23/8/2023 Chapter 8 Excretion in Humans Biology Matters for GCE ‘O’ Level (3Ed) 1 © 2023 Marshall Cavendish Education Pte Ltd 1 Are all the food that we eat get digested by the body? What happens to those that does not get digested? What is this process called? 2 © 2023 Marshall Cavendish Education Pte Ltd 2 1 23/8/2023 Sweating also helps to get rid of substances in the body that are not needed. Is sweating egestion? 3 © 2023 Marshall Cavendish Education Pte Ltd 3 Chapter 8 Excretion in Humans • 8.1 Why is Excretion Necessary? • 8.2 What Makes Up the Human Urinary System? • 8.3 How Is Urine Formed? • 8.4 What Is Osmoregulation? • 8.5 What Happens When the Kidneys Fail? 4 © 2023 Marshall Cavendish Education Pte Ltd 4 2 23/8/2023 Learning Outcome(s) • Define excretion and explain the importance of removing nitrogenous and other compounds from the body. 5 © 2023 Marshall Cavendish Education Pte Ltd 5 “Trigger” 1. What is excretion? How does it take place in humans? 2. What is a protein-high diet? What are some effects of this diet? 3. What are kidney stones? How does it affect a person? What should this person do? 6 © 2023 Marshall Cavendish Education Pte Ltd 6 3 23/8/2023 Textbook Page 152 Why Is Excretion Necessary? Chemical activities or metabolic activities occurs all the time in the body while carrying out life processes to sustain life. Produce harmful or toxic substances that are not needed by the body metabolic waste products or excretory products 7 Need to be removed by the body © 2023 Marshall Cavendish Education Pte Ltd 7 What Are Metabolic Waste Products? • Carbon dioxide • Urea • Mineral salts or ions CO2 Textbook Pages 152–153 Can you name some examples of metabolic waste products? CO(NH2)2 • Water H2O 8 Na+ Ca2+ © 2023 Marshall Cavendish Education Pte Ltd 8 4 23/8/2023 Textbook Page 152 Metabolic Waste Product: CO2 • waste product of aerobic respiration • remove through gaseous exchange in the lungs Abnormally high level of CO2 in the blood may lead to conditions such as headaches, confusion and rapid breathing. 9 Recall what you have learnt in Chapter 7 Respiration. © 2023 Marshall Cavendish Education Pte Ltd 9 Metabolic Waste Product: Urea Textbook Page 152 Proteins in food amino acids used by the body Abnormally high level of urea in blood may cause conditions such nausea and vomiting. excess liver urea excreted deamination 10 © 2023 Marshall Cavendish Education Pte Ltd 10 5 23/8/2023 Eating food high in protein increase urea level in blood. Textbook Page 152 Meats are high in protein. What are other examples of highprotein food? dairy, nuts, legumes 11 © 2023 Marshall Cavendish Education Pte Ltd 11 Metabolic Waste Product: Mineral Salts or Ions Textbook Page 153 Mineral salts or ions in food used by the body excess excreted 12 Challenge: What will happen if there is a high level of salts in the blood? © 2023 Marshall Cavendish Education Pte Ltd 12 6 23/8/2023 Metabolic Waste Product: H2O Textbook Page 153 • Produced as waste product of aerobic respiration From food and drink used by the body excess excreted 13 Challenge: What will happen if there is too much water in the body? © 2023 Marshall Cavendish Education Pte Ltd 13 Excretion is …. Textbook Pages 153–154 the process of removing metabolic waste products, toxic substances and excess substances from the body. Excretion is important … so that harmful substances will not build up in the body to cause harm. 14 © 2023 Marshall Cavendish Education Pte Ltd 14 7 23/8/2023 Have you tasted your own sweat? What does it taste like? Why do you think it has that taste? 