MCQ 91:
What is the primary function of the valves in the heart?
A) Increase blood flow
B) Allow blood to flow in one direction
C) Pump blood
D) Filter blood
Answer: B) Allow blood to flow in one direction
Explanation: Heart valves ensure that blood flows in one direction through the heart and prevent backflow during contractions.
MCA 92:
What is the role of the lymph nodes?
A) Filter blood
B) Store red blood cells
C) Produce platelets
D) Filter lymph fluid and trap pathogens
Answer: D) Filter lymph fluid and trap pathogens
Explanation: Lymph nodes filter lymph fluid, trapping pathogens and foreign substances, and play a vital role in the immune response.
MCQ 93:
What is the primary purpose of the aorta?
A) Transport deoxygenated blood
B) Pump blood
C) Distribute oxygenated blood from the heart
D) Regulate blood pressure
Answer: C) Distribute oxygenated blood from the heart
Explanation: The aorta is the largest artery and distributes oxygenated blood from the heart to the body.
MCQ 94:
Which of the following structures is responsible for maintaining blood pressure?
A) Capillaries
B) Veins
C) Arteries
D) Lymphatics
Answer: C) Arteries
Explanation: Arteries, especially the larger ones like the aorta, maintain blood pressure through their muscular walls that can constrict or dilate.
MCQ 95:
What is the effect of decreased blood volume on blood pressure?
A) Increase blood pressure
B) Decrease blood pressure
C) No effect on blood pressure
D) Stabilize blood pressure
Answer: B) Decrease blood pressure
Explanation: A decrease in blood volume leads to lower blood pressure as there is less fluid exerting pressure on the vessel walls.
MCQ 96:
Which part of the brain controls involuntary actions, including heart rate?
A) Cerebrum
B) Brainstem
C) Cerebellum
D) Hippocampus
Answer: B) Brainstem
Explanation: The brainstem, including the medulla oblongata, controls involuntary actions such as heart rate and breathing.
MCQ 97:
What is the role of the vena cava?
A) Supply oxygenated blood to the heart
B) Return deoxygenated blood to the heart
C) Pump blood to the lungs
D) Filter blood in the kidneys
Answer: B) Return deoxygenated blood to the heart
Explanation: The vena cava consists of the superior and inferior vena cavae, which carry deoxygenated blood from the body back to the right atrium of the heart.
MCQ 98:
What is the primary function of the heart’s atria?
A) Pump blood to the body
B) Receive blood returning to the heart
C) Regulate blood pressure
D) Generate electrical impulses
Answer: B) Receive blood returning to the heart
Explanation: The atria are the upper chambers of the heart that receive blood returning from the body (right atrium) and lungs (left atrium).
MCQ 99:
What is the role of the pulmonary veins?
A) Carry deoxygenated blood to the heart
B) Carry oxygenated blood from the lungs to the heart
C) Filter blood
D) Pump blood to the body
Answer: B) Carry oxygenated blood from the lungs to the heart
Explanation: The pulmonary veins transport oxygenated blood from the lungs to the left atrium of the heart.
MCQ 100:
Which condition is characterized by an irregular heartbeat?
A) Atherosclerosis
B) Arrhythmia
C) Bradycardia
D) Tachycardia
Answer: B) Arrhythmia
Explanation: Arrhythmia refers to any irregularity in the heart’s rhythm, which can affect the heart’s ability to pump blood effectively.
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