NCERT Exercises - Body Fluids and Circulation PDF

## NCERT Exercises **Q.1. Name the components of the formed elements in the blood and mention one major function of each of them.** **Ans.** The components of the formed elements in blood are as follows: * **Erythrocytes or red blood cells** - They carry oxygen and contain the pigment, haemoglobi...

## NCERT Exercises **Q.1. Name the components of the formed elements in the blood and mention one major function of each of them.** **Ans.** The components of the formed elements in blood are as follows: * **Erythrocytes or red blood cells** - They carry oxygen and contain the pigment, haemoglobin. Haemoglobin reacts with oxygen to form oxyhaemoglobin that carries oxygen to areas that are deprived of oxygen in the body. * **Leucocytes or white blood cells** - Lymphocytes are known to synthesize antibodies that neutralizes or kills germs. Neutrophils acts as a defense mechanism against bacteria known as phagocytosis. * **Thrombocytes or blood platelets** - They aid in coagulation of blood. **Q. 2. What is the importance of plasma proteins?** **Ans.** Fibrinogen, globulin and albumins are the proteins found in plasma. Fibrinogens are needed for clotting of blood. Globulins are involved in defense mechanisms of the body and albumins help in osmotic balance. **Q. 3. Match column I with column II.** | Column I | Column II | |---|---| | (a) Eosinophils | (i) Coagulation | | (b) RBC | (ii) Universal recipient | | (c) AB group | (iii) Resist infections | | (d) Platelets | (iv) Contraction of heart | | (e) Systole | (v) Gas transport | **Ans.** * (a) Eosinophils - (iii) Resist infections * (b) RBC - (v) Gas transport * (c) AB blood group - (ii) Universal recipient * (d) Platelets - (i) Coagulation * (e) Systole - (iv) Contraction of heart **Q. 4. Why do we consider blood as a connective tissue?** **Ans.** Blood is derived from mesoderm and contains an extra-cellular matrix known as plasma. It is abundant and a widely distributed tissue in the body. Connective tissues links and binds, providing support to other organs of the body thereby transporting oxygen and other nutrients within the body, eliminating wastes from the body and flows throughout the body. Hence, it is considered as a connective tissue. **Q. 5. What is the difference between lymph and blood?** | Blood | Lymph | |---|---| | Reddish in colour | Pale yellow in colour | | Red blood cells are present | Red blood cells are absent | | Bidirectional flow | Unidirectional flow | | Flow is rapid | Flow is slow | | Leucocyte count is relatively less | High leucocyte count | | Platelets are present | Platelets are absent | **Q. 6. What is meant by double circulation? What is its significance?** **Ans.** When the blood flows twice through the heart, it is called double circulation. **Pulmonary and systemic circulation:** The pulmonary circulation pertains to lungs. The blood flows from the right ventricle to the lungs. Pulmonary veins collect oxygenated blood from the lungs and carry it back to the heart (left auricle). The systemic circulation pertains to the major circulation of the body. The aorta receives the blood from the left ventricle and sends it to the various parts of the body. Veins collect the deoxygenated blood from the body parts and pour it back into the right auricle. **Importance of double circulation:** * This type of circulation checks and prevents the mixing of oxygenated and deoxygenated blood. * In double circulation, oxygen is utilised efficiently. **Q. 7. Write the differences between:** * **(a) Blood and Lymph** * **(c) Systole and Diastole** * **(b) Open and Closed system of circulation** * **(d) P-wave and T-wave** **Ans. (a)** | S.No. | Blood | Lymph | |---|---|---| | 1. | Reddish in colour | Pale yellow in colour | | 2. | Red blood cells are present | Red blood cells are absent | | 3. | Bidirectional flow | Unidirectional flow | | 4. | Flow is rapid | Flow is slow | | 