Human Circulatory System Quiz: Test Your Knowledge

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Human Circulatory System Quiz. The human circulatory system is a vital body system responsible for transporting blood, oxygen, nutrients, hormones, and waste products throughout the body. It consists mainly of the heart, blood, and blood vessels, which work together to maintain life by supplying cells with essential substances and removing harmful materials. Through continuous circulation, the system helps regulate body temperature, support immunity, and ensure that all organs function properly.

Human Circulatory System Quiz

1. Which organ is responsible for pumping blood throughout the human body?
A. Lungs
B. Heart
C. Liver
D. Kidneys

2. The main function of red blood cells is to
A. Fight infections
B. Produce hormones
C. Transport oxygen
D. Store nutrients

3. Which blood vessel carries blood away from the heart?
A. Veins
B. Capillaries
C. Arteries
D. Venules

4. Which blood vessel carries blood toward the heart?
A. Arteries
B. Veins
C. Capillaries
D. Aorta

5. The liquid part of blood is called
A. Serum
B. Plasma
C. Lymph
D. Cytoplasm

Human Circulatory System Quiz

6. Which part of the heart receives oxygenated blood from the lungs?
A. Right atrium
B. Left atrium
C. Right ventricle
D. Left ventricle

7. The smallest blood vessels in the body are
A. Arteries
B. Veins
C. Capillaries
D. Venules

8. Which blood cells are responsible for fighting diseases?
A. Red blood cells
B. Platelets
C. White blood cells
D. Plasma cells

9. The main function of platelets is to
A. Carry oxygen
B. Digest food
C. Clot blood
D. Produce hormones

10. Which chamber of the heart pumps blood to the rest of the body?
A. Right atrium
B. Left atrium
C. Right ventricle
D. Left ventricle

Human Circulatory System Quiz

11. The pulse felt in the wrist is caused by
A. Vein contraction
B. Heartbeat
C. Lung movement
D. Muscle activity

12. Which artery carries oxygenated blood from the heart to the body?
A. Pulmonary artery
B. Renal artery
C. Aorta
D. Carotid vein

13. The normal color of oxygenated blood is
A. Dark red
B. Bluish
C. Bright red
D. Yellow

14. Which vein carries deoxygenated blood to the heart?
A. Pulmonary vein
B. Aorta
C. Vena cava
D. Coronary artery

15. The double circulation system means that blood
A. Flows once through the heart
B. Passes through the heart twice per cycle
C. Flows without oxygen
D. Moves only in veins

16. The pulmonary circulation involves blood flow between the
A. Heart and kidneys
B. Heart and lungs
C. Heart and liver
D. Heart and brain

17. Which component of blood transports nutrients and wastes?
A. Plasma
B. Red blood cells
C. Platelets
D. White blood cells

18. The valve that separates the left atrium from the left ventricle is the
A. Tricuspid valve
B. Pulmonary valve
C. Mitral valve
D. Aortic valve

19. Which factor helps prevent backflow of blood in the heart?
A. Muscles
B. Valves
C. Nerves
D. Capillaries

20. Coronary arteries supply blood to the
A. Brain
B. Lungs
C. Heart muscles
D. Kidneys

Human Circulatory System Quiz

21. Which disease is caused by blockage of blood vessels?
A. Asthma
B. Hypertension
C. Atherosclerosis
D. Tuberculosis

22. The average adult human heart beats about
A. 20–30 times per minute
B. 40–50 times per minute
C. 60–80 times per minute
D. 100–120 times per minute

23. Lymph is mainly responsible for
A. Carrying oxygen
B. Transporting hormones
C. Returning tissue fluid to blood
D. Digesting food

24. Which structure controls the rhythm of the heartbeat?
A. Medulla oblongata
B. Pacemaker
C. Cerebellum
D. Spinal cord

25. Anaemia is a condition caused by deficiency of
A. White blood cells
B. Platelets
C. Red blood cells
D. Plasma

Human Circulatory System Quiz ANSWERS AND EXPLANATIONS

1. B — Heart
The heart is a muscular organ that works as a pump to circulate blood throughout the body. It contracts and relaxes rhythmically to push oxygenated blood to tissues and return deoxygenated blood to the lungs for purification.

