Human Body Circulatory System PDF

Chapter-7 Learning Objectives Let's learn about Human Body " Circulatory System Blood C...

Chapter-7 Learning Objectives Let's learn about Human Body " Circulatory System Blood Circulatory System Circulatory System " Blood " Blood Groups " Blood Vessels Human Heart " Structure of the Pacemaker-The Conduction livingorganism, whether they are unicellular or hall multicellular; a transport system is required for System of the Heart ransportation of nutrients, oxygen and other Double Circulation of Blood products Conditions Related to the the body. In lower organisms, the metabolic Functioning of Heart within Wres can pass freely throughout the body, reaching " Lymphatic System cell and be removed as metabolic wastes by every difusion.In higher organisms, nutrients,,OXVgen and other Useful substances transport through blood as it reaches everycelll ofthe body. The heart and the blood vessels ENRICHMENT and veins) through which blood is passed blood fboth.arteries circulatory system in which A blood throughoutthe body constitute a system called the is always present in the closed drculatorySystem. vessels is known as most circulatory system. It is the CIRCULATORYSYSTEM common type of circulatory system including found in vertebrates, cells in the human body are not in direct system Most of the human beings. Acirculatory and th external environment, so they relay on the contact withthe in which blood flows freely vessels transport service for them, does not require blood open circulatory system to act as a known as circulatory system for flowing is The two fluids that move through the vessels and heart circulatory system,e.g. circulatory blood are blood and lymph. The blood, The lymph, system ofarthropods. constitute the blood circulatory system. lymphatic system. ymph nodes and lymph vessels form the lymphatic system The blood circulatory system and system of human collectively make up the circulatory blood circulatory beings. Let us first study about the FACT ZONE system. Most of the invertebrates have system of Thecirculatory system can be defined as the colourless blood because their the heart, blood and blood blooddoes not contain haemoglo organs and tissues, including through the body. bin. For example, blood of vessels, involved in circulating blood cockroach and earthworm. BLOOD CIRCULATORY SYSTEM Haemoglobin is a blood protein blood. that causes the red colour of The blood circulatory system comprises of: and transports the substances to " The blood that from the cells of the body.  of transporting vessels, co dCisOtrmibpuihtsroeyug "A network capillaries that arteries, veins and from the bodu More to Know collects the blood to and There are three types of pump, i.e. heartthat pumps the blood present in blood plasma.Theseproteins are: A the body. Albumins that help to maintain blood volume. " BLOOD Globulins that target infection. important mode of " Fibrinogens that help clotting. in blood Blood is the most materials in human beings. that connects the It is a fluid different body parts and continuity within the body. It comprises of trConneCt ansportiavmteaiiontani ENRICHMENT ofthe body weight. It is plasma and blood cells. Compositionof Blood composed of a one-thTimrtiextunrey complex called Anaemia Blood consists of formed elements cells due to is a disease caused deficiency of RBCs in blood. The deficiency of RBCstheis about in a watery liquid called plasma. There are types of cells found in the blood. These are-red that moN caused by loss of blood, iron thre deficiency and diseases which cells, white blood cells and platelets. slow down the formation of Plasma It is a straw-coloured liquid part of blood. About 90% of plasma is water, 8% proteins, 1% the bloo bicarbonatinprorogductaeniandy " Haemophilia is a disease in salts such as sodium chloride and sodium which blood loses its clotting ability. The proteins prothrombin some other substances like hormones, waste and fibrinogen of blood are (urea and carbon dioxide) and antibodies. formed in the liver with the help Red blood cells of vitamin K. If a person has Platelets deficiency of any of them, the clotting of blood takes longer time and the person may die due to excessive blood loss. Nucleus " Haemorrhage is a condition in which internal bleeding or Plasma clotting of blood occurs. It may White be caused due to surgery or blood cell severe injury. Fig. 7.1Composition of blood THINK ZONE The red blood cells are called erythrocytes, white Why does the oxygenated blood blood cells leucocytes and the platelets thrombocytes appear bright red in colour? The comparative study of red blood cells, white blood cells and platelets is shown in Table 7.1. 