Chapter: 06. Human Circulatory System
A. Multiple Choice Questions
Blood cells which transport oxygen are The blood group which can receive blood from all the four blood groups is Sphygmomanometer is used to measure B. Assertion-Reason Type Questions
Assertion [A]: In mammals, RBCs are without nucleus (enucleated).
Reason [R]: Red pigment haemoglobin present in the cytoplasm of RBCs transports oxygen to body cells. (a) Both Assertion [A] and Reason [R] are true. Assertion [A]: Left atrium possesses thickest layer of muscles in its wall.
Reason [R]: Left atrium receives blood from the lungs. (d) Assertion [A] is false but Reason [R] is true. Assertion [A]: In human heart, oxygenated blood received from lungs and deoxygenated blood received from the body do not mix.
Reason [R]: Presence of valves in the heart allows the movement of blood in one direction only. (a) Both Assertion [A] and Reason [R] are true. C. Fill in the blanks with suitable words.
The red blood cells have red colour due to the presence of haemoglobin. WBCs / Leucocytes are called soldiers of the body. Pulmonary veins carry oxygenated blood. Arteries have thick walls and narrow lumen. The capillaries are the fine connecting vessels between arteries and veins. D. State whether the following statements are true or false. If false, rewrite the correct form of statements.
Clumping occurs between mismatched blood groups. Capillary wall is formed of many layers of cells. False. Capillary wall is formed of one cell thick layer. Veins have valves in their lumen. Low fat diet is good for heart. Antigens are present in the plasma and antibodies on the RBCs. False. Antigens are present on the RBCs and antibodies are present in the plasma. Blood in the arteries flows under pressure and with jerk. E. Define these terms.
The events, i.e., systole and diastole that occur during one heartbeat form one cardiac cycle. The rhythmic contraction and relaxation of auricles and ventricles is known as heartbeat. Special type of proteins found on the surface of RBCs that determine blood groups. Special type of proteins found in the blood plasma that react against specific antigens. F. Give one word for the following.
The valves present on the opening between right auricle and right ventricle The muscles that form heart walls The heart chamber that receives oxygenated blood from lungs Left auricle / Left atrium The blood group which has both types of antigens G. Give reasons for the following.
Ventricles have thicker walls than auricles. Ventricles have thicker walls because they are the distributing chambers of the heart, responsible for pumping blood with greater force to the lungs (right ventricle) or the entire body (left ventricle), thus requiring stronger muscular contractions. Openings of auricles into ventricles are guarded by valves. Openings of auricles into ventricles are guarded by valves (tricuspid and bicuspid) to prevent the backflow of blood from the ventricles into the auricles when the ventricles contract. Arteries have thick walls. Arteries have thick, muscular walls to withstand the high pressure and jerking flow of blood pumped directly from the heart. Leucocytes are called soldiers of our body. Leucocytes (WBCs) are called soldiers of our body because they defend the body against diseases by fighting against germs and providing immunity against infections. Valves are present in veins but not in arteries. Valves are present in veins to prevent the backflow of deoxygenated blood as it flows against gravity and under lower pressure towards the heart. Arteries do not require valves because blood flows in them under high pressure directly from the heart. H. Encircle the odd one out. Give reasons for your choice.
Arteries, veins, capillaries, ureters Reason: Arteries, veins, and capillaries are types of blood vessels involved in circulation, while ureters are part of the excretory system. Heartbeat, pulse, blood pressure, cardiac cycle Odd one out: Blood pressure Reason: Heartbeat, pulse, and cardiac cycle are all rhythmic events directly related to the heart’s pumping action, whereas blood pressure is the force exerted by blood on artery walls as a result of that pumping. RBCs, WBCs, antibodies, platelets Reason: RBCs, WBCs, and platelets are all types of blood cells (corpuscles), whereas antibodies are proteins found in blood plasma. I. Differentiate between the following.
Artery: Carries blood away from the heart; has thick, muscular walls; typically has a narrow lumen; generally carries oxygenated blood (except pulmonary artery); blood flows under high pressure with jerks; no valves (except at heart exits); generally deep-seated. Vein: Carries blood towards the heart; has thin walls; typically has a wide lumen; generally carries deoxygenated blood (except pulmonary vein); blood flows under low pressure, not jerky; has valves to prevent backflow; generally situated closer to the skin surface. RBC (Red Blood Corpuscle): Red in colour (due to haemoglobin); lacks a nucleus in mature mammalian cells; primarily transports oxygen; very numerous (~5 million/mL); lifespan ~120 days. WBC (White Blood Corpuscle): Colourless; has a nucleus (oval or lobed); fights infections and provides immunity; less numerous (~5000-6000/mL); lifespan ~12-20 days. Lub and dub sounds of heart Lub sound: The first heart sound; occurs due to the closing of the cuspid valves (tricuspid and bicuspid) when the ventricles contract; marks the beginning of ventricular systole. Dub sound: The second heart sound; occurs due to the closing of the pulmonary and aortic (semilunar) valves when the ventricles relax; marks the beginning of ventricular diastole. Systole: The phase of contraction of the heart muscles; during this phase, the heart pumps blood into the blood vessels; corresponds to the highest (systolic) blood pressure. Diastole: The phase of relaxation of the heart muscles; during this phase, the heart receives and fills with blood; corresponds to the lowest (diastolic) blood pressure. J. Match the columns.
Blood group O - (b) Universal donor Blood clotting - © Blood platelets Aorta - (e) Semilunar valves Diastole - (a) Joint relaxation K. Answer these questions.
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