Form 4 Biology Transport in Humans and Animals Past Paper PDF

10 CHAPTER Transport in Humans and Animals Do you KNOW... What are the co...

10 CHAPTER Transport in Humans and Animals Do you KNOW... What are the co mponents of the blood circulatory sy stem? How does the he art pump blood? How does the lym phatic system return tissue fluids into the blood circulatory system? What is a What are the he alth issues related mechanical heart? to the human circu latory and lymphatic systems? 166 BioT4(NC)-B10A-EN New 7th.indd 166 1/9/2020 12:09:18 PM  10.1 Types of Circulatory System 10.4 Mechanism of Blood Clotting 10.1.1 Justify the necessity of transport 10.4.1 Justify the necessity for blood systems in complex multicellular clotting mechanism. organisms. 10.4.2 Describe blood clotting 10.1.2 Identify substances that are mechanism. transported by the transport 10.4.3 Describe health issues related to system: substances required by blood clotting: thrombosis a cell waste products of a cell embolism haemophilia 10.1.3 Conceptualise types of circulatory system in complex multicellular 10.5 Blood Groups of Humans organisms. 10.5.1 Describe ABO blood group. open circulatory system 10.5.2 Correlate ABO blood group with closed circulatory system blood donation. 10.1.4 Compare and contrast circulatory 10.5.3 Describe the Rhesus factor. systems in complex multicellular 10.5.4 Reason out the incompatibility of organisms: insects Rhesus factor in pregnancies. fish amphibians humans 10.6 Health Issues Related to the Human 10.2 Circulatory System of Humans Circulatory System 10.2.1 Describe components of the 10.6.1 Justify the necessity for a healthy human circulatory system: circulatory system. heart blood vessel blood 10.6.2 Communicate about 10.2.2 Explain the composition of blood: cardiovascular diseases. blood plasma blood cells 10.2.3 Compare and contrast the types of 10.7 Lymphatic System of Humans blood vessels: 10.7.1 Synthesise the process of artery vein capillary formation of tissue fluid and lymph. 10.2.4 Label the structure of a human 10.7.2 Compare and contrast the heart and associated blood contents of lymph and: vessels: aorta vena cava tissue fluid blood pulmonary artery and pulmonary 10.7.3 Describe components of the vein lymphatic system: lymph coronary artery and coronary lymphatic capillaries vein. lymphatic vessels lymph nodes semilunar valve lymphatic organs bicuspid valve and tricuspid 10.7.4 Justify the necessity of the valve septum lymphatic system: 10.2.5 Describe the functions of parts of complements the blood the heart. circulatory system transports lipid-soluble 10.3 Mechanism of Heartbeat substances 10.3.1 Describe the human heartbeat body defence mechanism: sinoatrial node (pacemaker) 10.8 Health Issues Related to the Human atrioventricular node Lymphatic System bundle of His Purkinje fibres 10.8.1 Describe health issues related to 10.3.2 Communicate about forces that the lymphatic system. cause the blood to circulate in humans: pumping of the heart contraction of skeletal muscles 167 BioT4(NC)-B10A-EN New 7th.indd 167 1/9/2020 12:09:18 PM  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 nutrients, and expels cellular waste products such as carbon dioxide and nitrogenous wastes. In Chapter 2, you learned how unicellular organisms such as Amoeba sp. get their essentials and expel wastes by diffusion from and to its external 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? Substance Large complex multicellular organisms cannot obtain essential exchange can occur substances and expel wastes by diffusion because their TSA/V is small. by diffusion because The distance between the external environment and the cell is too far for the cells are in the direct substance exchange. So, how do complex multicellular organisms environment. get essential substances for their cells? external environment is far away from cells Substance exchange cannot occur by diffusion because the cells are too far epidermis away from the environment. body cells FIGURE 10.2 Substance exchange for multicellular organisms external environment FIGURE 10.1 Substance exchange for unicellular organisms 168 10.1.1 10.1.2 BioT4(NC)-B10A-EN New 7th.indd 168 1/9/2020 12:09:19 PM  To address this problem, multicellular organisms have an internal transportation system. In vertebrates, the transportation system is called the blood circulatory system. Before studying further the blood circulatory system, conduct an experiment to study the effects of changes in TSA/V on the diffusion ICT 10.1 rate. Activity: Studying the effects of changes in total surface area to volume ratio (TSA/V) on the 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. CHAPTER 10 haemolymph haemolymphvessel vessel blood bloodvessel vessel haemocoel haemocoel blood bloodcapillary capillary blood blood heart heart t t heart heart haemolymph haemolymph cells cells cells cells open-ended open-endedvessel vessel 10.1.3 169 BioT4(NC)-B10A-EN New 7th.indd 169 1/9/2020 12:09:19 PM  