Kerala 9th Std Biology Textbook - Respiration and Excretion PDF

# Respiration and Excretion ## What is Respiration? - Antoine Lavoisier (1743-1794) was an eighteenth century scientist who successfully explained the process of respiration in organisms. - He inferred that the process which takes place during burning of objects and during respiration in organism...

# Respiration and Excretion ## What is Respiration? - Antoine Lavoisier (1743-1794) was an eighteenth century scientist who successfully explained the process of respiration in organisms. - He inferred that the process which takes place during burning of objects and during respiration in organisms are the same. - To prove this, he placed a guinea pig in a small bucket, immersed it in another bucket filled with ice, and covered it with a net. - He took precautions to prevent the melting of ice due to external heat insulation; however, the ice melted. - This proved that the ice melted due to the heat from the guinea pig's body. - He calculated that 80 kilo calories of energy was used for this from the guinea pig's body. - This energy was received through respiration. - When a piece of wood is burned, oxygen is used and carbon dioxide and heat energy are formed. - The same happens during respiration when oxygen breaks down glucose. ## Human Respiratory System - **Human respiratory system** - **Gaseous exchange** - **Cellular respiration** - **Respiration in other organisms** - **Synthesis of urea** - **Formation of urine** - **Excretion in plants** - **Hemodialysis** - **Kidney transplantation** - **Homeostasis** ### Role of Oxygen in Respiration and Burning ### Products of Respiration and Burning - Oxygen is used and carbon dioxide is formed during respiration. - A suitable respiratory surface and related systems are required for the exchange of these gases. ### Respiratory Surface - A large respiratory surface is required in human beings to get sufficient oxygen to cells for the production of energy. - The respiratory surface in human beings is the lungs. ### Illustration 3.1: Human Respiratory System - **Lungs:** The main organs of respiration in human beings. - **Bronchiole:** The branches of bronchus which open to the alveoli (tiny air sacs in the lungs where gas exchange takes place). - **Pleura:** The membrane which covers the lungs, protecting them from friction during breathing. - **Diaphragm:** The muscular wall that separates the thoracic cavity (containing the heart and the lungs) and the abdominal cavity (containing the stomach, intestines, and liver), aiding in breathing. - **Alveolus:** These are delicate air sacs which are elastic in nature and are seen at the tip of bronchioles. - A network of numerous blood capillaries are found on their surface. - There are approximately 70 crores alveoli in both lungs together. - The surface area of alveoli is approximately 70 m². - It increases the area of the respiratory surface and makes the gaseous exchange efficient. ### Path of Air - Prepare a flowchart to illustrate the path of atmospheric air from the nostrils to the alveoli. ### Rate of Ventilation - Is there any change in the rate of ventilation (breathing) during physical activities like sports? - Form a group of two children each. - Take rest for 5 minutes. Both of them record the number of inspirations that happen within a minute. - Record the time using a stop watch. - In an interval of one minute, record the number of inspirations two more times. - Then record the number of inspirations of the two children after running for three minutes. - Continue to record the number of inspirations in every minute till they reach the normal condition. - Complete the table given below using the recorded results, draw a line graph, and compare the rate of ventilation of both the children. | Time in minutes | Number of inspirations in resting state | Number of inspirations after exercise | |---|---|---| | 1 | | | | 3 | | | | 5 | | | | 9 | | | | 11 | | | | 13 | | | - **Inference:** Since muscular activities increase during exercise, more energy is required. As more energy is required, the requirement of oxygen also increases. Besides more carbon dioxide has to be eliminated from the body. This is the reason for the rate of increase of breathing which is the first step of respiration. ## Ventilation - The movement of air from the atmosphere to the lungs and back is called ventilation. - **Inspiration (Inhalation):** The process by which atmospheric air enters the lungs. - **Expiration (Exhalation) :** The process by which air leaves the lungs. **Illustration 3.1: Ventilation** - **Intercostal muscle:** These muscles are located between the ribs and help to expand and contract