Body Fluids and Circulation MCQs (Set 1): 20 Questions with Answers & Detailed Explanations Boost your preparation with Body Fluids and Circulation MCQs (Set 1) featuring 20 expertly crafted multiple-choice questions with answers and detailed explanations. Ideal for students, medical aspirants, nursing learners, and biology enthusiasts worldwide. Practice key concepts such as blood composition, lymphatic system, heart circulation, blood clotting, and fluid balance to strengthen understanding and succeed in exams globally. 1 / 20 1) What are Korotkoff sounds, commonly used in clinical practice? Sounds produced by air escaping from the sphygmomanometer cuff Heart sounds generated by the closing of cardiac valves Electrical signals of the heart detected by electrodes Noises heard due to turbulent blood flow in an artery during blood pressure measurement Explanation:Korotkoff sounds are heard with a stethoscope while measuring blood pressure manually. As the cuff pressure is released, blood starts flowing through the compressed artery, creating turbulent flow. This turbulence produces characteristic sounds that help identify systolic and diastolic pressure. 2 / 20 2) Who discovered the ABO blood group system and later co-discovered the Rh factor? William Harvey Alexander Fleming Karl Landsteiner Joseph Lister Explanation:Karl Landsteiner discovered the ABO blood group system in 1900–1901 by observing agglutination reactions between blood samples. Later, he also helped identify the Rh factor in 1940 with Alexander Wiener. His discoveries greatly improved the safety of blood transfusions. 3 / 20 3) Who is credited with discovering the circulation of blood in the human body? Charles Darwin William Harvey Aristotle Joseph Lister Explanation:William Harvey was the scientist who explained the circulation of blood through the body and heart in the 17th century. He showed that the heart acts as a pump to move blood continuously. 4 / 20 4) Which of the following organs is not considered a primary component of the lymphatic system? Kidney Spleen Thymus Lymph nodes Explanation:The lymphatic system includes organs such as lymph nodes, spleen, and thymus, which help in immunity and fluid balance. The kidney belongs to the urinary system and is mainly responsible for filtering blood and forming urine. Therefore, it is not a lymphatic organ. 5 / 20 5) Which organ is commonly associated with the synthesis of heparin, a natural anticoagulant? Kidney Pancreas Salivary gland Liver Explanation:Heparin is a natural anticoagulant that helps prevent unwanted blood clotting. In standard biology contexts, it is associated with the liver, though it is also produced by mast cells and basophils. It works by inhibiting clotting factors in the blood. 6 / 20 6) What is one of the major physiological roles of lymph in the human body? Carry oxygen directly to nervous tissue Return excess tissue fluid back into the bloodstream Transport carbon dioxide from cells to the lungs Move red blood cells into lymphatic vessels Explanation:Lymph helps collect excess interstitial fluid from tissues and returns it to the blood circulation. This process maintains fluid balance and prevents swelling. The lymphatic system also supports immunity by transporting lymphocytes. 7 / 20 7) What type of blood is carried by the pulmonary artery? Oxygenated blood from the lungs to the heart Deoxygenated blood from the heart to the lungs Oxygen-rich blood from the heart to the stomach Mixed blood from the lungs to body tissues Explanation:The pulmonary artery carries deoxygenated blood from the right ventricle of the heart to the lungs. In the lungs, carbon dioxide is removed and oxygen is added. It is unusual because most arteries carry oxygenated blood. 8 / 20 8) What type of blood is transported by the pulmonary veins? Mixed blood containing both oxygenated and deoxygenated blood Oxygen-rich blood from the lungs to the heart Deoxygenated blood from the heart to the lungs Blood without respiratory gases Explanation:Pulmonary veins are unique because they carry oxygenated blood. They transport blood from the lungs to the left atrium of the heart after gas exchange has taken place. Most other veins usually carry deoxygenated blood. 9 / 20 9) What is serum in relation to blood composition? Blood plasma containing all clotting factors Lymph fluid rich in white blood cells Blood fluid lacking blood cells and fibrinogen Whole blood without red blood cells only Explanation:Serum is the liquid part of blood obtained after clotting has occurred. It does not contain blood cells or fibrinogen, since fibrinogen is used during clot formation. Serum still contains water, electrolytes, antibodies, and other proteins. Plasma=(Blood - Blood Cells) Serum=(Plasma - Fibrinogen) 10 / 20 10) Which type of blood vessels returns blood from various body tissues back to the heart? Arteries Veins Capillaries Lymph vessels Explanation:Veins are the blood vessels that carry blood toward the heart from different parts of the body. Most veins transport deoxygenated blood, except pulmonary veins. They often contain valves that help prevent backflow of blood. 