CIRCULATORY SYSTEM OPEN 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 Blood that leaves the ventricle is pumped into the haemocoel. to the gill capillaries to enable gaseous Haemolymph flows out from the heart exchange. into the haemocoel when the heart The gill capillaries carry blood to the contracts. blood vessels that transport oxygenated In the haemocoel, substance exchange blood to systemic capillaries. between haemolymph and body cells In the systemic capillaries, oxygen occurs through diffusion. diffuses into the tissues while carbon When the heart relaxes, haemolymph dioxide diffuses from the tissue into the flows back into the heart through tiny anterior capillaries. openings called ostium. The deoxygenated blood is then returned to the heart atrium through the veins. aorta As the blood flows in one direction, the fish circulatory system is known as a anterior single circulatory system. ostium aorta aorta gill capillaries posterior heart mixed blood aorta ostium ostium heart haemocoel artery FIGURE 10.4 The open heart circulatory system in insects ventricle atrium posterior FIGURE 10.3 Dorsal view of insect heart Indicator: vein 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 1/9/2020 12:09:20 PM  CLOSED CIRCULATORY SYSTEM Circulatory System of Humans The human heart consists of four Circulatory System of Amphibians chambers: two atria and two ventricles The heart of an amphibian has three chambers, that are separated completely. that is, two atria and a ventricle. Unlike the single Humans have a double circulatory circulatory system of fish, blood flows in two system. This means that in one directions: pulmocutaneous circulation and complete circulatory cycle, blood systemic circulation. Therefore, this system is flows in the blood vessels through the known as a double circulatory system. heart twice. As there are two different Amphibians are said to have an incomplete double circulations, humans are said to have circulatory system because the deoxygenated a complete double circulatory blood and the oxygenated blood are mixed. system because the deoxygenated Pulmocutaneous circulation transports blood to blood and the oxygenated blood do the lungs and skin, and the exchange of gases not mix. takes place here. Systemic circulation transports oxygenated blood to the body tissues and returns the deoxygenated blood to the right atrium through Pulmonary circulation the veins. Deoxygenated blood is transported through the pulmonary artery to the 1 Deoxygenated 2 Oxygenated blood lungs for gaseous exchange. blood from body is from lungs and skin Oxygenated blood from the lungs is transported to the is transported by returned to the left atrium and flows right atrium. the pulmonary vein to the left atrium. into the left ventricle. lung capillaries and skin lung capillaries 3 Blood from both atria enters one ventricle. Although pulmocutaneous there is some mixing pulmonary artery circulation of oxygenated and CHAPTER 10 deoxygenated blood vena cava aorta 4 in the ventricle, most pulmonary 1 of the oxygenated vein 2 blood remains on 3 left the left side of the left right atrium ventricle while the right atrium atrium deoxygenated blood atrium left ventricle right remains on the right ventricle systemic circulation side of the ventricle. ventricle Indicator: oxygenated blood deoxygenated systemic capillaries blood systemic capillaries Indicator: 4 The ventricle Systemic circulation oxygenated blood then pumps the Blood is pumped from the heart to all blood through the the body tissues through the aorta. deoxygenated blood pulmocutaneous (lungs Then the deoxygenated blood returns mixed blood and skin) and systemic to the right atrium through vena cava. circulations. FIGURE 10.6 The blood circulatory system of amphibians FIGURE 10.7 The blood circulatory system of humans 10.1.4 171 BioT4(NC)-B10A-EN New 7th.indd 171 1/9/2020 12:09:20 PM  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 circulatory system circulatory system circulatory system circulatory system 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) Formative Practice 10.1 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 2 Explain why the blood circulatory system of specialised transportation system to move amphibians is considered as a closed and substances in and out of the cell. Explain incomplete blood circulatory system. why. 