the chest cavity during breathing. - **Ribs:** The bony cage that protects the lungs and allows for chest expansion. - **Diaphragm:** The muscular wall that separates the thoracic cavity and the abdominal cavity. **Table 3.2: Ventilation** | Indicators | Inspiration | Expiration | |---|---|---| | Action of intercostal muscles | Contracts (lifts the ribs) | Relaxes (lowers the ribs) | | Movement of ribs | Rises | Lowers | | Change that occurs to the diaphragm | Contracts (flattens) | Relaxes (moves upwards) | | Volume of thoracic cavity | Increases | Decreases | | Pressure of air in the lungs | Decreases | Increases | | Movement of air | Enters the lungs | Leaves the lungs | ## Alveolar Exchange of Gases - The next stage of respiration is the exchange of oxygen from the air which has entered the alveolus, into the blood and exchange of carbon dioxide into the alveolus from the blood. - This is called **alveolar exchange of gases**. ### Illustration 3.3: Alveolar Exchange of Gases - **Alveolar wall:** The thin wall of the alveolus, made up of a single layer of cells. - **Blood capillary wall:** The thin wall of the blood capillary, also made up of a single layer of cells. - **RBC:** Red blood cells containing hemoglobin. - **CO₂ concentration is high:** The concentration of carbon dioxide is high in the blood, meaning that carbon dioxide diffuses out of the red blood cells into the alveolus. - **O₂ concentration is less:** The concentration of oxygen is low in the blood, meaning that oxygen diffuses from the alveolus into the red blood cells. - **The distance between the air in the alveolus and the blood in the alveolar capillary is less than one by thousand of a millimeter:** This ensures efficient gas exchange. ### Characteristic features of the walls of the alveolus and blood capillaries. - The walls of both the alveolus and the blood capillaries are very thin, which facilitates easy diffusion of gases between the two. ### Importance of moisture in the wall of the alveolus - Moisture in the wall of the alveolus helps dissolves respiratory gases, making their diffusion easier. ### Concentration of O₂ and CO₂ in the alveolus and in blood capillaries. - The concentration of oxygen is higher in the alveolus and lower in the blood capillaries. - In contrast, the concentration of carbon dioxide is lower in the alveolus and higher in the blood capillaries. ### The exchange of O₂ and CO₂ between alveolus and blood capillaries. - Oxygen diffuses from the alveolus into the blood capillaries, while carbon dioxide moves from the blood capillaries into the alveolus. ## Surfactant - The substances inside the alveoli which help them to expand freely when air enters and contract slowly when air is released is called **surfactant**. - If the level of surfactant is too low, breathing becomes difficult. - This condition is generally seen in premature babies. - Such new born babies are prone to death. ## Presence of Carbon Dioxide in Inhaled and Exhaled Air - **Illustration 3.2:** Conduct an experiment to observe the presence of carbon dioxide in inhaled and exhaled air. - **Arrange equipments as shown in the figure:** Use a glass tube, a bottle containing lime water or hydrogen carbonate solution, and two test tubes. - **Breathe slowly using mouth through tube A:** The glass tube delivers the breath to the bottle. - **Observe the colour change in the indicator solution in test tubes B and C:** The lime water or hydrogen carbonate solution in the bottle will change colour as carbon dioxide enters it. - The color change from red to yellow in the hydrogen carbonate solution or milky colour in lime water is an indication that carbon dioxide is present in the exhaled air. - The observation confirms that carbon dioxide is present in the exhaled air and is not present in the inhaled air. ## Cellular Respiration - **Illustration 3.4: Respiratory Process** - The process of breaking down of glucose using oxygen and releasing energy, which occurs in cells, is called **cellular respiration**. ### Illustration 3.4: Respiratory Process - **Glycolysis:** First phase of cellular respiration. Takes place in the cytoplasm. Oxygen is not required. Glucose is converted into pyruvic acid. 2ATP molecules are formed. - **Krebs Cycle:** Second phase of cellular respiration. Takes place in mitochondria. Oxygen is required. Pyruvic acid is converted to carbon dioxide and water. 