100) Innovative Biology-8  Table 7.1 Differenttypes of blood Red blood cells cells White blood cells Platelets (Erythrocytes) (Thrombocytes) (Leucocytes) ture They areformedin the boneThey are formed in the bone They are formedinthe red pAion marrow of long bones. marroW andin lymph nodes.bone marrow. colour They are red in They arecolourless. They are colourless. anour They are disc-shaped They are rounded or They are disc-shaped aructure structures. irregular in shape. structures. A.5 -6million per cubic 4000-11000 per cubic 200000-400000 per cubic Nmber millilitres ofblood millilitres of blood milliliters of blood afcells 120 days Only a couple of days 5to 10 days Lifespan Absent Present Absent clotting They help in blood Nucleus They transport nutrients They protect the body from Function and oxygen throughout disease-causing germs. the cells of the body. FACT ZONE ability White blood cells have the So they can to change their shape. of infection easily reach the site against infection (c) Platelets where they fightsubstances that blood cells (b) White blood cells and harmful engulfing them. (a)Red blood cells invade the body by Fig. 7.2 Different typesof FunctionsofBlood important liquid part of the body because it Blood is a very such as transportation, regulation ENRICHMENT nerforms the functions within the body. wound, some white protection intestine At the site of and and nutrients from the small blood cells surround the germs transports and digest. Blood body for assimilation. dead cells of the wound cells to all partsof the them, while some other white exchange of respiratory gases. The make a special type of chemical part in " It takes carrying oxygen is called oxygenated blood. called antibodies. The antibodies blood containing blood is called help the body to fight against The carbon dioxide diseases. deoxygenated blood. body temperature. " Blood regulates the excretory products from the liver dissolved from " Itcarries where they are eliminated to the kidney from the body along with urine. Human BodyCirculatory Syste  transports varioushormones AssESS YoURSELF Blood chemical coordination various endocrine glands to occurs organs due to clot which produced yh between the Answer the following questions. Blood has the property loss in case of injury. provide White blood cells keep the prevenotrsgans. 1. What are the two systems that constitute the circulatory system pathogens. They alsocells. body immunity clean bby of human beings? 2. What is the fluid part of the blood called? 3. Name the different types of up dead and BLOOD GROUPS damaged an Australian aglinegat blood cells present in the blood. 4. In which disease does a person lose the blood-clotting ability? In the early 1900s, ABO system Landsteiner developed the presence ofof on the basis of absence and scientbloiodst, Kan 5. Which component of blood responsible for blood clotting? is antibodies on the surface bloodblood this system, the human of red is There aretwo antiginensto cells, divided groups-A, B, AB and 0. associated with antigens A and B. antibodies andfob a The four possible blood groups of ABO ACTIVITY 1 Aim To study the shown below in Table 7.2 system ars content in different agehaemoglobin Table 7.2 Blood groups with their antigens and Antantibibodyodies groups Procedure Visit a nearby Antigen healthcare centre and collect data Blood group about the haemoglobin content in A A b different age groups. Find out the B B average values of haemoglobin. A and B Compare these values with AB No antibodies standard values available at the No antigens a and b centre and find out the cause of deviation from the normal value of haemoglobin. You may also find out the diseases due to which the A antigen B antigen haemoglobin content decreases. Blood group A Blood group B B antigen RoUGH WORK A antigen Blood group AB Blood group 0 (No antigens) Fig. 7.3 Types of blood groups according tothe antigens found on the surface of red blood cells 102 Innovative Biology-8  plasma ofblood groupAContains antibody called 'ENRICHMENT Thisantibody:attacks group B link witth group Bantigens. antigens.if Antigens are the proteins present ARglutnins Bisinjectedintoaperson with Thus, on the surface of RHCS while clumptogether. This bloodgroup A, antibodies are present in the blood proyp soinston will c e l l s process is called (notethat agglutination is not the same as plasma. Both antigens and s o o d antibodies