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 1/9/2020 12:09:21 PM  10.2 Circulatory System of Humans There are three main components in the circulatory system of humans. Blood: A type of connective tissue that is made up of blood plasma, blood cells and platelets. Blood acts as a medium of transportation. Heart: Functions as a muscular pump that circulates blood to the whole body. Blood vessels: Consist of arteries, capillaries and veins that are connected to the heart, and transport blood to all the body tissues. Malaysian Innovation A group of researchers Structure of the heart in Malaysia have Do you know that your heart is as big as your fist? The produced a device heart is located between the lungs in the thorax cavity called MyThrob that and contains four chambers, namely the left atrium, can be used as a right atrium, left ventricle and right ventricle. The left smart examination chamber is separated from the right chamber by a muscular and monitoring tool wall called septum. for heart diseases. The device studies the Atrium receives blood that returns to the heart original algorithm that while the ventricle pumps blood out of the can detect abnormal heart. The ventricle has thicker walls and heartbeat and is contract stronger than the atrium. suitable to be used for monitoring at home. 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 CHAPTER 10 aorta to the whole body while the right ventricle only has to pump blood to the lungs. Coronary arteries transport oxygenated blood for heart tissues while coronary veins transport deoxygenated blood. arteri koronari coronary arteries coronary vena veins koronari TABLE 10.8 The circulatory system of humans 10.2.1 10.2.4 10.2.5 173 BioT4(NC)-B10A-EN New 7th.indd 173 1/9/2020 12:09:21 PM  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 blood back to the heart. veins transports oxygenated blood from the lungs to the heart. The semilunar vena cava valves at the base of the pulmonary artery vena kava and the base of the aorta ensures that aorta blood which flows aorta out of the heart does arteri pulmonari not flow back into the pulmonary artery ventricle when the ventricle relaxes. vena pulmonari pulmonary veins semilunar valves atrium kiri atrium kanan left atrium right atrium injap bikuspid coronary vein injap sabit bicuspid valve The bicuspid injap trikuspid valve (located coronary artery between the septum arteri coronari left atrium tricuspid valve and the left ventricle) The tricuspid valve ensures that ventrikel (located kanan the between 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 right ventricle left atrium. This atrium. This valve consists septum valve consists of three leaflets. left ventricle of two leaflets. The septum separates the left part of the heart from the right part of the heart and ensures that the oxygenated blood does not mix with the deoxygenated blood. Brainstorm! What would happen FIGURE 10.9 Longitudinal section of a human heart to an individual if the bicuspid valve does not close completely ICT 10.2 when the ventricle Video: Animation of relaxes? the heart valves (Accessed on 21 August 2019) 174 10.2.4 10.2.5 BioT4(NC)-B10A-EN New 7th.indd 174 1/9/2020 12:09:23 PM  Composition of human blood Biological Lens The human blood consists of 55% plasma and 45% cell components. Perfluorocarbon (PFC) emulsions can be Plasma is the medium of transportation in the body. The components potentially used as of blood cells consist of red blood cells or erythrocytes, platelets and artificial blood. Studies white blood cells or leucocytes (Photographs 10.1 and 10.2). have shown that PFC has the capacity like blood to transport oxygen and carbon dioxide. erythrocyte Plasma (forms 55% of the blood volume) Leucocytes and platelets (less than 1% of the blood volume) platelet Erythrocytes (forms 45% of the blood volume) leucocyte 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 off from the body. urea and respiratory gas 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 1/9/2020 12:09:27 PM  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 enables a large TSA/V for efficient pigment that gives blood its red gaseous exchange colour. side It does not have a nucleus at Haemoglobin contains a heme 2.0 view m 7.5that m more the mature stage so group. The heme group consists pandangan sisi haemoglobin can be loaded of an iron atom which is the into it binding site for oxygen. pandangan atas in the bone It is produced Haemoglobin combines with marrow of bones such as the oxygen to form oxyhaemoglobin sternum and ribs in high oxygen partial pressure top view Can live up to 120 days and is conditions. destroyed in the liver or lymph Oxyhaemoglobin releases oxygen through the phagocytosis in tissues or cells when the partial FIGURE 10.10 process. pressure of oxygen is low. Erythrocyte structure Platelet 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 Brainstorm! The red blood cell of frogs has a nucleus and is larger than the red blood cell of iron humans. What are polypeptide the advantages and disadvantages of oxygen nucleated red blood cells? Haemoglobin 176 10.2.2 BioT4(NC)-B10A-EN New 7th.indd 176 1/9/2020 12:09:28 PM  Blood cell type Characteristics and functions Leucocyte The shape is irregular and is not fixed (white blood Contains nucleus cell) Does not contain haemoglobin 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. L Granulocytes E Neutrophil Eosinophil Basophil The nucleus is made up of The nucleus is made up of The number of basophils U two to five lobes. two lobes. is lowest in the blood Ingests bacterial cells and Releases enzymes that It