biology form 4 experiment 9.4

Laporan Amali 9.4 & 9.5 (Biologi Tingkatan 4- Bab 9)

NatasyaZulaikha

Aktiviti 9.4 (Mengkaji Nilai Tenaga dalam Sampel Makanan) Aktiviti 9.5 (Menentukan Kandungan Vitamin C dalam Jus Buah-buahan dan Sayur-sayuran)

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TEXTBOOK KSSM Biology Form 4 (DLP)

Description: textbook biology form 4 (dlp), read the text version.

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glycerol FIGURE 9.7 Transportation of nutrients and intestines the assimilation in the liver and cells carbohydrates protein lipid ASSIMILATION PROCESS IN CELLS AMINO ACIDS GLUCOSE LIPIDS • Amino acids are used • Glucose is oxidised through • Lipids such as phospholipid to synthesise new cellular respiration to release and cholesterol are the primary protoplasm and also energy, water and carbon components that build the plasma repair damaged dioxide. membrane. tissues. • Excess glucose is kept as • Excess fats are kept in adipose • Amino acids are used to glycogen in muscles. tissues found underneath the skin synthesise hormones as stored energy. and enzymes. • Energy is used for cell processes such as protein • Fat is oxidised to release energy synthesis. when there is insufficient glucose. 9.3Formative Practice I understand the difference between p 1 State the meaning of assimilation. 2 Explain the functions of the liver in the assimilation of digested food. 154 9.4.2 BioT4(NC)-B9-EN New 6th.indd 154 11/13/2019 12:32:02 AM 9.5 Defaecation Biological Lens Functions of the large intestine The large intestine has a huge population After the absorption of nutrients is of bacteria. There completed in the ileum, undigested food, are more than 1000 dead cells, epithelial cells, fibre and water different species of enter the large intestine and move slowly bacteria in the large through peristaltic action. Fibre consists intestine and a healthy of cellulose walls of plant cells. The large balance between intestine carries out two main functions: beneficial and less • absorption of water beneficial bacteria is very important for and vitamins health and a stable • formation of faeces colon environment in the alimentary canal. ABSORPTION OF WATER AND VITAMINS caecum rectum CHAPTER 9 appendix anus Substances absorbed are • water and mineral salts FIGURE 9.8 Large intestines • metabolic byproducts of some bacteria such as vitamin B, vitamin K and folic acid. FORMATION OF FAECES • After the water is absorbed, the remaining waste is a semisolid called faeces. Faeces contains dead cells from the inner layer of the intestine, waste products such as bile pigments, bacteria and toxic substances. • The walls of the large intestine secrete mucus to smoothen the movement of faeces until the anus. The movement of faeces takes about 12 to 24 hours before entering the rectum. • The faeces will accumulate in the rectum until the pressure in the rectum increases and triggers the need to expel faeces from the body. • The rectum muscles will contract to expel faeces from the anus. This process is called defaecation. Brainstorm! 9.4Formative Practice 3 Explain the importance of water absorption and What is the effect 1 State the main function of the vitamins in the large intestine. of antibiotics large intestine. on the large 4 Explain the formation process intestine’s bacterial 2 What are the substances of faeces. population? absorbed in the large intestine? 9.5.1 155 BioT4(NC)-B9-EN New 6th.indd 155 11/13/2019 12:32:03 AM 9.6 Balanced Diet Biological Lens Energy value in a food sample A balanced diet refers to a diet that consists of all seven food classes (carbohydrates, lipids, proteins, vitamins, mineral salts, fibre and water) in the correct proportion and balanced quantity according to individual needs so that optimal health can be maintained. 1 calorie (cal) = 4.2 joule (J) ENERGY VALUE 1 kilojoule = 1000 joule • Energy value is the total amount of energy released when one gram of food is oxidised completely. Across the fields • The energy value in food is measured in the form of heat energy, 4.2 J g-1 °C-1 refers that is, in kilojoule per gram (kJ g-1). to the specific heat capacity of water, • Another unit of heat energy is calorie. that is, the energy required to increase • 1 calorie or 4.2 joule is defined as the quantity of heat energy the temperature of 1 g needed to raise the temperature of 1 gram water by of water by 1 °C. 1 degree Celsius (°C) at a pressure of 1 standard atmosphere. • Energy value of food (kJ g-1) = Water mass (g) × 4.2 J g-1 °C-1 × Increase in water temperature (°C) Mass of food sample (g) × 1000 sAecit1iv.2itycA9.4 Studying the energy value of food samples Experiment Problem statement cotton barrier Which food sample has the highest energy value? wool thermometer Hypothesis boiling tube Groundnuts have a higher energy value compared to cashew nuts. distilled water Variables food sample Manipulated: Types of food samples needle Responding: Energy value of food sample Fixed: Water mass plasticine Materials retort Distilled water, food samples (cashew nuts and groundnuts), stand cotton wool and plasticine Apparatus Retort stand with a clamp, thermometer, boiling tube, long needle, electronic weighing scale, barrier, measuring cylinder and Bunsen burner 156 9.6.1 BioT4(NC)-B9-EN New 6th.indd 156 11/13/2019 12:32:03 AM Procedure 1 Weigh a cashew nut using an electronic weighing scale and record its mass. 2 Measure 20 ml of distilled water using a measuring cylinder and pour it into a boiling tube. 3 Clamp the boiling tube to the retort stand and put in the thermometer. 4 Fix the position of the thermometer using cotton wool. 5 Record the initial temperature of the distilled water. 6 Stick the cashew nut on the needle and hold the needle upright using plasticine. 7 Place the barrier around the apparatus set-up. 8 Light the cashew nut using a Bunsen burner and place it below the boiling tube. 9 Stir the water in the boiling tube slowly and record its highest temperature after the cashew nut has completely burned. 10 Replace the water in the boiling tube. 11 Repeat steps 1 to 9 using groundnuts. 12 Calculate the energy value for each food sample using the following formula: Energy value of = Water mass (g) × 4.2 J g-1 °C–1 × Increase in water temperature (°C) food (kJ g–1) Food sample mass (g) × 1000 13 Record your results in the table below. Results Food Food Initial Final Increase of Energy value CHAPTER 9 sample sample temperature temperature Temperature of food mass (g) of water (°C) (kJ g–1) of water (°C) (°C) Cashew nuts Groundnuts Discussion 1 Which food sample shows the highest energy value? 2 State two precautionary steps for this experiment. 3 Compare the energy value of food samples obtained from this experiment with their theoretical energy values. Are there any differences? If yes, explain why. Conclusion Is the hypothesis accepted? Suggest a suitable conclusion for this experiment. The contents of vitamin C in fruit or vegetables juices The nutrient content in various types of food is different. For example, the vitamin C content in fruits and vegetables are different. 9.6.2 157 BioT4(NC)-B9-EN New 6th.indd 157 11/13/2019 12:32:03 AM 1.2 9.5AcsteivitiitvyitcA Determining the contents of vitamin C in fruit juice Experiment and vegetable juice. Problem statement Which fruit juice or vegetable juice has the highest content of vitamin C? Hypothesis Orange juice has the highest content of vitamin C compared to lime juice and carrot juice. Variables Manipulated: Types of fruit and vegetable juices Response: Volume of fruit juice or vegetable juice needed to decolourise DCPIP solution Fixed: Concentration of DCPIP solution and concentration of an ascorbic acid solution Materials Orange juice, lime juice and fresh carrot juice, 0.1% ascorbic acid solution, 1% DCPIP solution and distilled water Apparatus Syringe needles (1 ml and 5 ml), knife, 50 ml beaker, specimen tube, juicer and sieve Procedure 1 Put 1 ml of 1% DCPIP solution in a specimen tube. 2 Fill the 5 ml syringe needle with a 0.1% ascorbic acid solution. ascorbic acid Ensure that there are no air bubbles trapped in it. specimen tube 3 Insert the tip of the syringe needle into the specimen tube and drip ascorbic acid drop by drop into the DCPIP solution while stirring slowly until the blue colour of the DCPIP solution is decolourised. 4 Record the volume of the 0.1% ascorbic acid solution needed to DCPIP solution decolourise the blue colour of the DCPIP solution. 5 Repeat steps 1 to 4 twice to get the average volume for each different juice. 6 Record the volume of each juice in the table below. 7 Calculate the concentration of vitamin C of each juice using the following formula. Percentage of vitamin C = volume of ascorbic acid solution × 0.1% volume of juice used Vitamin C concentration (mg ml-1) = volume of ascorbic acid solution × 1.0% volume of juice used Results Volume of solution/juice Vitamin C Vitamin C concentration Solution / Juice required to decolourise DCPIP concentration (mg ml-1) 0.1 solution (ml) (%) 123 Average 0.1% ascorbic acid solution Orange juice Lime juice Carrot juice 158 9.6.2 BioT4(NC)-B9-EN New 6th.indd 158 11/13/2019 12:32:03 AM Discussion 1 Which juice has the highest content of vitamin C? 2 Why is a 0.1% ascorbic acid solution used as the standard? Conclusion Is the hypothesis accepted? Suggest a suitable conclusion for this experiment. One of the factors that affect the loss of vitamin C content is temperature. Therefore, fruit or vegetables must be kept at a suitable temperature range to preserve vitamin C. 1.2 9.6ActivisteyitivitcSAtudying the effect of temperature on vitamin C in Experiment orange juice Problem statement What is the most suitable ambient temperature to keep orange juice? Hypothesis Orange juice stored at a low ambient temperature has the highest content of vitamin C. Variables Take Note! CHAPTER 9 Manipulated: Ambient temperature Responding: Volume of orange juice required to decolourise DCPIP solution Ensure that Fixed: Volume of DCPIP solution the juice is not exposed too long Materials to avoid oxidation. Oranges, 1% DCPIP solution and ice Apparatus Specimen tube, knife, syringe needles (1 ml and 5 ml), beakers (50 ml and 100 ml), Bunsen burner, tripod stand, sieve and wire gauze Procedure 1 Prepare 60 ml of orange juice. 2 Label the beakers A, B and C. Pour 20 ml of orange juice into each beaker. 3 Soak beaker A in ice, leave beaker B at room temperature and soak beaker C in boiling water for 30 minutes. 4 After 30 minutes, determine the vitamin C content in the orange juice as shown in Activity 9.5. 5 Calculate the concentration of vitamin C in the orange juice at each different temperature. Results Record your results in an appropriate table. 9.6.2 159 BioT4(NC)-B9-EN New 6th.indd 159 11/13/2019 12:32:04 AM Discussion 1 Is there a difference in the vitamin C content for the juice at different temperatures? 2 What is the effect of temperature on vitamin C in the orange juice? 3 Based on the results, suggest the best way to ensure that you get a high content of vitamin C from fruit juice or vegetable juice. Conclusion Is the hypothesis accepted? Suggest a suitable conclusion for this experiment. PHOTOGRAPH 9.2 Diet modifications for specific individuals A sample serving based on Pinggan Sihat Malaysia A balanced diet for each individual will vary according to lifestyle, health conditions and specific nutritional requirements. Each MMilillelennnniaall CCaarererer individual must make wise choices based on a nutrition guide. For example, suggestions for nutritional needs can be made based Nutritionists are on Pinggan Sihat Malaysia. Pinggan Sihat Malaysia illustrates specialists in the the relative quantity of various food classes in a balanced diet field of nutrition (Photograph 9.2). who advise Excessive food intake that is rich in saturated fats can cause health specific individuals problems such as obesity and cardiovascular diseases. on suitable diets. The cause of obesity Obesity is caused by the storage of excess fats as a result of imbalanced food intake and use of energy. Effects of obesity Individuals who are obese need to reduce the intake of carbohydrates and fats as well as increase the intake of vegetables and fruits. Otherwise, a diet with excessive saturated fats and high cholesterol may cause diabetes mellitus and various cardiovascular diseases such as atherosclerosis and hypertension which may result in heart attacks (myocardial infarction) or stroke if not treated. Activity Zone Cancer patients who are undergoing cancer treatment, need to modify their diet to ensure they receive sufficient energy, reduce the risk of Plan meals based infections and enable quick recovery. on Pinggan Sihat Malaysia for different individuals such as obese individuals, cancer patients and heart patients. 160 9.6.3 BioT4(NC)-B9-EN New 7th.indd 160 12/9/2019 9:35:16 AM 9.7 Health Issues Related to the Digestive System and Eating Habits Adaptation of digestive organs duodenum Obesity is a health issue on the rise throughout the world. Although jejunum obesity can be controlled through diet management and routine exercise programmes, at times, obesity requires medical treatment. Specialist doctors may suggest surgical procedures to reduce body weight such as gastric bypass (Figure 9.9). A gastric bypass involves a reduction of the stomach size using various methods of surgery. Among the short-term side effects of this surgery are acid reflux, nausea, vomiting, expanded oesophagus, certain food prohibitions and risk of infection. The long-term side effects are dizziness, low blood sugar level, malnutrition, stomach ulcer and defaecation problems. gastric sac Health issues related to defaecation Part of the The food class that is most important in the defaecation process CHAPTER 9 stomach is fibre. Intake of diet that is high in fibre such as fruits and that has vegetables can smoothen bowel movements. This can prevent been health problems such as constipation, colon cancer, rectum cancer bypassed and haemorrhoid. jejunum Some of the functions of fibre are to: • stimulate peristalsis Part of the • absorb and expel toxic substances duodenum • regulate the absorption of glucose especially for diabetes that has been bypassed mellitus patients • increase the population of beneficial bacteria in the large food intestine digestive juice Besides, the intake of a large amount of water can ensure that the FIGURE 9.9 Gastric bypass faeces stay soft and move easily along the large intestine to aid the process of defaecation. 9.7.1 9.7.2 161 BioT4(NC)-B9-EN New 6th.indd 161 11/21/2019 1:58:23 PM Health issues related to eating habits Apart from a balanced diet, eating habits also play an important role in fulfilling our energy requirements and maintaining our health. Poor eating habits and an imbalanced diet can cause numerous health problems such as gastritis, muscle dysmorphia, anorexia nervosa and bulimia nervosa. ANOREXIA NERVOSA GASTRITIS Anorexia Gastritis refers to the nervosa is quite common inflammation and corrosion of amongst the stomach epithelial layer teenage by gastric juice when there girls who are is no food in the stomach. obsessed with Untreated gastritis can result their body weight. in gastric ulcers. The causes Anorexics will avoid of gastritis include eating food to achieve their irregular quantities of food at ideal body weight. They also irregular hours and excessive suffer from psychological problems intake of alcohol or painkillers. and nutrient deficiency because of their normal digestive system is affected. BULIMIA NERVOSA MUSCLE DYSMORPHIA For people with bulimia nervosa who are also Some individuals obsessed with controlling feel that their size their body weight, they is small with not will eat a lot and vomit out enough growth. the food that they have So, they subject eaten or take laxatives that themselves cause diarrhoea. In the long to extreme run, the patient may suffer from weightlifting dehydration, nutritional problems and training and exercise. eventually cardiovascular disease or kidney failure. Sometimes, they consume steroids or muscle building supplements. This health issue is called muscle dysmorphia. Activity Zone 9.5Formative Practice 2 Predict the effect of modifying digestive organs Do a case study about 1 In your opinion, why is fibre such as gastric bypass on the following health issues important in the defaecation human health. related eating habits: process. Explain your • diabetes type 2 answer. 9.7.3 • obesity • acid reflux • pica 162 BioT4(NC)-B9-EN New 6th.indd 162 11/13/2019 12:32:10 AM Summary NUTRITION AND THE HUMAN DIGESTIVE SYSTEM Digestive System Balanced Diet Health Issues Related to the Digestive System and Eating • Digestion • Energy value • Absorption • Contents of vitamin C in Habits • Assimilation • Defaecation fruit or vegetables juices • The effects of modifying • Diet modifications for digestive organs on human health specific individuals • Health issues related to defaecation • Health issues related to eating habits Self Reflection CHAPTER 9 Have you mastered the following important concepts? 163 • Structure of the human digestive system • Mechanism of digestion 11/13/2019 12:32:10 AM • Process and products of carbohydrate digestion in the mouth • Process and products of protein digestion in the stomach • Digestions of carbohydrates, proteins and lipids in the small intestine • Adaptations of ileum and villus in the absorption of digested food • Assimilation of digested food and liver functions • Defaecation • Balanced diet and energy value in food samples • Diet modifications for specific individuals • Health issues related to the digestive system and eating habits BioT4(NC)-B9-EN New 6th.indd 163 Summative Practice 9 1 Some people cannot drink milk because it causes diarrhoea and a bloated stomach. Explain why. 2 Amin had some meat dishes for lunch. Explain how the protein is digested in Amin’s stomach. 3 An individual has the following eating habits: Overeating in a short period of time followed by intentional throwing up on purpose after each meal. Explain how this eating habit can affect the health of this individual. 4 Figure 1 shows the alimentary canal in humans. Z XY FIGURE 1 (a) Name structures X and Y. (b) (i) The enzymes in X are only effective in an alkaline environment. Explain how an alkaline environment is maintained in X. (ii) Explain how Y is involved in the digestion of carbohydrates in X. (c) Name the enzyme found in Z. Explain how this enzyme functions in the digestion of proteins. (d) A student enjoys eating a lot of oranges. Explain the effect of eating too many oranges on the digestion of starch in X. 164 11/13/2019 12:32:11 AM BioT4(NC)-B9-EN New 6th.indd 164 Essay Questions 5 Explain the processes that fat molecules undergo starting from the duodenum until it is finally used by body cells. 6 A teenager had the following for his breakfast. Buttered bread – 2 pieces Fresh milk – 1 glass Hard-boiled eggs – 2 Apple – 1 Explain what happens to the final digested products of his breakfast in his body cells. 7 (a) Explain why a diet rich in fats is not good for health. (b) Suggest suitable types of food for someone who wants to reduce weight and reduce the risk of contracting cardiovascular disease. Explain your answer. (c) Explain the processes of starch digestion, absorption and assimilation in the human body. Enrichment CHAPTER 9 8 Medicines in the form of capsules are not broken down in the stomach but absorbed easily by the small intestine. When the blood sample of the patient is taken and analysed, it is found that the molecular structure of this medicine is different from its original molecular structure. Explain why. 9 How are drinks with added artificial sweeteners produced and marketed? 10 Nowadays, many individuals prefer ready-to-eat or frozen food products due to their busy lifestyles. Predict the health risks that may arise if these foods are taken continuously for a long period of time and in large quantities. BioT4(NC)-B9-EN New 6th.indd 165 Complete answers are available by scanning the QR code provided 165 11/13/2019 12:32:11 AM CHAPTER Transport in Humans and 10 Animals What is a Do you KNOW... mechanical heart? ••• crHHbeWiroltocouhwwuoranldatddttaoocoisreierersyscsutusthtehlhyaeefestlcoutlheyoirdmeymmsas?ppriytnhosptantoueteimmctnhts?pesybbostllfooetoomhdde? • ltWyomhthpaethaahtruiecmtshayenshtceeimraclsuth?laitsosruyeasnrdelated 166 11/13/2019 12:37:32 AM BioT4(NC)-B10A-EN New 7th.indd 166 10.1 Types of Circulatory System 10.4 Mechanism of Blood Clotting 10.4.1 Justify the necessity for blood 10.1.1 Justify the necessity of transport clotting mechanism. systems in complex multicellular 10.4.2 Describe blood clotting organisms. mechanism. 10.4.3 Describe health issues related to 10.1.2 Identify substances that are blood clotting: • thrombosis transported by the transport • embolism • haemophilia system: • substances required by a cell • waste products of a cell 10.5 Blood Groups of Humans 10.5.1 Describe ABO blood group. 10.1.3 Conceptualise types of circulatory 10.5.2 Correlate ABO blood group with system in complex multicellular blood donation. organisms. 10.5.3 Describe the Rhesus factor. • open circulatory system 10.5.4 Reason out the incompatibility of • closed circulatory system Rhesus factor in pregnancies. 10.1.4 Compare and contrast circulatory 10.6 Health Issues Related to the Human systems in complex multicellular Circulatory System organisms: • insects • fish • amphibians • humans 10.6.1 Justify the necessity for a healthy circulatory system. 10.2 Circulatory System of Humans 10.6.2 Communicate about 10.2.1 Describe components of the cardiovascular diseases. human circulatory system: 10.7 Lymphatic System of Humans • heart • blood vessel • blood 10.7.1 Synthesise the process of 10.2.2 Explain the composition of blood: formation of tissue fluid and lymph. 10.7.2 Compare and contrast the • blood plasma • blood cells contents of lymph and: 10.2.3 Compare and contrast the types of • tissue fluid • blood 10.7.3 Describe components of the blood vessels: lymphatic system: • lymph • artery • vein • capillary • lymphatic capillaries 10.2.4 Label the structure of a human • lymphatic vessels• lymph nodes heart and associated blood • lymphatic organs vessels: • aorta • vena cava 10.7.4 Justify the necessity of the • pulmonary artery and pulmonary lymphatic system: vein • complements the blood • coronary artery and coronary circulatory system vein. • transports lipid-soluble • semilunar valve substances • bicuspid valve and tricuspid • body defence valve • septum 10.2.5 Describe the functions of parts of 10.8 Health Issues Related to the Human the heart. Lymphatic System 10.3 Mechanism of Heartbeat 10.8.1 Describe health issues related to the lymphatic system. 