work against each other is: )Thereverse salso true. Blood group Bhas An antigen never works with s cofresponding antibody This it Blood group AB has neither cotting anti-a nor why, when their similar types are bagElutnins working together, the red blood cells clump and burst. glood group A ontigen A iSpresent t h donor's e r eblood d cells ACTIVITY 2 blood Aim To find out more about group compatibility Mixed together Procedure Collect information of Blood group B about the blood groups of fourtwo members and !your family antia (antibodies a) note the in neighbours. Make a chart and their blood group compatibility. present natient's is plasma. The anti-a (antibodies 'a) causes the red blood cells to clump together (agglutination), RoUGH WORK agglutination Fig. 74 Reason for blood blood group AB can receive any blood People with becauseoftthe absence of clumping, For this reason, group with blood group AB is called a universal person 2 recpient. A person with blood group 0 is called a because his red blood cells have no universal donor antigens. system Table 7.3 Blood group compatibility in ABO Can receive Blood Can donate blood to blood from group Aand AB Aand 0 A Band 0 Band AB B AB All groups AB 10 Allgroups Human Body-Clreulatory System  mOOD VESSKLS vannpon the Vosnel In network vesselsaresense,a defned Wood general aroundthe body. In system,In blood FACT ZONE tubethat carrlossystemof as a channels system through, comprises IH all the hlood vesels (incduding work arteries, veins and capillartes) of a these lowThlsarterles, velns and ren person are joined end to end, the length would be more than 1,00,000 km and could stretch bloodcan namely, vessels, blood Aorta capl arten yy around the earth about wo and a Arterles half times. The capillaries, which are the smallest of blood vessels, yeln "Tunica media would make up about 80 per cent ofthis length. Valve "Tunica nterna Venules -Arterioles blhearAroodtenestofrormCathrey Capillary Veinscarryblood heart backtothe THINK ZONE from thebody. Capillaries carry the ud from blood to and 1. Why do arteries have thick the bodycells. walls and veins have thin walls? types ofFblood vessels Fig.7.5 Different Arteries Blood from theheart is carried through the body by a complex network of blood vessels. Arteries are the blood blood away from the heart to parts of the body. All arteries except pulmonary vari vessels that carry ous artery ACTIVITY3 carry oxygenated blood. The pulmonary artery carries Aim To observe the different types deoxygenated blood from the heart to the lungs. The wals of blood vessels of arteries are made up of three layers. The outermost Material Required A mirror with handle consists of elastic tissues called tunica externa, the Open your mouth wide in front of layer middle layer is made up of muscles called tunica media, the mirror and look at the portion below the tongue. You will see and the inner layer is made up of single-layered heart some blue-coloured thick lines. endothelium called tunica interna. Each timne the These are the veins. The red beats, the elastic walls of the arteries expand for the blood coloured lines are the arteries and the fine red ones are the capillaries. to flow into them. Then their muscular tissue slowy You may find out why the veins are contracts again. This squeezes the blood further along the blue in colour. length of the arteries and towards the capillaries. Arteries have a narrow lumen. The major arteries diverge into minor arteries, and then into smaller vessels called (104 Innovative Biology-8  Thearterles are deeply situated in the body. notpossessanyvalve because the ndirectional, (from hearttto differentblood flow in FACT ZONE sdo body parts). Veins appear blue hut, in reality. seem so they are not blue They ight can blood vessels tlhat carry because only the hlue gre the the various deoxygenated body partsto the heart. Only the penetrate the skin and reflect without back being gonY Velncarries oxygenated blood from the lungs om to the eyes veins absorbed by the skin. As the they The veins begin at the capillaries. At first, they are present superficdally, are called heart. e tiny and venules. Small veins join to larger ones also has |ofa vein less three layers as in an artery, wall The are thinner, muscular and less elastic as they the, arterial wal. AssEss YoURSELF mpared to of veins much wider than that of arteries. lumen. is to keep the blood moving easily Answer the following questions. s The helps to through the 1. Which blood group is called the regular intervals, veins have pocket-shaped