contains heparin that C dead cells or tissues from fight inflammation and prevents blood clotting O wounds by phagocytosis allergy reaction C Y T E S Agranulocyte Lymphocyte Monocyte CHAPTER 10 Contains a large nucleus with very little The biggest leucocyte cytoplasm Spherical-shaped nucleus Produces antibodies to destroy bacteria and Ingests bacteria and dead cells or viruses that enter the body tissues by phagocytosis Can also produce antitoxins against toxins that are produced by bacteria or viruses PHOTOGRAPH 10.3 Photomicrograph of leucocytes 177 10.2.2 BioT4(NC)-B10A-EN New 7th.indd 177 1/9/2020 12:09:29 PM  Human blood vessels Blood capillary endothelial cells endothelium endothelium smooth muscle smooth muscle connective connective tissue tissue Artery Vein venule arteriole FIGURE 10.12 Relationship between artery, blood capillaries and vein ARTERY BLOOD VEIN CAPILLARIES Arteries are blood vessels that transport Capillaries rejoin to blood out of the heart. The function of the Capillaries are form larger blood artery is to quickly transport blood at a high blood vessels with vessels called pressure to the tissues. thin walls, as thick venules. The venules The blood in the artery is under high as one cell. Blood combine to form pressure because of the pumping action of capillaries allow the veins that transport the heart. exchange of gases to blood back to the The aorta is the main artery that leaves occur between blood heart. Vena cava is the heart. The artery expands when blood and cells through the main vein that is received from the heart. Therefore, the diffusion. Nutrients, carries deoxygenated artery wall is elastic to stop it from breaking excretory substances blood back to the due to the high-pressured blood that flows and hormones heart. The differences through it. diffuse through blood between arteries, The branches of an artery become small capillaries. capillaries and veins vessels known as arterioles when they are given in Table 10.4. reach the body tissues. The arteriole continues to branch out and ends at the capillaries. The group of capillaries is called capillary network. 178 10.2.3 BioT4(NC)-B10A-EN New 7th.indd 178 1/9/2020 12:09:30 PM  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 Arteri Kapilari Vena Arteri not elasticKapilari Vena elastic wall (as thick as one cell) fibre Arteri Kapilari Vena lumen lumen wall lumen wall Lumen Small Very tiny Large No valve except for semilunar valve at Contain valves to maintain Valve the base of the aorta No one-way flow of blood and at the base of the pulmonary artery Blood pressure High Low Very low The direction of From the heart From the artery to the From the whole body blood flow to the entire body vein to the heart CHAPTER 10 lumen (middle space) connective tissues erythrocyte PHOTOGRAPH 10.4 Scanning electron microscope shows the cross section of an arteriole (4000x magnification) Formative Practice 10.2 1 What is the function of the bicuspid valve? 3 State two differences between the structures of erythrocyte and leucocyte. 2 Explain why some individuals feel nauseous and faint immediately after donating blood? 4 Explain why the left ventricle has a thicker Why do some blood donors need to take muscular wall than the right ventricle. iron pills? 10.2.3 179 BioT4(NC)-B10A-EN New 7th.indd 179 1/9/2020 12:09:33 PM  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. Blood circulation in humans PHOTOGRAPH 10.5 The produced force that enables blood to circulate in humans is Cardiac muscle tissue generated by the pumping of the heart and the contraction of the skeletal muscles. Our World of Biology The “Medtronic left atrium Micra” pacemaker is the smallest artificial pacemaker sinoatrial node in the world. The size is about the size of a vitamin pill and is placed in the heart without surgery. The artificial right atrium pacemaker sends small electrical charges to stimulate atrioventricular node bundle of His heartbeat. left ventricle right ventricle 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 1/9/2020 12:09:34 PM  Pumping of the heart The contraction of the heart is initiated and The pacemaker generates electrical impulses coordinated by the pacemaker. The pacemaker that spread rapidly through both walls of is a group of specific heart muscle cells that the atrium and causes the atrium to contract initiates the rate of heart contraction and is rhythmically. The main pacemaker is called located at the right atrium wall (Figure 10.14). sinoatrial node (SA). The sequence of heart muscle contraction that causes the pumping is shown in Figure 10.14. 1 The sinoatrial node (SA) generates electrical impulses. 