5. | Leucocyte count is relatively less | High leucocyte count | | 6. | Platelets present | Platelets are absent | **(b)** | S.No. | Open circulatory system | Closed circulatory system | |---|---|---| | 1. | In open circulatory system, blood flows through large vessels into open spaces called sinuses. | In closed circulatory system blood flows through closed network of blood vessels. | | 2. | Blood flow is less regulated. | Blood flows at high speed and is regulated in a better way. | | 3. | The pressure of blood flow is low. | The pressure of blood flow is high. | | 4. | E.g., Arthropods and Molluscs. | E.g., Annelids and Chordates. | **(c)** | S.No. | Systole | Diastole | |---|---|---| | 1. | During systole, blood pressure is increased inside the heart. Ventricles are contracted and they push the blood in this phase. | During diastole, blood pressure is decreased inside the heart. Ventricles are relaxed and filled with blood in this phase. | | 2. | | | **(d)** | S.No. | P-wave | T-wave | |---|---|---| | 1. | During this phase, the impulse of contraction is generated by the SA node, causing atrial depolarisation. | During this phase, the ventricles relax and return to their normal state. | | 2. | It is of atrial origin. | It is of ventricular origin. | **Q. 8. Describe the evolutionary change in the pattern of heart among the vertebrates.** **Ans.** The heart of fish has two chambers, this means there is no separate circulation for oxygenated and deoxygenated blood. There is separation of two chambers in the atrium of amphibians. This has further evolved to partial separation of ventricle in reptiles. Finally in birds there is complete separation of oxygenated and deoxygenated blood circulation with advent of four chambers in the heart. Mammal heart is the most developed having the most efficient double circulatory system. **Q. 9. Why do we call our heart myogenic?** **Ans.** Normal activities of the heart are regulated intrinsically, i.e., auto regulated by specialised muscles (nodal tissue), hence the heart is called myogenic. **Q. 10. Sino-atrial node is called the pacemaker of our heart. Why?** **Ans.** The SAN can generate the maximum number of action potentials, i.e., 70-75 min¯¹, and is responsible for initiating and maintaining the rhythmic contractile activity of the heart. Therefore, it is called the pacemaker. **Q. 11. What is the significance of atrio-ventricular node and atrio-ventricular bundle in the functioning of heart?** **Ans.** The atrio-ventricular bundle (AV) originating from the AV-node passes the cardiac impulse to the walls of the ventricles whereas the atrio-ventricular node (AVN) conveys the impulse from the SA node. Both AVN and AV are triggered by the action potential that is originated by the sino-atrial node thereby conducting the stimulus to the other parts of the heart. **Q. 12. Define a cardiac cycle and the cardiac output.** **Ans.** The sequential events in the heart which are cyclically repeated is called the cardiac cycle and it consists of systole and diastole of both the atria and ventricles. Cardiac output can be defined as the volume of blood pumped out by each ventricle per minute and averages 5000 mL or 5 litres in a healthy individual. **Q. 13. Explain heart sounds.** **Ans.** 'Lub’ is the first sound and is low pitched. It is caused when the bicuspid valve and the tricuspid valve closes. ‘Dub’ is the second sound which arises when the semi-lunar valve closes. This sound is high-pitched. **Q. 14. Draw a standard ECG and explain the different segments in it.** **Ans.** The P-wave represents the electrical excitation (or depolarisation) of the atria, which leads to the contraction of both the atria. The QRS complex represents the depolarisation of the ventricles, which initiates the ventricular contraction. The contraction starts shortly after Q and marks the beginning of the systole. The T-wave represents the return of the ventricles from excited to normal state (repolarisation). The end of the T-wave marks the end of systole. ## Multiple Choice Questions **1. How many impulse generating nodes are found in the mammalian heart?