MCQ 11:
What is the role of the sinoatrial (SA) node?
A) It pumps blood.
B) It generates electrical impulses.
C) It prevents backflow of blood.
D) It regulates blood pressure.
Answer: B) It generates electrical impulses.
Explanation: The SA node, located in the right atrium, is known as the natural pacemaker of the heart, initiating the electrical impulses that stimulate heartbeats.
MCQ 12:
Which blood type is considered the universal donor?
A) A
B) B
C) AB
D) O
Answer: D) O
Explanation: Blood type O negative is considered the universal donor because it has no A or B antigens on its red blood cells, making it compatible with all blood types in emergencies.
MCQ 13:
What is the normal range of blood pressure in adults?
A) 90/60 mmHg
B) 120/80 mmHg
C) 140/90 mmHg
D) 160/100 mmHg
Answer: B) 120/80 mmHg
Explanation: A normal blood pressure reading for adults is typically around 120/80 mmHg, known as the “gold standard.”
MCQ 14:
Which part of the circulatory system carries blood from the heart to the lungs?
A) Aorta
B) Pulmonary arteries
C) Veins
D) Coronary arteries
Answer: B) Pulmonary arteries
Explanation: The pulmonary arteries carry deoxygenated blood from the right ventricle to the lungs for oxygenation.
MCQ 15:
Which of the following is NOT a function of the circulatory system?
A) Transport of nutrients
B) Regulation of body temperature
C) Production of hormones
D) Removal of waste products
Answer: C) Production of hormones
Explanation: While the circulatory system transports hormones produced by endocrine glands, it does not produce hormones itself.
MCQ 16:
What is the role of the valves in the heart?
A) Preventing blood pressure
B) Allowing blood flow in one direction
C) Generating electrical impulses
D) Increasing heart rate
Answer: B) Allowing blood flow in one direction
Explanation: Heart valves ensure that blood flows in one direction through the heart and prevent backflow during contractions.
MCQ 17:
What is the primary function of the lymphatic system?
A) Oxygen transport
B) Nutrient absorption
C) Immune defense
D) Blood clotting
Answer: C) Immune defense
Explanation: The lymphatic system is essential for immune function, helping to defend against pathogens and maintain fluid balance in the body.
MCQ 18:
Which of the following is the smallest type of blood vessel?
A) Arteries
B) Veins
C) Capillaries
D) Aneurysms
Answer: C) Capillaries
Explanation: Capillaries are the smallest blood vessels and are responsible for the exchange of gases, nutrients, and waste between blood and tissues.
MCQ 19:
What is the function of the pulmonary circulation?
A) Carry oxygenated blood to the body
B) Carry deoxygenated blood to the lungs
C) Regulate body temperature
D) Supply blood to the heart muscle
Answer: B) Carry deoxygenated blood to the lungs
Explanation: Pulmonary circulation is the pathway in which deoxygenated blood is transported from the right side of the heart to the lungs for oxygenation.
MCQ 20:
What initiates the contraction of the heart?
A) Atrial contraction
B) Ventricular contraction
C) SA node
D) AV node
Answer: C) SA node
Explanation: The SA node generates electrical impulses that trigger heart contractions, starting with the atria.
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