15 © 2023 Marshall Cavendish Education Pte Ltd 15 Main Excretory Products and Their Excretory Organs 16 Textbook Page 153 © 2023 Marshall Cavendish Education Pte Ltd 16 8 23/8/2023 Concept Cartoon Textbook Page 154 Antiperspirant reduce sweating. Three people in the picture are discussing if it should be used while exercising. Comment on their views. 17 © 2023 Marshall Cavendish Education Pte Ltd 17 UTI Have you come across these terms? What are they associated with? Kidney Stones Hematuri Dysuria Incontinence 18 © 2023 Marshall Cavendish Education Pte Ltd 18 9 23/8/2023 Chapter 8 Excretion in Humans • 8.1 Why Is Excretion Necessary? • 8.2 What Makes Up the Human Urinary System? • 8.3 How Is Urine Formed? • 8.4 What Is Osmoregulation? • 8.5 What Happens When the Kidneys Fail? 19 © 2023 Marshall Cavendish Education Pte Ltd 19 Learning Outcome(s) • 20 Identify the kidneys, ureter, bladder and urethra and state their functions in excretion. © 2023 Marshall Cavendish Education Pte Ltd 20 10 23/8/2023 The Human Urinary System Textbook Page 155 Consists of: 1. a pair of kidneys 2. a pair of ureters 3. urinary blader 4. urethra 21 © 2023 Marshall Cavendish Education Pte Ltd 21 Structure of the Kidney Textbook Page 156 • bean-shaped • visible dark outer region and pale inner region • receives blood through the renal artery • returns blood through the renal vein • basic functional unit is the kidney tubule called the nephron 22 © 2023 Marshall Cavendish Education Pte Ltd 22 11 23/8/2023 Structure of a Nephron Textbook Page 157 Four main parts: 1. Bowman’s capsule 2. Proximal (first) convoluted tubule 3. Loop of Henlé 4. Distal (second) convoluted tubule Closely associated to the nephron is the collecting duct. 23 © 2023 Marshall Cavendish Education Pte Ltd 23 Blood Capillaries Around the Nephron 1. 2. 3. 4. 24 Textbook Page 158 Afferent arteriole Glomerulus Efferent arteriole Blood capillaries surrounding the nephron © 2023 Marshall Cavendish Education Pte Ltd 24 12 23/8/2023 Is it bad to hold your pee? What health problems would arise if you often hold your pee? 25 © 2023 Marshall Cavendish Education Pte Ltd 25 Video Time! 26 https://www.youtube.com/watch?v=KCWEedgFNCk © 2023 Marshall Cavendish Education Pte Ltd 26 13 23/8/2023 Video Time! https://www.youtube.com/watch?v=amdREFCo6OU 3D Anatomy of Human Urinary System 27 © 2023 Marshall Cavendish Education Pte Ltd 27 Video Time! https://www.youtube.com/watch?v=nLwc3ktk_jo Dissection of Sheep Kidney 28 © 2023 Marshall Cavendish Education Pte Ltd 28 14 23/8/2023 Here are some urine samples. Why are they of different colours? 29 © 2023 Marshall Cavendish Education Pte Ltd 29 Urine Colour Chart Transparent Pale yellow What does each urine colour means? Transparent yellow What affects the composition of urine? Dark yellow 30 Brownish orange Pinkish red © 2023 Marshall Cavendish Education Pte Ltd 30 15 23/8/2023 Chapter 8 Excretion in Humans • 8.1 Why is Excretion Necessary? • 8.2 What Makes Up the Human Urinary System? • 8.3 How is Urine Formed? • 8.4 What is osmoregulation? • 8.5 What Happens when the Kidney Fails? 31 © 2023 Marshall Cavendish Education Pte Ltd 31 Learning Outcome(s) • 32 Outline the function of the nephron with reference to ultrafiltration and selective reabsorption in the production of urine. © 2023 Marshall Cavendish Education Pte Ltd 32 16 23/8/2023 How Is Urine Formed? Textbook Page 159 Involves two main processes: 1. Ultrafiltration 2. Selective Reabsorption 33 © 2023 Marshall Cavendish Education Pte Ltd 33 Ultrafiltration is … Textbook Page 159 • the first stage of urine formation • process by which small molecules are filtered out of the blood by the glomerulus into the Bowman’s capsule 34 © 2023 Marshall Cavendish Education Pte Ltd 34 17 23/8/2023 ULTRAFILTRATION Textbook Page 160 1 What occurs during ultrafiltration? 