** **(a) One** **(c) Three** **(b) Two** **(d) Many** **Ans. (b)** **2. Leucopenia is** **(a) uncontrolled WBC** **(c) excess platelets** **(b) uncontrolled RBC** **(d) less production of WBC** **Ans. (d)** **3. Which of the following cells does not exhibit phagocytotic activity?** **(a) Monocyte** **(c) Basophil** **(b) Neutrophil** **(d) Macrophage** **Ans. (c)** **4. Hardening of arteries due to deposition of cholesterol is** **(a) thrombosis** **(b) rhinitis** **(c) atherosclerosis** **(d) stenosis** **Ans. (c)** **5. Myocardial infarction is due to** **(a) infection of heart muscles** **(b) weakening of heart muscles** **(c) clot in blood vessel** **(d) breakage of coronary vessel** **Ans. (c)** **6. One of the common symptoms observed in people infected with dengue fever is** **(a) significant decrease in RBC count** **(b) significant decrease in WBC count** **(c) significant decrease in platelets count** **(d) significant increase in platelets count** **Ans. (c)** **7. Purkinje fibres arise from** **(a) apex of ventricles** **(c) anterior part of auricles** **(b) middle of ventricles** **(d) posterior part of auricles** **Ans. (b)** **8. Which one of the following is not a factor in determining the flow rate of blood?** **(a) Viscosity of the blood in vessel** **(c) Radius of the vessel** **(b) Length of the blood vessel** **(d) Thickness of the vessel** **Ans. (d)** **9. Which among the following is correct during each cardiac cycle?** **(a) The volume of blood pumped out by the right and left ventricles is same.** **(b) The volume of blood pumped out by the right and left ventricles are different.** **(c) The volume of blood received by each atrium is different.** **(d) The volume of blood received by the aorta and pulmonary artery is different.** **Ans. (a)** **10. Pulmonary artery drains deoxygenated blood from** **(a) right ventricle** **(b) right atrium** **(c) left atrium** **(d) left ventricle** **Ans. (a)** **11. Cardiac output during normal working in man is about** **(a) 2 litres** **(b) 5 litres** **(c) 10 litres** **(d) 20 litres** **Ans. (b)** **12. Rate of heart beat is under the control of** **(a) sympathetic nerves** **(b) vagus nerve** **(c) glossopharyngeal nerve** **(d) both (a) and (b)** **Ans. (d)** **13. Cardiac activity could be moderated by the autonomous neural system. Choose the correct statement.** **(a) The parasympathetic system stimulates heart rate and stroke volume.** **(b) The sympathetic system stimulates heart rate and stroke volume.** **(c) The parasympathetic system decreases the heart rate but increases stroke volume.** **(d) The sympathetic system decreases the heart rate but increases stroke volume.** **Ans. (b)** **14. Mark the pair of substances among the following which is essential for coagulation of blood.** **(a) Heparin and calcium ions** **(c) Oxalates and citrates** **(b) Calcium ions and platelet factors** **(d) Platelet factors and heparin** **Ans. (b)** **15. Blood group A can be given only to person with blood group** **(a) B** **(c) O** **(b) AB** **(d) A and AB** **Ans. (d)** **16. Vasoconstriction causes** **(a) increase in heart beat** **(c) increase in blood pressure** **(b) decrease in heart beat** **(d) decrease in blood pressure** **Ans. (c)** **17. ECG depicts the depolarisation and repolarisation processes during the cardiac cycle. In the ECG of a normal healthy individual which one of the following waves is not represented?** **(a) Depolarisation of atria** **(b) Repolarisation of atria** **(c) Depolarisation of ventricles** **(d) Repolarisation of ventricles** **Ans. (b)** **18. Open vascular system occurs in** **(a) fish** **(b) earthworm** **(c) snake** **(d) prawn** **Ans. (b)** **19. Thrombokinase is produced in** **(a) RBC** **(c) blood vessels** **(b) WBC** **(d) blood clotting** **Ans. (a)** **20. Which one of the following types of cells lack nucleus in humans?