Higher Human Biology Unit 2 The continuation of

Higher Human Biology Unit 2: The continuation of life Chapter 22: Delivery of Materials to cells (NUTRIENTS) 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 1

Learning Intentions To understand how nutrients are delivered by the bloodstream to every living cell in the body. . 31/10/2020 Success Criteria 1. Explain how glucose and amino acids, the end products of digestion of carbohydrates and proteins, are absorbed into the blood stream. 2. Identify the parts of a villus and explain how it is adapted to its function. 3. Describe the role of the lacteal in transport of absorbed lipid. Mrs Smith Ch 22 The delivery of nutrients to cells 2

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…. . large insoluble food molecules View the Peristalsis animation: 31/10/2020 http: //www. westga. edu/~lkral/peristalsis/ Mrs Smith Ch 22 The delivery of nutrients to cells small soluble molecules 3

SG Revision: Labelling exercise Rectum Large intestine Gall bladder anus liver Oesophagus Salivary glands Small intestine stomach appendix mouth 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 4 Pancreas

Enzymes: Scholar Activity http: //courses. scholar. hw. ac. uk/vle/scholar/session. controller ? action=view. Content&content. GUID=e 6928 e 85 -bb 13 -a 0 f 0102 d-f 1072 a 4 fcd 30 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 5

Answers Scholar Activity http: //courses. scholar. hw. ac. uk/vle/scholar/session. controller ? action=view. Content&content. GUID=e 6928 e 85 -bb 13 -a 0 f 0102 d-f 1072 a 4 fcd 30 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 6

Digestive Enzymes: revision Digestive enzymes at various parts of the digestive system act on different types of food molecule… Small Intestine 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 7

1. Small Intestine 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 8

1. Small Intestine The small intestine is well suited to food absorption because: 1. It is long 2. It has a folded inner lining covered in villi …So has a large surface area for absorption 3. Each villus has a lacteal & blood capillary network for efficient transport of absorbed substances 31/10/2020 4. The lining of each villi is one cell thick – so nutrients can pass through easily 9

Epithelial cells, bearing microvilli, project into the lumen of the gut Intestinal gland between the villi; contains enzyme secreting cells and hormone releasing cells 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 10

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. 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 11

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 B 12 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. 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 12

2. Absorption of nutrients large insoluble food molecules digestion small soluble molecules Carbohydrates Glucose Proteins amino acids Lipids fatty acids and glycerol phosphates Nutrients that don’t need to be digested (e. g. calcium, iron & vitamins) by enzymes are also absorbed by the small intestine. 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells Absorbed into blood B L O O D Absorbed into lacteal 13

Learning Intentions To understand how nutrients are delivered by the bloodstream to every living cell in the body. 31/10/2020 Success Criteria 4. Carry out an experiment to examine the effects of bile salts i) as an emulsifier and ii) on the activity of lipase Mrs Smith Ch 22 The delivery of nutrients to cells 14

Bile salts are…. Produced in the liver Stored in the gall bladder. Pass into the small intestine via the bile duct 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 15

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. 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 16

Investigating the effect of bile salts as an emulsifier Lipids are, insoluble in water and less dense than water (so float). A Olive oil B A B Shaken Olive oil Water Bile salts solution Emulsification – oil droplets in water Water Emulsifier = a substance that preserves emulsion. 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells Bile salts act as an emulsifier so oil still 17 emulsified

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. 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 18

Conclusion • An EMULSIFYER is an agent which reserves an emulsion. From this experiment it can be concluded that bile salts act as an emulsifier. 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 19

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 Droplet of lipid so the lipid droplets repel each other and Bile salt molecule acting don’t rejoin. This is emulsification. as an emulsifier 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 20

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. 31/10/2020 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 Ch 22 The delivery of nutrients to cells 21

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. 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 22

Lipase SUBSTRATE END PRODUCTS LIPASE + Lipid molecule (triglyceride) 31/10/2020 monoglyceride Mrs Smith Ch 22 The delivery of nutrients to cells Free fatty acids 23

Investigating the effect of bile salts on the action of lipase Universal indicator A B C Shaken + alkali added to make p. H 7 Olive oil then left for 30 mins in water bath at 37˚C Lipase Bile salts 31/10/2020 Water Bile salts p. H 4 Lower p. H shows bile salts aid digestion of lipid to fatty acid p. H 5 p. H 7 Acid conditions due to breakdown of lipids to fatty acids Mrs Smith Ch 22 The delivery of by lipase nutrients to cells No digestion from bile salts 24 alone

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 p. H 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. 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 25

Significance of the control tube • Since no change in p. H 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 p. H than B. It is therefore concluded that more digestion of lipid to fatty acids occurs when bile salts are present. 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 26

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. Droplet of lipid 31/10/2020 Bile salt molecule acting as an emulsifier Mrs Smith Ch 22 The delivery of nutrients to cells 27

Absorption of the end products of lipid digestion Following digestion, monoglycerides and fatty acids, the end products of lipid digestion, combine with bile salts to form tiny water-soluble particles called micelles. 31/10/2020 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. 28