2 3 35 © 2023 Marshall Cavendish Education Pte Ltd 35 ULTRAFILTRATION Textbook Page 160 2 How is the glomerulus suited to urine formation? 36 1 © 2023 Marshall Cavendish Education Pte Ltd 36 18 23/8/2023 Video Time! https://www.youtube.com/watch?v=pv5-GwJ90ZM Ultrafiltration Animation Watch till 1.19 37 © 2023 Marshall Cavendish Education Pte Ltd 37 Think-Pair-Share Activity 1. Think about the answers to the questions. 2. Pair up with another student. 3. Share the answers with each other. Then check and correct each other. 38 1. What are the events involved during ultrafiltration in the kidney? 2. How is the glomerulus suited to urine formation? © 2023 Marshall Cavendish Education Pte Ltd 38 19 23/8/2023 Let’s Investigate 8.1 Textbook Page 162 In groups, think of an analogy to demonstrate the process of ultrafiltration. Present your analogy to the class. 39 © 2023 Marshall Cavendish Education Pte Ltd 40 © 2023 Marshall Cavendish Education Pte Ltd 39 40 20 23/8/2023 41 © 2023 Marshall Cavendish Education Pte Ltd 41 Capture Interest 42 © 2023 Marshall Cavendish Education Pte Ltd 42 21 23/8/2023 Textbook Page 151 • Read the write-up on the Chapter Opener (TB p.151). • Why do you think it was a bad idea for John Low to drink sea water? • How was John Low able to survive without drinking fresh water for three days? 43 © 2023 Marshall Cavendish Education Pte Ltd 43 Chapter 8 Excretion in Humans • 8.1 Why is Excretion Necessary? • 8.2 What Makes Up the Human Urinary System? • 8.3 How is Urine Formed? • 8.4 What is osmoregulation? • 8.5 What Happens when the Kidney Fails? 44 © 2023 Marshall Cavendish Education Pte Ltd 44 22 23/8/2023 Learning Outcome(s) • 45 Outline the function of the nephron with reference to ultrafiltration and selective reabsorption in the production of urine. © 2023 Marshall Cavendish Education Pte Ltd 45 How Is Urine Formed? Textbook Page 159 Involves two main processes: 1. Ultrafiltration 2. Selective Reabsorption 46 © 2023 Marshall Cavendish Education Pte Ltd 46 23 23/8/2023 Textbook Page 160 Recall! What is ultrafiltration? Selective absorption is … • the second stage of urine formation • the process in which useful substances that the body needs is reabsorbed into the blood capillaries 47 © 2023 Marshall Cavendish Education Pte Ltd 47 Textbook Page 160 Ultrafiltration 1 Selective Reabsorption 2 48 © 2023 Marshall Cavendish Education Pte Ltd 48 24 23/8/2023 Textbook Page 161 Selective Reabsorption Along the Nephron 49 © 2023 Marshall Cavendish Education Pte Ltd 49 Video Time! https://youtu.be/pv5-GwJ90ZM?t=80 Reabsorption Animation Note: Although urea is a waste product, some urea is still reabsorbed into the proximal convoluted tubule by diffusion down a concentration gradient. The remaining urea that is not reabsorbed along the nephron or collecting duct will be excreted in the urine. 50 © 2023 Marshall Cavendish Education Pte Ltd 50 25 23/8/2023 Textbook Page 161 3 What substances are reabsorbed during selective reabsorption? 51 1 4 2 © 2023 Marshall Cavendish Education Pte Ltd 51 Textbook Page 162 Urine Test 7th Century: precipitate excess protein in urine 17th Century: identify healthy an unhealthy urine 19th Century: detect sugar and bacteria in urine 52 20th Century: ? 