2. C — Transport oxygen
Red blood cells contain haemoglobin, a protein that binds with oxygen in the lungs and carries it to body tissues. This process is essential for cellular respiration and energy production.

3. C — Arteries
Arteries are thick-walled blood vessels that carry blood away from the heart under high pressure. Most arteries transport oxygen-rich blood to different organs and tissues.

4. B — Veins
Veins carry blood back to the heart after it has delivered oxygen and nutrients. They contain valves that prevent the backward flow of blood, especially in the limbs.

5. B — Plasma
Plasma is the pale yellow liquid part of blood that transports nutrients, hormones, gases, and waste products. It also helps in maintaining body temperature and blood pressure.

6. B — Left atrium
The left atrium receives oxygenated blood from the lungs through the pulmonary veins. It then transfers this blood to the left ventricle for distribution to the body.

7. C — Capillaries
Capillaries are extremely tiny blood vessels with thin walls. They allow the exchange of oxygen, nutrients, and wastes between blood and body tissues.

8. C — White blood cells
White blood cells defend the body against infections by destroying harmful microorganisms and producing antibodies. They are a vital part of the immune system.

9. C — Clot blood
Platelets help stop bleeding by forming blood clots at injured sites. They gather at wounds and release chemicals that promote clot formation and tissue repair.

10. D — Left ventricle
The left ventricle has thick muscular walls and pumps oxygenated blood into the aorta. This allows blood to reach all parts of the body efficiently.

11. B — Heartbeat
The pulse is caused by the rhythmic contraction of the heart. Each heartbeat sends a wave of blood through the arteries, which can be felt at certain points.

12. C — Aorta
The aorta is the largest artery in the body. It carries oxygen-rich blood from the left ventricle to the rest of the body under high pressure.

13. C — Bright red
Oxygenated blood appears bright red due to the presence of oxyhaemoglobin. This form of haemoglobin reflects light differently from deoxygenated blood.

14. C — Vena cava
The superior and inferior vena cava return deoxygenated blood from the body to the right atrium. They are the largest veins in the circulatory system.

15. B — Passes through the heart twice per cycle
In double circulation, blood passes through the heart twice during one complete cycle. This includes pulmonary and systemic circulation, ensuring efficient oxygen supply.

16. B — Heart and lungs
Pulmonary circulation carries blood from the heart to the lungs for oxygenation and back to the heart. It is essential for gas exchange.

17. A — Plasma
Plasma transports digested food, hormones, waste products, and gases. It also contains proteins that support immunity and blood clotting.

18. C — Mitral valve
The mitral valve controls blood flow between the left atrium and left ventricle. It prevents blood from flowing backward during ventricular contraction.

19. B — Valves
Valves ensure that blood flows in one direction through the heart. They close and open in response to pressure changes during heartbeats.

20. C — Heart muscles
Coronary arteries supply oxygen and nutrients to the heart muscles. Blockage of these arteries can lead to heart attacks and serious health problems.

21. C — Atherosclerosis
Atherosclerosis is caused by the buildup of fatty deposits in blood vessels. This reduces blood flow and increases the risk of heart disease and stroke.

22. C — 60–80 times per minute
The normal resting heart rate of an adult is about 60 to 80 beats per minute. It may change due to exercise, emotions, or health conditions.

23. C — Returning tissue fluid to blood
Lymph collects excess tissue fluid and returns it to the bloodstream. It also helps in transporting immune cells and fighting infections.

24. B — Pacemaker
The pacemaker controls the heartbeat by producing electrical impulses. It regulates the rhythm and ensures that the heart beats regularly.

25. C — Red blood cells
Anaemia occurs when there is a shortage of red blood cells or haemoglobin. This reduces oxygen supply to tissues, causing weakness and fatigue.

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