Unit 23: The Continuation of Life

1. Higher Human Biology Unit 23: The Continuation of Life Chapter 23: Removal of Materials from the Blood. Mrs Smith Ch23 The Removal of Materials from Blood

2. Learning Intentions Success Criteria Mrs Smith Ch22 The delivery of nutrients to cells To understand how the liver, lungs and kidneys are involved in the removal of materials from the blood. • Describe the role of the liver in: • Conservation of useful substances • Detoxification of toxic materials • Removal of bilirubin • Production of urea

3. The liver The lungs Removal of materials from the body The circulatory system is vital for the removal of materials from the body. The main organs that help remove unwanted materials are: The kidney Mrs Smith Ch23 The Removal of Materials from Blood

4. So CO2 diffuses out of the blood into the lungs down a concentration gradient. Breathing, which exhales air rich in CO2, maintains this gradient. 1. The Lungs • Carbon Dioxide is a waste product of respiration • CO2 is transported to the lungs, via the blood plasma, to be removed from the body in the form of bicarbonate ions (HCO-3). • As blood flows through the pulmonary system these bicarbonate ions combine with hydrogen ions (H+) to form carbonic acid (H2CO3). An enzyme then breaks the carbonic acid down into water and CO2: enzyme + H2CO3 H2O CO2 Concentration of CO2 in blood plasma > Concentration CO2 in air Mrs Smith Ch23 The Removal of Materials from Blood

5. Diffusion in the alveoli Mrs Smith Ch23 The Removal of Materials from Blood

6. Excretion of carbon dioxide Excretion = the elimination of waste products of metabolism • e.g. • Removal of CO2 (waste product of respiration) at the lungs. • Release of bile pigment in bile. Mrs Smith Ch23 The Removal of Materials from Blood

7. 2. Role of Liver The liver removes materials from the blood by: • Conservation of useful substances. • e.g. glucose, plasma proteins • Detoxification of toxic materials which are potentially toxic. • Removal of bilirubin and its excretion as bile. • Production of urea. Liver maintains a stable internal environment, and provides cells with optimum conditions Mrs Smith Ch23 The Removal of Materials from Blood

8. 3 types of • Plasma proteins • Maintains a stable pool • some undergo deamination in the liver • meanwhile new molecules are synthesised • Glucose • Level regulated • excess stored as glycogen which can be converted to glucose as needed. • Components of blood plasma Regulated • Stable internal environment maintained • living cells have optimum conditions for growth & development Liver: Conservation of useful substances Mrs Smith Ch23 The Removal of Materials from Blood

9. Detoxification of toxic materials • Certain substances which gain access to or are produced by the body as a result of metabolic reactions are potentially toxuc. • They would do the body harm if left unaltered. • These substances are detoxified by liver cells. Mrs Smith Ch23 The Removal of Materials from Blood

10. Detoxification occurs in one of 4 ways • Substances are detoxified by liver cells in one of 4 ways….. • Chemical Alteration • Chemical Breakdown • Chemical attachment (conjugation). • Uptake by macrophages Mrs Smith Ch23 The Removal of Materials from Blood

11. A. Chemical alteration • Biologically active molecules (e.g. Drugs) are rendered inactive by being chemically altered in the liver. • The products are then excreted in bile or released into the bloodstream and removed by the kidneys. Mrs Smith Ch23 The Removal of Materials from Blood

12. B. Chemical breakdown Hydrogen peroxide, a highly toxic by-product of metabolism is broken down by the enzyme catalase into harmless substances. Liver cells are rich in catalase. catalase 2H2O2 2H2O + O2 Harmless TOXIC Mrs Smith Ch23 The Removal of Materials from Blood

13. B. Chemical breakdown • Alcohol(ethanol) gets converted in the liver, by a series of enzyme –controlled steps to acetyl CoA, which acts as a respiratory substrate for aerobic respiration. • Too much alcohol damages cells. Regular consumption of alcohol to excess can cause permanent liver damage leading to a fatal liver condition called cirrhosis. Mrs Smith Ch23 The Removal of Materials from Blood