10.3.1 Describe the human heartbeat mechanism: 167 • sinoatrial node (pacemaker) • atrioventricular node • bundle of His • Purkinje fibres 10.3.2 Communicate about forces that cause the blood to circulate in humans: • pumping of the heart • contraction of skeletal muscles BioT4(NC)-B10A-EN New 7th.indd 167 11/13/2019 12:37:33 AM 10.1 Types of Circulatory System The necessity for transport systems in complex multicellular organisms Each living cell requires essential substances such as oxygen and Substance nutrients, and expels cellular waste products such as carbon dioxide exchange can occur and nitrogenous wastes. by diffusion because In Chapter 2, you learned how unicellular organisms such as Amoeba sp. the cells are in the get their essentials and expel wastes by diffusion from and to its external environment. surroundings. Unicellular organisms have a small body mass. Therefore, the total surface area to volume ratio (TSA/V) of the organism is large. As such, Amoeba sp. does not require a specialised transport system to transport substances in and out of the cell. What about multicellular organisms? Can multicellular organisms obtain all essential substances and expel wastes by simple diffusion like unicellular organisms? Large complex multicellular organisms cannot obtain essential substances and expel wastes by diffusion because their TSA/V is small. The distance between the external environment and the cell is too far for direct substance exchange. So, how do complex multicellular organisms get essential substances for their cells? external environment Substance is far away from cells exchange cannot epidermis occur by diffusion because the external environment cells are too far away from the environment. body cells FIGURE 10.2 Substance exchange for multicellular organisms FIGURE 10.1 Substance 10.1.1 10.1.2 exchange for unicellular 11/13/2019 12:37:33 AM 168 organisms BioT4(NC)-B10A-EN New 7th.indd 168 To address this problem, multicellular organisms have an internal ICT 10.1 transportation system. In vertebrates, the transportation system is called the blood circulatory system. Activity: Studying the effects of Before studying further the blood circulatory system, conduct an changes in total surface area experiment to study the effects of changes in TSA/V on the diffusion to volume ratio (TSA/V) on the rate. diffusion rate. Types of circulatory systems in multicellular organisms The circulatory system in multicellular organisms is divided into two types: open circulatory system and closed circulatory system. OPEN CIRCULATORY SYSTEM CLOSED CIRCULATORY SYSTEM • In an open circulatory system, • In a closed circulatory system, blood is haemolymph flows directly into the always contained in a continuous closed body cavity (haemocoel) and bathes the blood vessel and is distributed to the cells. whole body. • Haemolymph is a blood-like nutritious • The exchange of substances that are liquid found in most invertebrates such essential to cells such as oxygen and as insects and molluscs. nutrients occurs across the walls of blood capillaries. haheamemolyomlymphphvevsesseslel blobolododvevsesseslel CHAPTER 10 haheamemocooceolel blobolodod blobolododcacpailplailrlayry haheamemolyomlymphph hehaerat rt hehaerat rt ceclleslls ceclleslls opoepne-ne-nedneddedvevsesseslel 10.1.3 169 BioT4(NC)-B10A-EN New 7th.indd 169 11/13/2019 12:37:34 AM OPEN CIRCULATORY SYSTEM CIRCULATORY SYSTEM Circulatory System of Insects Circulatory System of Fish • The circulatory system of insects is • The heart of the fish has two chambers, an open circulatory system. This that is, an atrium (plural: atria) and a means that one or more hearts pump ventricle. haemolymph through the blood vessels into the haemocoel. • Blood that leaves the ventricle is pumped to the gill capillaries to enable gaseous • Haemolymph flows out from the heart exchange. into the haemocoel when the heart contracts. • The gill capillaries carry blood to the blood vessels that transport oxygenated • In the haemocoel, substance exchange blood to systemic capillaries. between haemolymph and body cells occurs through diffusion. • In the systemic capillaries, oxygen diffuses into the tissues while carbon • When the heart relaxes, haemolymph dioxide diffuses from the tissue into the flows back into the heart through tinanyterior capillaries. openings called ostium. • The deoxygenated blood is then returned aorta to the heart atrium through the veins. anterior • As the blood flows in one direction, the aorta fish circulatory system is known as a aorta single circulatory system. ostium gill capillaries posterior mixed blood aorta heart ostium ostium haemocoel heart artery FIGURE 10.4 The open circulatory system in insects heart ventricle posterior atrium FIGURE 10.3 Dorsal view of Indicator: vein insect heart oxygenated blood deoxygenated blood mixed blood mixed blood systemic capillaries FIGURE 10.5 The blood circulatory system of fish 170 10.1.4 BioT4(NC)-B10A-EN New 7th.indd 170 11/13/2019 12:37:35 AM CLOSED CIRCULATORY SYSTEM Circulatory System of Humans Circulatory System of Amphibians • The human heart consists of four • The heart of an amphibian has three chambers, chambers: two atria and two ventricles that are separated completely. that is, two atria and a ventricle. Unlike the single circulatory system of fish, blood flows in two • Humans have a double circulatory directions: pulmocutaneous circulation and system. This means that in one systemic circulation. Therefore, this system is complete circulatory cycle, blood known as a double circulatory system. flows in the blood vessels through the • Amphibians are said to have an incomplete double heart twice. As there are two different circulatory system because the deoxygenated circulations, humans are said to have blood and the oxygenated blood are mixed. a complete double circulatory • Pulmocutaneous circulation transports blood to system because the deoxygenated the lungs and skin, and the exchange of gases blood and the oxygenated blood do takes place here. Systemic circulation transports not mix. oxygenated blood to the body tissues and returns the deoxygenated blood to the right atrium through Pulmonary circulation the veins. • Deoxygenated blood is transported 1 Deoxygenated 2 Oxygenated blood through the pulmonary artery to the blood from body is from lungs and skin lungs for gaseous exchange. transported to the is transported by right atrium. the pulmonary vein • Oxygenated blood from the lungs is to the left atrium. returned to the left atrium and flows lung capillaries and skin into the left ventricle. 3 Blood from both atria enters one lung capillaries ventricle. Although pulmocutaneous there is some mixing pulmonary artery CHAPTER 10 circulation of oxygenated and deoxygenated blood in the ventricle, most vena cava aorta of the oxygenated 4 blood remains on pulmonary 12 the left side of the vein ventricle while the right 3 left deoxygenated blood right left atrium atrium remains on the right atrium side of the ventricle. atrium ventricle right left ventricle systemic circulation ventricle Indicator: oxygenated blood systemic capillaries systemic capillaries deoxygenated Indicator: blood oxygenated blood 4 The ventricle Systemic circulation then pumps the • Blood is pumped from the heart to all deoxygenated blood blood through the mixed blood pulmocutaneous (lungs the body tissues through the aorta. FIGURE 10.6 The blood and skin) and systemic • Then the deoxygenated blood returns circulatory system of amphibians circulations. to the right atrium through vena cava. 10.1.4 FIGURE 10.7 The blood circulatory system of humans 171 BioT4(NC)-B10A-EN New 7th.indd 171 11/13/2019 12:37:35 AM TABLE 10.1 Similarities and differences between circulatory systems in complex multicellular organisms Similarities The circulatory system is found in all multicellular organisms. The circulatory system consists of a heart to pump blood or haemolymph (in insects). The circulatory system functions to transport nutrients and wastes. The heart has valves that ensure blood flows in one direction. Differences Organism Insects Fish Amphibians Humans Types of Open blood Closed blood Closed blood Closed blood circulatory system circulatory system circulatory system circulatory system circulatory system Number of Single (blood Double Double circulations flows in the blood (blood flows in (blood flows in vessel and through the blood vessel the blood vessel – the heart once and through the and through the in a complete heart twice in heart twice in circulation) one complete one complete circulation) circulation) Number of The heart is made Two (one atrium Three (two atria Four (two atria and heart cavities up of many cavity and one ventricle) and one ventricle) two ventricles) segments Separation of Incomplete (some Complete oxygenated –– oxygenated blood (oxygenated blood blood and is mixed with the does not mix with deoxygenated deoxygenated deoxygenated blood blood in the blood in the ventricle) ventricle) 10.1Formative Practice 1 State two differences between the circulatory 3 The flatworm is a multicellular organism. systems of fish and humans. However, the flatworm does not require a specialised transportation system to move 2 Explain why the blood circulatory system of substances in and out of the cell. Explain amphibians is considered as a closed and why. incomplete blood circulatory system. 4 Explain why insects need one separate system (the tracheal system) to transport oxygen. 172 10.1.4 BioT4(NC)-B10A-EN New 7th.indd 172 11/13/2019 12:37:35 AM 10.2 Circulatory System of Humans Malaysian Innovation There are three main components in the circulatory system of humans. A group of researchers • Blood: A type of connective tissue that is made up of blood plasma, in Malaysia have produced a device blood cells and platelets. Blood acts as a medium of transportation. called MyThrob that • Heart: Functions as a muscular pump that circulates blood to the can be used as a smart examination whole body. and monitoring tool • Blood vessels: Consist of arteries, capillaries and veins that for heart diseases. The device studies the are connected to the heart, and transport blood to all original algorithm that the body tissues. can detect abnormal heartbeat and is Structure of the heart suitable to be used for monitoring at home. Do you know that your heart is as big as your fist? The heart is located between the lungs in the thorax cavity and contains four chambers, namely the left atrium, CHAPTER 10 right atrium, left ventricle and right ventricle. The left chamber is separated from the right chamber by a muscular wall called septum. Atrium receives blood that returns to the heart while the ventricle pumps blood out of the heart. The ventricle has thicker walls and contract stronger than the atrium. The muscular wall of the left ventricle is much thicker than the muscular wall of the right ventricle. This is because the left ventricle has to generate greater pressure to pump blood out of the aorta to the whole body while the right ventricle only has to pump blood to the lungs. Coronary arteries 173 transport oxygenated blood for heart tissues while coronary veins transport deoxygenated blood. coarrotenrai rkyoarorntearriies vceonraonkaoryonvaeriins TABLE 10.8 The circulatory system of humans 10.2.1 10.2.4 10.2.5 BioT4(NC)-B10A-EN New 7th.indd 173 11/13/2019 12:37:36 AM Aorta is the main blood artery that transports The pulmonary artery transports oxygenated blood to the whole body while the vena deoxygenated blood from the heart cava is the main vein that transports deoxygenated to the lungs while the pulmonary veins transports oxygenated blood blood back to the heart. from the lungs to the heart. The semilunar vena cava vena kava valves at the base of the pulmonary artery aorta and the base of the aorta aorta ensures that arteri pulmonari blood which flows pulmonary artery out of the heart does not flow back into the vena pulmonari ventricle when the pulmonary veins ventricle relaxes. atrium kiri left atrium semilunar valves cionrjaopnabriykuvsepinid bicuspid valve atrium kanan right atrium injap sabit incjaoprotnriakruysapridtery right ventricle septum The bicuspid arteri coronari valve (located lbeefttwastereeiupntmumthe tricuspid valve and the left ventricle) The tricuspid valve ensures that (locvaetnetrdikeblektawnaenen the blood which right atrium and the right flows into the ventricle) ensures that left ventricle blood which flows into the does not flow right ventricle does not back into the flow back into the right left atrium. This atrium. This valve consists valve consists of three leaflets. left ventricle of two leaflets. Brainstorm! The septum separates the left part of the heart What would happen from the right part of the heart and ensures that to an individual the oxygenated blood does not mix with the if the bicuspid deoxygenated blood. valve does not close completely FIGURE 10.9 Longitudinal section of a human heart when the ventricle relaxes? ICT 10.2 174 Video: Animation of the heart valves (Accessed on 21 August 2019) 10.2.4 10.2.5 BioT4(NC)-B10A-EN New 7th.indd 174 11/13/2019 12:37:38 AM Composition of human blood Biological Lens The human blood consists of 55% plasma and 45% cell components. Perfluorocarbon (PFC) Plasma is the medium of transportation in the body. The components emulsions can be of blood cells consist of red blood cells or erythrocytes, platelets and potentially used as white blood cells or leucocytes (Photographs 10.1 and 10.2). artificial blood. Studies have shown that PFC has the capacity like blood to transport oxygen and carbon dioxide. erythrocyte Plasma (forms 55% of the blood platelet volume) leucocyte Leucocytes and platelets (less than 1% of the blood volume) Erythrocytes (forms 45% of the blood volume) PHOTOGRAPH 10.1 Main components of blood PHOTOGRAPH 10.2 Main structural components of blood CHAPTER 10 TABLE 10.2 Blood plasma components and the main function of each component Component Main function Water Blood plasma consists of 90% water. Water is a medium of transportation and a solvent for respiratory gas, ions, digestive products and excretory substances. Plasma proteins • Fibrinogen plays a role in blood clotting. • Albumin controls blood osmotic pressure. • Globulin is a type of antibody that is involved in the body’s defence. Solutes – nutrients such • Nutrients are important for energy, growth and maintenance of health. as glucose, excretory • Excretory substances are toxic substances that need to be disposed substances such as urea and respiratory gas off from the body. • Oxygen is required in the respiration of cells. Hormones and enzymes Hormones control physiological activities in the body. Enzymes are involved in the metabolic processes of cells. 10.2.2 175 BioT4(NC)-B10A-EN New 7th.indd 175 11/13/2019 12:37:42 AM Table 10.3 shows the characteristics and functions of each blood cell type. TABLE 10.3 Characteristics and functions of blood cell types Blood cell type Characteristics Functions Erythrocyte • Has an elastic plasma membrane • Each erythrocyte has a (red blood cell) • The biconcave disc shape haemoglobin which is the red pigment that gives blood its red s2id.e0 viemw enables a large TSA/V for efficient colour. gaseous exchange pandangan sisi • It does not have a nucleus at • Haemoglobin contains a heme the mature stage s7o.5thamt more group. The heme group consists top view haemoglobin can be loaded of an iron atom which is the into it binding site for oxygen. FIGURE 10.10 •p aIntdiasnpgarondautacsed in the bone Erythrocyte structure marrow of bones such as the • Haemoglobin combines with Platelet sternum and ribs oxygen to form oxyhaemoglobin • Can live up to 120 days and is in high oxygen partial pressure destroyed in the liver or lymph conditions. through the phagocytosis process. • Oxyhaemoglobin releases oxygen in tissues or cells when the partial pressure of oxygen is low. • Platelets are produced from • Involved in the blood clotting fragments or scraps of cell process cytoplasm that originate from the bone marrows. • The life span is less than one week. FIGURE 10.11 Platelet polypeptide iron oxygen Brainstorm! The red blood cell of frogs has a nucleus and is larger than the red blood cell of humans. What are the advantages and disadvantages of nucleated red blood cells? Haemoglobin 176 10.2.2 BioT4(NC)-B10A-EN New 7th.indd 176 11/13/2019 12:37:43 AM Blood cell type Characteristics and functions Leucocyte (white blood • The shape is irregular and is not fixed cell) • Contains nucleus • Does not contain haemoglobin L Granulocytes • Produced in the bone marrow • Life span is less than five days • Leucocyte can diffuse out of the capillary pore and fight pathogens in tissue fluids. It is divided into two types: granulocytes (contain granules) and agranulocytes (no granules). • Granulocytes include neutrophils, eosinophils and basophils. Agranulocytes include lymphocytes and monocytes. E Neutrophil Eosinophil Basophil • The nucleus is made up of • The number of basophils U • The nucleus is made up of two to five lobes. two lobes. is lowest in the blood • Releases enzymes that • It contains heparin that C • Ingests bacterial cells and dead cells or tissues from fight inflammation and prevents blood clotting allergy reaction O wounds by phagocytosis C Y T E S Agranulocyte Lymphocyte Monocyte CHAPTER 10 • Contains a large nucleus with very little • The biggest leucocyte • Spherical-shaped nucleus cytoplasm • Ingests bacteria and dead cells or • Produces antibodies to destroy bacteria and tissues by phagocytosis viruses that enter the body • Can also produce antitoxins against toxins that are produced by bacteria or viruses PHOTOGRAPH 10.3 Photomicrograph of leucocytes 10.2.2 177 BioT4(NC)-B10A-EN New 7th.indd 177 11/13/2019 12:37:44 AM Human blood vessels Blood capillary endothelial cells endothelium endothelium smooth smooth muscle muscle connective tissue connective tissue Artery Vein venule arteriole FIGURE 10.12 Relationship between artery, blood capillaries and vein ARTERY BLOOD VEIN Arteries are blood vessels that transport CAPILLARIES blood out of the heart. The function of the Capillaries rejoin to artery is to quickly transport blood at a high Capillaries are form larger blood pressure to the tissues. blood vessels with vessels called The blood in the artery is under high thin walls, as thick venules. The venules pressure because of the pumping action of as one cell. Blood combine to form the heart. capillaries allow the veins that transport The aorta is the main artery that leaves exchange of gases to blood back to the the heart. The artery expands when blood occur between blood heart. Vena cava is is received from the heart. Therefore, the and cells through the main vein that artery wall is elastic to stop it from breaking diffusion. Nutrients, carries deoxygenated due to the high-pressured blood that flows excretory substances blood back to the through it. and hormones heart. The differences The branches of an artery become small diffuse through blood between arteries, vessels known as arterioles when they capillaries. capillaries and veins reach the body tissues. The arteriole are given in Table 10.4. continues to branch out and ends at the capillaries. The group of capillaries is called 10.2.3 capillary network. 178 BioT4(NC)-B10A-EN New 7th.indd 178 11/13/2019 12:37:45 AM TABLE 10.4 Differences between arteries, capillaries and veins Characteristics Artery Capillaries Veins Wall Wall is thick, muscular Wall is as thick as one Wall is thin, less muscular and elastic cell, not muscular and and less elastic not elastiKcaKpaiplailariri Arteri Vena Arteri Vena elastic wall (as thick as one cell) Vena fibre Kapilari Arteri lumen lumen Lumen wall lumen wall Very tiny Large Valve Small No Contain valves to maintain Blood pressure No valve except for one-way flow of blood The direction of semilunar valve at blood flow the base of the aorta Low Very low and at the base of the pulmonary artery From the artery to the From the whole body vein to the heart High From the heart to the entire body lumen (middle space) connective CHAPTER 10 erythrocyte tissues PHOTOGRAPH 10.4 Scanning electron microscope shows the cross section of an arteriole (4000x magnification) 10.2Formative Practice 3 State two differences between the structures of erythrocyte and leucocyte. 1 What is the function of the bicuspid valve? 4 Explain why the left ventricle has a thicker 2 Explain why some individuals feel nauseous muscular wall than the right ventricle. and faint immediately after donating blood? Why do some blood donors need to take iron pills? 10.2.3 179 BioT4(NC)-B10A-EN New 7th.indd 179 11/13/2019 12:37:48 AM 10.3 Mechanism of Heartbeat How is blood circulated to the whole body? In every contraction, the heart acts as a pump that pumps blood to the whole body. How is every heartbeat triggered and sustained? The heart is made up of cardiac muscles (Photograph 10.5) that intersect and are connected with one another. This arrangement allows electric impulses to spread rapidly through the heart and at the same time, stimulates the cardiac muscle cells to contract simultaneously and uniformly. Cardiac muscles are myogenic. This means that the heart contracts and relaxes without receiving any impulse signal from the nervous system. If the cardiac muscles are stored in a warm oxygenated solution that contains nutrients, these muscles will contract and relax rhythmically on their own. PHOTOGRAPH 10.5 Blood circulation in humans Cardiac muscle tissue The produced force that enables blood to circulate in humans is Our World of Biology generated by the pumping of the heart and the contraction of the skeletal muscles. The “Medtronic Micra” pacemaker left atrium is the smallest artificial pacemaker sinoatrial node in the world. The size is about the right atrium bundle of His size of a vitamin atrioventricular node left ventricle pill and is placed in the heart without right ventricle surgery. The artificial pacemaker sends small electrical charges to stimulate heartbeat. Purkinje fibres FIGURE 10.13 The location of sinoatrial node, atrioventricular node, bundle of His and Purkinje fibres 180 10.3.1 BioT4(NC)-B10A-EN New 7th.indd 180 11/13/2019 12:37:49 AM Pumping of the heart The pacemaker generates electrical impulses that spread rapidly through both walls of The contraction of the heart is initiated and the atrium and causes the atrium to contract coordinated by the pacemaker. The pacemaker rhythmically. The main pacemaker is called is a group of specific heart muscle cells that sinoatrial node (SA). The sequence of heart initiates the rate of heart contraction and is muscle contraction that causes the pumping is located at the right atrium wall (Figure 10.14). shown in Figure 10.14. 1 The sinoatrial node (SA) generates 2 Electrical impulses spread rapidly electrical impulses. in both the atria, causing the atria to contract simultaneously. The sinoatrial nodes contraction of the atria helps to pump (SA nodes) blood into the ventricles. atria Purkinje fibres AR ventricles 4 The electrical impulses spread atrioventricular node (AV node) CHAPTER 10 from the apex of the heart to the whole ventricle wall. As a result, the ventricles contract to pump blood out to the lungs and body. bundle of His Across the fields apex of Electrical impulses the heart in the heart can be detected by 3 Purkinje fibres putting electrodes The electrical impulses reach the on the skin. The atrioventricular node. The electrical electrocardiogram impulses spread through the bundle of is a record of the His, and the Purkinje fibres up to the electrical activity apex of the heart. that triggers every heartbeat. FIGURE 10.14 The sequence of heart contraction that causes the pumping of the heart 10.3.2 181 BioT4(NC)-B10A-EN New 7th.indd 181 11/13/2019 12:37:50 AM During heart pumping, the lub-dub sound can be heard. Do you know what causes this lub-dub sound? The lub-dub sound is the closing sound of the heart valves. 