11 / 20 11) Which plasma protein plays a direct role in the clotting process of blood? Albumin Fibrinogen Alpha globulin Serum amylase Explanation:Fibrinogen is a soluble plasma protein essential for blood coagulation. During clotting, it is converted into insoluble fibrin threads by the action of thrombin. These fibrin threads form a mesh that helps stop bleeding. 12 / 20 12) Which vessel transports nutrient-rich blood absorbed from the intestines to the liver for processing? Hepatic portal vein Thoracic artery Renal portal vein Dorsal aorta Explanation:The hepatic portal vein carries blood rich in absorbed nutrients from the digestive tract to the liver. The liver stores, processes, and detoxifies substances before the blood enters general circulation. This is an important part of nutrient metabolism. 13 / 20 13) Which blood vessel carries oxygen-rich blood to nourish the muscles of the heart? Pulmonary vein Coronary artery Coronary sinus Coronary vein Explanation:The coronary arteries supply oxygenated blood directly to the cardiac muscle (myocardium). This blood is essential for the continuous pumping action of the heart. Coronary veins and the coronary sinus collect deoxygenated blood from the heart tissue and return it to the right atrium. 14 / 20 14) How does lymph differ from blood in terms of cellular composition? It contains more red blood cells and fewer white blood cells It has no fluid component similar to plasma It contains more white blood cells and lacks red blood cells It is made only of plasma proteins without cells Explanation:Lymph is a clear tissue fluid that contains white blood cells, especially lymphocytes, which help in immunity. Unlike blood, it normally does not contain red blood cells. Lymph also has fewer proteins than blood plasma and helps return excess tissue fluid to circulation. 15 / 20 15) Why does blood normally remain fluid and fail to clot within healthy blood vessels? Due to the presence of heparin acting as a natural anticoagulant Because fibrin is constantly removed from the bloodstream Due to continuous oxygen supply in circulating blood Because blood cells prevent clotting reactions Explanation:Blood does not usually clot inside intact vessels because natural anticoagulants such as heparin help prevent unnecessary clot formation. Heparin interferes with clotting factors and keeps blood flowing smoothly. This mechanism is important for normal circulation. 16 / 20 16) A person has a systolic blood pressure of 130 mm Hg and a diastolic pressure of 76 mm Hg. What is the pulse pressure? 54 mm Hg 206 mm Hg 76 mm Hg 130 mm Hg Explanation:Pulse pressure is the difference between systolic and diastolic blood pressure. It is calculated as: Pulse Pressure = Systolic Pressure − Diastolic Pressure. Therefore, 130 − 76 = 54 mm Hg. It reflects the force generated by the heart with each beat. 17 / 20 17) Which positively charged ion is essential for the activation of prothrombin into thrombin during the blood clotting process? Calcium ion (Ca²⁺) Copper ion (Cu²⁺) Ferrous ion (Fe²⁺) Ferric ion (Fe³⁺) Explanation:Calcium ions play a vital role in several steps of blood coagulation. During clot formation, Ca²⁺ helps thromboplastin convert prothrombin into active thrombin. Thrombin then changes fibrinogen into fibrin, leading to clot formation. 18 / 20 18) Which event is responsible for producing the second heart sound, commonly heard as “dup”? Opening of the bicuspid valve during ventricular filling Closure of the tricuspid valve at the start of systole Opening of the mitral valve during blood ejection Closure of the semilunar valves at the beginning of ventricular relaxation Explanation:The “dup” sound is the second heart sound. It occurs when the aortic and pulmonary semilunar valves close after ventricular contraction ends. This prevents backflow of blood into the ventricles. It marks the beginning of ventricular diastole. 19 / 20 19) In the ABO blood group system, where are agglutinogens mainly found? On the surface of red blood cells Dissolved in blood plasma Inside hemoglobin molecules Present in blood serum only Explanation:Agglutinogens are antigens present on the membrane of red blood cells. These antigens determine a person's ABO blood group type. Plasma contains antibodies (agglutinins), not agglutinogens. The interaction between antigens and antibodies is important in blood transfusion compatibility. 20 / 20 20) Which statement most accurately defines blood pressure in the human body? The amount of blood ejected by the heart in one cardiac cycle The pressure exerted by circulating blood on the walls of vessels The speed at which blood travels through veins and capillaries The resistance offered by blood due to its viscosity Explanation:Blood pressure refers to the force applied by blood as it flows through blood vessels, especially arteries. It is mainly generated by the pumping action of the heart. This pressure is essential for maintaining proper blood circulation and delivering oxygen and nutrients to body tissues. Your score isThe average score is 0% 0% Restart quiz
