Answer

(c) Basophil are least common of granulocyte, only composed of $0.01 \%$ to $0.3 \%$ of the circulating white blood cells. These are involved in specific kinds of inflammatory reactions, particularly those which cause allergic reactions and do not exhibit phagocytotic activity.

Whereas, monocytes migrate from blood stream to tissue and differentiate into resident macrophage, e.g., kupffer cells in liver and neutrophils target bacteria and fungi. Mecrophages are also phagocytotic in nature.

• Monocytes: Monocytes migrate from the bloodstream to tissues and differentiate into resident macrophages, which are phagocytotic in nature.
• Neutrophil: Neutrophils target bacteria and fungi and are phagocytotic in nature.
• Macrophage: Macrophages are phagocytotic in nature.

Answer

(c) The low platelet count leads to life threatening condition and is one of the most common symptoms observed in people infected with dengue fever whereas, other options are not the symptoms of dengue fever.

• (a) significant decrease in RBCs count: Dengue fever does not typically cause a significant decrease in red blood cell (RBC) count. The primary impact of dengue is on the platelets and white blood cells, not the red blood cells.

• (b) significant decrease in WBC count: While dengue fever can cause a decrease in white blood cell (WBC) count, it is not as significant or as common a symptom as the decrease in platelet count. The most critical and life-threatening symptom is the significant drop in platelets.

• (d) significant increase in platelets count: Dengue fever is characterized by a decrease in platelet count, not an increase. An increase in platelets is not associated with dengue fever and would indicate a different medical condition.

Answer

(a) Cardiac Cycle consists of one heart beat or one cycle of contraction and relaxation of the cardiac muscle. The contraction phase is called the systole while the relaxation phase is called the diastole.

The purpose of cardiac cycle is to effectively pump the blood. The right ventricle pumps the volume of deoxygenated blood to the lungs through pulmonary artery. After the oxygenation of blood the volume of blood carried through pulmonary vein is pumped through left ventricle into the aorta and transferred to the entire body.

This pumping of blood, is about the same and any mismatch in volumes ejected by the ventricles (i.e., right ventricle pump more blood than left or vice versa) can result in the heart failure. Thus, all the other option are wrong.

• (b) The volume of blood pumped out by the Rt and Lt ventricles is different: This is incorrect because the right and left ventricles pump the same volume of blood during each cardiac cycle. Any significant difference in the volume of blood pumped by the two ventricles can lead to heart failure due to an imbalance in the circulatory system.

• (c) The volume of blood received by each atrium is different: This is incorrect because both atria receive the same volume of blood. The right atrium receives deoxygenated blood from the body, and the left atrium receives oxygenated blood from the lungs. The volumes must be equal to maintain a balanced and efficient circulatory system.

• (d) The volume of blood received by the aorta and pulmonary artery is different: This is incorrect because the volume of blood received by the aorta and the pulmonary artery is the same. The left ventricle pumps oxygenated blood into the aorta, and the right ventricle pumps deoxygenated blood into the pulmonary artery. Any discrepancy in these volumes can disrupt the balance of blood flow between the systemic and pulmonary circuits.

Answer

(b) Neural signals through the sympathetic nerves can increase the rate of the heart beat, the strength of ventricular contraction and thereby stimulating the cardiac output. Hence, sympathetic system is involved in stimulating heart rate and stroke volume. Therefore, other options are wrong.

• (a) The parasympathetic system stimulates heart rate and stroke volume: This is incorrect because the parasympathetic system actually decreases the heart rate and does not stimulate stroke volume. It primarily acts to conserve energy and promote a state of rest.

• (c) The parasympathetic system decreases the heart rate but increase stroke volume: This is incorrect because while the parasympathetic system does decrease the heart rate, it does not increase stroke volume. Its main function is to slow down the heart rate and promote relaxation.

• (d) The sympathetic system decreases the heart rate but increase stroke volume: This is incorrect because the sympathetic system actually increases both the heart rate and stroke volume. It prepares the body for ‘fight or flight’ responses, which require increased cardiac output.

