Questions on Circulatory System
Multiple-Choice Questions: Circulatory System
1. What is the main function of the circulatory system?
A) Producing hormones
B) Transporting nutrients, gases, and wastes
C) Digesting food
D) Controlling movement
E) Filtering urine
2. Which of the following is a component of the circulatory system?
A) Lungs
B) Kidneys
C) Blood vessels
D) Intestines
E) Skin
3. Which organ pumps blood throughout the body?
A) Liver
B) Kidney
C) Brain
D) Heart
E) Lung
4. The liquid component of blood is called:
A) Platelets
B) Plasma
C) Serum
D) Hemoglobin
E) Cytoplasm
5. Which blood cells are primarily responsible for oxygen transport?
A) Platelets
B) White blood cells
C) Red blood cells
D) Plasma cells
E) Stem cells
6. What type of blood vessel carries blood away from the heart?
A) Capillaries
B) Veins
C) Arteries
D) Lymphatic vessels
E) Venules
7. Which vessel returns deoxygenated blood to the heart?
A) Aorta
B) Pulmonary vein
C) Pulmonary artery
D) Vena cava
E) Coronary artery
8. The right atrium receives blood from:
A) Pulmonary vein
B) Left ventricle
C) Body via vena cava
D) Aorta
E) Coronary sinus only
9. Which valve prevents backflow into the left atrium?
A) Pulmonary valve
B) Tricuspid valve
C) Mitral (bicuspid) valve
D) Aortic valve
E) Semilunar valve
10. Blood is oxygenated in the:
A) Heart
B) Brain
C) Lungs
D) Liver
E) Intestines
11. The heart is made up of which type of muscle?
A) Skeletal
B) Voluntary
C) Smooth
D) Cardiac
E) Striated
12. What is the function of platelets?
A) Transport nutrients
B) Destroy bacteria
C) Carry oxygen
D) Help in clotting
E) Regulate pH
13. The largest artery in the body is the:
A) Pulmonary artery
B) Carotid artery
C) Vena cava
D) Aorta
E) Coronary artery
14. Which chamber of the heart has the thickest walls?
A) Right atrium
B) Left atrium
C) Right ventricle
D) Left ventricle
E) Atria
15. What does the pulmonary artery carry?
A) Oxygenated blood to the lungs
B) Deoxygenated blood to the lungs
C) Oxygenated blood to the heart
D) Deoxygenated blood to the brain
E) Oxygenated blood to the body
16. What is the function of capillaries?
A) Store blood
B) Prevent backflow
C) Exchange gases and nutrients
D) Pump blood
E) Break down red blood cells
17. Which component of blood fights infections?
A) Plasma
B) Platelets
C) White blood cells
D) Red blood cells
E) Hormones
18. Which part of the circulatory system helps regulate body temperature?
A) Lymph nodes
B) Blood vessels
C) Liver
D) Spleen
E) Kidneys
19. What is systole?
A) Relaxation of the heart
B) Contraction of the heart
C) Blood filtration
D) Exchange in capillaries
E) Clot formation
20. What structure separates the left and right sides of the heart?
A) Pericardium
B) Septum
C) Tricuspid valve
D) Aortic arch
E) AV node
21. The heart’s natural pacemaker is:
A) AV node
B) SA node
C) Purkinje fibers
D) Bundle of His
E) Mitral valve
22. Which type of circulation goes from the heart to the lungs and back?
A) Systemic
B) Coronary
C) Pulmonary
D) Portal
E) Renal
23. The coronary arteries supply blood to:
A) Lungs
B) Liver
C) Brain
D) Heart muscle
E) Kidneys
24. A person with type AB blood has:
A) A antigens only
B) B antigens only
C) A and B antigens
D) No antigens
E) Rh antibodies
25. Which of the following is true about veins?
A) They always carry oxygenated blood
B) They have thick, elastic walls
C) They carry blood under high pressure
D) They have valves to prevent backflow
E) They never connect to capillaries
26. What is the main function of red blood cells?
A) Immunity
B) Clotting
C) Oxygen transport
D) Hormone transport
E) Waste digestion
27. Which of the following conditions affects red blood cells?
A) Leukemia
B) Anemia
C) Hemophilia
D) Thrombosis
E) Scurvy
28. What is hematopoiesis?
A) Blood clotting
B) Heart contraction
C) Blood formation
D) Artery hardening
E) White cell destruction
29. What causes the “lub-dub” sound of the heartbeat?
A) Breathing rhythm
B) Valve closures
C) Muscle stretching
D) Blood pressure
E) Blood oxygenation
30. Which blood vessel carries oxygenated blood from the lungs to the heart?
A) Pulmonary vein
B) Pulmonary artery
C) Aorta
D) Superior vena cava
E) Coronary vein
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Answers and Explanations
1. B – The circulatory system transports oxygen, nutrients, hormones, and waste throughout the body.
2. C – Blood vessels (arteries, veins, and capillaries) are key components of the circulatory system.
3. D – The heart is the muscular pump that moves blood through the circulatory system.
4. B – Plasma is the liquid part of the blood that carries cells, nutrients, and waste.
5. C – Red blood cells (RBCs) contain hemoglobin, which binds oxygen.
6. C – Arteries carry blood away from the heart.
7. D – The vena cava returns deoxygenated blood to the heart’s right atrium.
8. C – The right atrium receives blood from the body through the superior and inferior vena cava.
9. C – The mitral (bicuspid) valve prevents backflow from the left ventricle to the left atrium.
10. C – Blood gets oxygenated in the lungs during pulmonary circulation.
11. D – The heart consists of specialized cardiac muscle.
12. D – Platelets help the blood to clot and prevent bleeding.
13. D – The aorta is the main and largest artery, distributing oxygenated blood to the body.
14. D – The left ventricle has the thickest wall to pump blood through the aorta to the entire body.
15. B – The pulmonary artery carries deoxygenated blood from the heart to the lungs.
16. C – Capillaries are the site of exchange of gases and nutrients between blood and tissues.
17. C – White blood cells (leukocytes) are the body’s defense against infection.
18. B – Blood vessels help dissipate or retain heat, thus regulating body temperature.
19. B – Systole is the contraction phase of the cardiac cycle.
20. B – The septum divides the left and right sides of the heart.
21. B – The sinoatrial (SA) node initiates the electrical signal that sets heart rate.
22. C – Pulmonary circulation carries blood from the heart to the lungs and back.
23. D – Coronary arteries deliver oxygenated blood directly to the heart muscle.
24. C – Type AB blood has both A and B antigens on red blood cells.
25. D – Veins have valves to prevent the backflow of blood, especially in limbs.
26. C – RBCs transport oxygen to tissues via hemoglobin.
27. B – Anemia is a condition involving low red blood cell count or hemoglobin.
28. C – Hematopoiesis is the process of forming blood cells, mainly in bone marrow.
29. B – The heartbeat sounds are caused by the closing of heart valves.
30. A – The pulmonary vein carries oxygen-rich blood from the lungs to the left atrium of the heart.
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