1 The first ‘lub’ sound is produced when the tricuspid valve and the bicuspid valve close. 2 The second ‘dub’ sound is tricuspid valve bicuspid valve produced when the semilunar valves close. FIGURE 10.15 The lub-dub sound of the heart semilunar valves open valve Contraction of skeletal muscles around the veins veins muscle The pumping of the heart helps in the distribution and flow contraction of blood through the arteries, arterioles and blood capillaries. contricts vein However, the force produced by the pumping of the heart is insufficient for the blood flow to continue through the veins and closed valve return to the heart. Besides, the blood is forced to flow against the force of gravity. The presence valve in the veins ensures that the blood flows in one direction to the heart. muscles relax The blood flow in the veins is assisted by: FIGURE 10.16 Contraction (a) contraction of the smooth muscles found in the venule and and relaxation of the foot vein walls; skeletal muscles (b) contraction of skeletal muscles around the veins. The contraction of skeletal muscles presses and constricts the veins, causing the valve to open and allow blood to flow towards the heart. The valve is then closed to prevent the blood from flowing back towards the foot (Figure 10.16). Brainstorm! 10.3Formative Practice What would happen 1 Name the main heart 4 In what circumstances would to the valve in the pacemaker. fingers turn pale? blood vessels of our legs if we stand or sit 2 What does the term for too long? myogenic mean? 3 Explain why a person who stands too long may faint. 182 10.3.2 BioT4(NC)-B10A-EN New 7th.indd 182 11/13/2019 12:37:50 AM 10.4 Mechanism of Blood Clotting The necessity for blood clotting mechanism STEM Bulletin What happens when your finger is injured? Blood will flow from the Scientists have wound until you apply pressure directly on the wound. The pressure developed a you apply may appear to restrict bleeding temporarily; however, the nanomagnetic blood flow is actually stopped by the blood clotting process. particle that Why must the blood clot on the wound? Blood clotting will stop or contains thrombin. minimise the loss of blood on the injured blood vessel. Blood clotting This nanoparticle also prevents microorganisms such as bacteria from entering the is injected into bloodstream through the damaged blood vessel. The blood pressure is the injured part also maintained because excessive blood loss will lower blood pressure to trigger blood to a dangerous level. How does blood clotting occur? clotting and to stop bleeding. Mechanism of blood clotting Blood clotting involves a series of chemical reactions that takes place in the blood when someone is injured to prevent excessive bleeding. The coagulated platelets, damaged cells and clotting factors CHAPTER 10 in the blood plasma will form an activator (thrombokinase). Thrombokinase, with the aid of calcium ions and vitamin K, converts prothrombin to thrombin. Prothrombin (inactive Thrombin (active plasma plasma protein) protein that acts as an enzyme). Thrombin catalyses the conversion of fibrinogen to fibrin. Fibrinogen (soluble) Fibrin (insoluble) TABLE 10.17 Fibrin is a threadlike protein fibre that Mechanism of blood clotting forms a network on the wound surface to trap erythrocytes and to close the wound to prevent blood loss. 10.4.1 10.4.2 183 BioT4(NC)-B10A-EN New 7th.indd 183 11/13/2019 12:37:51 AM Our World of Biology Health issues related to blood clotting When you sit for too long, the risk of Under normal conditions, blood does not thrombosis in legs clot in blood vessels that are not damaged will increase. Make because of some anticoagulants such as sure that you move heparin. What happens when the blood your legs once in a clotting mechanism of an individual does while. not function? Activity Zone HAEMOPHILIA Work in groups • Haemophilia is an example of an illness that to collect and prevents blood from clotting. interpret information about thrombosis, • Haemophilia is a hereditary illness caused by the embolism and lack of certain clotting factors in the blood. haemophilia. Present your • Excessive bleeding due to small wounds or findings to the bruises can result in death. class. THROMBOSIS • Formation of a blood clot (thrombus). • Thrombosis happens as a result of: – damage in blood vessels, or – sluggish blood flow that causes clotting factors to accumulate EMBOLISM • When a blood clot is transported by blood flow, the blood clot is called embolus. • If the embolus gets stuck in a tiny blood vessel, the blood flow will stop. 10.4Formative Practice 1 At the end of the blood clotting mechanism, 3 Explain the mechanism of blood clotting. fibrin will be formed to trap erythrocytes. Explain the meaning of fibrin and its function. 4 Explain why the formation of blood clots in the blood vessel can cause a heart attack. 2 Describe two health issues related to blood clotting. 184 10.4.3 BioT4(NC)-B10A-EN New 7th.indd 184 11/13/2019 12:37:52 AM 10.5 Blood Groups of Humans ABO blood group Do you know your blood group? Human blood is classified into A, B, AB and O groups. Donation and transfusion of blood is based on the compatibility of the blood group of the donor and the recipient. TcaBhnliosaoicsdt baggerocaauinupsstBetthheearnetcigipeinenotnhtahsearnetdibbolodoieds in the blood serum that Blood group A cells of the donor. Blood antigen A transfruesdiobnloofdrocmella donor to a recipient must take into consideration the blood group type of the donor and the recipient (Table 10.6). If anti-B antibody the blood group of both the donor and receiver is not compatible, anti-t(Ahcoeaanrgteiubdloadtbiyloonao)nd.tigceenllsB of the recipient will experience agglutination red blood cell Blood group AB Blood group O TABLE 10.5 Antigen and antibody in blood groups antigBelnoAod groupanBtigen B BgBrloonloouoopdardendgtigrboelounAopsndtBicgeelln on red blood cells  ood group A Blooreddgbrloouopd cAell Antibody in the blood antigen A serum tibody annotigaenntibAodies A red blood cell Antigen A Anti-B ed blood cell arnetid-Bblaonotdibcoedlyl antigen B B anti-A antibodyAntigen B Anti-A anti-A antibody anti-B antibody AB Antigen A and Antigen B No Anti-A and Anti-B O antigen B No od group AB BloreoddbglorooudpceOll anti-A antibody TABLE 10.6 Compatibility of blood donor group with the recipient A antigen B BnloooardendgtigrboelounopsdAcBell ood group A antigBenloAod groupanBtigen B BBloloodd group OCan donate blood to Can receive blood from blood groups groupred blood cell blood groups A and O only annotiagnetnibAodies red blood cell nAo antigens A and AB only CHAPTER 10 dtibcoedlly anti-A antibody B and O only B B and AB only anti-B antibody no antibodies AB anti-A antibody AB only A, B, AB and O red blood cell antigen B anti-B aOntibody A, B, AB and O O only ed blood cell anti-A antibody od group AB Blood group O Rhesus Factor A antigen B red blood cell Another antigen found on the surface of the red blood cells is the no antigens Rhesus factor (Rh factor). The red blood cells of an individual with the Rh factor or antigen D are known as Rh-positive. An no antibodies anti-A antibody individual who does not possess the Rh factor or antigen D is known d cell anti-B antibody as Rh-negative. FIGURE 10.18 Antigens and If the blood of a Rh-positive donor mixes with the blood of a Rh- antibodies in different blood negative recipient, the blood of the recipient will react by producing groups the Rhesus antibody or anti-D antibody. When the recipient receives another dose of Rh-positive blood, the Rhesus antibody will cause the agglutination of the donor blood cells. This situation could result in the death of the recipient. 10.5.1 10.5.2 10.5.3 185 BioT4(NC)-B10A-EN New 7th.indd 185 11/13/2019 12:37:52 AM Pregnancy and the Rhesus factor Usually, problems During the last month of However, the Indicator: will arise when an pregnancy, fragments concentration Rh-negative mother of foetal blood cells of antibodies Rh-positive marries an containing antigen D produced is Rh-positive father cross the placenta not enough Rh-negative and conceives an and enter the blood to affect the Rh-positive foetus. circulation of the mother. first child. But Anti-D the anti-D antibodies As a result, the white antibodies blood cells in the will last in The problem arises when mother’s blood will react the blood the second child is also and produce anti-D circulatory Rh-positive. The anti-D antibodies that will system of the antibodies that are present flow back through the mother. in the mother’s blood cross placenta into the foetal the placenta and destroy blood circulatory system. the red blood cells of that foetus. The symptoms The antibodies will destroy of this disease are called the red blood cells of the erythroblastosis fetalis. Rh-positive baby before The second foetus dies if or immediately after birth. the blood is not replaced with Rh-negative blood 10.5Formative Practice through blood transfusion. In a less serious situation, the baby may suffer from anaemia and mental retardation. However, this problem can now be addressed by treating the affected mother with anti-Rhesus globulins after the first pregnancy to stop the formation of anti-D antibodies. 1 State the blood group which is the universal The first pair of parents: B and O donor. The second pair of parents: A and B The third pair of parents: AB and O 2 Predict what will happen if the blood group of both recipient and donor is not compatible. Match the babies with their correct parents. 3 Three babies P, Q and R have blood groups 4 An Rh-positive male marries an Rh-negative B, O and AB respectively. Three pairs of female. The first Rh-positive child is alive but parents have the following blood groups: the second child who is also Rh-positive did not survive. Explain why. 186 10.5.4 BioT4(NC)-B10B-EN New 6th.indd 186 11/13/2019 12:12:10 PM 10.6 Health Issues Related to the Human Circulatory System Activity Zone The necessity for a healthy circulatory system Work in groups and conduct a A healthy circulatory system is important to ensure optimum health. case study on How do we ensure that our circulatory system is healthy? Among the the practices of practices for maintaining the circulatory system are a balanced intake of maintaining a healthy food that is low in fat and regular exercise. The practice of not smoking human circulatory and not drinking alcoholic drinks also ensures a healthy circulatory system. system. Cardiovascular diseases Do you know that cardiovascular diseases are the leading cause of death in our country? Cardiovascular diseases include diseases related to the heart and the blood circulatory system such as atherosclerosis, arteriosclerosis, angina, hypertension, myocardial infarction (heart attack) and stroke. Activity Zone CARDIOVASCULAR DISEASES CHAPTER 10 Discuss a suitable • Atherosclerosis is the formation and deposition of plaque on the treatment for heart artery walls. failure. • The plaque is formed from cholesterol, lipid, dead muscle tissues and coagulated platelets. • The plaque will clog and narrow the lumen in blood vessels. • The restricted blood flow can cause hypertension. • Hypertension causes fine arteries to break and the patient can suffer from stroke if this happens in the brain. • Stroke is also caused by blood clots (thrombus) that clog the flow of blood in the brain. • Atherosclerosis is the early stage of arteriosclerosis. • Arteriosclerosis occurs when calcium is deposited on the plaque and causes the artery to become hard and lose its elasticity. • If the lumen of the coronary artery (artery for the heart) is narrowed, the insufficient oxygen supply to the heart muscles can cause angina (severe chest pain). • If the artery is completely clogged, myocardial infarction (heart attack) will occur. PHOTOGRAPH 10.6 Myocardial infarction (heart attack) 10.6.1 10.6.2 187 BioT4(NC)-B10B-EN New 6th.indd 187 11/13/2019 12:12:10 PM artery blood clot restricts the flow of blood coronary artery plaque is formed in the artery dead cardiac muscle tissues STEM Bulletin FIGURE 10.19 Formation and deposition of plaque on artery wall Nanotechnology is What is the treatment for a patient who suffers from heart failure? What used in the diagnosis are the risk factors that contribute to cardiovascular diseases and what and treatment of can we do to ensure that the cardiovascular system is healthy? atherosclerosis and plaque formation 10.6Formative Practice in arteries. In this technique, nanoparticles 1 What is the meaning of 3 In your opinion, what are the are designed to myocardial infarction? factors that contribute to an resemble high-density individual’s risk of getting lipoprotein cholesterol 2 Explain how stroke happens. cardiovascular disease? (HDL) (“good” cholesterol) to help 4 Explain how atherosclerosis reduce plaque. happens. 188 10.6.1 10.6.2 BioT4(NC)-B10B-EN New 6th.indd 188 11/13/2019 12:12:12 PM 10.7 Human Lymphatic System The formation of tissue fluid In addition to the blood circulatory system, there is one more system in the body whose function is closely related to the blood circulatory system. This system is called the lymphatic system. The formation of tissue fluid is illustrated in Figure 10.20. 1 Blood that reaches the arterial end of the 2 This pressure allows the blood blood capillary has a high pressure due to the plasma to diffuse continuously small diameter of capillaries and the pumping from the blood capillaries to the force of the heart. intercellular space. blood plasma cell arteriole oxygenated deoxygenated blood at a high blood at a low pressure pressure tissue fluid blood capillary lymphatic capillary FIGURE 10.20 Exchange of substances between blood capillaries and body cells CHAPTER 10 3 • Blood plasma that occupies the 4 • Tissue fluid allows the exchange of intercellular space and constantly • materials in the blood and cells to • bathes cells is called tissue fluid. • occur. Nutrients and oxygen diffuse from The tissue fluid does not contain tissue fluid to body cells. any erythrocyte, platelet and Simultaneously, excretory products and plasma protein because these carbon dioxide diffuse from body cells are too large to diffuse out of the to blood capillaries through the tissue blood capillaries. fluid. Lymph formation and components of the lymphatic system At the venule end of the blood capillary, blood plasma is hypertonic compared to the tissue fluid surrounding it. Blood pressure is also lower. As a result, the reabsorption of water, mineral salts and waste takes place in the venule capillary. However, only 85% of the fluid that leaves the blood at the arteriole end of blood capillary diffuses back into the venule end. What happens to the remaining 15% that is left in the intercellular space? This remainder forms about 4 litres of fluid that is lost from capillaries each day. How does the blood circulatory system regain this fluid? 10.7.1 189 BioT4(NC)-B10B-EN New 6th.indd 189 11/13/2019 12:12:12 PM The lost fluid is collected and returned to the blood through the lymphatic capillary, which is the smallest vessel in the lymphatic system. This fluid is known as lymph and is pale yellow in colour. Table 10.7 and Table 10.8 show the similarities and differences between lymph with tissue fluid and blood. TABLE 10.7 Comparison between lymph and tissue fluid Similarity Both contain plasma without the plasma proteins, erythrocytes and platelets. Differences Lymph Tissue fluid Higher content of fat and fat-soluble substances Low content of fat and fat-soluble substances High content of lymphocytes Low content of lymphocytes TABLE 10.8 Comparison between lymph and blood Similarity Both contain all the contents of plasma such as nutrients, hormones, enzymes, cellular wastes, respiratory gases and leucocytes. Differences Lymph Blood Does not contain plasma protein, erythrocyte and Contains plasma proteins, erythrocytes and platelet platelets The lymphatic capillary wall consists of one layer of cells only. The lymphatic capillary differs from blood capillary because one of its end is blocked or closed while the other end is connected to the lymphatic vessel (Figure10.21). Lymphatic capillaries found in intercellular spaces merge to form a larger lymphatic vessel. Along the lymphatic vessel, there are lymph nodes at certain distances. lymphatic capillary tissue cell fluid arteriole venule lymph tissue fluid lymphatic vessel lymphatic capillary 190 FIGURE 10.21 Lymph formation valve 10.7.2 10.7.3 BioT4(NC)-B10B-EN New 6th.indd 190 11/13/2019 12:12:13 PM The lymphatic system consists of organs such as lymph nodes, spleen, thymus gland, bone marrow, tonsils and appendix (Figure 10.22). The lymphatic system does not have its own pump to circulate the lymph along the lymphatic vessel. The flow of lymph is aided by heartbeat pulse, contraction of skeletal muscles, peristalsis in the digestive tract and changes in pressure during inhalation and exhalation of breath. In the lymphatic vessel, one-way valves ensure the lymph flows continuously to the heart. These valves also prevent the lymph from flowing back. Relationship between the blood circulatory system and the lymphatic system All lymphatic vessels will eventually join with one of the two main lymphatic vessels which are the thoracic duct dan right lymphatic duct (Figure 10.22). The right right lymphatic duct tonsils lymphatic duct right receives lymph subclavian thoracic duct from the right vein left subclavian hand, chest and vein right side of the thymus head and neck. bone marrow lymphatic The thoracic vessel spleen duct receives lymph from the left side of the head, neck and chest, and all the body parts below the ribs. appendix CHAPTER 10 lymphatic lymph nodes lymph node capillary lymphocyte valve 191 10.7.3 blood vessel tissue fluid FIGURE 10.22 Lymphatic system BioT4(NC)-B10B-EN New 6th.indd 191 11/13/2019 12:12:14 PM Systemic circulation Pulmonary circulation The thoracic duct will deliver its lymphatic contents into the left subclavian right subclavian lymph capillaries vein while the right lymphatic duct vein node will transport lymph into the right pulmonary subclavian vein. right lymphatic capillaries So the lymph collected from the whole duct body will flow back into the blood circulatory system. Figure 10.23 shows lymphatic the relationship between the lymphatic vessel system and the blood circulatory system that complement each other. valve vein artery lymph systemic node capillaries lymphatic FIGURE 10.23 Relationship between lymphatic system capillaries and blood circulatory system The necessity of the lymphatic system The necessity of the lymphatic system is summarised in Figure 10.24. COMPLEMENTS THE NECESSITIES OF BODY DEFENCE BLOOD CIRCULATORY THE LYMPHATIC Lymph nodes produce and store SYSTEM SYSTEM lymphocytes that are involved in the production of antibodies. The lymphatic system returns the excess tissue fluid in the TRANSPORTATION OF FAT- intercellular space into the SOLUBLE SUBSTANCES blood flow. The composition, pressure and volume of blood are Fats and fat-soluble substances maintained at a normal range. diffuse into the lacteal in the villus of the small intestine. Lacteals are FIGURE 10.24 The necessity of the lymphatic capillaries. Lipid droplets lymphatic system are transported to the thoracic duct and blood circulatory system through the left subclavian vein. 10.7Formative Practice 3 State the differences between the composition of blood plasma, tissue fluid and lymph. 1 Name the two main lymphatic vessels. 4 After eating fatty food, the number of lipid 2 State three main functions of the lymphatic molecules in the lymph increases by 1%. system. Explain why. 192 10.7.4 BioT4(NC)-B10B-EN New 6th.indd 192 11/13/2019 12:12:15 PM 10.8 Health Issues Related to the Human Lymphatic System Have you ever wondered what would happen if our lymphatic system Brainstorm! does not function properly? What would happen if the excess tissue fluid is not returned to the blood flow? Tissue fluid that is not returned to the Why do our legs blood circulatory system will accumulate in the intercellular space. This swell after we sit for will result in the swelling of the body tissues. This condition is known too long? as oedema (Photograph 10.7). Oedema may be caused by a number of factors (Figure 10.25). PARASITIC INFECTION PREGNANCY DEFICIENCY IN • The parasite worm Brugia sp. The body will produce more PLASMA PROTEIN infects the lymphatic vessel body fluid to fulfill the needs of a and prevents the flow of growing foetus. Deficiency of albumin lymphatic fluid. in the blood. PROLONGED BEDRIDDEN • The infected part, for example, PATIENTS leg will swell. Paralysed or stroke patients with • The patient contracts limited mobility can suffer from lymphatic filariasis (Photograph oedema in the legs. 10.8). • This worm is transmitted through mosquito bites. CAUSES OF CHAPTER 10 OEDEMA normal leg leg with oedema FIGURE 10.25 Causes of PHOTOGRAPH 10.7 oedema Oedema PHOTOGRAPH 10.8 10.8Formative Practice Swollen leg caused by lymphatic filariasis 1 How do parasitic infections happen? 3 Predict what would happen to the legs of a patient who has been bedridden for a long 2 Explain what would happen when the tissue period of time? Explain your answer. fluid fails to return to the blood circulatory system. 4 Lipid droplets or fat globules cannot diffuse into the villus blood capillary but must diffuse through the lacteal. Explain why. 10.8.1 193 BioT4(NC)-B10B-EN New 6th.indd 193 11/13/2019 12:12:16 PM Summary TRANSPORT IN HUMANS AND ANIMALS Circulatory System Lymphatic System Components of the Open Circulatory Closed Circulatory System lymphatic system System Blood is contained in the • Lymph Haemolymph closed blood vessel that is • Lymphatic capillaries flows into the continuous and is distributed • Lymphatic vessel body cavities to the whole body • Lymph nodes (haemocoel) and • Lymphatic organs bathes cells Fish The necessity of the The fish heart has two Lymphatic System Insects chambers: an atrium and a • Complements the blood One or more hearts ventricle circulatory system pump haemolymph • Transportation of fat- through the Amphibians soluble substances haemolymph vessel The heart of an amphibian • Body defence into the haemocoel consists of three chambers: Health Issues Related to two atria and one ventricle the Human Lymphatic System Humans • Lymphatic filariasis The human heart consists • Parasitic infection of four chambers: two atria • Deficiency in plasma and two ventricles that are protein completely separated • Pregnancy • Prolonged bedridden patients Circulatory Mechanism Mechanism Blood Groups of Health Issues Related System of of of Blood Humans to the Human Humans Heartbeat Clotting Circulatory System • Blood type A • Blood Health Issues • Blood type B • Arteriosclerosis • Heart Related to Blood • Blood type AB • Atherosclerosis • Blood vessel Clotting • Blood type O • Hypertension • Rhesus factor • Angina • Myocardial • Thrombosis • Embolism infarction • Haemophilia • Stroke 194 BioT4(NC)-B10B-EN New 6th.indd 194 11/13/2019 12:12:16 PM