14. C. Chemical attachement • Some unwanted substances (e.g. Certain types of food preservative) become attached to liver cells to the amino acid glycerine. • This acts as a molecular label which is recognised as waste by the kidneys and excreted. Mrs Smith Ch23 The Removal of Materials from Blood

15. D. Uptake by macrophages • Foreign particles are removed by macrophages (phagocytic cells) which line the liver’s blood vessels. • If for example an animal is injected intravenously with a suspension of carbon particles, samples of liver obtained only minutes later show numerous carbon-laden macrophage cells. Mrs Smith Ch23 The Removal of Materials from Blood

16. Liver: Detoxification of Materials: SUMMARY Toxic substances, that have either been eaten or produced in metabolic reactions, must be destroyed to prevent them harming the body. Liver cells detoxify such substances. Detoxification by liver cells Uptake by macrophages Macrophages line the liver’s blood vessels removing foreign particles Chemical alteration Biologically active molecules altered in the liver. Chemical attachment (conjugation) Unwanted substance become attached by liver cells to the amino acid glycine. Products excreted in bile or released into blood and removed by kidneys This acts as a chemical label which is recognised as a waste by the kidneys and excreted Chemical breakdown (see next page)

17. Learning Intentions Success Criteria Mrs Smith Ch22 The delivery of nutrients to cells To understand how the liver, lungs and kidneys are involved in the removal of materials from the blood. • 3. Describe the role of the liver in: • Conservation of useful substances • Detoxification of toxic materials • Removal of bilirubin • Production of urea

18. 3. Removal of bilirubin • When red blood cells reach the end of their 120 day life span, they are destroyed by macrophage cells in the liver, bone marrow and spleen, • Haemoglobin is broken down by theses cells into a yellow pigment called bilirubin. Biliruben is releases into the blood giving blood plasma its yellowish colour. Mrs Smith Ch23 The Removal of Materials from Blood

19. Excretion of bilirubin • Bilirubin molecules, removed from the blood plasma by the liver, are added to bile with the aid of enzymes and become bile pigment (Conjugated bilirubin). This has no useful role in digestion so is released in bile. • In the gut, bilirubin is converted by bacteria to the brown pigment that gives faeces its brown colour. Mrs Smith Ch23 The Removal of Materials from Blood

20. 4. Jaundice Bilirubin accumulates in the bloodstream when: • Liver cells can’t absorb bilirubin (due to illness e.g. hepatitis). • The bile duct becomes blocked preventing the release of bile to small intestine. • Red blood cell destruction is excessively high. Mrs Smith Ch23 The Removal of Materials from Blood

21. 4. Jaundice Jaundice is caused by excessively high concentrations of bilirubin. Baby’s can be screened for Bilirubin using a light meter that is placed on the baby’s head.

22. Learning Intentions Success Criteria Mrs Smith Ch22 The delivery of nutrients to cells To understand how the liver, lungs and kidneys are involved in the removal of materials from the blood. Determining the quantity of urea in urine samples

23. Production of Urea: Deamination • Unlike carbohydrate and lipid, protein is not stored in the body. Excess amino acids are absorbed from the gut then undergo deaminationin liver cells. • De-amination needs oxygen • It produces an organic acid • It produces ammonia which goes to the ornithine cycle. Mrs Smith Ch23 The Removal of Materials from Blood

24. Organic acid (Kreb cycle intermediate or pyruvic acid) Ammonia 5. Production of urea During this process, the amino acid is broken down to form ammonia and an organic acid. Used for energy release in respiation Breakdown of amino acids + CO2 Passes into blood and leaves the liver by the hepatic vein. It is removed from the blood at the kidneys. Very toxic Urea + H2O Less toxic Mrs Smith Ch23 The Removal of Materials from Blood

25. Fate of deaminated amino acids • Depending on which amino acid has been deaminated the organic acid may be pyruvic acid or one of Krebs Cycle intermediates. • It can then enter the respiratory pathway or be used for energy release. Mrs Smith Ch23 The Removal of Materials from Blood