** **(a) Erythrocytes** **(c) Eosinophils** **(b) Neutrophils** **(d) Monocytes** **Ans. (a)** **21. Which one of the following blood cells is involved in antibody production?** **(a) B-lymphocytes** **(c) RBC** **(b) T-lymphocytes** **(d) Neutrophils** **Ans. (a)** **22. The cardiac impulse is initiatiated and conducted further upto ventricle. The correct sequence of conduction of impulse is** **(a) SA node, AV node, Purkinje fiber, AV bundle** **(b) SA node, Purkinje fiber, AV Node, AV bundle** **(c) SA node, AV node, AV bundle, Purkinje fiber** **(d) SA node, Purkinje fiber, AV Bundle, AV node** **Ans. (c)** **23. The cells involved in inflammatory reactions are** **(a) basophils** **(b) neutrophils** **(c) eosinophils** **(d) lymphocytes** **Ans. (b)** **24. The second heart sound (dub) is associated with the closure of** **(a) tricuspid valve** **(c) bicuspid valve** **(b) semilunar valves** **(d) tricuspid and bicuspid valves** **Ans. (b)** **25. Which of the following has least urea?** **(a) Hepatic vein** **(c) Pulmonary vein** **(b) Renal vein** **(d) Hepatic portal vein** **Ans. (c)** **26. Serum is** **(a) blood without fibrinogen.** **(b) lymph without corpuscles.** **(c) blood without corpuscles and fibrinogen.** **(d) lymph.** **Ans. (a)** **27. Which of the following correctly explains a phase/event in cardiac cycle in a standard electrocardiogram?** **(a) QRS complex indicates atrial contraction.** **(b) QRS complex indicates ventricular contraction.** **(c) Time between S and T represents atrial systole.** **(d) P-wave indicates beginning of ventricular contraction.** **Ans. (b)** **28. Which of the following statements is incorrect?** **(a) A person of 'O' blood group has anti 'A' and anti 'B' antibodies in his blood plasma.** **(b) A person of 'B' blood group can't donate blood to a person of 'A' blood group.** **(c) Blood group is designated on the basis of the presence of antibodies in the blood plasma.** **(d) A person of 'AB' blood group is universal recipient.** **Ans. (c)** **29. What would be the cardiac output of a person having 72 heart beats per minute and a stroke volume of 50 mL?** **(a) 360 mL** **(c) 7200 mL** **(b) 3600 mL** **(d) 5000 mL** **Ans. (b)** **30. Joint diastole phase of the cardiac cycle is in between** **(a) 'dub' and 'lub' sound.** **(b) 'lub' and 'dub' sound.** **(c) beginning of auricular systole and end of ventricular systole.** **(d) none of these.** **Ans. (a)** **31. Match the terms given under Column 'A' with their functions given under Column 'B' and select the answer from the options given below:** | Column I | Column II | |---|---| | (a) Lymphatic system | (i) Carries oxygenated blood | | (b) Pulmonary vein | (ii) Immune response | | (c) Thrombocytes | (iii) To drain back the tissue fluid to the circulatory system | | (d) Lymphocytes | (iv) Coagulation of blood | **Options:** **(a) a-(ii), b-(i), c-(iii), d-(iv)** **(c) a-(ii), b-(i), c-(iii), d-(iv)** **(b) a-(iii), b-(i), c-(iv), d-(ii)** **(d) a-(ii), b-(i), c-(iii), d-(iv)** **Ans. (a)** **32. In myogenic heart the blood during diastole** **(a) leaves the heart** **(c) enters lungs** **(b) enters the heart** **(d) leaves the ventricles** **Ans. (b)** **33. Artificial pacemaker is normally grafted at which site?** **(a) Atrioventricular bundle** **(c) Atrioventricular node** **(b) Purkinje system** **(d) SA node** **Ans. (c)** **34. Blood group O has** **(a) antigen A and antibody B** **(c) no antigen but both A and B antibodies** **(b) no antigen nor antibody** **(d) antigens A and B and antibodies A and B** **Ans. (b)** ## Short Answer Questions **Each of the following questions are of 2 marks.** **Q. 1. (a) Define polycythemia.** **(b) Which coronary artery disease is caused due to narrowing of the lumen of arteries?** **Ans. (a) Polycythemia is a condition in which the body produces too many red blood cells.