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9.4 Signaling in Single-Celled Organisms

Learning objectives.

By the end of this section, you will be able to do the following:

• Describe how single-celled yeasts use cell signaling to communicate with one another
• Relate the role of quorum sensing to the ability of some bacteria to form biofilms

Within-cell signaling allows bacteria to respond to environmental cues, such as nutrient levels. Some single-celled organisms also release molecules to signal to each other.

Signaling in Yeast

Yeasts are eukaryotes (fungi), and the components and processes found in yeast signals are similar to those of cell-surface receptor signals in multicellular organisms. Budding yeasts ( Figure 9.16 ) are able to participate in a process that is similar to sexual reproduction that entails two haploid cells (cells with one-half the normal number of chromosomes) combining to form a diploid cell (a cell with two sets of each chromosome, which is what normal body cells contain). In order to find another haploid yeast cell that is prepared to mate, budding yeasts secrete a signaling molecule called mating factor . When mating factor binds to cell-surface receptors in other yeast cells that are nearby, they stop their normal growth cycles and initiate a cell signaling cascade that includes protein kinases and GTP-binding proteins that are similar to G-proteins.

Signaling in Bacteria

Signaling in bacteria enables bacteria to monitor extracellular conditions, ensure that there are sufficient amounts of nutrients, and ensure that hazardous situations are avoided. There are circumstances, however, when bacteria communicate with each other.

The first evidence of bacterial communication was observed in a bacterium that has a symbiotic relationship with Hawaiian bobtail squid. When the population density of the bacteria reaches a certain level, specific gene expression is initiated, and the bacteria produce bioluminescent proteins that emit light. Because the number of cells present in the environment (cell density) is the determining factor for signaling, bacterial signaling was named quorum sensing . In politics and business, a quorum is the minimum number of members required to be present to vote on an issue.

Quorum sensing uses autoinducers as signaling molecules. Autoinducers are signaling molecules secreted by bacteria to communicate with other bacteria of the same kind. The secreted autoinducers can be small, hydrophobic molecules, such as acyl-homoserine lactone (AHL), or larger peptide-based molecules; each type of molecule has a different mode of action. When AHL enters target bacteria, it binds to transcription factors, which then switch gene expression on or off. When the number of bacteria increases so does the concentration of the autoinducer, triggering increased expression of certain genes including autoinducers, which results in a self-amplifying cycle, also known as a positive feedback loop ( Figure 9.17 ). The peptide autoinducers stimulate more complicated signaling pathways that include bacterial kinases. The changes in bacteria following exposure to autoinducers can be quite extensive. The pathogenic bacterium Pseudomonas aeruginosa has 616 different genes that respond to autoinducers.

Some species of bacteria that use quorum sensing form biofilms, complex colonies of bacteria (often containing several species) that exchange chemical signals to coordinate the release of toxins that will attack the host. Bacterial biofilms ( Figure 9.18 ) can sometimes be found on medical equipment; when biofilms invade implants such as hip or knee replacements or heart pacemakers, they can cause life-threatening infections.

Visual Connection

Which of the following statements about quorum sensing is false?

• Autoinducer must bind to receptor to turn on transcription of genes responsible for the production of more autoinducer.
• The receptor stays in the bacterial cell, but the autoinducer diffuses out.
• Autoinducer can only act on a different cell: it cannot act on the cell in which it is made.
• Autoinducer turns on genes that enable the bacteria to form a biofilm.

What advantage might biofilm production confer on the S. aureus inside the catheter?

Research on the details of quorum sensing has led to advances in growing bacteria for industrial purposes. Recent discoveries suggest that it may be possible to exploit bacterial signaling pathways to control bacterial growth; this process could replace or supplement antibiotics that are no longer effective in certain situations.

Link to Learning

Watch geneticist Bonnie Bassler discuss her discovery of quorum sensing in biofilm bacteria in squid.

Evolution Connection

Cellular communication in yeasts.

The first cellular form of life on our planet likely consisted of single-celled prokaryotic organisms that had limited interaction with each other. While some external signaling occurs between different species of single-celled organisms, the majority of signaling within bacteria and yeasts concerns only other members of the same species. The evolution of cellular communication is an absolute necessity for the development of multicellular organisms, and this innovation is thought to have required approximately 2 billion years to appear in early life forms.

Yeasts are single-celled eukaryotes and, therefore, have a nucleus and organelles characteristic of more complex life forms. Comparisons of the genomes of yeasts, nematode worms, fruit flies, and humans illustrate the evolution of increasingly complex signaling systems that allow for the efficient inner workings that keep humans and other complex life forms functioning correctly.

Kinases are a major component of cellular communication, and studies of these enzymes illustrate the evolutionary connectivity of different species. Yeasts have 130 types of kinases. More complex organisms such as nematode worms and fruit flies have 454 and 239 kinases, respectively. Of the 130 kinase types in yeast, 97 belong to the 55 subfamilies of kinases that are found in other eukaryotic organisms. The only obvious deficiency seen in yeasts is the complete absence of tyrosine kinases. It is hypothesized that phosphorylation of tyrosine residues is needed to control the more sophisticated functions of development, differentiation, and cellular communication used in multicellular organisms.

Because yeasts contain many of the same classes of signaling proteins as humans, these organisms are ideal for studying signaling cascades. Yeasts multiply quickly and are much simpler organisms than humans or other multicellular animals. Therefore, the signaling cascades are also simpler and easier to study, although they contain similar counterparts to human signaling. 2

Watch this collection of interview clips with biofilm researchers in “What Are Bacterial Biofilms?”

• 2 G. Manning, G.D. Plowman, T. Hunter, S. Sudarsanam, “Evolution of Protein Kinase Signaling from Yeast to Man,” Trends in Biochemical Sciences 27, no. 10 (2002): 514–520.

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7.1 Introduction to Respiration

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7.3 Anaerobic Respiration of Human

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Chapter 9: Nutrition and the Human Digestive System