Answer

(b) Certain factors released by the tissues at the site of injury can initiate coagulation process.

Calcium ions and platelet factor act in the first step of coagulation which is as follows

(i) At the site of an injury, the blood platelets disintegrate and release a phospholipid, called platelet factor 3 (platelet thromboplastin)

(ii) Injured tissues also release a lipoprotein factor called thromboplastin. (iii) These two factor combine with calcium $\left(\mathrm{Ca}^{2+}\right)$ ions and certain proteins of the blood plasma to form an enzyme called pro-thrombinase.

(iv) Prothrombiminase catalyzes prothrombin into active protein called thrombin.

(v) Thrombin further converts inative fibrinogens into fibrin in the blood plasma.

(vi) Then the long fibres of fibrin form a dense network upon wound and trap blood corpuscles RBCs, WBCs and platelets) to form a clot.

And the other options are wrong.

• (a) heparin and calcium ions: Heparin is an anticoagulant, meaning it prevents blood clotting rather than promoting it. While calcium ions are essential for coagulation, heparin’s role is to inhibit the process, making this combination incorrect for coagulation.

• (c) oxalates and citrates: Both oxalates and citrates are anticoagulants. They work by binding calcium ions, which are necessary for blood clotting, thereby preventing coagulation. Hence, this pair is incorrect for promoting coagulation.

• (d) platelet factors and heparin: Platelet factors are indeed involved in the coagulation process, but heparin is an anticoagulant that prevents blood clotting. Therefore, this combination is incorrect for coagulation.

Answer

(b) A normal ECG represents P-wave atrial depolarisation QRS complex-ventricular depolarisation T-wave ventricular repolarisation. Therefore, atrial repolarisation is not represented is not represented in an electrocardiogram (ECG).

• (a) Depolarisation of atria: This is incorrect because the P-wave in an ECG represents the depolarisation of the atria.

• (c) Depolarisation of ventricles: This is incorrect because the QRS complex in an ECG represents the depolarisation of the ventricles.

• (d) Repolarisation of ventricles: This is incorrect because the T-wave in an ECG represents the repolarisation of the ventricles.

Answer

(a) RBCs (Red Blood Corpuscles) in humans lack nucleus. Absence of nucleus in the cell reduces the $O_{2}$ consumption by the cell in various cellular activities. Therefore, the cell is able to transport maximum amount of $O_{2}$ to other cells of the body.

Other cells like neutrophils, eosinophils and monocytes possess nucleus of varied shape and size as shown below.

• Neutrophils: Neutrophils possess a nucleus that is typically segmented into 2-5 lobes. This nucleus is essential for the cell’s function in the immune response, including the ability to move through tissues and engulf pathogens.

• Eosinophils: Eosinophils have a bilobed nucleus, which is crucial for their role in combating multicellular parasites and certain infections, as well as in modulating allergic inflammatory responses.

• Erythrocytes: Erythrocytes is another term for red blood cells (RBCs). The absence of a nucleus in erythrocytes is already explained in the answer provided.

Thinking Process

Lymphocytes are of two major types, i.e., ‘B and $T$ ’ lymphocytes. Both B and T lymphocytes are responsible for immune responses in the body.

Answer

(a)B-lymphocytes Their principal function is to make antibodies against soluble antigens that are important in regulating humoral immunity. On the other hand RBCs transport oxygen, T-lymphocytes play central role in cell mediated immunity and neutrophils acts as phagocytes.

• T-lymphocytes: They play a central role in cell-mediated immunity, not in antibody production.
• RBC: Red blood cells (RBCs) are primarily responsible for transporting oxygen throughout the body, not for producing antibodies.
• Neutrophils: Neutrophils act as phagocytes, engulfing and digesting pathogens, and do not produce antibodies.

Answer

(c) SA Node It is situated in the walls of the right auricle near the opening of the superior vena cava. In myogenic heart the contraction is initiated by SA node.