28 ATP molecules are formed. ### Transportation of Gases - **Transport of Oxygen:** Oxygen is transported from the lungs to the body tissues. - **Entry of Oxygen from the blood to tissues:** Oxygen diffuses out of the blood into the cells where it is needed for cellular respiration. - **Cellular Respiration:** The process of breaking down glucose to release energy in the cells. - **Entry of Carbon Dioxide from the tissues to blood:** Carbon dioxide produced from cellular respiration diffuses from the tissues into the blood. - **Transport of Carbon Dioxide:** The blood carries carbon dioxide to the lungs. - **Elimination of Carbon Dioxide:** Carbon dioxide is exhaled out of the lungs. - **Phases of Respiration:** Respiration can be broken down into several stages; these include inhalation, diffusion of gases between alveoli and blood, transport of gases through the circulatory system, and exhalation. ### Table 3.3: Cellular Respiration | Indicators | Glycolysis | Krebs Cycle | |---|---|---| | Site of activity | Cytoplasm (outside of the mitochondria) | Mitochondria | | Substances that take part in the chemical process | Glucose, 2 ATP molecules | Pyruvic acid, 28 ATP molecules | | Products | Pyruvic acid, 2 ATP molecules | Carbon dioxide, water, 28 ATP molecules | | Requirement of oxygen | Not required | Required | ### Importance of Cellular Respiration - ATP molecules formed as a result of respiration is the source of energy for body activities. - The byproducts, carbon dioxide and to some extent, water, are eliminated immediately through exhaled air. - The process of transport of respiratory gases and the breaking down of glucose in cells using oxygen to release energy, together constitute **respiration**. ### Anaerobic Respiration - **Illustration 3.8: Anaerobic Respiration** - Some situations in daily life are given below. - Discuss how anaerobic respiration is beneficial in such situations and prepare short notes on the same. - **Requirement of oxygen:** Anaerobic respiration doesn't require oxygen. - **Similarities and differences in the phases of respiration:** Anaerobic respiration has similar phases to aerobic respiration, but it does not involve the Krebs Cycle or electron transport chain. - **Number of ATP:** Anaerobic respiration produces significantly less ATP than aerobic respiration. - **Difference in the cellular respiratory processes in bacteria and yeast:** The final product of anaerobic respiration is lactic acid in bacteria and ethanol and carbon dioxide in yeast. - **Does anaerobic respiration take place in human beings?** Yes, anaerobic respiration takes place in human beings during strenuous exercise when oxygen supply is insufficient. This process leads to the production of lactic acid which contributes to muscle fatigue and soreness. - **Yeast is added to leaven the dough:** The yeast ferments carbohydrates in the dough, producing carbon dioxide gas which causes the dough to rise. - **Curd is added to milk to prepare curd:** Bacteria in the curd, like Lactobacillus, ferment lactose in the milk, producing lactic acid which gives curd it's distinctive taste and texture. ## Excretion - Removal of waste materials from the body is called **excretion.** - **Major excretory substances** in our body include: - Carbon dioxide - Nitrogenous waste (urea, uric acid, creatinine) - Excess water - Salts - **Carbon dioxide** is a byproduct of cellular respiration, and is excreted by the lungs. - **Nitrogenous waste** is produced as a result of protein metabolism, and is excreted mainly through urine. - **Excess water and salts** are excreted through urine and sweat. ## Synthesis of Urea - **Illustration 3.9: Synthesis of urea** - **Protein metabolism:** The breakdown of proteins in the body produces ammonia. - **Ammonia** is a toxic substance, and the liver converts it to urea, a less toxic form. - **Urea** is then excreted through urine. - **The organ where urea is synthesised is the liver.** ## Excretion of Urine - **Illustration 3.10: Kidney and related parts** - **Illustration 3.11: Structure of nephron** - **Kidney:** The main excretory organ in the human body. - **Renal artery:** The blood vessel that carries blood to the kidney. - **Renal vein:** The blood vessel that carries blood away from the kidney. - **Pelvis:** The funnel-shaped space in the kidney that collects urine. - **Ureter:** The tube that carries urine from the kidney to the urinary bladder. - **Urinary bladder:** The sac that stores urine before it is released from the body. - **Urethra:** The tube that carries urine from the urinary bladder to the outside of the body. - Nephrons are the basic structural and functional units of kidneys. - Around 12 lakh nephrons are present in each kidney. ### Components of Glomerular Filtrate - **Water:** Makes up the majority of the fluid in the glomerular filtrate. - **Glucose:** A simple sugar that is filtered out of the blood but is normally reabsorbed back into the blood stream. - **Amino acids:** The building