9.1 Types of Nutrition

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• Saliva contains salivary amylase that hydrolyses starch to maltose. • The pH of the saliva ranges between 6.5–7.5, which is suitable for salivary amylase to act at its optimum. Salivary amylase Starch + water maltose tohweeacsolmolsnputohrsafacctguhtuleasr Saliva helps food to form bolus and makes it easier oesophagus to be swallowed. When swallowing, the epiglottis will close the trachea opening to prevent food from entering the trachea. In the oesophagus, the food bolus is moved by peristalsis. Peristalsis is the rhythmic contraction and relaxation tohweeaslmorlsepulohasfaxctguhuleasr bolus of muscles along the alimentary canal. Peristalsis pushes the bolus through the oesophagus until it FIGURE 9.2 Peristalsis enters the stomach (Figure 9.2). Brainstorm! Digestion of protein in the Chew slowly a stomach small piece of bread. Observe The surface of the stomach wall is lined with epithelial the taste when CHAPTER 9 cells that have undergone adaptations in structure you first started and function to form gastric glands (Figure 9.3). chewing and after These epithelial cells are chief cells, parietal cells a few minutes of and mucous cells. chewing. Is there • Chief cells secrete pepsinogen. any difference in the • Parietal cells secrete hydrochloric acid. taste of the bread? • Mucous cells secrete mucus. oesophagus gastric gland stomach epithelium duodenum sphincter FIGURE 9.3 Structure of stomach and gastric mucous gland tissues cells parietal Pmeupksoisnaogen is an inactive enzyme that is activated cells by hydrochloric acid to become pepsin. Pepsin then chief hydrolyses proteins into polypeptides. cells pepsin polypeptides 145 submukosParotein + water 9.2.3 The functions of hydrochloric acid are to: The food in the stomach is mixed with gastric (a) prepare a medium with a suitable pH (pH juice made up of hydrochloric acid and pepsin. Food is churned by the peristaltic action of 1.5–2.0) for pepsin to act the stomach wall muscles for a few hours. (b) stop the enzymatic action of salivary The contents in the stomach finally change to a semifluid called chyme. Chyme enters the amylase duodenum slowly when the sphincter muscle (c) kill bacteria in food relaxes. The function of mucus is to protect the stomach wall from the reaction of hydrochloric acid and digestive enzymes. Digestions of carbohydrates, proteins and lipids in the small intestine The small intestine consists of duodenum, jejunum and ileum. Duodenum is the first part of the small intestine which receives chyme from the stomach. Duodenum also receives bile produced by the liver and pancreatic juice secreted by the pancreas (Figure 9.4). PANCREAS liver stomach bile duct The pancreas secretes pancreatic amylase, trypsin and lipase into the duodenum through the pancreatic duct. LIVER gallbladder chyme pancreas • Produces bile duodenum • The gallbladder stores bile. pancreatic duct • The bile flows into the duodenum through the bile FIGURE 9.4 Components that are involved duct. in digestion that take place in the small intestine • Functions of bile DUODENUM – neutralise the acidic chyme • Pancreatic amylase hydrolyses starch to maltose Starch + water pancreatic amylase maltose – prepare an alkali condition (pH 7.6–8.6) • Trypsin hydrolyses polypeptides into shorter peptides. for enzyme action in the Polypeptide + water trypsin duodenum peptides – emulsify lipids by • Lipase hydrolyses lipids into fatty acids and glycerols. breaking down lipids into Lipid + water lipase fatty acid and glycerol tiny droplets to increase surface area for lipase activity. 146 9.2.4 Glands on the ileum wall secrete mucus and intestinal juice that contains maltase, sucrase, lactase, lipase and erepsin. The alkali medium in the ileum allows enzymes to act at its optimum. CARBOHYDRATE DIGESTION LIPID DIGESTION ICT 9.1 • Maltase hydrolyses maltose into Lipase hydrolyses lipids Video: Processes of digestion, glucose. absorption and defaecation into fatty acids and (Accessed on 21 August 2019) Maltose + water maltase glucose glycerols. Across the fields • Sucrase hydrolyses sucrose into glucose and fructose. Lipid lipase Fatty acids Chemical digestion involves enzyme- Sucrose + water sucrase glucose + + water + glycerol catalysed hydrolysis fructose reaction. For example, PROTEIN DIGESTION an enzyme is needed • Lactase hydrolyses lactose into in the decomposition glucose and galactose. Erepsin hydrolyses of starch into glucose. peptides into amino acids. Lactose + water lactase glucose + galactose Peptides erepsin amino + water acids 1.2 9.1ActivistyeitivitcA Studying the digestion of starch in a Experiment food sample Problem statement tthhetehrrmemromomomemteeetrter CHAPTER 9 What is the effect of amylase on starch? AAA B BB AB Hypothesis 3ossuofmo3ssls0uuofpl.mt5sl0ieouop%l.nft5nieoso1%nfain%os1mnai%osym+ntlaasy3+rstlcaaem3hrscelmh l s3oufm3sosdufplimssdeotpliinfsleols1teinfil%dols1eniw%dos+natwast3+eratcartm3hercrlmh l Amylase hydrolyses starch to a reducing sugar. w(3aw7w(3teaa°7rtCtee°b)rCrabt)bhaathth Variables (37 °C) Manipulated: Presence of amylase Responding: Presence of reducing sugar Fixed: Temperature of water bath at 37˚C, concentration of starch suspension and volume of mixture Materials 0.5% amylase solution, 1% starch suspension, iodine solution, Benedict’s solution and distilled water Apparatus Tripod stand, Bunsen burner, wire gauze, 500 ml beaker, test tube holder, thermometer, stopwatch, test tube, dropper, glass rod and measuring cylinder 9.2.5 147 Procedure 1 Label 2 test tubes as A and B. 2 Add 3 ml of 1% starch suspension to each test tube. 3 Fill test tube A with 3 ml of 0.5% amylase solution and test tube B with 3 ml of distilled water. 4 Soak both test tubes in a water bath with a temperature of 37 °C for 10 minutes. 5 After 10 minutes, remove 2 ml of the solution from test tube A and put it into a different test tube. Add 3 drops of Benedict’s solution to that test tube and heat the test tube in a boiling water bath for 1 minute. Record the colour of the content. 6 Add 2 drops of iodine solution to the remainder of test tube A. Observe and record the colour of the contents. 7 Repeat steps 5 and 6 for test tube B. Results Contents Iodine test Benedict’s test Test tube A 1% starch suspension + 0.5% amylase solution B 1% starch suspension + distilled water Discussion 1 Explain the reaction that occurs in test tube A. 2 What is the purpose of preparing test tube B? Conclusion Is the hypothesis accepted? Suggest a suitable conclusion for this experiment. Activity 9.2 Studying digestion of protein in a food Experiment sample Problem statement What is the effect of pepsin on protein? Hypothesis Pepsin hydrolyses proteins in the albumen suspension into polypeptides. Variables Manipulated: Presence of pepsin Responding: Clarity or turbidity of mixture after 20 minutes. Fixed: Temperature at 37˚C, concentration of pepsin solution and dilute hydrochloric acid Materials Albumen suspension (egg white), 1% pepsin solution, distilled water and 0.1 M dilute hydrochloric acid Apparatus Test tube, measuring cylinder, 500 ml beaker, water bath at 37 °C, dropper, thermometer and stopwatch. 148 9.2.5 Procedure thermometer 1 Prepare an apparatus set-up as follows. AB Test tube A: 5 ml of albumen suspension + 1 ml of 0.1 M hydrochloric water bath acid + 1 ml 1% pepsin solution (37 °C) Test tube B: 5 ml of albumenAsuspensBion + 1 ml of 0.1 M hydrochloric acid + 1 ml distilled water 2 Soak all test tubes in a water bath at 37 °C. 3 Observe the condition of mixtures in test tubes A and B at the beginning of the experiment and after 20 minutes. Results Test tube 0 minute Clarity or turbidity 20 minute A B Discussion 1 Explain the results achieved in test tube A and B. 2 What is the purpose of adding hydrochloric acid into each test tube? Conclusion Is the hypothesis accepted? Suggest a suitable conclusion for this experiment. CHAPTER 9 Activity 9.3 Studying the digestion of lipids in a food Experiment sample Problem statement What is the effect of lipase on lipid? Hypothesis Lipase hydrolyses lipids into fatty acids and glycerols. Variables Manipulated: Presence of lipase Responding: Time taken for the phenolphthalein indicator to turn from pink to colourless Fixed: Temperature at 37°C, volume of cooking oil and combined volume Materials Cooking oil, 0.2 M sodium carbonate solution, dishwashing liquid, phenolphthalein indicator, distilled water and lipase 9.2.5 149 Apparatus Two test tubes, test tube rack, water bath at 37 °C, 5 ml and 1 ml syringes, dropper, stopper and stopwatch Procedure thermometer 1 Prepare two test tubes aAnd label tBhem as A and B. AB 2 Fill each test tube A and B with the following: • 2 ml of cooking oil water bath • 1 ml of 0.2 M sodium carbonate solution (37 °C) • 1 ml of dishwashing liquid 3 Close both test tubes with stoppers. Shake both test tubes vigorously after adding the dishwashing liquid. 4 Add 3 drops of phenolphthalein indicator to each test tube and shake the test tube. 5 Add 1 ml of lipase into test tube A and 1 ml of distilled water into test tube B. 6 Soak both test tubes in a water bath at 37°C. 7 Record the time taken for the phenolphthalein indicator to turn from pink to colourless. Results Test tube Contents Time taken for the phenolphthalein indicator to turn from pink to colourless (minute) A 1 ml of lipase B 1 ml of distilled water Discussion 1 Why is a phenolphthalein indicator used in this experiment? 2 What is the purpose of adding dishwashing liquid into each test tube? 3 Explain the reaction that happens in test tube A. 4 Explain the results obtained in test tube B. Conclusion Is the hypothesis accepted? State the suitable conclusion for this experiment. 9.1Formative Practice 4 The small intestine secretes a few types of enzymes to complete the digestion process. 1 Explain the importance of the digestion Explain how these enzymes complete the process for humans. digestion process. 2 Name the structures in the alimentary canal that are involved in food digestion. 3 Name the main cells in the gastric glands and explain the functions of these cells. 150 9.2.5 Absorption 9.3 The adaptations of ileum and villus in the absorption of digested food Simple molecules produced from the digested food are absorbed in the ileum of the small intestine. ILEUM ileum CHAPTER 9 cross section of a small The long ileum is adapted to absorb nutrients intestine because its internal layer is folded and covered by villus tiny projections called villi (singular: villus) (Figure 9.5). lacteal epithelial cells VILLUS (PLURAL: VILLI) blood capillaries Villus has the following lymph vessel adaptations to absorb nutrients (Figure 9.5): microvillus nucleus • The epithelial layer of the basement membrane villus is one cell thick. This helps accelerate nutrient absorption. mucus • Goblet cells secrete mucus to aid goblet digestion. cells • The network of blood capillaries helps to transport digestive products to the FIGURE 9.5 Adaptations of ileum and villi whole body. to absorb digested food. • Lacteal carries droplets of fatty acids and glycerol. 151 • The intestinal glands secrete intestinal juices that have digestive enzymes. MICROVILLUS On the surface of the villus epithelium, there are many tiny projections called microvillus. Microvillus provides a large surface area to increase the rate of nutrient absorption (Figure 9.5). 9.3.1 9.3.2 Absorption of digested food is summarised in Figure 9.6 and Table 9.1. Petunjuk: Glukosa ICT 9.2 Indicator: Asid amino Video: View inside the laLacktteeaall GlucAosidselemak small intestine (Accessed on 21 Giserol August 2019) Amino acids Titisan halus lipid FattGyaalacktiodssa MMilillelennnnilaaaclltCeCaaalrererer Fruktosa A gastroenterologist Glycerol is a medical specialist who specialises in blood cKaappiillalarirdiaersah Lipid droplets the human digestive Galactose system. Fructose FIGURE 9.6 Absorption of digested food blood capillaries TABLE 9.1 Method of food absorption in the ileum Activity Zone Digested food Absorbed Methods of Gather information through absorption about the absorption of Fructose Facilitated diffusion alcohol and drugs. Glucose and galactose Epithelial cells Active transport Amino acids into blood Active transport Vitamins B and C capillaries Absorbed with water Water Osmosis Fatty acids and glycerols Simple diffusion recombine through the condensation process to Epithelial cells form tiny droplets of lipids into lacteal in the epithelial cells Vitamins A, D, E, K Simple diffusion dissolve in the lipid 9.2Formative Practice 3 Explain the adaptations of the small intestine to increase the surface area for absorption of 1 Name the main structures for the absorption nutrients. of digested food. 4 Explain how the following substances can be 2 Name the structure in the villus involved in transported across the plasma membrane. the transporting of the following nutrients: (a) Glucose, galactose and amino acids (a) amino acids (b) Fatty acids and glycerol (b) vitamins A and E 152 9.3.2 9.4 Assimilation CHAPTER 9 Biological Lens The role of the circulatory system Liver cirrhosis The human circulatory system consists of the blood circulation system is a type of liver and the lymphatic system to help transport nutrients to be assimilated. disease caused In the assimilation process that occurs in cells, nutrients are used to form by factors such as complex compounds or structures of components. The blood capillaries alcoholic drinks, in the small intestine combine to form the hepatic portal vein that toxic substances transports blood to the liver. and hepatitis. Liver Lacteals combine to form bigger lymph vessels in the lymphatic system. cells are replaced Then, the contents of the lymph vessels enter the thoracic duct that by scarred cells flows into the left subclavian vein. This lipid is then transported by that can cause blood throughout the body. failure in the liver functions. Hepatitis Functions of liver in the assimilation of is an inflammation digested food of the liver caused by viral infection, The liver is the regulator that controls the quantity of nutrients that toxic substances enter the blood circulatory system. The liver carries out the following or autoimmune functions. reaction (Photograph 9.1). METABOLISM OF DIGESTED FOOD • Glucose is used for cellular respiration. Amino acids are used for Activity Zone Conduct a research synthesising plasma proteins and enzymes. on the various • Through the deamination process, excess amino acids are turned functions of the liver and produce a into urea to be excreted through the urine. scrap book DETOXIFICATION • Liver cells expel toxic substances from the blood. • Toxic substances are expelled through the urine. STORAGE OF NUTRIENTS Excess glucose is converted to glycogen to be stored. PHOTOGRAPH 9.1 Normal Normal liver Liver of a cirrhosis liver and liver of a cirrhosis patient patient 153 9.4.1 9.4.2 ASSIMILATION PROCESS IN THE LIVER AMINO ACIDS GLUCOSE • The liver synthesises plasma protein and • Glucose in the liver is used for cellular respiration enzymes from amino acids. when required by the body and the excess is converted to glycogen and stored in the liver. • Excess amino acids cannot be stored in the body and are broken down through the • When the glucose level in the blood decreases and deamination process to form urea which is the body needs energy, glycogen is converted to then expelled. glucose. • When the glucose supply is insufficient, the • When the glycogen supply reaches a maximum liver converts amino acids into glucose. level, the excess glucose is converted to fats. liver cellular respiration body cell excess aamcliidinso excess synthesis of synthesis of plasma glycogen plasma proteins protoplasm membrane is stored and enzymes (in the cell) synthesis glucose urea excreted by hepatic the kidneys portal vein glucose amino acid lipid small fatty acids + glycerol FIGURE 9.7 Transportation of nutrients and intestines the assimilation in the liver and cells carbohydrates protein lipid ASSIMILATION PROCESS IN CELLS AMINO ACIDS GLUCOSE LIPIDS • Amino acids are used • Glucose is oxidised through • Lipids such as phospholipid to synthesise new cellular respiration to release and cholesterol are the primary protoplasm and also energy, water and carbon components that build the plasma repair damaged dioxide. membrane. tissues. • Excess glucose is kept as • Excess fats are kept in adipose • Amino acids are used to glycogen in muscles. tissues found underneath the skin synthesise hormones as stored energy. and enzymes. • Energy is used for cell processes such as protein • Fat is oxidised to release energy synthesis. when there is insufficient glucose. 9.3Formative Practice I understand the difference betwe 1 State the meaning of assimilation. 2 Explain the functions of the liver in the assimilation of digested food. 154 9.4.2 9.5 Defaecation Biological Lens Functions of the large intestine The large intestine has a huge population After the absorption of nutrients is of bacteria. There completed in the ileum, undigested food, are more than 1000 dead cells, epithelial cells, fibre and water different species of enter the large intestine and move slowly bacteria in the large through peristaltic action. Fibre consists intestine and a healthy of cellulose walls of plant cells. The large balance between intestine carries out two main functions: beneficial and less • absorption of water beneficial bacteria and vitamins is very important for colon health and a stable • formation of faeces environment in the alimentary canal. ABSORPTION OF WATER AND VITAMINS caecum rectum CHAPTER 9 appendix anus Substances absorbed are • water and mineral salts FIGURE 9.8 Large intestines • metabolic byproducts of some bacteria such as vitamin B, vitamin K and folic acid. FORMATION OF FAECES • After the water is absorbed, the remaining waste is a semisolid called faeces. Faeces contains dead cells from the inner layer of the intestine, waste products such as bile pigments, bacteria and toxic substances. • The walls of the large intestine secrete mucus to smoothen the movement of faeces until the anus. The movement of faeces takes about 12 to 24 hours before entering the rectum. • The faeces will accumulate in the rectum until the pressure in the rectum increases and triggers the need to expel faeces from the body. • The rectum muscles will contract to expel faeces from the anus. This process is called defaecation. Brainstorm! 9.4Formative Practice 3 Explain the importance of water absorption and What is the effect 1 State the main function of the vitamins in the large intestine. of antibiotics large intestine. on the large 4 Explain the formation process intestine’s bacterial 2 What are the substances of faeces. population? absorbed in the large intestine? 9.5.1 155 9.6 Balanced Diet Biological Lens Energy value in a food sample A balanced diet refers to a diet that consists of all seven food classes (carbohydrates, lipids, proteins, vitamins, mineral salts, fibre and water) in the correct proportion and balanced quantity according to individual needs so that optimal health can be maintained. 1 calorie (cal) = 4.2 joule (J) ENERGY VALUE 1 kilojoule = 1000 joule • Energy value is the total amount of energy released when one gram of food is oxidised completely. Across the fields • The energy value in food is measured in the form of heat energy, 4.2 J g-1 °C-1 refers that is, in kilojoule per gram (kJ g-1). to the specific heat capacity of water, • Another unit of heat energy is calorie. that is, the energy required to increase • 1 calorie or 4.2 joule is defined as the quantity of heat energy the temperature of 1 g needed to raise the temperature of 1 gram water by of water by 1 °C. 1 degree Celsius (°C) at a pressure of 1 standard atmosphere. • Energy value of food (kJ g-1) = Water mass (g) × 4.2 J g-1 °C-1 × Increase in water temperature (°C) Mass of food sample (g) × 1000 sAecit1iv.2itycA9.4 Studying the energy value of food samples Experiment Problem statement cotton barrier Which food sample has the highest energy value? wool thermometer Hypothesis boiling tube Groundnuts have a higher energy value compared to cashew nuts. distilled water Variables food sample Manipulated: Types of food samples needle Responding: Energy value of food sample Fixed: Water mass plasticine Materials retort Distilled water, food samples (cashew nuts and groundnuts), stand cotton wool and plasticine Apparatus Retort stand with a clamp, thermometer, boiling tube, long needle, electronic weighing scale, barrier, measuring cylinder and Bunsen burner 156 9.6.1 Procedure 1 Weigh a cashew nut using an electronic weighing scale and record its mass. 2 Measure 20 ml of distilled water using a measuring cylinder and pour it into a boiling tube. 3 Clamp the boiling tube to the retort stand and put in the thermometer. 