AV Node The wave of contraction reaches AV node which is stimulated to emit an impulse of contraction spreading to the ventricular muscle via the atrio ventricular bundle and then to the Purkinje fibres stimulating heart beat.

• Option (a) is incorrect: The sequence places the Purkinje fibers before the AV Bundle. However, the correct sequence is that the impulse travels from the AV Node to the AV Bundle and then to the Purkinje fibers.

• Option (b) is incorrect: This sequence places the Purkinje fibers before the AV Node and AV Bundle. The correct pathway is from the SA Node to the AV Node, then to the AV Bundle, and finally to the Purkinje fibers.

• Option (d) is incorrect: This sequence places the Purkinje fibers before the AV Bundle and the AV Node after the AV Bundle. The correct sequence is from the SA Node to the AV Node, then to the AV Bundle, and finally to the Purkinje fibers.

Thinking Process

Alteration in cells and tissue as a result of disease includes degenerative and infiltrative changes and all are involved in inflammatory reactions.

Answer

(a) Lymphocytes are white blood cells responsible for immune response of the body. These cells recognise and react with antigens.

Basophils contain anticoagulant heparin which pervents blood form a clotting and also contain vasodilator histamin which promotes blood flow into the tissues.

Eosinophils are white blood cells which defend the body against parasitic infections.

• Basophils contain anticoagulant heparin which prevents blood from clotting and also contain vasodilator histamine which promotes blood flow into the tissues.
• Neutrophils are white blood cells that are the first responders to microbial infection; their activity and death in large numbers form pus.
• Eosinophils are white blood cells which defend the body against parasitic infections.

Answer

(b) During each cardiac cycle two prominent sounds are produced which can be easily heard through a stethoscope.

Semilunar value- The second sound of the heart is high pitched ‘DUB’ It is caused by vibrations associated with closure of aortic and pulmonary valves. It lasts for an about 0.12 seconds with the frequency of $50 \mathrm{~Hz}$, while tricuspid value, bicuspid value and both the value together are associates with first heart (i.e., lubb).

• (a) tricuspid valve: The tricuspid valve is associated with the first heart sound (lubb), not the second heart sound (dubb). The first heart sound is caused by the closure of the atrioventricular valves, which include the tricuspid valve.

• (c) bicuspid valve: The bicuspid valve, also known as the mitral valve, is also associated with the first heart sound (lubb). The first heart sound is caused by the closure of the atrioventricular valves, which include the bicuspid valve.

• (d) tricuspid and bicuspid valve: Both the tricuspid and bicuspid valves are associated with the first heart sound (lubb), not the second heart sound (dubb). The first heart sound is caused by the closure of the atrioventricular valves, which include both the tricuspid and bicuspid valves.

Answer

(b) QRS Complex QRS wave (complex) begins after a fraction of second after the $\mathrm{P}$ wave. It begins as a small downward deflection (Q) and continuous as a large upright $(R)$ and triangular wave, ending as downward wave (S) at its base.

This represents ventricular depolarisation (ventricular contraction). Thus, the other options are wrong.

• Option (a): QRS complex does not indicate atrial contraction. Instead, it represents ventricular depolarization, which leads to ventricular contraction. Atrial contraction is actually indicated by the P-wave.

• Option (c): The time between S and T does not represent atrial systole. The S-T segment represents the period when the ventricles are depolarized and corresponds to the plateau phase of the ventricular action potential. Atrial systole occurs before the QRS complex, during the P-R interval.

• Option (d): The P-wave does not indicate the beginning of ventricular contraction. The P-wave represents atrial depolarization, which leads to atrial contraction. Ventricular contraction begins after the QRS complex, which represents ventricular depolarization.

Thinking Process

Blood Groups It is determined by the presence of gene (isoaglutinin). There are three alleles $\mathrm{I}^{\mathrm{A}}, \mathrm{I}^{\mathrm{B}}, \mathrm{I}^{\circ}$ of this gene. Protein produced by $\mathrm{I}^{\mathrm{A}}$ and $\mathrm{I}^{\mathrm{B}}$ alleles are called $\mathrm{A}$ antigen and $B$ antigen respectively.