26. Ornithine cycle • Since ammonia is formed during deamination of an amino acid is highly toxic, it is immediately passed to the ornithine cycle. • This cycle is controlled by enzymes in the liver cells. • Here Ornithine is constantly regenerated. • During this cycle , ammonia reacts with carbon dioxide to form less toxic urea and water. Mrs Smith Ch23 The Removal of Materials from Blood

27. Urea production • During the conversion of ammonia into urea, two molecules of ammonia and one molecule of carbon dioxide combine to form one molecule of urea and one of water. Assisting this process there is a cyclical conversion of ornithine into citrulline, arginine, and then back to ornithine again. Mrs Smith Ch23 The Removal of Materials from Blood

28. Where does the urea go? • Urea is then passed into the bloodstream and then leaves the liver by the hepatic vein. • It is removed from blood by the kidneys. Mrs Smith Ch23 The Removal of Materials from Blood

29. urease Determining the quantity of urea in ‘urine’ samples The combination of urea with water is catalysed by the enzyme urease: + Urea H2O ammonium carbonate (an alkali) The quantity of urea in the original solution is directly related to the quantity of alkali produced. This can be determined by the volume of acid needed to neutralise the alkali. Methyl orange, an indicator, is used to show the change from alkali (orange) to acid (red). Mrs Smith Ch23 The Removal of Materials from Blood

30. Using solutions of known concentration to plot a calibration graph Using urea solutions of known concentration a calibration graph can be drawn. • Four solutions of know urea concentration are made up. • Following enzyme activity at 37oC, each solution is titrated against hydrochloric acid. • The volume of hydrochloric acid needed to neutralise the alkali in each solution is indicated by methyl orange changing colour. • This is repeated for each conc many times and results are pooled and averaged. • The results are then plotted to make a calibration graph. Mrs Smith Ch23 The Removal of Materials from Blood

31. Urea Concentration Calibration Curve Mrs Smith Ch23 The Removal of Materials from Blood

32. Optimum temperature for enzyme activity Using a calibration graph to calculate the urea content of unknown samples The following experiment is carried out on a sample of urine (urea concentration unknown) and compared to the calibration curve. Many repeats done to increase reliability of results. to increase surface area to aid mixing of enzyme & substrate + 2 crushed urease tablets Flasks shaken at 15min intervals After 90 mins, 20 drops of methyl orange added + 0.1M HCl until indictor turns red In water bath at 37oC for 90 mins 50 cm3 urea solution (urea + water) Mrs Smith Ch23 The Removal of Materials from Blood

33. Task: Torrance-TYK pg178 Qu 1-3 Mrs Smith Ch20: Transport Mechanisms - The Cardiac Cycle

34. Learning Intentions Success Criteria Mrs Smith Ch22 The delivery of nutrients to cells To understand how the liver, lungs and kidneys are involved in the removal of materials from the blood. • Label a diagram of a kidney nephron • Explain the mechanism of kidney function to include • Ultrafiltration

35. 6. Structure of the Kidney Mrs Smith Ch23 The Removal of Materials from Blood

36. 6.The Kidneys: Structure Each kidney has about a million tiny filtering units called nephrons.

37. glomerulus Bowman's capsule nephron blood capillaries collecting duct Each nephron is composed of several part The capillaries in the glomerulus are narrower than the capillary that supplied it with blood. What effect will this have on the blood pressure in the glomerulus?

38. Nephrons • Each nephron is composed of several parts. • A glomerulus is enclosed in a cup-shaped Bowman’s capsule which leads into a long kidney tubule surrounded by a dense network of blood capillaries. • Two regions of the tubule possess several twists and turns and are therefore described as convoluted. The proximal convoluted tubule is the twisted region at the greater distance from the Bowman’s capsule. • The long, U-shaped stretch of tubule between the convoluted regions is called the loop of Henle. • Each kidney tubule leads to a communal collecting duct. Mrs Smith Ch23 The Removal of Materials from Blood

39. Bowman’s capsule Loop of Henle The Kidney Nephron Has many twists & turns Knot of tiny blood vessels The blood enters the nephron via the renal arteryand leaves via the renal vein. At theglomerulusthe blood is filtered and the filtrate gathers in the bowman’s capsule. The filtrate then passes along the tubule to the communal collecting duct.