** **(b) Atherosclerosis.** **Q. 2. (a) Name the pacemaker and pacesetter of the heart.** **(b) When the right atrium contracts, blood flows from it to which part of the heart?** **Ans. (a) Pacemaker- SA node, pacesetter- AV node.** **(b) As the atrium contracts, blood flows from right atrium into right ventricle through the tricuspid valve.** **Q. 3. What is systolic pressure and diastolic pressure in a normal adult man?** **Ans. Systolic pressure = 120 mm of Hg.** **Diastolic pressure= 80 mm of Hg.** **Q. 4. Given below are the abnormal conditions related to blood circulation. Name the disorders.** **(a) Acute chest pain due to failure of O₂ supply to heart muscles** **(b) Increased systolic pressure** **Ans. (a) Acute chest pain due to failure of O₂ supply to heart muscles-Angina.** **(b) Increased systolic pressure-Hypertension/high blood pressure.** **Q. 5. Define the following terms and give their location.** **(a) Purkinje fibre** **(b) Bundle of His** **Ans. (a) Purkinje fibre-Right and left bundles give rise to minute fibres throughout the ventricular musculature of the respective sides and are called Purkinje fibres.** **(b) Bundle of His—Purkinje fibres along with right and left bundles are known as bundle of His and are present in ventricles.** **Q. 6. State the functions of the following in blood:** **(a) Fibrinogen** **(c) Neutrophils** **(b) Globulin** **(d) Lymphocytes** **Ans. (a) Fibrinogen-Fibrinogens are needed for clotting or coagulation of blood.** **(b) Globulin-Globulins primarily are involved in immunity, i.e., defence mechanisms of the body.** **(c) Neutrophils-Helps in phagocytosis.** **(d) Lymphocytes-Provides immunity.** **Q. 7. What is pulse pressure? State its value. Name the instrument that measures blood pressure.** **Ans. Pulse pressure is the difference between systolic and diastolic blood pressure. Its 40 mm Hg. Sphygmomanometer is used to measure blood pressure.** ## Long Answer Questions-l **Each of the following questions are of 3 marks.** **Q. 1 (a) Given below is the diagrammatic representation of a standard ECG. Label its different peaks.** **(b) How will you interpret an electrocardiogram (ECG) in which time taken in QRS complex is higher?** **Ans. (a)** **(b) If QRS complex is normal, it shows normal functioning of heart. A longer QRS complex shows myocardial infarction (heart attack).** **Q. 2. (a) Define cardiac output.** **(b) List the factors that affect cardiac output.** **Ans. (a) Cardiac output can be defined as the volume of blood pumped out by each ventricle per minute and averages 5000 mL or 5 litres in a healthy individual.** **(b) Factors affect cardiac output by changing heart rate and stroke volume. Primary factors include blood volume reflexes, autonomic innervation and hormones. Secondary factors include extracellular fluid ion concentration, body temperature, emotions, sex, and age.** **Q. 3. (a) The walls of ventricles are much thicker than atria. Explain.** **(b) Why blood is always at high pressure in arteries?** **Ans. (a) The walls of ventricles are much thicker than atrial walls. Ventricles have to pump the blood out of the heart and hence need to exert a greater force. Thicker walls enable the ventricles to pump with greater force.** **(b) Arteries carry blood from the heart to the tissues. The heart actively pumps blood. Blood in the arteries is directly under the pumping action of the heart, and with a small lumen, it is always under high pressure.** **Q. 4. (a) Name the blood component which is viscous and straw- coloured fluid.** **(b) Describe the constituents of plasma.** **Ans. (a) Plasma which constitutes about 90% of blood.** **(b) Plasma is a straw coloured, viscous fluid constituting nearly 55 per cent of the blood. 