4 Fix the position of the thermometer using cotton wool. 5 Record the initial temperature of the distilled water. 6 Stick the cashew nut on the needle and hold the needle upright using plasticine. 7 Place the barrier around the apparatus set-up. 8 Light the cashew nut using a Bunsen burner and place it below the boiling tube. 9 Stir the water in the boiling tube slowly and record its highest temperature after the cashew nut has completely burned. 10 Replace the water in the boiling tube. 11 Repeat steps 1 to 9 using groundnuts. 12 Calculate the energy value for each food sample using the following formula: Energy value of = Water mass (g) × 4.2 J g-1 °C–1 × Increase in water temperature (°C) food (kJ g–1) Food sample mass (g) × 1000 13 Record your results in the table below. Results Food Food Initial Final Increase of Energy value CHAPTER 9 sample sample temperature temperature Temperature of food mass (g) of water (°C) (kJ g–1) of water (°C) (°C) Cashew nuts Groundnuts Discussion 1 Which food sample shows the highest energy value? 2 State two precautionary steps for this experiment. 3 Compare the energy value of food samples obtained from this experiment with their theoretical energy values. Are there any differences? If yes, explain why. Conclusion Is the hypothesis accepted? Suggest a suitable conclusion for this experiment. The contents of vitamin C in fruit or vegetables juices The nutrient content in various types of food is different. For example, the vitamin C content in fruits and vegetables are different. 9.6.2 157 1.2 9.5AcsteivitiitvyitcA Determining the contents of vitamin C in fruit juice Experiment and vegetable juice. Problem statement Which fruit juice or vegetable juice has the highest content of vitamin C? Hypothesis Orange juice has the highest content of vitamin C compared to lime juice and carrot juice. Variables Manipulated: Types of fruit and vegetable juices Response: Volume of fruit juice or vegetable juice needed to decolourise DCPIP solution Fixed: Concentration of DCPIP solution and concentration of an ascorbic acid solution Materials Orange juice, lime juice and fresh carrot juice, 0.1% ascorbic acid solution, 1% DCPIP solution and distilled water Apparatus Syringe needles (1 ml and 5 ml), knife, 50 ml beaker, specimen tube, juicer and sieve Procedure 1 Put 1 ml of 1% DCPIP solution in a specimen tube. 2 Fill the 5 ml syringe needle with a 0.1% ascorbic acid solution. ascorbic acid Ensure that there are no air bubbles trapped in it. specimen tube 3 Insert the tip of the syringe needle into the specimen tube and drip ascorbic acid drop by drop into the DCPIP solution while stirring slowly until the blue colour of the DCPIP solution is decolourised. 4 Record the volume of the 0.1% ascorbic acid solution needed to DCPIP solution decolourise the blue colour of the DCPIP solution. 5 Repeat steps 1 to 4 twice to get the average volume for each different juice. 6 Record the volume of each juice in the table below. 7 Calculate the concentration of vitamin C of each juice using the following formula. Percentage of vitamin C = volume of ascorbic acid solution × 0.1% volume of juice used Vitamin C concentration (mg ml-1) = volume of ascorbic acid solution × 1.0% volume of juice used Results Volume of solution/juice Vitamin C Vitamin C concentration required to decolourise DCPIP concentration (mg ml-1) Solution / Juice 0.1 solution (ml) (%) 0.1% ascorbic acid solution 123 Average Orange juice Lime juice Carrot juice 158 9.6.2 Discussion 1 Which juice has the highest content of vitamin C? 2 Why is a 0.1% ascorbic acid solution used as the standard? Conclusion Is the hypothesis accepted? Suggest a suitable conclusion for this experiment. One of the factors that affect the loss of vitamin C content is temperature. Therefore, fruit or vegetables must be kept at a suitable temperature range to preserve vitamin C. 1.2 9.6ActivisteyitivitcSAtudying the effect of temperature on vitamin C in Experiment orange juice Problem statement What is the most suitable ambient temperature to keep orange juice? Hypothesis Orange juice stored at a low ambient temperature has the highest content of vitamin C. Variables Take Note! CHAPTER 9 Manipulated: Ambient temperature Responding: Volume of orange juice required to decolourise DCPIP solution Ensure that Fixed: Volume of DCPIP solution the juice is not exposed too long Materials to avoid oxidation. Oranges, 1% DCPIP solution and ice Apparatus Specimen tube, knife, syringe needles (1 ml and 5 ml), beakers (50 ml and 100 ml), Bunsen burner, tripod stand, sieve and wire gauze Procedure 1 Prepare 60 ml of orange juice. 2 Label the beakers A, B and C. Pour 20 ml of orange juice into each beaker. 3 Soak beaker A in ice, leave beaker B at room temperature and soak beaker C in boiling water for 30 minutes. 4 After 30 minutes, determine the vitamin C content in the orange juice as shown in Activity 9.5. 5 Calculate the concentration of vitamin C in the orange juice at each different temperature. Results Record your results in an appropriate table. 9.6.2 159 Discussion 1 Is there a difference in the vitamin C content for the juice at different temperatures? 2 What is the effect of temperature on vitamin C in the orange juice? 3 Based on the results, suggest the best way to ensure that you get a high content of vitamin C from fruit juice or vegetable juice. Conclusion Is the hypothesis accepted? Suggest a suitable conclusion for this experiment. PHOTOGRAPH 9.2 Diet modifications for specific individuals A sample serving based on Pinggan Sihat Malaysia A balanced diet for each individual will vary according to lifestyle, health conditions and specific nutritional requirements. Each MMilillelennnniaall CCaarererer individual must make wise choices based on a nutrition guide. For example, suggestions for nutritional needs can be made based Nutritionists are on Pinggan Sihat Malaysia. Pinggan Sihat Malaysia illustrates specialists in the the relative quantity of various food classes in a balanced diet field of nutrition (Photograph 9.2). who advise Excessive food intake that is rich in saturated fats can cause health specific individuals problems such as obesity and cardiovascular diseases. on suitable diets. The cause of obesity Obesity is caused by the storage of excess fats as a result of imbalanced food intake and use of energy. Effects of obesity Individuals who are obese need to reduce the intake of carbohydrates and fats as well as increase the intake of vegetables and fruits. Otherwise, a diet with excessive saturated fats and high cholesterol may cause diabetes mellitus and various cardiovascular diseases such as atherosclerosis and hypertension which may result in heart attacks (myocardial infarction) or stroke if not treated. Activity Zone Cancer patients who are undergoing cancer treatment, need to modify their diet to ensure they receive sufficient energy, reduce the risk of Plan meals based infections and enable quick recovery. on Pinggan Sihat Malaysia for different individuals such as obese individuals, cancer patients and heart patients. 160 9.6.3 Health Issues Related to the 9.7 Digestive System and Eating Habits Adaptation of digestive organs duodenum Obesity is a health issue on the rise throughout the world. Although jejunum obesity can be controlled through diet management and routine exercise programmes, at times, obesity requires medical treatment. Specialist doctors may suggest surgical procedures to reduce body weight such as gastric bypass (Figure 9.9). A gastric bypass involves a reduction of the stomach size using various methods of surgery. Among the short-term side effects of this surgery are acid reflux, nausea, vomiting, expanded oesophagus, certain food prohibitions and risk of infection. The long-term side effects are dizziness, low blood sugar level, malnutrition, stomach ulcer and defaecation problems. gastric sac Health issues related to defaecation Part of the The food class that is most important in the defaecation process CHAPTER 9 stomach is fibre. Intake of diet that is high in fibre such as fruits and that has vegetables can smoothen bowel movements. This can prevent been health problems such as constipation, colon cancer, rectum cancer bypassed and haemorrhoid. jejunum Some of the functions of fibre are to: • stimulate peristalsis Part of the • absorb and expel toxic substances duodenum • regulate the absorption of glucose especially for diabetes that has been bypassed mellitus patients • increase the population of beneficial bacteria in the large food intestine digestive juice Besides, the intake of a large amount of water can ensure that the FIGURE 9.9 Gastric bypass faeces stay soft and move easily along the large intestine to aid the process of defaecation. 9.7.1 9.7.2 161 Health issues related to eating habits Apart from a balanced diet, eating habits also play an important role in fulfilling our energy requirements and maintaining our health. Poor eating habits and an imbalanced diet can cause numerous health problems such as gastritis, muscle dysmorphia, anorexia nervosa and bulimia nervosa. ANOREXIA NERVOSA GASTRITIS Anorexia Gastritis refers to the nervosa is quite common inflammation and corrosion of amongst the stomach epithelial layer teenage by gastric juice when there girls who are is no food in the stomach. obsessed with Untreated gastritis can result their body weight. in gastric ulcers. The causes Anorexics will avoid of gastritis include eating food to achieve their irregular quantities of food at ideal body weight. They also irregular hours and excessive suffer from psychological problems intake of alcohol or painkillers. and nutrient deficiency because of their normal digestive system is affected. BULIMIA NERVOSA MUSCLE DYSMORPHIA For people with bulimia nervosa who are also Some individuals obsessed with controlling feel that their size their body weight, they is small with not will eat a lot and vomit out enough growth. the food that they have So, they subject eaten or take laxatives that themselves cause diarrhoea. In the long to extreme run, the patient may suffer from weightlifting dehydration, nutritional problems and training and exercise. eventually cardiovascular disease or kidney failure. Sometimes, they consume steroids or muscle building supplements. This health issue is called muscle dysmorphia. Activity Zone 9.5Formative Practice 2 Predict the effect of modifying digestive organs Do a case study about 1 In your opinion, why is fibre such as gastric bypass on the following health issues important in the defaecation human health. related eating habits: process. Explain your • diabetes type 2 answer. 9.7.3 • obesity • acid reflux • pica 162 Summary NUTRITION AND THE HUMAN DIGESTIVE SYSTEM Digestive System Balanced Diet Health Issues Related to the Digestive System and Eating • Digestion • Energy value • Absorption • Contents of vitamin C in Habits • Assimilation • Defaecation fruit or vegetables juices • The effects of modifying • Diet modifications for digestive organs on human health specific individuals • Health issues related to defaecation • Health issues related to eating habits Self Reflection CHAPTER 9 Have you mastered the following important concepts? • Structure of the human digestive system • Mechanism of digestion • Process and products of carbohydrate digestion in the mouth • Process and products of protein digestion in the stomach • Digestions of carbohydrates, proteins and lipids in the small intestine • Adaptations of ileum and villus in the absorption of digested food • Assimilation of digested food and liver functions • Defaecation • Balanced diet and energy value in food samples • Diet modifications for specific individuals • Health issues related to the digestive system and eating habits 163 Summative Practice 9 1 Some people cannot drink milk because it causes diarrhoea and a bloated stomach. Explain why. 2 Amin had some meat dishes for lunch. Explain how the protein is digested in Amin’s stomach. 3 An individual has the following eating habits: Overeating in a short period of time followed by intentional throwing up on purpose after each meal. Explain how this eating habit can affect the health of this individual. 4 Figure 1 shows the alimentary canal in humans. Z XY FIGURE 1 (a) Name structures X and Y. (b) (i) The enzymes in X are only effective in an alkaline environment. Explain how an alkaline environment is maintained in X. (ii) Explain how Y is involved in the digestion of carbohydrates in X. (c) Name the enzyme found in Z. Explain how this enzyme functions in the digestion of proteins. (d) A student enjoys eating a lot of oranges. Explain the effect of eating too many oranges on the digestion of starch in X. 164 Essay Questions 5 Explain the processes that fat molecules undergo starting from the duodenum until it is finally used by body cells. 6 A teenager had the following for his breakfast. Buttered bread – 2 pieces Fresh milk – 1 glass Hard-boiled eggs – 2 Apple – 1 Explain what happens to the final digested products of his breakfast in his body cells. 7 (a) Explain why a diet rich in fats is not good for health. (b) Suggest suitable types of food for someone who wants to reduce weight and reduce the risk of contracting cardiovascular disease. Explain your answer. (c) Explain the processes of starch digestion, absorption and assimilation in the human body. Enrichment CHAPTER 9 8 Medicines in the form of capsules are not broken down in the stomach but absorbed easily by the small intestine. When the blood sample of the patient is taken and analysed, it is found that the molecular structure of this medicine is different from its original molecular structure. Explain why. 9 How are drinks with added artificial sweeteners produced and marketed? 10 Nowadays, many individuals prefer ready-to-eat or frozen food products due to their busy lifestyles. Predict the health risks that may arise if these foods are taken continuously for a long period of time and in large quantities. Complete answers are available by scanning the QR code provided 165 CHAPTER Transport in Humans and 10 Animals What is a Do you KNOW... mechanical heart? ••• crHHbeWiroltocouhwwuoranldatddttaoocoisreierersyscsutusthtehlhyaeefestlcoutlheyoirdmeymmsas?ppriytnhosptantoueteimmctnhts?pesybbostllfooetoomhdde? • ltWyomhthpaethaahtruiecmtshayenshtceeimraclsuth?laitsosruyeasnrdelated 166 10.1 Types of Circulatory System 10.4 Mechanism of Blood Clotting 10.4.1 Justify the necessity for blood 10.1.1 Justify the necessity of transport clotting mechanism. systems in complex multicellular 10.4.2 Describe blood clotting organisms. mechanism. 10.4.3 Describe health issues related to 10.1.2 Identify substances that are blood clotting: • thrombosis transported by the transport • embolism • haemophilia system: • substances required by a cell • waste products of a cell 10.5 Blood Groups of Humans 10.5.1 Describe ABO blood group. 10.1.3 Conceptualise types of circulatory 10.5.2 Correlate ABO blood group with system in complex multicellular blood donation. organisms. 10.5.3 Describe the Rhesus factor. • open circulatory system 10.5.4 Reason out the incompatibility of • closed circulatory system Rhesus factor in pregnancies. 10.1.4 Compare and contrast circulatory 10.6 Health Issues Related to the Human systems in complex multicellular Circulatory System organisms: • insects • fish • amphibians • humans 10.6.1 Justify the necessity for a healthy circulatory system. 10.2 Circulatory System of Humans 10.6.2 Communicate about 10.2.1 Describe components of the cardiovascular diseases. human circulatory system: 10.7 Lymphatic System of Humans • heart • blood vessel • blood 10.7.1 Synthesise the process of 10.2.2 Explain the composition of blood: formation of tissue fluid and lymph. 10.7.2 Compare and contrast the • blood plasma • blood cells contents of lymph and: 10.2.3 Compare and contrast the types of • tissue fluid • blood 10.7.3 Describe components of the blood vessels: lymphatic system: • lymph • artery • vein • capillary • lymphatic capillaries 10.2.4 Label the structure of a human • lymphatic vessels• lymph nodes heart and associated blood • lymphatic organs vessels: • aorta • vena cava 10.7.4 Justify the necessity of the • pulmonary artery and pulmonary lymphatic system: vein • complements the blood • coronary artery and coronary circulatory system vein. • transports lipid-soluble • semilunar valve substances • bicuspid valve and tricuspid • body defence valve • septum 10.2.5 Describe the functions of parts of 10.8 Health Issues Related to the Human the heart. Lymphatic System 10.3 Mechanism of Heartbeat 10.8.1 Describe health issues related to the lymphatic system. 10.3.1 Describe the human heartbeat mechanism: 167 • sinoatrial node (pacemaker) • atrioventricular node • bundle of His • Purkinje fibres 10.3.2 Communicate about forces that cause the blood to circulate in humans: • pumping of the heart • contraction of skeletal muscles Types of Circulatory System 10.1 The necessity for transport systems in complex multicellular organisms Each living cell requires essential substances such as oxygen and Substance nutrients, and expels cellular waste products such as carbon dioxide exchange can occur and nitrogenous wastes. by diffusion because In Chapter 2, you learned how unicellular organisms such as Amoeba sp. the cells are in the get their essentials and expel wastes by diffusion from and to its external environment. surroundings. Unicellular organisms have a small body mass. Therefore, the total surface area to volume ratio (TSA/V) of the organism is large. As such, Amoeba sp. does not require a specialised transport system to transport substances in and out of the cell. What about multicellular organisms? Can multicellular organisms obtain all essential substances and expel wastes by simple diffusion like unicellular organisms? Large complex multicellular organisms cannot obtain essential substances and expel wastes by diffusion because their TSA/V is small. The distance between the external environment and the cell is too far for direct substance exchange. So, how do complex multicellular organisms get essential substances for their cells? external environment Substance is far away from cells exchange cannot epidermis occur by diffusion because the external environment cells are too far away from the environment. body cells FIGURE 10.2 Substance exchange for multicellular organisms FIGURE 10.1 Substance 10.1.1 10.1.2 exchange for unicellular 168 organisms To address this problem, multicellular organisms have an internal ICT 10.1 transportation system. In vertebrates, the transportation system is called the blood circulatory system. Activity: Studying the effects of Before studying further the blood circulatory system, conduct an changes in total surface area experiment to study the effects of changes in TSA/V on the diffusion to volume ratio (TSA/V) on the rate. diffusion rate. Types of circulatory systems in multicellular organisms The circulatory system in multicellular organisms is divided into two types: open circulatory system and closed circulatory system. OPEN CIRCULATORY SYSTEM CLOSED CIRCULATORY SYSTEM • In an open circulatory system, • In a closed circulatory system, blood is haemolymph flows directly into the always contained in a continuous closed body cavity (haemocoel) and bathes the blood vessel and is distributed to the cells. whole body. • Haemolymph is a blood-like nutritious • The exchange of substances that are liquid found in most invertebrates such essential to cells such as oxygen and as insects and molluscs. nutrients occurs across the walls of blood capillaries. haheamemolyomlymphphvevsesseslel blobolododvevsesseslel CHAPTER 10 haheamemocooceolel blobolodod blobolododcacpailplailrlayry haheamemolyomlymphph hehaerat rt hehaerat rt ceclleslls ceclleslls opoepne-ne-nedneddedvevsesseslel 10.1.3 169 OPEN CIRCULATORY SYSTEM CIRCULATORY SYSTEM Circulatory System of Insects Circulatory System of Fish • The circulatory system of insects is • The heart of the fish has two chambers, an open circulatory system. This that is, an atrium (plural: atria) and a means that one or more hearts pump ventricle. haemolymph through the blood vessels into the haemocoel. • Blood that leaves the ventricle is pumped to the gill capillaries to enable gaseous • Haemolymph flows out from the heart exchange. into the haemocoel when the heart contracts. • The gill capillaries carry blood to the blood vessels that transport oxygenated • In the haemocoel, substance exchange blood to systemic capillaries. between haemolymph and body cells occurs through diffusion. • In the systemic capillaries, oxygen diffuses into the tissues while carbon • When the heart relaxes, haemolymph dioxide diffuses from the tissue into the flows back into the heart through tinanyterior capillaries. openings called ostium. • The deoxygenated blood is then returned aorta to the heart atrium through the veins. anterior • As the blood flows in one direction, the aorta fish circulatory system is known as a aorta single circulatory system. ostium gill capillaries posterior mixed blood aorta heart ostium haemocoel ostium FIGURE 10.4 The open heart circulatory system in insects artery posterior heart FIGURE 10.3 Dorsal view of ventricle insect heart atrium Indicator: vein oxygenated blood mixed blood deoxygenated blood systemic capillaries mixed blood FIGURE 10.5 The blood circulatory system of fish 170 10.1.4 CLOSED CIRCULATORY SYSTEM Circulatory System of Humans Circulatory System of Amphibians • The human heart consists of four • The heart of an amphibian has three chambers, chambers: two atria and two ventricles that are separated completely. that is, two atria and a ventricle. Unlike the single circulatory system of fish, blood flows in two • Humans have a double circulatory directions: pulmocutaneous circulation and system. This means that in one systemic circulation. Therefore, this system is complete circulatory cycle, blood known as a double circulatory system. flows in the blood vessels through the • Amphibians are said to have an incomplete double heart twice. As there are two different circulatory system because the deoxygenated circulations, humans are said to have blood and the oxygenated blood are mixed. a complete double circulatory • Pulmocutaneous circulation transports blood to system because the deoxygenated the lungs and skin, and the exchange of gases blood and the oxygenated blood do takes place here. Systemic circulation transports not mix. oxygenated blood to the body tissues and returns the deoxygenated blood to the right atrium through Pulmonary circulation the veins. • Deoxygenated blood is transported 1 Deoxygenated 2 Oxygenated blood through the pulmonary artery to the blood from body is from lungs and skin lungs for gaseous exchange. transported to the is transported by right atrium. the pulmonary vein • Oxygenated blood from the lungs is to the left atrium. returned to the left atrium and flows lung capillaries and skin into the left ventricle. 