?action=viewContent&contentGUID=ae01a001-7a3a-b119-c268-9aa0c7ae8160 Mrs Smith Ch22 The delivery of nutrients to cells

38. Image source: .biomed.brown.edu 5. Role of the Liver in MetabolismA. Carbohydrate metabolism • Animals gain glucose by eating carbohydrates. The liver regulates the concentration of the glucose in the blood (blood sugar). • After a carbohydrate rich meal, blood entering the liver by the hepatic portal vein contains a concentration of glucose in excess of the bodies immediate requirements. • In response to the hormone insulin from the pancreas, an enzyme in the liver promotes the conversion glucose to glycogen Mrs Smith Ch22 The delivery of nutrients to cells

39. Image source: .biomed.brown.edu 5. Role of the Liver in MetabolismA. Carbohydrate metabolism • Up to 100g of excess glucose is stored in the liver as glycogen. Any more excess glucose is stored as lipids in the body’s fat reserves. • If glucose is needed the glycogen breaks down releasing the glucose into the bloodstream. • When the blood’s sugar level is low, a different hormone called glucagon is secreted by the pancreas. • This activates a different enzyme in the liver which promotes the conversion of glycogen to glucose. • Glucose is then released into the blood stream for use by living cells. Insulin Glucose Glycogen Glucagon

40. 5. Role of the Liver in MetabolismB. Lipids Liver cells remove certain lipid molecules from blood and alter them to make other lipids e.g. cholesterol. • Cholesterol in cell membranes needed to make steroid hormones are synthesised in liver • Excess cholesterol is processed by the liver & excreted in bile Lipoproteins - formed in the liver Mrs Smith Ch22 The delivery of nutrients to cells

41. Fat-soluble vitamins are stored in liver cells e.g. Vitamins A, D, E & K Mrs Smith Ch22 The delivery of nutrients to cells Image sources: www.nlm.nih.gov

42. Mrs Smith Ch22 The delivery of nutrients to cells Image sources: www.nlm.nih.gov

43. Image sources: www.nlm.nih.gov

44. 5. Role of the Liver in MetabolismC. Proteins 3 types of plasma proteins are made in the liver. The amino acids needed for this are absorbed from the bloodstream by liver cells. Albumins Cause osmotic return of water from tissue fluid in capillary beds Globulins Cause transport of lipids and fat-soluble vitamins Fibrinogen Have an essential role in clotting of blood . Transaminase enzymes in liver cells can convert one amino acid to another. So even when amino acids aren’t obtained from food, many can be synthesised by the liver cells. Mrs Smith Ch22 The delivery of nutrients to cells

45. 6. Fate of absorbed materials Mrs Smith Ch22 The delivery of nutrients to cells

46. 6. Fate of absorbed materials D. Vitamins & minerals Some vitamins & minerals absorbed from food play a key role in enzyme reactions: • Metal ions • Zinc • Iron • Copper • Magnesium Enzyme activators = Co-factors Co-enzyme = a small non-protein co-factor composed of an organic substance (e.g. a vitamins). Iron = the co-factor responsible for activating the enzyme catalase. Vitamin B = an essential component of co-enzymes: acts as hydrogen carriers during aerobic respiration Mrs Smith Ch22 The delivery of nutrients to cells

47. What is the function of villi? • What is the name given to the central lymph vessel in a villus? • Which foodstuffs are transported by lacteals. • What substances are required for the proper absorption of vit B12. • What is the name of the process in which amino acids are broken down in the liver? • What is the toxic end-product of this process? • Where is bile stored? • What is the prime function of bile? • What vitamins can be stored in the liver? Mrs Smith Ch22 The delivery of nutrients to cells

48. To increase the surface area of the small intestine for the absorption of food. • Lacteal • Fats. • Intrinsic Factor • Deamination • Urea • In the gall bladder • Bile emulsifiers (breaks up) fats. • A,B12 and D Mrs Smith Ch22 The delivery of nutrients to cells

49. Label the diagram best you can to describe the blood flow to the Liver

50. Liver – Morton sheet Pulmonary Artery Pulmonary Vein Aorta Vena cava Hepatic Artery Hepatic Vein Hepatic Portal Vein