blocks of proteins. They too are reabsorbed into the blood. - **Sodium, potassium, calcium ions:** Inorganic ions that help regulate fluid balance, nerve impulses, and muscle contractions. - **Vitamins:** Essential organic compounds not synthesized by the body. - **Urea:** The main nitrogenous waste product in urine. - **Uric acid:** A waste product of purine metabolism. - **Creatinine:** A waste product of muscle metabolism. ### Table 3.4: Kidney and Related Parts | Hints | Parts | |---|---| | Blood vessel which carries blood to the kidneys | Renal artery | | Blood vessel which carries blood away from the kidneys | Renal vein | | Ultra filters present in the kidneys | Glomerulus | | The double walled cup-shaped structure present at one end of the nephron | Bowman's capsule | | Network of minute capillaries present in the Bowman's capsule | Glomerulus | | Blood vessel which carries blood to the capillary network | Afferent arteriole | | Blood vessel which carries blood away from the capillary network | Efferent arteriole | | The long tubule which connects the Bowman's capsule and the collecting duct | Renal tubule | | The part where renal tubules enter, collects urine and carries it to the pelvis | Renal pelvis | | The initial part of ureter | Ureter | | Part that carry urine to urinary bladder | Ureter | ## Urine Formation - **Illustration 3.12: Formation of Urine** - **Ultrafiltration:** When blood flows through the glomerulus, ultrafiltration takes place through its small pores. This creates a fluid called glomerular filtrate. - **Reabsorption:** As the glomerular filtrate flows through the renal tubules to the collecting duct, essential components are reabsorbed from it back into the blood. - **Secretion:** Excess components that are retained in the blood are secreted into the renal tubules. They are eliminated through urine. ### Work Sheet 3.1: Formation of Urine - **Why all components in the glomerular filtrate are not present in urine?** - The glomerular filtrate contains all components of blood except blood cells and large proteins. However, a large proportion of the water, glucose, amino acids, electrolytes, and other useful substances are reabsorbed into the bloodstream, while waste products like urea, uric acid, and creatinine are reabsorbed only to a small extent. - **Find out the components which are reabsorbed and the components which are secreted.** - **Reabsorbed components** include most of the water, glucose, amino acids, and electrolytes. - **Secreted components** include waste products like urea, creatinine, uric acid, and some drugs. - **How does urine flow out of the body?** - Urine from the nephrons reaches the pelvis through the collecting duct. - From there it reaches the urinary bladder through the ureter and then it gets excreted through the urethra. ## Health of Kidneys - Several factors are to be considered for the health of kidneys. - The washing out of disease causing germs from the urinary tract takes place during the process of micturition. - Avoiding urination for a long time prevents the expulsion of bacteria that may be present in the urinary tract. - This may cause infection in the inner membrane of the urinary bladder and may lead to serious kidney diseases. - Drinking sufficient quantity of water and timely urination are necessary to avoid urinary tract infection. ## Diagnosis of Diseases - **Can diseases be diagnosed through urine tests?** Yes, certain diseases can be diagnosed by testing the abnormal constituents found in urine. - **Table 3.5: Abnormal components in urine ** | Components | Possible Diseases | |---|---| | Glucose | Diabetes | | Albumin | Kidney diseases | | Blood | Kidney diseases | | Bilirubin | Jaundice | | Calcium oxalate crystals | Kidney stone | | Pus cells | Urinary tract infections | ### Detection of Glucose in Urine - **Take two clean and dry test tubes.** Take 2 ml urine sample in one of them. - **In the second test tube take 2 ml of glucose solution.** - **Add 2 ml Benedict reagent in both the test tubes using a dropper.** - **Heat for 2 minutes.** - **Observe the colour change in both the samples.