2 Electrical impulses spread rapidly sinoatrial nodes in both the atria, causing the atria (SA nodes) to contract simultaneously. The contraction of the atria helps to pump blood into the ventricles. atria Purkinje fibres AR ventricles 4 atrioventricular node (AV node) CHAPTER 10 The electrical impulses spread 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. Across the fields bundle of His Electrical impulses apex of in the heart can the heart be detected by Purkinje fibres putting electrodes 3 on the skin. The The electrical impulses reach the electrocardiogram atrioventricular node. The electrical is a record of the impulses spread through the bundle of electrical activity His, and the Purkinje fibres up to the that triggers every apex of the heart. 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 1/9/2020 12:09:35 PM  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. tricuspid valve bicuspid valve 2 The second ‘dub’ sound is produced when the semilunar valves close. semilunar FIGURE 10.15 The lub-dub sound of the heart valves open valve Contraction of skeletal muscles around the veins veins The pumping of the heart helps in the distribution and flow of blood through the arteries, arterioles and blood capillaries. muscle However, the force produced by the pumping of the heart is contraction insufficient for the blood flow to continue through the veins and contricts vein return to the heart. Besides, the blood is forced to flow against the force of gravity. The presence valve in the veins ensures that closed valve the blood flows in one direction to the heart. muscles relax The blood flow in the veins is assisted by: (a) contraction of the smooth muscles found in the venule and vein walls; (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 FIGURE 10.16 Contraction towards the heart. The valve is then closed to prevent the and relaxation of the foot blood from flowing back towards the foot (Figure 10.16). skeletal muscles Brainstorm! What would happen to the valve in the Formative Practice 10.3 blood vessels of our 1 Name the main heart 4 In what circumstances would legs if we stand or sit pacemaker. fingers turn pale? for too long? 2 What does the term 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 1/9/2020 12:09:37 PM  10.4 Mechanism of Blood Clotting The necessity for blood clotting mechanism What happens when your finger is injured? Blood will flow from the STEM Bulletin wound until you apply pressure directly on the wound. The pressure Scientists have you apply may appear to restrict bleeding temporarily; however, the developed a blood flow is actually stopped by the blood clotting process. nanomagnetic Why must the blood clot on the wound? Blood clotting will stop or particle that 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. CHAPTER 10 The coagulated platelets, damaged cells and clotting factors in the blood plasma will form an activator (thrombokinase). Thrombokinase, with the aid of calcium ions and vitamin K, converts prothrombin to thrombin. Thrombin (active plasma Prothrombin (inactive protein that acts as an enzyme). plasma protein) Thrombin catalyses the conversion of fibrinogen to fibrin. Fibrinogen (soluble) Fibrin (insoluble) Fibrin is a threadlike protein fibre that forms a network on the wound surface to TABLE 10.17 trap erythrocytes and to close the wound to Mechanism of blood clotting prevent blood loss. 10.4.1 10.4.2 183 BioT4(NC)-B10A-EN New 7th.indd 183 1/9/2020 12:09:37 PM  Health issues related to blood clotting Under normal conditions, blood does not clot in blood vessels that are not damaged because of some anticoagulants such as heparin. What happens when the blood clotting mechanism of an individual does not function? HAEMOPHILIA Haemophilia is an example of an illness that prevents blood from clotting. Haemophilia is a hereditary illness caused by the lack of certain clotting factors in the blood. Our World of Biology Excessive bleeding due to small wounds or bruises can result in death. When you sit for too long, the risk of thrombosis in legs will increase. Make THROMBOSIS sure that you move your legs once in a Formation of a blood clot (thrombus). while. Thrombosis happens as a result of: – damage in blood vessels, or – sluggish blood flow that causes clotting factors to Activity Zone accumulate Work in groups to collect and interpret information EMBOLISM about thrombosis, embolism and When a blood clot is transported by blood flow, the blood clot is haemophilia. called embolus. Present your If the embolus gets stuck in a tiny blood vessel, the blood flow will findings to the class. stop. Formative Practice 10.4 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 2 Describe two health issues related to blood the blood vessel can cause a heart attack. clotting. 