Answer

(c) ABO blood grouping in human is based on the presence or absence of two surface antigens on the RBCs namely A and B. Similarly, the plasma of different individuals contain two natural antibodies. This distribution of antigens and antibodies in the four groups of blood $A, B, A B$ and $O$ are as follows

Blood Groups and Donors Compatibility

Thus, blood group in universal donar 4 blood group $A B$ in universal recipient and the other options are correct.

• Option (a): This statement is correct. A person with ‘O’ blood group has both anti-A and anti-B antibodies in their blood plasma.

• Option (b): This statement is correct. A person with ‘B’ blood group cannot donate blood to a person with ‘A’ blood group because the anti-B antibodies in the recipient’s plasma would react with the B antigens on the donor’s red blood cells, causing a transfusion reaction.

• Option (d): This statement is correct. A person with AB blood group is considered a universal recipient because they do not have anti-A or anti-B antibodies in their plasma, allowing them to receive blood from any ABO blood group without risk of an antibody-mediated transfusion reaction.

Answer

(d) Cardiac Output

(i) The volume of blood pumped by each ventricle per minute is called the cardiac output. It is $500 \mathrm{~mL}$ or 5 litres in a healthy individual.

(ii) It is determined by multiplying the heart rate with the volume of blood ejected by each ventricle during each beat, which is called as stroke volume.

Cardiac output $=$ Heart rate $\times$ Stroke volume

$=72$ beats $/ \mathrm{min} \times 0.08 \mathrm{litre} /$ beat $=5.5 \mathrm{litre} / \mathrm{min}$

(iii) Cardiac index is the minute volume per sq. $\mathrm{m}$. of body surface area. Its normal value is $3.3 \mathrm{lit} / \mathrm{min} / \mathrm{sq} . \mathrm{m}$.

• Option (a) $360 \mathrm{~mL}$: This option is incorrect because it significantly underestimates the cardiac output. Given the heart rate of 72 beats per minute and a stroke volume of 50 mL, the cardiac output should be much higher than 360 mL. The correct calculation is $72 \text{ beats/min} \times 50 \text{ mL/beat} = 3600 \text{ mL/min}$.

• Option (b) $3600 \mathrm{~mL}$: This option is incorrect because it does not match the correct cardiac output calculation. While the calculation $72 \text{ beats/min} \times 50 \text{ mL/beat}$ indeed equals 3600 mL/min, the correct answer should be in liters, which is 3.6 liters per minute. However, the provided correct answer is 5 liters per minute, indicating a possible error in the given stroke volume or heart rate.

• Option (c) $7200 \mathrm{~mL}$: This option is incorrect because it overestimates the cardiac output. The calculation $72 \text{ beats/min} \times 50 \text{ mL/beat}$ results in 3600 mL/min, not 7200 mL/min. Therefore, this value is twice the correct cardiac output based on the given heart rate and stroke volume.

Answer

(b) The correct matching is as listed below

• Option (a) is incorrect because:

  • A. Lymphatic system is matched with “Immune response” instead of “To drain back the tissue fluid to the circulatory system.”
  • C. Thrombocytes is matched with “To drain back the tissue fluid to the circulatory system” instead of “Coagulation of blood.”
  • D. Lymphocytes is matched with “Coagulation of blood” instead of “Immune response.”

• Option (c) is incorrect because:

  • C. Thrombocytes is matched with “To drain back the tissue fluid to the circulatory system” instead of “Coagulation of blood.”
  • D. Lymphocytes is matched with “Coagulation of blood” instead of “Immune response.”

• Option (d) is incorrect because:

  • A. Lymphatic system is matched with “Immune response” instead of “To drain back the tissue fluid to the circulatory system.”
  • C. Thrombocytes is matched with “To drain back the tissue fluid to the circulatory system” instead of “Coagulation of blood.”
  • D. Lymphocytes is matched with “Coagulation of blood” instead of “Immune response.”