** - The colour of the sample changes from blue to green, then to yellow, orange and red depending up on the amount of glucose. | Glucose concentration | Color change | |---|---| | 0% | No change (remains blue) | | 0.5 – 1% | Green | | 1 - 1.5% | Yellow | | 1.5 - 2% | Orange | | > 2% | Red/Brick red | ### Observation: - The observation depends on the glucose concentration in the urine sample. - The color change is an indication of the presence of glucose in the urine, and the intensity of the color change can be correlated with the glucose concentration. ### Inference: - If glucose is detected in the urine, it indicates that the body is either unable to regulate blood sugar levels properly (as in diabetes mellitus), or there is a problem with the reabsorption of glucose in the kidneys. ### Visit the Medical Lab - Visit a medical lab in your area and collect information regarding urine tests. - Then prepare a table which includes the normal level of urine constituents and exhibit it in the class. ## Hemodialysis - **Illustration 3.13: Hemodialysis** - The process of removal of waste materials from the blood will get interrupted if both the kidneys stop functioning. - Therefore excretory materials may remain in the blood without being filtered. - This in turn disrupts homeostasis. - **Hemodialysis** is done in such situations to save life. ### Steps in Hemodialysis - **1:** Blood is drawn from the patient and passed through a dialysis machine after adding heparin to prevent coagulation. - **2:** Blood is circulated through the dialysis unit, where waste products and excess fluids diffuse from the blood into the dialysis fluid. - **3:** The dialysis fluid is then removed, and the purified blood is returned to the patient's body. - **Why is the dialysis fluid removed from the dialysis unit in due course of time?** The dialysis fluid is constantly replaced because it becomes saturated with waste products, and a fresh dialysis fluid is needed to continue the removal process. ## Kidney Transplantation - **Illustration 3.14: Kidney Transplant** - **When is kidney transplantation required?** Kidney transplantation may be required when both kidneys fail to function adequately, and other treatment options like dialysis have proven ineffective or are not feasible. ### Steps in Kidney Transplant - **Donor:** A healthy person or a healthy person who died in accident or by other means. - **Preparation:** Blood group matching, tissue matching, cross matching must be done to reduce the risk of rejection. - **Surgery:** The blood vessels and ureter of the donated kidney are connected to the recipient's body. - **Post Surgery:** The recipient receives medications to suppress the immune system and prevent rejection of the new kidney. - **Follow up examinations:** The recipient will need follow-up examinations to monitor the health of the new kidney and to assess the effectiveness of medication. ## Excretion in Other Organisms - **Table 3.6: Excretion in other organisms** | Organism | Main excretory product | Main excretory organ/mechanism | |---|---|---| | Amoeba | Ammonia | Contractile vacuole | | Earthworm | Ammonia | Nephridia | | Insects | Uric acid | Malpighian tubules | | Fish | Ammonia | Kidneys | | Frog | Ammonia and urea | Kidneys | | Reptiles | Uric acid | Kidneys | | Birds | Uric acid | Kidneys | - Animals have extensive systems for excretion. - Plants do not have special excretory systems like animals. ### Excretion in Plants - **Illustration 3.15: Excretion in plants** - Plants excrete various waste products through different mechanisms: - **O₂, CO₂, water vapor:** These are released through stomata, the small pores on the surface of leaves and young stem. - **Water, salts:** They are excreted through hydathodes, specialized pores on the leaf margins. - **Solid wastes:** These include resins, bark, dropping of mature leaves and fruits, and the formation of heart wood. ## Maintenance of Homeostasis - **Illustration 3.16: Maintenance of homeostasis** - Maintenance of homeostasis is the sign of life. - **How do liver, kidney, lungs, and skin help maintain homeostasis:** - **Liver:** Filters blood, detoxifies harmful substances, and produces bile for digestion. - **Kidney:** Filters waste products from the blood and produces urine. - **Lungs:** Exchange gases, removing carbon dioxide and taking in oxygen. - **Skin:** Regulate body temperature, excretes sweat, and provides a barrier against infection. ### Factors that Affect Homeostasis - **Any change in the internal environment disrupts homeostasis.** - **Our improper life styles play a major role in this.** - **Sub-themes:** Conduct a discussion on factors that affect homeostasis, including: - **Wrong food habits, over nutrition, under nutrition:** An unbalanced diet can disrupt normal body function and lead to various health problems. - **Lack of exercise, mental stress:** Lack of physical activity and stress can contribute to weight gain, cardiovascular disease, and other health issues. - **Alcoholism, smoking, use of addictive drugs:** Substance abuse has severe detrimental impacts on various organ systems and overall health. - **Pollution, lack of hygiene, abundance of pathogens:** Exposure to environmental pollutants and pathogens can weaken the immune system and lead to various diseases. - **Improper use of medicines, contact with toxic substances:** Misuse of medications and exposure to toxic substances can have adverse effects on body functions. ### External Environment - **Observe the figure 3.3, ‘Environment and pollution.'