90-92 per cent of plasma is water and proteins contribute 6-8 per cent of it. Fibrinogen, globulins and albumins are the major proteins. Plasma also contains small amounts of minerals like Na⁺, Ca²⁺, Mg²⁺, HCO₃⁻, Cl⁻, etc., glucose, amino acids, lipids, etc. Factors for coagulation or clotting of blood are also present in the plasma in an inactive form.** **Q. 5. (a) Name the vascular connection that exists between the digestive tract and liver.** **(b) What is the significance of hepatic portal system in the circulatory system?** **Ans. (a) Hepatic portal system.** **(b) The hepatic portal vein carries blood from intestine to liver before it is delivered to systemic circulation. This is significant because excess of nutrients like glucose is converted into glycogen in liver and stored there. It helps in removing many toxic materials from the body.** **Q. 6. (a) Name the antigen and antibody present in blood group B.** **(b) State the function of neutrophils.** **(c) How are fibrins formed?** **Ans. (a) Antigens- B.** **Antibody- Anti-A.** **(b) Neutrophils are phagocytic cells which destroy foreign organisms entering the body.** **(c) Fibrins are formed by the conversion of inactive fibrinogens in the plasma by the enzyme thrombin.** **Q. 7. (a) What physiological circumstances lead to erythroblastosis foetalis?** **(b) What is CAD? What is the cause of it?** **Ans. (a) A special case of Rh incompatibility (mismatching) has been observed between the Rh-negative blood of a pregnant mother with Rh-positive blood of the foetus.** **(b) Coronary Artery Disease (CAD), Coronary Artery Disease, often referred to as atherosclerosis, affects the vessels that supply blood to the heart muscle. It is caused by deposits of calcium, fat, cholesterol and fibrous tissues, which makes the lumen of arteries narrower.** **Q. 8. Explain the consequences of a situation in which blood does not coagulate.** **b) Thrombocytes are essential for coagulation of blood. Comment.** **Ans. (a) If blood does not coagulate, it can lead to excessive blood loss resulting in death. Excessive blood loss is called haemorrhage.** **(b) Coagulation of blood is an important safety feature which helps in preventing excessive blood loss. Thrombocytes or platelets play an important role in blood coagulation. These are the thrombocytes which form the bulk of the blood clot. The network of fibrin makes a mesh around the cluster of platelets. Hence, along with fibrin, platelets are essential for blood coagulation.** **Q. 9. (a) What is stroke volume?** **(b) When are the heart sounds produced?** **Ans. (a) During a cardiac cycle, each ventricle pumps out approximately 70 mL of blood which is called the stroke volume.** **(b) The first heart sound (lub) is associated with the closure of the tricuspid and bicuspid valves whereas the second heart sound (dub) is associated with the closure of the semilunar valves. These sounds are of clinical diagnostic significance.** **Q. 10. (a) Explain the advantage of the complete partition of ventricle among birds and mammals and hence leading to double circulation.** **(b) What is single circulation?** **Ans. (a) Complete partition of ventricle among birds and mammals results in complete separation of oxygenated and deoxygenated blood. This results in double circulation which is more efficient than single circulation in other animals.** **(b) The type of circulatory system that occurs in fishes, in which the blood passes only once through the heart in each complete circuit of the body.** **Q. 11. (a) How is heart failure different from heart attack?** **(b) What are the symptoms of hypertension?** **Ans. (a) Heart failure means the state of heart when it is not pumping blood effectively enough to meet the needs of the body and heart attack is when the heart muscle is suddenly damaged by an inadequate blood supply.** **(b) Severe headaches** **• Fatigue or confusion** **• Chest pain** **• Irregular heartbeat** **• Nosebleed** **• Vision problems** **• Difficulty breathing** **Q. 12. Answer the following:** **(a) Name the major site where RBCs are formed.