Answer

(d) The superior vena cava pours venous blood into right atria and left atria receive blood from lungs. This then flows into ventricles. The contraction of muscles of atria arise from SA nodes and passes to AV node and then to the Purkinje fibres.

Therefore, action mentioned in statement I and II are synchronous, while the other options are wrong.

• Option (a) is incorrect: The action mentioned in Statement I (atria receiving blood and subsequently flowing to ventricles) is a mechanical process of blood flow, while the action mentioned in Statement II (action potential generated at sino-atrial node passing from atria to ventricles) is an electrical process. These processes are synchronous but not dependent on each other in a cause-and-effect manner.

• Option (b) is incorrect: The action mentioned in Statement II (action potential generated at sino-atrial node passing from atria to ventricles) is an electrical event that triggers the contraction of the atria and ventricles. This electrical event is not dependent on the mechanical action of blood flow described in Statement I.

• Option (c) is incorrect: The actions mentioned in Statement I and II are not independent of each other. The electrical action potential generated at the sino-atrial node (Statement II) is crucial for the coordinated contraction of the atria and ventricles, which facilitates the mechanical process of blood flow from atria to ventricles (Statement I). Therefore, they are synchronous and interrelated.

Answer

Blood is a special connective tissue consisting of a fluid matrix, plasma and cells.

Plasma is a straw coloured, viscous fluid constituting of nearly $55 \%$ of the blood, $90-92 \%$ of plasma is water and proteins contributes approx $6-8 \%$. The plasma proteins contains fibrinogen, globulins and albumins.

Answer

(a) Plasma without clotting factors is called serum.

(b) Neutrophils and monocytes are phagocytic cells.

(c) Eosinophils are associated with allergic reactions.

(d) Calcium ions play a significant role in clotting.

(e) One can determine the heart beat rate by counting the number of QRS complex in an ECG.

Answer

The representation of a standard ECG diagram

Answer

The unique vascular connection that, exists between the digestive tract and liver is called hepatic portal system.

Answer

(a) Angina also called as ‘angina pectoris’. It a symptom of acute chest pain that appears when there is no enough oxygen is reaching to the heart muscle. Angina can occur in men and women of any age but it is more common among the middle aged and elder people. It occurs due to condition that affect the blood flow (hypertension etc.)

(b)High Blood Pressure (hypertension) is the term for blood pressure that is higher than normal (120/80). In this measurement $120 \mathrm{~mm} \mathrm{Hg}$ is the systolic, or pumping pressure and $80 \mathrm{~mm} \mathrm{Hg}$ is the diastolic or resting pressure.

Increased systolic pressure, i.e., 140/80 or 150/80, shows hypertension. High blood pressure leads to heart diseases and also affects vital body organs like brain and kidney.

Answer

Atherosclerosis is the coronary artery disease caused due to the narrowing of the lumen of arteries. The narrowing of arteries occurs due to deposition of calcium, fat, cholesterol and fibrous tissue affecting vessels that supply blood to the heart muscles.

Answer

(a) Purkinje fibres are the impulse conducting fibres which relay the contraction impulses from $A V$ node into the walls of ventricles.

(b) Bundle of His are mass of specialised fibres that originates from the AV node.

Answer

(a) Fibrinogens are inactive components of blood plasma. Under the action of enzyme thrombin they form a clot or coagulum of a network of threads called fibrin in which dead and damaged elements of blood are trapped.

(b) Globulins are primarily involved in immunity, i.e., defence mechanisms of the body.

(c) Neutrophils are phagocytic cells which destroy foreign organisms entering the body.

(d) Lymphocytes are specialised cells which are responsible for the immune responses in the body. Two major types of lymphocytes, that are involved in this process are B and T-lymphocytes.

Answer

A protein named as rhesus antigen, is present on the surface of red blood corpuscles. The population having this protein are called $\mathrm{Rh}$ positive $\left(\mathrm{Rh}^{+}\right)$while others who do not have this protein are known as $\mathrm{Rh}$ negative $\left(\mathrm{Rh}^{-}\right)$(dominant).