Video: Micelles 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 29

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 into lipid molecules (triglycerides). + monoglyceride fatty acids Lipid molecule (triglyceride) E. R. 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. 31/10/2020 Exocytosis Lipoprotein coat Mrs Smith Ch 22 The delivery of nutrients to cells Absorbed by lacteal 30

Task: Torrance-TYK pg 169 Qu 1 -3 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 31

Learning Intentions To understand how nutrients are delivered by the bloodstream to every living cell in the body. 31/10/2020 Success Criteria 5. Explain why the liver needs a dual blood supply 6. Analyse data on the composition of plasma of hepatic artery, hepatic vein and hepatic portal vein. Mrs Smith Ch 22 The delivery of nutrients to cells 32

4. The Liver Hepatic vein carries deoxygenated blood from the liver to the vena cava Hepatic artery carries oxygenated blood to liver Hepatic portal vein carries deoxygenated blood to the liver directly from the gut 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 33

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. 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 34

Composition of plasma Try the scholar activity: http: //courses. scholar. hw. ac. uk/vle /scholar/session. controller? action= view. Content&content. GUID=8 f 3097 7 c-4 cb 9 -fe 59 -4 dfa-86 bf 98 b 62 bdd 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 In liver: • excess glucose stored as glycogen • excess amino acid converted to urea 31/10/2020 Hepatic portal vein contains blood plasma with high concentrations of the end products of digestion + normal urea concentration Mrs Smith Ch 22 The delivery of nutrients to cells 35

Scholar Activity Try the scholar activity: http: //courses. scholar. hw. ac. uk/vle/scholar/session. controller? action=view. Content&content. GUID =ae 01 a 001 -7 a 3 a-b 119 -c 268 -9 aa 0 c 7 ae 8160 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 36

Answers: Scholar Activity Try the scholar activity: http: //courses. scholar. hw. ac. uk/vle/scholar/session. controller? action=view. Content&content. GUID =ae 01 a 001 -7 a 3 a-b 119 -c 268 -9 aa 0 c 7 ae 8160 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 37

5. Role of the Liver in Metabolism A. 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 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 38 Image source: . biomed. brown. edu

5. Role of the Liver in Metabolism A. Carbohydrate metabolism • Up to 100 g 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. Image source: . biomed. brown. e

5. Role of the Liver in Metabolism B. 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 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 40

Fat-soluble vitamins are stored in liver cells e. g. Vitamins A, D, E & K 31/10/2020 Image sources: www. nlm. nih. gov Mrs Smith Ch 22 The delivery of nutrients to cells 41

31/10/2020 Image sources: www. nlm. nih. gov Mrs Smith Ch 22 The delivery of nutrients to cells 42

43 Image sources: www. nlm. nih. gov

5. Role of the Liver in Metabolism C. 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 Globulins Fibrinogen Cause osmotic return of water from tissue fluid in capillary beds Cause transport of lipids and fatsoluble vitamins 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. 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 44

6. Fate of absorbed materials Material Use In Body Fate of Excess Carbohydrate Glucose used by cells to obtain energy (for aerobic respiration) Stored as glycogen in liver and muscles as fat in fatty tissues Used by cells as a source of energy Converted back to lipid & stored in fatty (adipose) tissue Lipids Proteins 31/10/2020 Amino acids used for NOT STORED some protein synthesis (e. g. used as an energy source to produce enzymes, by cells following hormones, deamination in liver (converted to urea) Mrs Smith Ch 22 The delivery of 45 antibodies) nutrients to cells

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. 31/10/2020 Vitamin B = an essential component of co-enzymes: acts as hydrogen carriers respiration 46 Mrs Smith Ch 22 during The delivery aerobic of nutrients to cells

1. 2. 3. 4. 5. 6. 7. 8. 9. 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 B 12. 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? 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 47

1. To increase the surface area of the small intestine for the absorption of food. 2. Lacteal 3. Fats. 4. Intrinsic Factor 5. Deamination 6. Urea 7. In the gall bladder 8. Bile emulsifiers (breaks up) fats. 9. A, B 12 and D 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 48

Label the diagram best you can to describe the blood flow to the Liver 31/10/2020 49

Liver – Morton sheet Pulmonary Artery Pulmonary Vein Aorta Vena cava Hepatic Artery Hepatic Vein 31/10/2020 Hepatic Portal Vein 50

Label A, B and C and organ X, try other bits if you can 31/10/2020 51

Class Worksheet Aorta Hepatic Artery Hepatic Vein Vena Cava Gall bladder Hepatic Portal Vein 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 52

Essay Questions: 2005 Describe the functions of the liver under the following headings 1. Production of urea. (2) 2. Metabolism of carbohydrates. (5) 3. Breakdown of red blood cells. (3) 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 53

Task: Torrance-TYK pg 172 Qu 1 -4 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 54

Task: Torrance AYK pg 173 -4 Qu’s 1 -4 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 55

Humour? 31/10/2020 Mrs Smith Ch 22 The delivery of nutrients to cells 56