40. The Kidneys: Function: Production of Urine • The kidneys remove waste material from the blood and excrete them in urine. • The production of urine involves the • ultrafiltration of blood • reabsorption of useful materials from the filtrate. • Since urine contains urea, a nitrogenous waste, the kidneys are described as organs of nitrogenous excretion. Mrs Smith Ch23 The Removal of Materials from Blood

41. 7. Ultrafiltration • Ultrafiltration happens at the Bowman’s capsule. • Blood containing waste products enters the kidney by the renal artery which divides into about a million branches each supplying a glomerulus. • Each glomerulus consists of a coiled knot of blood capillaries. This arrangement enables a large surface area of blood vessel to be in contact with the inner lining of the Bowman’s capsule. • It is at this interface ultrafiltration takes place Mrs Smith Ch23 The Removal of Materials from Blood

42. Mrs Smith Ch23 The Removal of Materials from Blood

43. Ultrafiltration- Basement membrane filter. The layer of cells which makes up the capillary wall of a glomerulus differs from a normal capillary because..... • It has pores which are large enough to let ALL the substances within plasma pass through. • The porous layer is attached to a highly permeable thin layer of non-living material called the basement membrane. • The basement membrane has no pores but acts as a filter that... • Allows small molecules such as glucose, water, salts & urea to pass through. • Prevents large molecules of plasma protein from leaving the blood stream. Mrs Smith Ch23 The Removal of Materials from Blood

44. water ions protein urea Protein molecules pass through the fenestrated endothelial layer of the capillaries, but are prevented from passing into the cavity of Bowman’s capsule by the basement membrane glucose Mrs Smith Ch23 The Removal of Materials from Blood

45. Blood Pressure • Plasma proteins which remain in the blood plasma tend to draw water back from the filtrate in the capsule by osmosis. • In addition filtrate already present in the capsule tends to resist the delivery of further filtrate into the capsule. • Successful ultrafiltration of blood depends on the blood in the glomeruli being at high enough pressure to overcome both of these factors and force filtrate out of the plasma. Mrs Smith Ch23 The Removal of Materials from Blood

46. Ultrafiltration and Blood Pressure. • High blood pressure in the glomerulus is needed to force the filtrate out of the blood plasma. This is maintained because: • The blood vessels leading to the glomerulus come from the renal artery, which is a branch from the aorta so carries blood at high pressure • The blood vessels entering the glomerulus are wider than the blood vessels leaving it, causing a bottle-neck and the blood to be squeezed Did you know? An adult has ~ 4.5 l of blood, but the kidneys filter ~ 1500 l of blood/day! Mrs Smith Ch23 The Removal of Materials from Blood

47. Ultrafiltration – Rate of production of filtrate and urine. • A human adult contains about 4.5 litres of blood. • During its continuous circulation round the body, blood repeatedly enters the kidneys and undergoes filtration. • Each day a human adult’s kidneys filter a total volume of around 1500 litres of blood and produce about 180 litres of glomerular filtrate. • However the production of urine is only about 1-2 litres. Mrs Smith Ch23 The Removal of Materials from Blood

48. Learning Intentions Success Criteria Mrs Smith Ch22 The delivery of nutrients to cells To understand how the liver, lungs and kidneys are involved in the removal of materials from the blood. • Explain the mechanism of kidney function to include • Re-absorption

49. 8. Reabsorption About 180 l of glomerular filtrate is produced every day but only 1-2 l of urine is produced, because ~ 99% of the water in the filtrate is reabsorbed into the bloodstream. Apart from the plasma proteins and water, the chemicals in blood plasma and glomerular filtrate are very similar. Reabsorption occurs at various points along the tubule that come into contact with the blood capillaries. Mrs Smith Ch23 The Removal of Materials from Blood

50. A. Reabsorption of Salts: Proximal convoluted tubule Glucose & amino acids absorbed by epithelial cells lining the tubule. 90% Sodium ions (Na+) from glomerular filtrate actively pumped across epithelial cells, as they are combined with Chloride (Cl-) ions in the form of salt, they to pass into the blood