184 10.4.3 BioT4(NC)-B10A-EN New 7th.indd 184 1/9/2020 12:09:39 PM  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. This is because the recipient has antibodies in the blood serum that Blood group A Blood group B can act against the antigen on the red blood cells of the donor. Blood antigen A red blood transfusion cella donor to a recipient must take into consideration from anti-B antibody the blood group type of the donor and the recipient (Table 10.6). If the blood group of both the donor and receiver is not compatible, the red blood cellsB of the recipient will experience agglutination antigen red blood cell (coagulation). anti-A antibody Blood group AB Blood group O TABLE 10.5 Antigen and antibody in blood groups ood group A Blood antigen B red blood cell antigen A group B Blood Antigen on red blood cells Antibody in the blood no antigens antigen A red blood cell group serum Blood group A Blood group B tibody A red blood cell Antigen A Anti-B antigen A no antibodies anti-B antibody B anti-A antibodyAntigen B Anti-A red blood cell anti-B antibody antigen B AB Antigen A and Antigen B No ed blood cell anti-A antibody O antigen B No Anti-A and Anti-B od group AB Blood groupcell red blood O anti-A antibody TABLE 10.6 Compatibility of blood donor group with the recipient antigen B red blood cell A Blood group AB Blood Can donate blood to Blood group O Can receive blood from no antigens antigen B group blood groups blood groups ood group A Blood red blood cell antigen A group B no A antigens A and AB only A and O only CHAPTER 10 antigen A red blood cell no antibodies anti-A antibody tibody B B and AB only B and O only d cell anti-B antibody no antibodies AB anti-A antibody AB only A, B, AB and O red blood cell anti-B antibody antigen B O A, B, AB and O O only ed blood cell anti-A antibody od group AB Blood group O Rhesus Factor antigen B red blood cell A 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 individual who does not possess the Rh factor or antigen D is known anti-A antibody 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 1/9/2020 12:09:40 PM  Pregnancy and the Rhesus factor Indicator: Rh-positive Rh-negative Anti-D antibodies During the last month of However, the The problem arises when pregnancy, fragments concentration the second child is also of foetal blood cells of antibodies Rh-positive. The anti-D containing antigen D produced is antibodies that are present Usually, problems cross the placenta not enough in the mother’s blood cross will arise when an and enter the blood to affect the the placenta and destroy Rh-negative mother circulation of the mother. first child. But the red blood cells of that marries an the anti-D foetus. The symptoms Rh-positive father antibodies of this disease are called and conceives an As a result, the white will last in erythroblastosis fetalis. Rh-positive foetus. blood cells in the the blood The second foetus dies if mother’s blood will react circulatory the blood is not replaced and produce anti-D system of the with Rh-negative blood antibodies that will mother. through blood transfusion. flow back through the placenta into the foetal blood circulatory system. In a less serious situation, the baby may suffer from The antibodies will destroy anaemia and mental the red blood cells of the retardation. However, Rh-positive baby before this problem can now be or immediately after birth. addressed by treating the affected mother with anti-Rhesus globulins after the first pregnancy to stop the formation of anti-D antibodies. Formative Practice 10.5 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 2 Predict what will happen if the blood The third pair of parents: AB and O 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 1/9/2020 12:09:33 PM  10.6 Activity Zone Health Issues Related to the Human Circulatory System The necessity for a healthy circulatory system A healthy circulatory system is important to ensure optimum health. Work in groups How do we ensure that our circulatory system is healthy? Among the and conduct a practices for maintaining the circulatory system are a balanced intake of case study on food that is low in fat and regular exercise. The practice of not smoking the practices of maintaining a healthy and not drinking alcoholic drinks also ensures a healthy circulatory human 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. CARDIOVASCULAR DISEASES Activity Zone Atherosclerosis is the formation and deposition of plaque on the artery walls. Discuss a suitable The plaque is formed from cholesterol, lipid, dead muscle tissues treatment for heart and coagulated platelets. CHAPTER 10 failure. 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 1/9/2020 12:09:33 PM  artery blood clot restricts the flow of blood coronary artery plaque is formed in the artery dead cardiac muscle tissues FIGURE 10.19 Formation and deposition of plaque on artery wall STEM Bulletin What is the treatment for a patient who suffers from heart failure? What are the risk factors that contribute to cardiovascular diseases and what Nanotechnology is can we do to ensure that the cardiovascular system is healthy? used in the diagnosis and treatment of atherosclerosis and plaque formation in arteries. In this Formative Practice 10.6 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 2 Explain how stroke happens. lipoprotein cholesterol 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 1/9/2020 12:09:36 PM  10.7 Human Lymphatic System The formation of tissue fluid In addition to the blood circulatory system, there is one more system