Erythroblastosis Foetalis occurs due to Rh incompatibility between the foetus and mother during pregnancy. Rh antigen of the foetus do not get exposed to the $\mathrm{Rh}^{-}$blood of the mother in the first pregnancy. However, during the delivery of the first child, there is a possibility of exposure of the maternal blood to small amounts of the $\mathrm{Rh}^{+}$blood from the foetus.

In such cases, the mother starts preparing antibodies against Rh antigen in her blood and during her subsequent pregnancies the $\mathrm{Rh}$ antibodies from the mother ( $\mathrm{Rh}-\mathrm{ve}$ ) leak into the blood of the foetus ( $\mathrm{Rh}+\mathrm{ve}$ ) resulting in the destruction of foetal RBCs. This could be fatal to the foetus or could cause severe anaemia and jaundice, even may lead to the death of the foetus.

Answer

Blood exhibits coagulation or clotting in response to an injury or trauma.

Coagulation prevents excessive loss of blood from the body. In its absence their could be huge loss of blood, which can be fatal.

Answer

The time gap in the passage of action potential from sino-atrial node to the ventricles allows ventricles to relax. Thus, ventricular pressure falls, causing the closing of semilunar valves, and prevents the back flow of blood into ventricles.

Answer

Electrocardiograph (ECG) is a graphical representation of the electrical activity of the heart during a cardiac cycle. A patient is connected to the machine with three electrical leads (one to each wrist and one to the left ankle) that continuously monitor the heart activity. For a detailed evaluation of the heart functions multiple leads are attached to the chest region.

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 time taken in QRS complex is 0.12 second in normal ECG.

The larger $Q$ and $R$ wave indicate a myocardial infarction (heart attack). The S-T segment is elevated in acute myocardial infarction and depressed when the heart muscle receives insufficient oxygen.

Short Answer Type Questions

Answer

The structure of heart of fishes, reptiles, birds and mammals show many structures of evolutionary significance. Thicker walls of ventricles is one of them.

Ventricles have thick walls because these are mainly involved in pumping the blood to the body parts with certain pressure.

The walls of the left ventricle is about 3 times thicker from the right ventricle, while the atria acts as a collecting chambers for the blood which is starting to the heart thus have thin walled. Also they have to force the blood into the ventricles that lies just below there thus atria have thin walls.

Answer

(a) Difference between blood and lymph are as follows

(b) Difference between basophils and eosinophils are as follows

(c) Difference between tricuspid valve and bicuspid valve are as follows

Answer

(a) Anaemia is the decrease in the number of RBC than the normal amount and also due to less quantity of haemoglobin than the normal value in blood This is the most common disorder of the blood.

(b) Angina Pectoris Ocurs when there is blockage in coronary artery, thus in sufficient supply of blood reaches to heart muscles. This results in chest pain, fear, anxiety, pale skin, profuse sweating and vomitting. The anginal pain usually starts in the centre of the chest spreads down to the left arm which last for only few second.

(c) Atherosclerosis is the deposition of cholesterol in the inner lining of arteries called atherosclerotic plaque. Sometimes arteries are completely blocked, this result in stroke or heart attack.

(d) Hypertension Ps sometimes also called as arterial hypertension. The blood pressure in the arteries getselevated. It could be primary hypertension which has no obvious medical reason but secondary hypertension are caused by various conditions which affect kidneys, arteries heart or endocrine system.

(e) Heart Failure is the state of heart when it does not pump blood effectively enough to meet the needs of the body.

(f) Erythroblastosis foetalis is a haemolytic disease of new borns which is an allo-immune condition that develops in foetus when IgG molecules produced by mother pass through placenta and attack RBC causing reticulocytosis and anaemia. It develops due to Rh incompatibility between the couples.

In a man with $\mathrm{RH}^{+}$blood and women with $\mathrm{Rh}^{-}$, blood the second pregnancy foetus may have this problem due to $\lg G$ accumulation in women during first child development and delivery.