21st Century: ? © 2023 Marshall Cavendish Education Pte Ltd 52 26 23/8/2023 Why does drinking plenty of tea or coffee makes you go to the toilet often? 53 © 2023 Marshall Cavendish Education Pte Ltd 53 Coffee and tea contain substances that are diuretic. Diuretic means causing frequent passing of urine. What does antidiuretic means? 54 © 2023 Marshall Cavendish Education Pte Ltd 54 27 23/8/2023 Chapter 8 Excretion in Humans • 8.1 Why Is Excretion Necessary? • 8.2 What Makes Up the Human Urinary System? • 8.3 How Is Urine Formed? • 8.4 What Is Osmoregulation? • 8.5 What Happens When the Kidneys Fail? 55 © 2023 Marshall Cavendish Education Pte Ltd 55 Learning Outcome(s) • 56 Outline the role of antidiuretic hormone (ADH) in osmoregulation. © 2023 Marshall Cavendish Education Pte Ltd 56 28 23/8/2023 Challenge: What will happen to a freshwater fish if placed in a saltwater environment? 57 © 2023 Marshall Cavendish Education Pte Ltd 57 Textbook Page 163 Osmoregulation is … is the maintenance of a constant body water potential by controlling the water potential and solute concentration in the blood. H2 O Too diluted blood plasma 58 H2 O Too concentrated blood plasma © 2023 Marshall Cavendish Education Pte Ltd 58 29 23/8/2023 Recall! What is water potential? 59 … tendency of water molecules to move from one place to another. dilute solution (high water potential) movement of water concentrated solution (low water potential) © 2023 Marshall Cavendish Education Pte Ltd 59 The water potential in the blood is… • • Textbook Page 163 dependent on the amount of water and mineral salts in the blood plasma controlled by antidiuretic hormone (ADH) Antidiuretic hormone… • • • 60 released in the hypothalamus released by the pituitary gland increases water reabsorption in the nephrons © 2023 Marshall Cavendish Education Pte Ltd 60 30 23/8/2023 Video Time! https://www.youtube.com/watch?v=r15H_xQqOd8 Role of ADH during dehydration 61 © 2023 Marshall Cavendish Education Pte Ltd 61 Kidneys Are Osmoregulators 62 Textbook Page 163 © 2023 Marshall Cavendish Education Pte Ltd 62 31 23/8/2023 Textbook Page 164 How Do the Kidneys Help to Regulate the Water Potential of Blood? 63 © 2023 Marshall Cavendish Education Pte Ltd 63 Video Time! https://www.youtube.com/watch?v=AJ5DWgxBCYw Osmoregulation in the kidneys 64 © 2023 Marshall Cavendish Education Pte Ltd 64 32 23/8/2023 Summary 1 Osmoregulation is the process of maintaining a constant body water potential by controlling the water potential and solute concentration in the body. 2 3 When the body water potential is high, water enters the cells. The cells will swell and possibly burst. 4 5 When the body water potential is low, water exits the cells. The cells will become dehydrated and shrink. Antidiuretic hormone (ADH) has a primary role in osmoregulation by controlling 6 the amount of urine formed in the kidneys. 65 © 2023 Marshall Cavendish Education Pte Ltd 65 How Do Fish Osmoregulate? How do you think a freshwater fish maintains the internal balance of salt and water in its body? How do you think a marine fish maintains the internal balance of salt and water in its body? • Read the article in the following website to find out more: https://www.petmd.com/fish/care/evr_fi_o smoregulation 66 © 2023 Marshall Cavendish Education Pte Ltd 66 33 23/8/2023 Can a person live with only one kidney? What are some circumstances that could lead a person to only have one functioning