** - If such a situation prevails in your area, find out how this would affect the external environment and prepare a report on the same. ### Steps to Be Taken - **Conduct a panel discussion on the steps to be taken to avoid such harmful changes in the external environment.** - **Sub-themes:** - **Individuals:** Individuals can make a difference by adopting eco-friendly practices, reducing waste, and conserving natural resources. - **Society:** Communities and organizations can work together to implement policies that promote environmental conservation and sustainable practices. - **Local self government bodies:** Local authorities have a crucial role to play in waste management, pollution control, and ensuring the health and safety of the environment. ## "Waste Free New Kerala" - Perform a role play on the topic "Waste Free New Kerala' based on the ideas generated from the discussion." - **Master Plan for a Waste-Free School:** Develop a comprehensive plan for making the school and its surroundings waste-free. - **Wellbeing of both external and internal environments is required for a healthy life.** - It's our responsibility to keep the external environment waste free and follow the life style that does not disrupt the balance of the internal environment. - **So let us follow a life style which is required to preserve good health.** ## Let us Assess 1. **Which among the following given below is not the characteristic feature of an efficient gaseous exchange surface?** - a) Thick cell wall - b) Proximity to blood capillaries - c) Moist membrane - **d) Large surface area** 2. **Redraw the diagram and label the parts:** - **a** - Trachea - **b** - Lungs - **c** - Diaphragm 3. **Write the role of each of the following in the exchange of gases:** - **a) Plasma:** Plasma carries red blood cells, white blood cells, and platelets. - **b) RBC:** Red blood cells contain hemoglobin, which carries oxygen to the body's tissues and removes carbon dioxide. - **c) Haemoglobin:** Hemoglobin binds with oxygen and carbon dioxide, enabling efficient transport of gases between the lungs and tissues. - **d) Tissue fluid:** This fluid surrounds the body's cells and allows for the diffusion of gases between blood and cells. 4. **Redraw the diagram, label the parts and write their functions.** - **a** - Bowman's capsule: Captures the glomerular filtrate. - **b** - Glomerulus: Filters blood to produce glomerular filtrate. - **c** - Renal tubule: Site of reabsorption of useful substances back into the blood and secretion of waste products into the urine. - **d** - Collecting duct: Collecting duct concentrates and transports urine into the renal pelvis. 5. **Analyse the figure and answer the questions.** - **a) Write the names of the circulations X and Y.** - **X:** Pulmonary circulation - **Y:** Systemic circulation - **b) Write the names of the blood vessels i, ii, iii, iv, v.** - **i:** Pulmonary veins - **ii:** Left atrium - **iii:** Left ventricle - **iv:** Aorta - **v:** Vena cava - **c) What is the role of these circulations in the exchange and transport of gases?** - The pulmonary circulation carries deoxygenated blood from the heart to the lungs to pick up oxygen and releases carbon dioxide. - The systemic circulation carries oxygenated blood from the heart to all the body tissues, delivering oxygen and picking up carbon dioxide. - **d) Explain the role of these circulations in the process of excretion.** - The kidneys are involved in filtering waste products from the blood, which is carried by the systemic circulation. - The waste products in the blood are transported back to the heart by the vena cava and then pumped to the kidneys by the aorta through the systemic circulation. ## Extended Activities 1. Visit the medical lab in your area and collect information regarding urine tests. Then prepare a table which includes the normal level of urine constituents and exhibit it in the class. 2. **Construct models of the respiratory system, kidney, and related parts and display them in the class.** 3. **Organise an awareness class on organ donation.** This could involve inviting a medical professional or a kidney transplant recipient to speak about the importance of organ donation and how to become a donor. 4. **Organise and implement programs to make your home and school waste free.** This could include starting a school garden, setting up recycling bins, or organizing clean-up activities.