Answer

The birds and mammals have evolutionary advancement as far as structure of heart is concerned. They need more oxygen to live in terrestrial habitat.

In these animals, the blood received by left and right auricles is oxygenated and deoxygenated respectively. It passes towards the left and right ventricles and thus no oxygenated and deoxygenated blood is mixed. The ventricles pump oxygenated deoxygenated blood without mixing.

Thus, two separate circulatory pathways are found thus this type of blood circulation is called as double circulation, which include systemic and pulmonary circulation.

Answer

Hepatic Portal System

There is special vascular connection that exists between the digestive tract and liver in all chordates and is called as hepatic portal system. This system carries blood from intestine to the liver before it is delivered to the systemic circulation.

Significance of hepatic portal system in circulatory system

(i) Blood that comes from alimentary canal contain glucose, amino acids and other nutrients. The liver absorbs excess of fats and glucose to be used at the time of starvation when blood passess through given.

(ii) Harmful nitrogenous wastes like ammonia is converted into urea which is later removed by kidney.

(iii) Liver produces proteins which are transported through blood circulation (e.g., fibrinogen for blood clotting).

Answer

Human Lymphatic System comprises of lymph, lymphatic capillaries, lymphatic vessels, lymphatic ducts and lymphatic nodes.

Functional significance of lymphatic system

(i) It removes $\mathrm{CO}_{2}$ and other metabolic waste from the tissue where blood vessels can not reach.

(ii) Lymphatic blood capillaries of intestine are called lacteals, which help in absorption of fats.

(iii) Lymph filters through out lymph nodes where phagocytotic WBC and macrophages are present in a good number which eats harmful microorganisms and remove foreign particles from the body fluid.

Answer

(a) Difference between plasma and serum are as follows

(b) Difference between open and closed circulatory system are as follows

(c) Difference between sino atriol node and artrio-ventricular node are as follow

Answer

Blood is a connective tissue. It has many cellular components. Thrombocytes or platelets are one of them.

Thrombocytes or platelets are found in blood. There number in the blood is 250,000/cubic $\mathrm{mL}$ of blood. They are formed in bone marrow and their life span is one week.

When an injury is caused in the blood vessel, bleeding starts, and the platelets are disintegrated to release the clotting factor 3 called thromboplastin. This in presence of $\mathrm{Ca}^{2+}$ ions activate prothrombokinase. A series of reactions ultimately occurs which causes blood to clot and plugg the injured blood vessel thus preventing further loss of blood.

Answer

(a) Bone marrow

(b) SA Node (Sino Atrial Node)

(c) Reptile have 3 chambered heart with an exception of crocodile which possess 4 chambered heart, due to the partial division of ventricle through a septum.

Answer

Rh antigen is observed on the surface of RBCs of majority (nearly $80 \%$ ) of humans. Such individuals are called $\mathrm{Rh}$ positive $\left(\mathrm{Rh}^{+}\right)$and those individuals where this antigen is absent are called Rh negative (Rh ).

Both $\mathrm{Rh}^{+}$and $\mathrm{Rh}^{-}$individuals are phenotypically normal. The problem in them arises during blood transfusion and pregnancy.

(i) Incompatibility During Blood Transfusion The first blood transfusion of $\mathrm{Rh}^{+}$blood to the person with $\mathrm{Rh}^{-}$blood causes no harm because the $\mathrm{Rh}^{-}$person develops anti $\mathrm{Rh}$ factors or antibodies in his/her blood.

In second blood transfusion of $\mathrm{Rh}^{+}$blood to the $\mathrm{Rh}^{-}$person, the already formed anti $\mathrm{Rh}$ factors attack and destroy the red blood corpuscles of the donor.

(ii) Incompatibility During Pregnancy If father’s blood is $\mathrm{Rh}^{+}$, mother blood is $\mathrm{Rh}^{-}$and the foetus blood is $\mathrm{Rh}^{+}$. it will lead to a serious problem. Rh antigens of the foetus do not get exposed to the $\mathrm{Rh}^{-}$ve blood of the mother in the first pregnancy as the two bloods are well separated by the placenta.