universal donor? At valvesthat open towards the heart to stop the emllunar called the 2. Which blood group is in backward howing direction. The semilunar valves universal recipient? folds of inner walls of the blood vessels ood upof fthe veins. The 3. Name the type ofaway from the e made pressure of blood forces the vales to open, as a that carry blood brward heart to various body parts. which blood flows towards the heart. The blood vessels of backilow.ofbloodcauses the valve to close. esult 4. Name the type of towards the that carry blood heart from various body parts. blood are Pressure applied by the body muscles 5. Which types of carried by the pulmonary artery and the pulmonary vein? Direction of blood flow RoUGHwORK Open valve Closed valve Pressure applied by the body muscles (a) An open valve of a vein showing (b) A closed valve of a vein prevents the backward flow of blood the flow of blood Fig. 7.6 Action of semilunar valve in a vein 105) Human Body-circulatory System  More " to Know In veins, blood flows with a \ower pressure Capillaries arteries. The blood keep moving in arteries to carry blood arterioles and from around the veins to venules. from contraction of muscles large veins in yourlegs are squezed by For them. yyoureins han by " They carry both deoxygenated blood.oxygenated and " They have only one cell thick walls. Valves are absent in capillaries. (calf) when you walk. This helps to the heart. push eKa\megmpaes, the Table 7.4 Differences between arteries and veins Charact Locationeristics Arteries They are located deep beneath the skin. They are located Veins Function close to skin, They carry oxygenated blood away from They bring the heart to various body parts. deoxygenated blo d various body parts into the Only pulmonary artery carries the lungs to the heart. Only pulmonary vein carries from Wall deoxygenated blood from the heart to the lungs. blood from They have three-layered,,thick, muscular They have thin, less 0Xygehearnatt.ed Lumen wall. muscular wall. elastic and less They have a narrowlumen in which the They have a wide lumen blood flows with high speed and under blood flows with in Valve high pressure. low pressure. speed which and the low They do not have any valve. They have valves which control the unidirectional flow of blood. Thin muscular wall Thick muscular wall Structure Narrow lumen Large lumen Fig. 7.7 T. S. of an artery Fig. 7.8 T.S. of avein RouGH wORK STRUCTURE OF THE HUMAN HEART Shape, Size and Location of the Heart The human heart is a muscular organ which is somewhat conical in shape. It is located between the thoracic cavity (it is not situated on the two lungs in the chest). An adult human heart is about 12leftcmside in of the and 9 cm in breadth. It is equal to the length The average weight of the heart is about size of your ist 300 gin females. 350 gin males and 106 Innovative Biology-8  Aorta Aorta Pulmonary artery Pulmonary artery -Pulmonary veins Pulmonary Let auricle veins (LA) Leftauricle Left ventricle Right auricle (LA) (RA) Bicuspid valve (Lv) Tricuspid valve Leftventricle Right ventricle (LV) (RV) Inferior vena cava (RV) (a)External view (b)Section through the heart Fig. 7.9 The human heart oof MuScular Wall the Heart humanhheart is enclosed externally by a membrane More to Know the epicardium.Internally, the heart is surrounded by alled pericardium. The space between the two membranes Actual Pump of the Heart pumps The ventricles are the actual the dpericardialIcavity which is filled with pericardial of the heart. The oxygen-rich blood Bcalled the secreted bythe wall of pericardium. The pericardial returns from the lungs andentersand Auid heart through the left atrium protects the heart from mechanical and physical into valve fuid passes through the mitral ventricle, shocks.Italsohelpsin frictionless movement of the heart. the left ventricle. The left Heart the largest and mnost muscular part, is Chambersofthe the actual pump of the heart. Thehuman heart is afour-chambered organ divided by the halves-the right enta (singular: septum) into two equal half. Each half is further divided into two halfand the left called chambers. The upper, small-sized chambers are auricle or atrium and the lower, large-sized chambers are called ventricles.. Auricles They act as receiving chambers for blood ENRICHMENT coming from outside of the heart. They are further The heart is made up of cardiac divided into right atrium and left atrium. The right muscles, which continuously atrium receives blood from the large veins, namely, contract and relax throughoutone's