kidney. What precautions should someone with only one kidney take? 67 © 2023 Marshall Cavendish Education Pte Ltd 67 Chapter 8 Excretion in Humans • 8.1 Why Is Excretion Necessary? • 8.2 What Makes Up the Human Urinary System? • 8.3 How Is Urine Formed? • 8.4 What Is Osmoregulation? • 8.5 What Happens When the Kidneys Fail? 68 © 2023 Marshall Cavendish Education Pte Ltd 68 34 23/8/2023 Learning Outcome(s) • 69 Outline the mechanism of dialysis in the case of kidney failure. © 2023 Marshall Cavendish Education Pte Ltd 69 Why Are the Kidneys Important? As excretory organs: • excrete metabolic waste products such as urea, excess water and mineral salts Textbook Page 165 What are two important roles of the kidneys? As osmoregulators: • regulate water potential and solute concentration to maintain a constant water potential level in the body 70 © 2023 Marshall Cavendish Education Pte Ltd 70 35 23/8/2023 Kidney Facts Number of kidneys in a human: 2 Shape: bean-shaped Location: at the back of the abdomen, near the spine Amount of blood filtered: ~200 L per day Amount of wastes excreted: ~ 2 L per day Functions: filter blood, osmoregulator, facilitate red blood cells production, facilitate blood pressure regulation 71 © 2023 Marshall Cavendish Education Pte Ltd 71 Common Causes of Kidney Failure • • • • • 72 Textbook Page 165 high blood pressure diabetes alcohol abuse severe accidents complications from major surgeries © 2023 Marshall Cavendish Education Pte Ltd 72 36 23/8/2023 Video Time! https://www.youtube.com/watch?v=ok1eoHHzQT4 Five Stages of Chronic Kidney Disease 73 © 2023 Marshall Cavendish Education Pte Ltd 73 Discuss 1. Explain the important roles of kidneys in the human body. 2. What are some causes of kidney failure? 3. If a person suffers from kidney failure, what are his options to survive? 74 © 2023 Marshall Cavendish Education Pte Ltd 74 37 23/8/2023 Artificial Kidneys Textbook Page 168 1. Read the write-up in Tech Connect. 2. What do you think are the prospects of ‘artificial kidneys’? 75 © 2023 Marshall Cavendish Education Pte Ltd 75 Chapter 8 Excretion in Humans • 8.1 Why Is Excretion Necessary? • 8.2 What Makes Up the Human Urinary System? • 8.3 How Is Urine Formed? • 8.4 What Is Osmoregulation? • 8.5 What Happens When the Kidneys Fail? 76 © 2023 Marshall Cavendish Education Pte Ltd 76 38 23/8/2023 Learning Outcome(s) • 77 Outline the mechanism of dialysis in the case of kidney failure. © 2023 Marshall Cavendish Education Pte Ltd 77 Undergoing Dialysis On average: • 3 times per week • ~4 h per treatment 78 © 2023 Marshall Cavendish Education Pte Ltd 78 39 23/8/2023 How Does a Dialysis Machine Work? 79 Textbook Page 166 © 2023 Marshall Cavendish Education Pte Ltd 79 What Are the Features of a Dialysis Machine? 80 Textbook Page 167 © 2023 Marshall Cavendish Education Pte Ltd 80 40 23/8/2023 TB eBook Page 167 Biology Connect • Explore a simulation on the mechanism of dialysis. Mechanism of Dialysis 81 © 2023 Marshall Cavendish Education Pte Ltd 81 During World War II, Willem Kolff used repurposed materials to make the first ‘artificial kidney’. rotating drum of old washing machine juice cans This is the kind of creative solution that only the human mind could devise. 82 cellophane sausage casing © 2023 Marshall Cavendish Education Pte Ltd 82 41 23/8/2023 Video Time! https://www.youtube.com/watch?v=87c56BysMoo History of Dialysis 83 © 2023 Marshall Cavendish Education Pte Ltd 83 Let’s Map It 84 Textbook Page 169 © 2023 Marshall Cavendish Education Pte Ltd 84 42