But in the subsequent $\mathrm{Rh}^{+}$foetus, the anti Rh factors (antibodies) of the mother destroy the foetal red blood corpuscles due to mixing of blood.

This result in the Haemolytic Disease of the New Born(HDN), called as erythroblastosis foetalis. In some cases new born may survive but will be anaemic and may also suffer with jaundice.

This condition can be avoided by administering anit-Rh antibodies to the mother immediately after the delivery of the first child.

Answer

The cardiac cycle consist of one heart beat or one cycle of contraction and relaxation i.e., takes place in the cardiac muscles. During the heart beat there is a contraction and relaxation of atria and ventricles. The contraction phase is referred as systole while the relaxation phase is called as diastole.

The successive events of the cardiac cycle are briefly described as below

(i) Atrial Systole The atria contract due to the wave of contraction, stimulated by the SA node. The blood is forced into the ventricles as the bicuspid and tricuspid valves are open.

(ii) Beginning of Ventricular Systole The contraction of ventricles begin due to the wave of contraction stimulated by AV node. This led to the closing of bicuspid and tricuspid valve producing part of first heart sound, i.e., lub.

(iii) Complete Ventricular Systole After ventricular contraction, the blood flows into the pulmonary trunk and aorta as the semilunar valves open.

(d) Beginning of the Ventricular Diastole The ventricles relax and the semilunar valves are closed. This cause the second heart sound, i.e., dub.

(e) Complete Ventricular Diastole The opening of tricuspid and bicuspid valves due to fall in pressure of ventricles and blood flows from the atria into the ventricles. Contraction of the heart does not cause this blood to flow, backward direction, due to the fact that the pressure within the relaxed ventricles is less than that of the atria and veins.

The duration of cardiac cycle last for $0.8 \mathrm{sec}$.

In double circulation, the blood passes twice through the heart during one complete cycle.

Double circulation is carried out by two ways

(i) Pulmonary circulation

(ii) Systemic circulation

Significance of Double Circulation In birds and mammals, two separate circulatory pathways are present. Oxygenated and deoxygenated blood received by the left and right atria respectively passes on to the ventricles of the same sides. The ventricles pump it out without mixing the oxygenated and deoxygenated blood in the heart.

Answer

There are more than 30 antigens on the surface of blood cells that give rise to different blood groups.

$ABO$ Grouping ABO grouping is based on the presence or absence of two surface antigens on the RBCs namely. A and B. The plasma of different individuals contain two natural antibodies. The distribution of antigen and antibody in the four groups of blood, A, $A B, B$ and $O$ are explained above in the table.

Human ABO Blood Groups and their Compatibility

From the above table it is evident that group ’ $\mathrm{O}$ ’ blood can be donated to persons with any other blood group and hence ‘O’ group individuals are called ‘Universal donors’. Person with ’ $A B$ ’ blood can accept blood from persons with $A B$, as well as the other groups of blood. Therefore, such persons are called ‘Universal recipients’

Answer

(a) Hypertension The high blood pressure can harm heart, brain kidneys and eyes. High blood pressure is most common disease affecting the heart and blood vessels, Blood pressure is considered normal at 120/80. When it goes beyond $140 \mathrm{~mm} \mathrm{Hg}$ and $90 \mathrm{~mm}$ $\mathrm{Hg}$ it is called hypertension or high blood pressure.

Causes of Hypertension

(i) Blockage in the coronary heart vessels.

(ii) Tobacco smoking speeds up heart rate. It constrict blood vessels and raises blood pressure.

(b) Coronary Artery Disease (CAD) It is caused due to the deposition of fatty substances on the arterial wall causing atherosclerotic plaques. The lumen of artery decreases, thus obstructing the blood flow and sometimes completely blocks the artery resulting into thus, heart attack.

Answer

The diagrammatic presentation of heart with labelled SAN, AVN, AV bundles bundle of His and purkinje fibres in heart is show as follows