superior and inferior vena cava. The left atrium life and never get tired. Their receives blood from the lungs through the pulmonary rhythmic movement causes the flow of bloodwithin the heart. veins. That is why, the pulmonary veins carry Oxygenated blood. Both the atria are smaller than the ventricles and have thinner, less muscular walls. " Ventricles They act as discharging chambers for blood so they are connected to the arteries that carry blood away from the heart. The ventricles are thick walled chambers. The wall of left ventricle is thicker 107 Human BodyCirculatory System  thanthat of right ventriclebeecause the has to pump blood into the vessels, tothe entire body. The ENRICHMENT carrythe blood pulmonary: Both the bicuspld and tricuspld valves allow blood to flow from auricles to the ventricles pumps bloodtothe the lungs, deoxygenated bloodto arterles,rhytve prevent the hacklow of blood. and Valves of the Heart arethin Valves of thehuman heart attached tothe wall of the heart. membrareanous There valves present in the heart within the heart. that control the floouWr tyofe valve is Bicuspid or mitralventricle. located FACT ZONE Valves regulate the auricle and theleft It hence is called a bicuspid valve. Tricuspid valve is located between the betwe twnocuthe consists of three cusps. Theriphl aur one has unidirectional of blood through and the right ventricle. It the heart. They have flaps that valve guards the auriculo-vetricular open as blood pours from a chamber. When the flaps cose, they prevent blood from flowing Pulmonary valve is located ventricle and pulmonary artery. It aperturhee, between back into the chamber. of blood intothe ventricle. checks the righ. Aortic valve is located between the left retun the aorta. Septum of the Heart ventricle a The septum of the heart is a dividing, muscular between the right and left sides of the heart. RouGH wORK that separates the two upper chambers (the rightThe sandeptum atria) of the heart is termed as inter-auricular septum while the portion of the septum that lies between the two lower chambers (the right and left ventricles) of the is called the inter-ventricular septum. hean Great Vessels of the Heart The great vessel is a term used to refer collectively to large vessel that brings blood to and from the heart. Thethe include:. Superior vena cava "The great venous trunks that return deoxygenated blood from the systemic circulation of the upper body (head and arms) to the right atrium of the heart.. Inferior vena cava The great venous trunks that return deoxygenated blood from the systemic circulation of the lower body (trunk and legs) to the 108) right atrium of the heart. Innovatlve Blology-8  arteries,that carry pulmonar deoxygenated blood rghtventricletothe lungs. 'ENRICHMENT the veins, that receive contracts to pump lungsanddrain into the oxygenated pom Pulmonary blood The left atrium through the left atrium of the oxygenated biood the left into bicuspid(mitral) valve fom the ventricle pumps 9stemicaaorta heart isthe largest artery ventricle. The left through the originatingfrom ventricle.It receives Oxygenated blood from oxygenated blood valve into the left aortic semilunar blood enters ventricleand aorta, the lett distributes it throughout the body aorta. From the circulation through Coronaryarteries The first arteries that branch the into systemictissuesuntilit returns outthe body deoxygenatedblood aortaarethe two major coronary arteries. the supplyingOxygenated bloodItothe heart and so totheheartas and inferior vena via the superior repeats. from They itto continue enable pumping These two arteries cavaand thecycle intomany branches as they cover the heart. divide ACEMAKER-THECONDUCTION SYSTEM OF HEHEART the heart pump blood at the same time. As sidesof and conveys blood into the right ventricle contracts ste the left ventricle contracts and pumps blood hngs hroughout thebody.The heart's cycle of activity has two RoUGH WORK systoleand diastole.Systole occurs when the periods, Contract and diastole occurs when they relax. rentricles relaxation of the heart complete Contraction and One upone heartbeat. MUSclemakes n Heartbeat must be controlled so that each chamber only when flled with blood. To achieve this, the ontracts coordinated. carefully atsofthe cardiac cycle are Aorta Vena cava Sinoatrial Left atrium node -Bundle of His Atrioventricular node Right atrium -Left ventricle Purkinje fibres Right ventricle Ventricular septum system of the Fig. 7.10 The conduction and controls a heartbeat human heart initiates 109) Human Body-Circulatory