** **(b) Which part of heart is responsible for initiating and maintaining its rhythmic activity?** **(c) What is specific in the heart of crocodiles among reptilians?** **Ans. (a) Bone marrow.** **(b) Sino-atrial node (SA node).** **(c) Reptiles have 3-chambered heart but crocodiles have 4-chambered heart.** ## Long Answer Questions—II **Each of the following questions are of 5 marks.** **Q. 1. (a) Name the artery that carries deoxygenated blood.** **(b) Name two arches of human heart.** **(c) Which type of heart is found in the human beings?** **Ans. (a) Pulmonary artery.** **(b) Pulmonary arch and systemic (aortic) arch.** **(c) Normal activities of the heart are regulated intrinsically, i.e., auto regulated by specialised muscles (nodal tissue), hence the heart is called myogenic.** **Q. 2. (a) Explain the functional significance of lymphatic system.** **(b) Give the full form of ECG.** **Ans. (a) (i) It collects interstitial fluid from tissues.** **(ii) It plays special role in immunity building and memory generation.** **(iii) It transports many important nutrients and hormones.** **(iv) Fat is only absorbed through the lymph from small intestine. Thus, lymphatic system plays an important role in absorption of fat.** **(b) Electrocardiogram.** **Q. 3. (a) How is open circulatory system different from closed system?** **(b) What are plasma cells? Which lymphocytes form the humoral immune system?** **Ans. (a) In closed circulatory system, the heart pumps blood through vessels that are separate from the interstitial fluid of the body. In an open circulatory system, the blood is not enclosed in the blood vessels, but is pumped into a cavity called a hemocoel.** **(b) Plasma cells, also called plasma B cells, are white blood cells that originate in the bone marrow and secrete large quantities of proteins called antibodies. B-cells form the humoral immune system.** **Q. 4. (a) What is cardiomegaly? State its causes.** **(b) Name the organ which is known as the graveyard of RBCs.** **(c) What is the significance of time gap in the passage of action potential from sino-atrial node to the ventricle?** **Ans. (a) An enlarged heart, cardiomegaly is usually a sign of another condition such as a heart valve problem or heart disease. It may also signal a prior heart attack. It can also occur from bodily stress caused by pregnancy or certain infections.** **(b) Spleen is known as the graveyard of RBCs.** **(c) The time gap in the passage of action potential from SA node to the ventricle gives the ventricle enough time to relax. This results in a fall in ventricular pressure and allows the closing of semilunar valves. This prevents the backflow of blood into ventricles.** **Q. 5. (a) How AV bundle is essential for conduction of cardiac impulse?** **(b) Define Starlings law of heart.** **Ans. (a) The atrioventricular bundle (bundle of His) is a continuation of the specialised tissue of the AV node, and serves to transmit the electrical impulse from the AV node to the Purkinje fibres of the ventricles.** **It descends down the membranous part of the interventricular septum, before dividing into two main bundles:** **• Right bundle branch – conducts the impulse to the Purkinje fibres of the right ventricle.** **• Left bundle branch – conducts the impulse to the Purkinje fibres of the left ventricle.** **(b) The Frank-Starling Law is the description of cardiac hemodynamics as it relates to myocyte stretch and contractility. The Frank-Starling Law states that the stroke volume of the left ventricle will increase as the left ventricular volume increases due to the myocyte stretch causing a more forceful systolic contraction.** **Q. 6. (a) Write a short on leucocytes and its types.** **(b) List the functions of blood.** **Ans. (a) Refer to Points to remember 3.** **(b) Functions of blood:** **• Blood is fluid connective tissue.** **• Blood provides the body's cells with oxygen and removes carbon dioxide.