3 Blood from both atria enters one lung capillaries ventricle. Although pulmocutaneous there is some mixing pulmonary artery CHAPTER 10 circulation of oxygenated and vena cava deoxygenated blood 4 in the ventricle, most aorta 12 of the oxygenated blood remains on pulmonary the left side of the vein ventricle while the right 3 left deoxygenated blood right left atrium atrium remains on the right atrium atrium side of the ventricle. right ventricle ventricle left ventricle systemic circulation systemic capillaries systemic capillaries Indicator: Indicator: oxygenated blood oxygenated blood deoxygenated blood deoxygenated mixed blood blood FIGURE 10.6 The blood circulatory system of amphibians 4 The ventricle Systemic circulation then pumps the • Blood is pumped from the heart to all 10.1.4 blood through the pulmocutaneous (lungs the body tissues through the aorta. and skin) and systemic • Then the deoxygenated blood returns circulations. to the right atrium through vena cava. FIGURE 10.7 The blood circulatory system of humans 171 TABLE 10.1 Similarities and differences between circulatory systems in complex multicellular organisms Similarities The circulatory system is found in all multicellular organisms. The circulatory system consists of a heart to pump blood or haemolymph (in insects). The circulatory system functions to transport nutrients and wastes. The heart has valves that ensure blood flows in one direction. Differences Organism Insects Fish Amphibians Humans Types of Open blood Closed blood Closed blood Closed blood circulatory system circulatory system circulatory system circulatory system circulatory system Number of Single (blood Double Double circulations flows in the blood (blood flows in (blood flows in vessel and through the blood vessel the blood vessel – the heart once and through the and through the in a complete heart twice in heart twice in circulation) one complete one complete circulation) circulation) Number of The heart is made Two (one atrium Three (two atria Four (two atria and heart cavities up of many cavity and one ventricle) and one ventricle) two ventricles) segments Separation of Incomplete (some Complete oxygenated –– oxygenated blood (oxygenated blood blood and is mixed with the does not mix with deoxygenated deoxygenated deoxygenated blood blood in the blood in the ventricle) ventricle) 10.1Formative Practice 1 State two differences between the circulatory 3 The flatworm is a multicellular organism. systems of fish and humans. However, the flatworm does not require a specialised transportation system to move 2 Explain why the blood circulatory system of substances in and out of the cell. Explain amphibians is considered as a closed and why. incomplete blood circulatory system. 4 Explain why insects need one separate system (the tracheal system) to transport oxygen. 172 10.1.4 10.2 Circulatory System of Humans Malaysian Innovation There are three main components in the circulatory system of humans. A group of researchers • Blood: A type of connective tissue that is made up of blood plasma, in Malaysia have produced a device blood cells and platelets. Blood acts as a medium of transportation. called MyThrob that • Heart: Functions as a muscular pump that circulates blood to the can be used as a smart examination whole body. and monitoring tool • Blood vessels: Consist of arteries, capillaries and veins that for heart diseases. The device studies the are connected to the heart, and transport blood to all original algorithm that the body tissues. can detect abnormal heartbeat and is Structure of the heart suitable to be used for monitoring at home. Do you know that your heart is as big as your fist? The heart is located between the lungs in the thorax cavity and contains four chambers, namely the left atrium, CHAPTER 10 right atrium, left ventricle and right ventricle. The left chamber is separated from the right chamber by a muscular wall called septum. Atrium receives blood that returns to the heart while the ventricle pumps blood out of the heart. The ventricle has thicker walls and contract stronger than the atrium. The muscular wall of the left ventricle is much thicker than the muscular wall of the right ventricle. This is because the left ventricle has to generate greater pressure to pump blood out of the aorta to the whole body while the right ventricle only has to pump blood to the lungs. Coronary arteries 173 transport oxygenated blood for heart tissues while coronary veins transport deoxygenated blood. coarrotenrai rkyoarorntearriies vceonraonkaoryonvaeriins TABLE 10.8 The circulatory system of humans 10.2.1 10.2.4 10.2.5 Aorta is the main blood artery that transports The pulmonary artery transports oxygenated blood to the whole body while the vena deoxygenated blood from the heart cava is the main vein that transports deoxygenated to the lungs while the pulmonary veins transports oxygenated blood blood back to the heart. from the lungs to the heart. The semilunar vena cava vena kava valves at the base of the pulmonary artery aorta and the base of the aorta aorta ensures that arteri pulmonari blood which flows pulmonary artery out of the heart does not flow back into the vena pulmonari ventricle when the pulmonary veins ventricle relaxes. atrium kiri left atrium semilunar valves cionrjaopnabriykuvsepinid bicuspid valve atrium kanan right atrium injap sabit incjaoprotnriakruysapridtery right ventricle septum The bicuspid arteri coronari valve (located bleefttwastereeiupntmumthe tricuspid valve and the left ventricle) The tricuspid valve ensures that (locvaetnetrdikeblektawnaenen the blood which right atrium and the right flows into the ventricle) ensures that left ventricle blood which flows into the does not flow right ventricle does not back into the flow back into the right left atrium. This atrium. This valve consists valve consists of three leaflets. left ventricle of two leaflets. Brainstorm! The septum separates the left part of the heart What would happen from the right part of the heart and ensures that to an individual the oxygenated blood does not mix with the if the bicuspid deoxygenated blood. valve does not close completely FIGURE 10.9 Longitudinal section of a human heart when the ventricle relaxes? ICT 10.2 174 Video: Animation of the heart valves (Accessed on 21 August 2019) 10.2.4 10.2.5 Composition of human blood Biological Lens The human blood consists of 55% plasma and 45% cell components. Perfluorocarbon (PFC) Plasma is the medium of transportation in the body. The components emulsions can be of blood cells consist of red blood cells or erythrocytes, platelets and potentially used as white blood cells or leucocytes (Photographs 10.1 and 10.2). artificial blood. Studies have shown that PFC has the capacity like blood to transport oxygen and carbon dioxide. erythrocyte Plasma (forms 55% of the blood platelet volume) leucocyte Leucocytes and platelets (less than 1% of the blood volume) Erythrocytes (forms 45% of the blood volume) PHOTOGRAPH 10.1 Main components of blood PHOTOGRAPH 10.2 Main structural components of blood CHAPTER 10 TABLE 10.2 Blood plasma components and the main function of each component Component Main function Water Blood plasma consists of 90% water. Water is a medium of transportation and a solvent for respiratory gas, ions, digestive products and excretory substances. Plasma proteins • Fibrinogen plays a role in blood clotting. • Albumin controls blood osmotic pressure. • Globulin is a type of antibody that is involved in the body’s defence. Solutes – nutrients such • Nutrients are important for energy, growth and maintenance of health. as glucose, excretory • Excretory substances are toxic substances that need to be disposed substances such as urea and respiratory gas off from the body. • Oxygen is required in the respiration of cells. Hormones and enzymes Hormones control physiological activities in the body. Enzymes are involved in the metabolic processes of cells. 10.2.2 175 Table 10.3 shows the characteristics and functions of each blood cell type. TABLE 10.3 Characteristics and functions of blood cell types Blood cell type Characteristics Functions Erythrocyte • Has an elastic plasma membrane • Each erythrocyte has a (red blood cell) • The biconcave disc shape haemoglobin which is the red pigment that gives blood its red s2id.e0 viemw enables a large TSA/V for efficient colour. gaseous exchange pandangan sisi • It does not have a nucleus at • Haemoglobin contains a heme the mature stage s7o.5thamt more group. The heme group consists top view haemoglobin can be loaded of an iron atom which is the into it binding site for oxygen. FIGURE 10.10 •p aIntdiasnpgarondautacsed in the bone Erythrocyte structure marrow of bones such as the • Haemoglobin combines with Platelet sternum and ribs oxygen to form oxyhaemoglobin • Can live up to 120 days and is in high oxygen partial pressure destroyed in the liver or lymph conditions. through the phagocytosis process. • Oxyhaemoglobin releases oxygen in tissues or cells when the partial pressure of oxygen is low. • Platelets are produced from • Involved in the blood clotting fragments or scraps of cell process cytoplasm that originate from the bone marrows. • The life span is less than one week. FIGURE 10.11 Platelet polypeptide iron oxygen Brainstorm! The red blood cell of frogs has a nucleus and is larger than the red blood cell of humans. What are the advantages and disadvantages of nucleated red blood cells? Haemoglobin 176 10.2.2 Blood cell type Characteristics and functions Leucocyte (white blood • The shape is irregular and is not fixed cell) • Contains nucleus • Does not contain haemoglobin L Granulocytes • Produced in the bone marrow • Life span is less than five days • Leucocyte can diffuse out of the capillary pore and fight pathogens in tissue fluids. It is divided into two types: granulocytes (contain granules) and agranulocytes (no granules). • Granulocytes include neutrophils, eosinophils and basophils. Agranulocytes include lymphocytes and monocytes. E Neutrophil Eosinophil Basophil • The nucleus is made up of • The number of basophils U • The nucleus is made up of two to five lobes. two lobes. is lowest in the blood • Releases enzymes that • It contains heparin that C • Ingests bacterial cells and dead cells or tissues from fight inflammation and prevents blood clotting allergy reaction O wounds by phagocytosis C Y T E S Agranulocyte Lymphocyte Monocyte CHAPTER 10 • Contains a large nucleus with very little • The biggest leucocyte • Spherical-shaped nucleus cytoplasm • Ingests bacteria and dead cells or • Produces antibodies to destroy bacteria and tissues by phagocytosis viruses that enter the body • Can also produce antitoxins against toxins that are produced by bacteria or viruses PHOTOGRAPH 10.3 Photomicrograph of leucocytes 10.2.2 177 Human blood vessels Blood capillary endothelial cells endothelium endothelium smooth smooth muscle muscle connective tissue connective tissue Artery Vein venule arteriole FIGURE 10.12 Relationship between artery, blood capillaries and vein ARTERY BLOOD VEIN Arteries are blood vessels that transport CAPILLARIES blood out of the heart. The function of the Capillaries rejoin to artery is to quickly transport blood at a high Capillaries are form larger blood pressure to the tissues. blood vessels with vessels called The blood in the artery is under high thin walls, as thick venules. The venules pressure because of the pumping action of as one cell. Blood combine to form the heart. capillaries allow the veins that transport The aorta is the main artery that leaves exchange of gases to blood back to the the heart. The artery expands when blood occur between blood heart. Vena cava is is received from the heart. Therefore, the and cells through the main vein that artery wall is elastic to stop it from breaking diffusion. Nutrients, carries deoxygenated due to the high-pressured blood that flows excretory substances blood back to the through it. and hormones heart. The differences The branches of an artery become small diffuse through blood between arteries, vessels known as arterioles when they capillaries. capillaries and veins reach the body tissues. The arteriole are given in Table 10.4. continues to branch out and ends at the capillaries. The group of capillaries is called 10.2.3 capillary network. 178 TABLE 10.4 Differences between arteries, capillaries and veins Characteristics Artery Capillaries Veins Wall Wall is thick, muscular Wall is as thick as one Wall is thin, less muscular and elastic cell, not muscular and and less elastic not elastiKcaKpaiplailariri Arteri wall (as thick as one cell) Vena Arteri Vena Kapilari elastic Vena fibre lumen Arteri lumen Lumen wall lumen wall Very tiny Large Valve Small No Contain valves to maintain Blood pressure No valve except for one-way flow of blood The direction of semilunar valve at blood flow the base of the aorta Low Very low and at the base of the pulmonary artery From the artery to the From the whole body vein to the heart High From the heart to the entire body lumen (middle space) connective CHAPTER 10 erythrocyte tissues PHOTOGRAPH 10.4 Scanning electron microscope shows the cross section of an arteriole (4000x magnification) 10.2Formative Practice 3 State two differences between the structures of erythrocyte and leucocyte. 1 What is the function of the bicuspid valve? 4 Explain why the left ventricle has a thicker 2 Explain why some individuals feel nauseous muscular wall than the right ventricle. and faint immediately after donating blood? Why do some blood donors need to take iron pills? 10.2.3 179 10.3 Mechanism of Heartbeat How is blood circulated to the whole body? In every contraction, the heart acts as a pump that pumps blood to the whole body. How is every heartbeat triggered and sustained? The heart is made up of cardiac muscles (Photograph 10.5) that intersect and are connected with one another. This arrangement allows electric impulses to spread rapidly through the heart and at the same time, stimulates the cardiac muscle cells to contract simultaneously and uniformly. Cardiac muscles are myogenic. This means that the heart contracts and relaxes without receiving any impulse signal from the nervous system. If the cardiac muscles are stored in a warm oxygenated solution that contains nutrients, these muscles will contract and relax rhythmically on their own. PHOTOGRAPH 10.5 Blood circulation in humans Cardiac muscle tissue The produced force that enables blood to circulate in humans is Our World of Biology generated by the pumping of the heart and the contraction of the skeletal muscles. The “Medtronic Micra” pacemaker left atrium is the smallest artificial pacemaker sinoatrial node in the world. The size is about the right atrium bundle of His size of a vitamin atrioventricular node left ventricle pill and is placed in the heart without right ventricle surgery. The artificial pacemaker sends small electrical charges to stimulate heartbeat. Purkinje fibres FIGURE 10.13 The location of sinoatrial node, atrioventricular node, bundle of His and Purkinje fibres 180 10.3.1 Pumping of the heart The pacemaker generates electrical impulses that spread rapidly through both walls of The contraction of the heart is initiated and the atrium and causes the atrium to contract coordinated by the pacemaker. The pacemaker rhythmically. The main pacemaker is called is a group of specific heart muscle cells that sinoatrial node (SA). The sequence of heart initiates the rate of heart contraction and is muscle contraction that causes the pumping is located at the right atrium wall (Figure 10.14). shown in Figure 10.14. 1 The sinoatrial node (SA) generates 2 Electrical impulses spread rapidly electrical impulses. in both the atria, causing the atria to contract simultaneously. The sinoatrial nodes contraction of the atria helps to pump (SA nodes) blood into the ventricles. atria Purkinje fibres AR ventricles 4 The electrical impulses spread atrioventricular node (AV node) CHAPTER 10 from the apex of the heart to the whole ventricle wall. As a result, the ventricles contract to pump blood out to the lungs and body. bundle of His Across the fields apex of Electrical impulses the heart in the heart can be detected by 3 Purkinje fibres putting electrodes The electrical impulses reach the on the skin. The atrioventricular node. The electrical electrocardiogram impulses spread through the bundle of is a record of the His, and the Purkinje fibres up to the electrical activity apex of the heart. that triggers every heartbeat. FIGURE 10.14 The sequence of heart contraction that causes the pumping of the heart 10.3.2 181 During heart pumping, the lub-dub sound can be heard. Do you know what causes this lub-dub sound? The lub-dub sound is the closing sound of the heart valves. 1 The first ‘lub’ sound is produced when the tricuspid valve and the bicuspid valve close. 2 The second ‘dub’ sound is tricuspid valve bicuspid valve produced when the semilunar valves close. FIGURE 10.15 The lub-dub sound of the heart semilunar valves open valve Contraction of skeletal muscles around the veins veins muscle The pumping of the heart helps in the distribution and flow contraction of blood through the arteries, arterioles and blood capillaries. contricts vein However, the force produced by the pumping of the heart is insufficient for the blood flow to continue through the veins and closed valve return to the heart. Besides, the blood is forced to flow against the force of gravity. The presence valve in the veins ensures that the blood flows in one direction to the heart. muscles relax The blood flow in the veins is assisted by: FIGURE 10.16 Contraction (a) contraction of the smooth muscles found in the venule and and relaxation of the foot vein walls; skeletal muscles (b) contraction of skeletal muscles around the veins. The contraction of skeletal muscles presses and constricts the veins, causing the valve to open and allow blood to flow towards the heart. The valve is then closed to prevent the blood from flowing back towards the foot (Figure 10.16). Brainstorm! 10.3Formative Practice What would happen 1 Name the main heart 4 In what circumstances would to the valve in the pacemaker. fingers turn pale? blood vessels of our legs if we stand or sit 2 What does the term for too long? myogenic mean? 3 Explain why a person who stands too long may faint. 