System  Sa r heatt uair filet wts Puae CROLATIONOFELO DIELE rust-imaT PumaaT Craaiut ety e apilary RoUcH WORK Systemic Circalatioa This ype of ciroin nciudes the ne i Kyzenaed binod from the heat wszis e boTpas (erepe lngs) nd retun of deorygenated biooc axI the hear The lef atrm conracts to pup cEYg bioni through the bicuspid (mitra) vae i t ventncie The lef ventricie pumps aVgented hiu Huty vntthate  CONDITIONS RELATED TO THE ASIHIN Viait a narby hasptal and the instument used for observe the blo wesurn nd measuring OF HEART Palpitation ofHeart Palpations arethe hard, rapid or irregular FUNCTION ame Also discuss about iwttning With the help out its of iloct tuy to easue the blood weurv of any lve eople its the develop due to following reasons: " Skipping beats. Fluttering heartbeas. Beating too fast " Pumping harder than usual Aperson may feel heart palpitation in the More to Know well ason the chest. throat or neck Cardiac Arrest Causes oftypertension " Being overweight or obese Sudden Cardiac Arrest (SCA) is a condition " Lack of physical heart suddenly and unexpectedly stops in which th " Too much salt in activity one's diet happens, blood stops flowing to the brain beating, If th "Too much alcohol organs. and other " Stress consumption SCA usually causes death if it is not " Family history of high blood minutes. Its symptoms include loss of treated it hir pressure " Chronic kidney disease abnormal or absent breathing. Sometimes, conscioUsnessanc have chest pain, shortness of breath or nausea people may " Adrenal and thyroid disorders occurs. before the Hypertension Blood pressure is the force exerted by the blood against th RouGH wORK walls of arteries. The magnitude of this force depends or the cardiac output and the resistance of the arteries. Ifvou blood pressure is too high, it puts extra strain on you= arteries (as well as on your heart) and this may lead to heart attacks and strokes. Blood pressure is measured in terms of systolic blood pressure and diastolic blood pressure. The first one measures the pressure in the blood vessels when the heart beats. The second one measures the pressure im vessels when the heart takes rest between the beats. The normal blood pressure of a person is 120/80 mm Hg which means that for a normal person, the systollt pressure and diastolic pressure of blood should be 120 mm Hg and 80 mm Hg, respectively. Clinically, the blood pressure is measured by means of:fsphygmomanometer. 112) Innovative Biology-8  HATIC SYSTEM mphattc,system comprises acolourless fluid called More to Know networkoflymphatic vessels and the lympl1 lymphatie Cirulaion hody i s ome wy wyalen wli fhuid Heart bloodsystun, lyjha enlers ib valywil hom heissues abl valyes whis h Spleen lymphat ducts ts ihe Lymph duct fwy the lymph node make sue tho lymplh progronslvely largu lyphs lymplh vessels lympha dut Wusw duta ab) lto the yuaory oyslum belngs Fig. 7.13 Lymphatic system of human ENRICHMNI bymph Lymphis an alkaline fluid that originates as interstitial blond vells (lypl ylen), whih interstitlal spaces id in our body and flows in the cells of multicellular leteen and around the tissues and rells, Wste oludo h s a colourless o nimals, including human beings, It plasma with lower destroyel barteria Fe theWHWed taw-coloured fluid, similar to blood whenpasses to thelymph orotein content. The fluid matrix Unlike blood, the lymph le body with ohe wAoluo lnph podes, receives white blood cells. does not have red blood cells. Whwnyo liaye n eon, lymph odes nhen well bernmw Lymph Vessels The fine lymph capillaries join together to forn the lymph vessels and Vessels. The fluid travels through the lymph vessels are lymph drains into the hloodstream, The walls of lymph vessels small thin and have numerous valves, AIl the wmite to form alarge lymphatic duct. Lymph Nodes vessels, some bead ika R speific points in the lymphcaled lymph nodes, Thr rtures are found, These are Fyh is filtered through the lymph nodes Humm Body ruwory byenm  Table 7.5 Differences between blood AsSESs YoURSELF Blood and lymph 1. It is a red colour fluid. 1. It is a Lymph o Answer the 1. What are followingquestions. venules? 2. It contains plasma proteins. 2. colouredcolofluid. urless Sran- 2. Why is the lumen of veins so Plasma low proteins concentration 3. 4. large? What is lymph? What is the function of valves 3. It flows in the blood vessels. 3. It flows in vessels. the lymph areinve present in the heart? 