** **• Blood transports nutrients and hormones.** **• Blood regulates body temperature.** **• Platelets clot blood at sites of injury.** **• Blood brings waste products to the kidneys and liver.** **• WBCs helps in defence mechanism.** **Q. 7. Briefly describe the following:** **(a) Anaemia** **(c) Atherosclerosis** **(e) Heart failure** **(b) Angina pectoris** **(d) Hypertension** **(f) Erythroblastosis foetalis** **Ans. (a) Anaemia: Decrease in oxygen carrying capacity of blood either due to reduced RBCs production or low haemoglobin content is called anaemia.** **(b) Angina pectoris: A symptom of acute chest pain appears when not enough oxygen is reaching the heart muscle. Angina can occur in men and women of any age but it is more common among the middle-aged and elderly. It occurs due to conditions that affect the blood flow.** **(c) Atherosclerosis: Sometimes deposition of calcium, fat, cholesterol and fibrous tissues occurs in the blood vessel (e.g., coronary artery) supplying blood to the heart muscles. This condition makes the lumen of arteries narrower affecting blood supply to heart; which leads to Coronary Artery Disease (CAD) also referred to as atherosclerosis.** **(d) Hypertension: An elevated blood pressure is called hypertension. Hypertension can happen without a known cause or can be caused by some other conditions.** **(e) Heart failure: Stoppage of pumping action of heart is called heart failure. This is also called cardiac arrest.** **(f) Erythroblastosis foetalis: A special case of Rh incompatibility between Rh negative mother and Rh positive foetus may be present during second pregnancy. This can be fatal to the foetus and cause severe anaemia in the baby. The case of severe anaemia in foetus is called erythroblastosis foetalis.** **Q. 8. Differentiate between** **(a) Blood and Lymph** **(b) Basophils and Eosinophils** **(c) Tricuspid and Bicuspid valve** **Ans. (a)** | S.No. | Blood | Lymph | |---|---|---| | 1. | Reddish in colour. | Pale yellow in colour. | | 2. | Red blood cells are present. | Red blood cells are absent. | | 3. | Bidirectional flow. | Unidirectional flow. | | 4. | Flow is rapid. | Flow is slow. | | 5. | Leucocyte count is relatively less. | High leucocyte count. | | 6. | Platelets are present. | Platelets are absent. | **(b)** | S.No. | Basophil | Eosinophil | |---|---|---| | 1. | Have 3-lobed nucleus and less, number of coarse granules. | Have bilobed nucleus and coarse granules. | | 2. | They comprise 0.5 – 1% of the blood volume. | They comprise 1 - 6% of the blood volume. | | 3. | They secrete heparin, histamine and serotonin. | They resist infection. | **(c)** | S.No. | Tricuspid valve | Bicuspid valve | |---|---|---| | 1. | The tricuspid valve is formed by three flaps and it guards the opening between right atrium and right ventricle. | The bicuspid valve is formed by two flaps which opens between the left atrium and left ventricle. | **Q. 9. Write the features that distinguish between the two.** **(a) Plasma and Serum** **(b) Open and closed circulatory system** **(c) Sino-atrial node and Atrio-ventricular node** **Ans. (a)** | S.No. | Plasma | Serum | |---|---|---| | 1. | The fluid without blood corpuscles is called plasma. | The fluid without clotting elements is called serum. | | 2. | Fibrinogen and other clotting materials are present. | Clotting materials are absent. | | 3. | Plays important role in blood clotting | Has no role in blood clotting. | **(b)** | S.No. | Open circulatory system | Closed circulatory system | |---|---|---| | 1. | Blood is directly showered on target organs. | Blood is supplied to organs through a closed network of vessels. | | 2. | Respiratory pigment is absent in most of the cases. | Respiratory pigment is present in all cases. | **(c)** | S.No. | Sino-atrial node | Atrio-ventricular node | |---|---|---| | 1. | Present on the upper side of the right auricle. | Present at the junction of right auricle and right ventricle. | |