182 10.3.2 Mechanism of Blood 10.4 Clotting The necessity for blood clotting mechanism STEM Bulletin What happens when your finger is injured? Blood will flow from the Scientists have wound until you apply pressure directly on the wound. The pressure developed a you apply may appear to restrict bleeding temporarily; however, the nanomagnetic blood flow is actually stopped by the blood clotting process. particle that Why must the blood clot on the wound? Blood clotting will stop or contains thrombin. minimise the loss of blood on the injured blood vessel. Blood clotting This nanoparticle also prevents microorganisms such as bacteria from entering the is injected into bloodstream through the damaged blood vessel. The blood pressure is the injured part also maintained because excessive blood loss will lower blood pressure to trigger blood to a dangerous level. How does blood clotting occur? clotting and to stop bleeding. Mechanism of blood clotting Blood clotting involves a series of chemical reactions that takes place in the blood when someone is injured to prevent excessive bleeding. The coagulated platelets, damaged cells and clotting factors CHAPTER 10 in the blood plasma will form an activator (thrombokinase). Thrombokinase, with the aid of calcium ions and vitamin K, converts prothrombin to thrombin. Prothrombin (inactive Thrombin (active plasma plasma protein) protein that acts as an enzyme). Thrombin catalyses the conversion of fibrinogen to fibrin. Fibrinogen (soluble) Fibrin (insoluble) TABLE 10.17 Mechanism of blood clotting Fibrin is a threadlike protein fibre that forms a network on the wound surface to trap erythrocytes and to close the wound to prevent blood loss. 10.4.1 10.4.2 183 Our World of Biology Health issues related to blood clotting When you sit for too long, the risk of Under normal conditions, blood does not thrombosis in legs clot in blood vessels that are not damaged will increase. Make because of some anticoagulants such as sure that you move heparin. What happens when the blood your legs once in a clotting mechanism of an individual does while. not function? Activity Zone HAEMOPHILIA Work in groups • Haemophilia is an example of an illness that to collect and prevents blood from clotting. interpret information about thrombosis, • Haemophilia is a hereditary illness caused by the embolism and lack of certain clotting factors in the blood. haemophilia. Present your • Excessive bleeding due to small wounds or findings to the bruises can result in death. class. THROMBOSIS • Formation of a blood clot (thrombus). • Thrombosis happens as a result of: – damage in blood vessels, or – sluggish blood flow that causes clotting factors to accumulate EMBOLISM • When a blood clot is transported by blood flow, the blood clot is called embolus. • If the embolus gets stuck in a tiny blood vessel, the blood flow will stop. 10.4Formative Practice 1 At the end of the blood clotting mechanism, 3 Explain the mechanism of blood clotting. fibrin will be formed to trap erythrocytes. Explain the meaning of fibrin and its function. 4 Explain why the formation of blood clots in the blood vessel can cause a heart attack. 2 Describe two health issues related to blood clotting. 184 10.4.3 Blood Groups of Humans 10.5 ABO blood group Do you know your blood group? Human blood is classified into A, B, AB and O groups. Donation and transfusion of blood is based on the compatibility of the blood group of the donor and the recipient. TcaBhnliosaoicsdt baggerocaauinupsstBetthheearnetcigipeinenotnhtahsearnetdibbolodoieds in the blood serum that Blood group A cells of the donor. Blood antigen A transfruesdiobnloofdrocmella donor to a recipient must take into consideration the blood group type of the donor and the recipient (Table 10.6). If anti-B antibody the blood group of both the donor and receiver is not compatible, anti-t(Ahcoeaanrgteiubdloadtbiyloonao)nd.tigceenllsB of the recipient will experience agglutination red blood cell Blood group AB Blood group O TABLE 10.5 Antigen and antibody in blood groups antigBelnoAod groupanBtigen B BgBrloonlouooopdardendgtigrboelounAopsndtBicgeelln on red blood cells  group A Blooreddgbrloouopd cAell Antibody in the blood nA serum y annotigaenntibAodies A red blood cell Antigen A Anti-B ood cell arnetid-Bblaonotdibcoedlyl antigen B B anti-A antibodyAntigen B Anti-A anti-A antibody anti-B antibody AB Antigen A and Antigen B No Anti-A and Anti-B O antigen B No roup AB BloreoddbglorooudpceOll anti-A antibody Compatibility of blood donor group with the recipient TABLE 10.6 antigen B BnloooardendgtigrboelounopsdAcBell group A antigBenloAod groupanBtigen B BBloloodd group OCan donate blood to Can receive blood from groupred blood cell blood groups blood groups tnibAodies red blood cell CHAPTER 10 y anti-A antibody nAo antigens A and AB only A and O only anti-B antibody B B and AB only B and O only no antibodies AB anti-A antibody AB only A, B, AB and O red blood cell antigen B anti-B aOntibody A, B, AB and O O only ood cell anti-A antibody roup AB Blood group O Rhesus Factor antigen B red blood cell Another antigen found on the surface of the red blood cells is the no antigens Rhesus factor (Rh factor). The red blood cells of an individual with the Rh factor or antigen D are known as Rh-positive. An tibodies anti-A antibody individual who does not possess the Rh factor or antigen D is known anti-B antibody as Rh-negative. FIGURE 10.18 Antigens and If the blood of a Rh-positive donor mixes with the blood of a Rh- antibodies in different blood negative recipient, the blood of the recipient will react by producing groups the Rhesus antibody or anti-D antibody. When the recipient receives another dose of Rh-positive blood, the Rhesus antibody will cause the agglutination of the donor blood cells. This situation could result in the death of the recipient. 10.5.1 10.5.2 10.5.3 185 Pregnancy and the Rhesus factor Usually, problems During the last month of However, the Indicator: will arise when an pregnancy, fragments concentration Rh-negative mother of foetal blood cells of antibodies Rh-positive marries an containing antigen D produced is Rh-positive father cross the placenta not enough Rh-negative and conceives an and enter the blood to affect the Rh-positive foetus. circulation of the mother. first child. But Anti-D the anti-D antibodies As a result, the white antibodies blood cells in the will last in The problem arises when mother’s blood will react the blood the second child is also and produce anti-D circulatory Rh-positive. The anti-D antibodies that will system of the antibodies that are present flow back through the mother. in the mother’s blood cross placenta into the foetal the placenta and destroy blood circulatory system. the red blood cells of that foetus. The symptoms The antibodies will destroy of this disease are called the red blood cells of the erythroblastosis fetalis. Rh-positive baby before The second foetus dies if or immediately after birth. the blood is not replaced with Rh-negative blood 10.5Formative Practice through blood transfusion. In a less serious situation, the baby may suffer from anaemia and mental retardation. However, this problem can now be addressed by treating the affected mother with anti-Rhesus globulins after the first pregnancy to stop the formation of anti-D antibodies. 1 State the blood group which is the universal The first pair of parents: B and O donor. The second pair of parents: A and B The third pair of parents: AB and O 2 Predict what will happen if the blood group of both recipient and donor is not compatible. Match the babies with their correct parents. 3 Three babies P, Q and R have blood groups 4 An Rh-positive male marries an Rh-negative B, O and AB respectively. Three pairs of female. The first Rh-positive child is alive but parents have the following blood groups: the second child who is also Rh-positive did not survive. Explain why. 186 10.5.4 10.6 Health Issues Related to the Human Circulatory System Activity Zone The necessity for a healthy circulatory system Work in groups and conduct a A healthy circulatory system is important to ensure optimum health. case study on How do we ensure that our circulatory system is healthy? Among the the practices of practices for maintaining the circulatory system are a balanced intake of maintaining a healthy food that is low in fat and regular exercise. The practice of not smoking human circulatory and not drinking alcoholic drinks also ensures a healthy circulatory system. system. Cardiovascular diseases Do you know that cardiovascular diseases are the leading cause of death in our country? Cardiovascular diseases include diseases related to the heart and the blood circulatory system such as atherosclerosis, arteriosclerosis, angina, hypertension, myocardial infarction (heart attack) and stroke. Activity Zone CARDIOVASCULAR DISEASES CHAPTER 10 Discuss a suitable • Atherosclerosis is the formation and deposition of plaque on the treatment for heart artery walls. failure. • The plaque is formed from cholesterol, lipid, dead muscle tissues and coagulated platelets. • The plaque will clog and narrow the lumen in blood vessels. • The restricted blood flow can cause hypertension. • Hypertension causes fine arteries to break and the patient can suffer from stroke if this happens in the brain. • Stroke is also caused by blood clots (thrombus) that clog the flow of blood in the brain. • Atherosclerosis is the early stage of arteriosclerosis. • Arteriosclerosis occurs when calcium is deposited on the plaque and causes the artery to become hard and lose its elasticity. • If the lumen of the coronary artery (artery for the heart) is narrowed, the insufficient oxygen supply to the heart muscles can cause angina (severe chest pain). • If the artery is completely clogged, myocardial infarction (heart attack) will occur. PHOTOGRAPH 10.6 Myocardial infarction (heart attack) 10.6.1 10.6.2 187 artery blood clot restricts the flow of blood coronary artery plaque is formed in the artery dead cardiac muscle tissues STEM Bulletin FIGURE 10.19 Formation and deposition of plaque on artery wall Nanotechnology is What is the treatment for a patient who suffers from heart failure? What used in the diagnosis are the risk factors that contribute to cardiovascular diseases and what and treatment of can we do to ensure that the cardiovascular system is healthy? atherosclerosis and plaque formation 10.6Formative Practice in arteries. In this technique, nanoparticles 1 What is the meaning of 3 In your opinion, what are the are designed to myocardial infarction? factors that contribute to an resemble high-density individual’s risk of getting lipoprotein cholesterol 2 Explain how stroke happens. cardiovascular disease? (HDL) (“good” cholesterol) to help 4 Explain how atherosclerosis reduce plaque. happens. 188 10.6.1 10.6.2 Human Lymphatic System 10.7 The formation of tissue fluid In addition to the blood circulatory system, there is one more system in the body whose function is closely related to the blood circulatory system. This system is called the lymphatic system. The formation of tissue fluid is illustrated in Figure 10.20. 1 Blood that reaches the arterial end of the 2 This pressure allows the blood blood capillary has a high pressure due to the plasma to diffuse continuously small diameter of capillaries and the pumping from the blood capillaries to the force of the heart. intercellular space. blood plasma cell arteriole oxygenated deoxygenated blood at a high blood at a low pressure pressure tissue fluid blood capillary lymphatic capillary FIGURE 10.20 Exchange of substances between blood capillaries and body cells CHAPTER 10 3 • Blood plasma that occupies the 4 • Tissue fluid allows the exchange of intercellular space and constantly • materials in the blood and cells to • bathes cells is called tissue fluid. • occur. Nutrients and oxygen diffuse from The tissue fluid does not contain tissue fluid to body cells. any erythrocyte, platelet and Simultaneously, excretory products and plasma protein because these carbon dioxide diffuse from body cells are too large to diffuse out of the to blood capillaries through the tissue blood capillaries. fluid. Lymph formation and components of the lymphatic system At the venule end of the blood capillary, blood plasma is hypertonic compared to the tissue fluid surrounding it. Blood pressure is also lower. As a result, the reabsorption of water, mineral salts and waste takes place in the venule capillary. However, only 85% of the fluid that leaves the blood at the arteriole end of blood capillary diffuses back into the venule end. What happens to the remaining 15% that is left in the intercellular space? This remainder forms about 4 litres of fluid that is lost from capillaries each day. How does the blood circulatory system regain this fluid? 10.7.1 189 The lost fluid is collected and returned to the blood through the lymphatic capillary, which is the smallest vessel in the lymphatic system. This fluid is known as lymph and is pale yellow in colour. Table 10.7 and Table 10.8 show the similarities and differences between lymph with tissue fluid and blood. TABLE 10.7 Comparison between lymph and tissue fluid Similarity Both contain plasma without the plasma proteins, erythrocytes and platelets. Differences Lymph Tissue fluid Higher content of fat and fat-soluble substances Low content of fat and fat-soluble substances High content of lymphocytes Low content of lymphocytes TABLE 10.8 Comparison between lymph and blood Similarity Both contain all the contents of plasma such as nutrients, hormones, enzymes, cellular wastes, respiratory gases and leucocytes. Differences Lymph Blood Does not contain plasma protein, erythrocyte and Contains plasma proteins, erythrocytes and platelet platelets The lymphatic capillary wall consists of one layer of cells only. The lymphatic capillary differs from blood capillary because one of its end is blocked or closed while the other end is connected to the lymphatic vessel (Figure10.21). Lymphatic capillaries found in intercellular spaces merge to form a larger lymphatic vessel. Along the lymphatic vessel, there are lymph nodes at certain distances. lymphatic capillary tissue cell fluid arteriole venule lymph tissue fluid lymphatic vessel lymphatic capillary 190 FIGURE 10.21 Lymph formation valve 10.7.2 10.7.3 The lymphatic system consists of organs such as lymph nodes, spleen, thymus gland, bone marrow, tonsils and appendix (Figure 10.22). The lymphatic system does not have its own pump to circulate the lymph along the lymphatic vessel. The flow of lymph is aided by heartbeat pulse, contraction of skeletal muscles, peristalsis in the digestive tract and changes in pressure during inhalation and exhalation of breath. In the lymphatic vessel, one-way valves ensure the lymph flows continuously to the heart. These valves also prevent the lymph from flowing back. Relationship between the blood circulatory system and the lymphatic system All lymphatic vessels will eventually join with one of the two main lymphatic vessels which are the thoracic duct dan right lymphatic duct (Figure 10.22). The right right lymphatic duct tonsils lymphatic duct right receives lymph subclavian thoracic duct from the right vein left subclavian hand, chest and vein right side of the thymus head and neck. bone marrow lymphatic The thoracic vessel spleen duct receives lymph from the left side of the head, neck and chest, and all the body parts below the ribs. appendix CHAPTER 10 lymphatic lymph nodes lymph node capillary lymphocyte valve 191 10.7.3 blood vessel tissue fluid FIGURE 10.22 Lymphatic system Systemic circulation Pulmonary circulation The thoracic duct will deliver its lymphatic contents into the left subclavian right subclavian lymph capillaries vein while the right lymphatic duct vein node will transport lymph into the right pulmonary subclavian vein. right lymphatic capillaries So the lymph collected from the whole duct body will flow back into the blood circulatory system. Figure 10.23 shows lymphatic the relationship between the lymphatic vessel system and the blood circulatory system that complement each other. valve vein artery lymph systemic node capillaries lymphatic FIGURE 10.23 Relationship between lymphatic system capillaries and blood circulatory system The necessity of the lymphatic system The necessity of the lymphatic system is summarised in Figure 10.24. COMPLEMENTS THE NECESSITIES OF BODY DEFENCE BLOOD CIRCULATORY THE LYMPHATIC Lymph nodes produce and store SYSTEM SYSTEM lymphocytes that are involved in the production of antibodies. The lymphatic system returns the excess tissue fluid in the TRANSPORTATION OF FAT- intercellular space into the SOLUBLE SUBSTANCES blood flow. The composition, pressure and volume of blood are Fats and fat-soluble substances maintained at a normal range. diffuse into the lacteal in the villus of the small intestine. Lacteals are FIGURE 10.24 The necessity of the lymphatic capillaries. Lipid droplets lymphatic system are transported to the thoracic duct and blood circulatory system through the left subclavian vein. 10.7Formative Practice 3 State the differences between the composition of blood plasma, tissue fluid and lymph. 1 Name the two main lymphatic vessels. 4 After eating fatty food, the number of lipid 2 State three main functions of the lymphatic molecules in the lymph increases by 1%. system. Explain why. 192 10.7.4 Health Issues Related to the 10.8 Human Lymphatic System Have you ever wondered what would happen if our lymphatic system Brainstorm! does not function properly? What would happen if the excess tissue fluid is not returned to the blood flow? Tissue fluid that is not returned to the Why do our legs blood circulatory system will accumulate in the intercellular space. This swell after we sit for will result in the swelling of the body tissues. This condition is known too long? as oedema (Photograph 10.7). Oedema may be caused by a number of factors (Figure 10.25). PARASITIC INFECTION PREGNANCY DEFICIENCY IN • The parasite worm Brugia sp. The body will produce more PLASMA PROTEIN infects the lymphatic vessel body fluid to fulfill the needs of a and prevents the flow of growing foetus. Deficiency of albumin lymphatic fluid. in the blood. PROLONGED BEDRIDDEN • The infected part, for example, PATIENTS leg will swell. Paralysed or stroke patients with • The patient contracts limited mobility can suffer from lymphatic filariasis (Photograph oedema in the legs. 10.8). • This worm is transmitted through mosquito bites. CAUSES OF CHAPTER 10 OEDEMA normal leg leg with oedema FIGURE 10.25 Causes of PHOTOGRAPH 10.7 oedema Oedema PHOTOGRAPH 10.8 10.8Formative Practice Swollen leg caused by lymphatic filariasis 1 How do parasitic infections happen? 3 Predict what would happen to the legs of a patient who has been bedridden for a long 2 Explain what would happen when the tissue period of time? Explain your answer. fluid fails to return to the blood circulatory system. 4 Lipid droplets or fat globules cannot diffuse into the villus blood capillary but must diffuse through the lacteal. Explain why. 10.8.1 193 Summary TRANSPORT IN HUMANS AND ANIMALS Circulatory System Lymphatic System Components of the Open Circulatory Closed Circulatory System lymphatic system System Blood is contained in the • Lymph Haemolymph closed blood vessel that is • Lymphatic capillaries flows into the continuous and is distributed • Lymphatic vessel body cavities to the whole body • Lymph nodes (haemocoel) and • Lymphatic organs bathes cells Fish The necessity of the The fish heart has two Lymphatic System Insects chambers: an atrium and a • Complements the blood One or more hearts ventricle circulatory system pump haemolymph • Transportation of fat- through the Amphibians soluble substances haemolymph vessel The heart of an amphibian • Body defence into the haemocoel consists of three chambers: Health Issues Related to two atria and one ventricle the Human Lymphatic System Humans • Lymphatic filariasis The human heart consists • Parasitic infection of four chambers: two atria • Deficiency in plasma and two ventricles that are protein completely separated • Pregnancy • Prolonged bedridden patients Circulatory Mechanism Mechanism Blood Groups of Health Issues Related System of of of Blood Humans to the Human Humans Heartbeat Clotting Circulatory System • Blood type A • Blood Health Issues • Blood type B • Arteriosclerosis • Heart Related to Blood • Blood type AB • Atherosclerosis • Blood vessel Clotting • Blood type O • Hypertension • Rhesus factor • Angina • Myocardial • Thrombosis • Embolism infarction • Haemophilia • Stroke 194

Fleur de Lis Homeschool Blog

After growing up going to FDL, I decided to name my homeschool (like my daughter) after the place I learned the most from. Sharing what books we've added into each SL core, by Core and Week. I'm also sharing our events with family and friends who check in on us here. If nothing else, I'm keeping a great, though epic, transcript of my Dd's education! May the good Lord bless and keep each of you, whether near or far away!

Friday, May 13, 2016

Apologia general science module 9 experiments...in process 9.1, 9.2, 9.3, 9.4, 9.5.

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