4. It helps in transportation 4. It acts as a middle 5. What are the two types of blood of various materials such the exchange of man for 6. circulations found in human beings? What do you the understand by as dissolved gases and nutrients. between blood body tissues. iamndaterthiael; lymphatic system of human beings? LET'S RECAPITULATE The circulatory system is an effective transport system that includes the heart, blood and blod vessels, involved in circulating blood through the body. Blood is a fluid connective tissue that connects different body parts and also maintains conhe within the body. The liquid part of blood contains plasma and the cellular part contains red blood cells, white hlnna cells and platelets. " Bloodperforms functions such as transportation, regulation and protection within a body. According to the ABOsystem of blood group, blood isof four types-A, B, AB and 0. Blood group AR is called universal acceptor and blood group 0 is called universal donor. Blood vessels work as a system of channels through which the blood can flow. There are three types of blood vessels-arteries, veins and capillaries. The heart is a muscular organ located between the two lungs in the thoracic cavity. It is equal to the size of your fist. The average weight of the heart is about 350 g in males and 300 g in females. The human heart is a four-chambered organ divided by the septa into two equal half and the left half. The upper, small-sized chambers are called auricle or atrium halves-the right and the lower large-sized chambers are called ventricles. Valves of human heart are the thin membranous structures that control the flow of blood within the heart in one direction only. The sinoatrial node of the wall of the right atrium acts as a pacemaker. Inthe human heart, to complete one cycle of circulation, blood flows twice through the heart. Thi type of circulation is called double circulation. It consists of two types of circulations-pulmona circulation and systemic circulation. 114 Innovative Biology-8  ALATEYOLRRUNDERSTANDING ng lieas nlvng taICe ungs oapaies (a) arterioles (aj four-camberei structure b) threhambe structurr c) two-chambered structure (d) ivechamberd structur Pericardium Ís the protective membrane outside the (b) heart (a) kungs (d) stomach () kidney L. Fi in the blanks with the correct option. membrane. (pericardium/epicandium) 1. Pericardial fuid is secreted by the..(haemoglobin/haemocynin) of 2. The red colour of blood is caused due to presence 9, In double circulation, heart pumps blood to the lungs. (oxygenatedAdeoxygenated} carry blood back to the heart. (Veins/Arteries).(trunk andlegs/head and arms) 4 brings blood from the 5. The superior vena cava flaps. (two/three) 6. Each semilunar valve has statement. State ifthe following statements are True or False. Correct the False IL. two-way valves. T 1, The lymphatic systemcontains called the bieuspid valve. 2. The valve between the right auricle and right ventricle is is separated by avalve. 3. The left and right side ofthe heart 4. Velnshaethick, elastic walls. 1o measured by athermometer: ventricle,yu S. The blood pressure can be 119 the left auricle and the left 6. The mitral valve lies between Human Body-Circulatory System  IV. Match the Columnfollowing. A Column B 1 Pulmonary artery Oxygenated blood {a) Deoxygenated blood 2. Pulmonary vein {b) 3. SAnode fc) Universal donor 4. Plasma (d) Pacemakerofheart 5. Oblood group e) Fluid part ofblood V. Choose the odd one out andgive scientific 1. WBCs, RBCs, reasons 2. Blood, plasma,platelets, lymph plasma urine 3. Blood, blood vessels, heart, 4. kidney1., r capillary Superior vena cava,, inferior vena cava,, aorta, Understanding I. ldeas Give one word for the following. 1. The thickest blood vessel. Z. Apigment that causes red colour of blood. 3 The universal recipient. 4 Pressure exerted by the blood against the wall of arteries. 5. Bead-like structures found in the lymph vessels. II. Answer the following questions in short. 1. What is the use of valvesin the veins? 2. Why are capillaries so thin? 3. What are the different types of blood groups present of human beings? 4. What are the four chambers of the heart in human beings? 116) Innovative Biology-8  the mainfunction of lymph nodes? Whatis followingquestions in detail. rthe thefunctionoffpericardial fluid and where is it found? is What thefunctions offdifferent types of blood vessels? Whatare Explaindoubleecirculation of blood. Whyis it called so? Why is it necessary? comparison to veins? ,Why doarteries have thick walls in even though it beats non-stop throughout the life of an 5. Why is the heart not fatigued individual? 117 Human Body-Circulatory System