The heart sound 'lub' is produced when:
Correct answer: A. The mitral valve is closed
- A. The mitral valve is closed
- B. The semilunar valves at the base of the aorta get closed
- C. The tricuspid valve is opened
- D. The mitral valve is opened
Explanation
Therefore, the correct answer is B) The semilunar valves at the base of the aorta get closed, as their closure contributes to the 'dub' sound of the heart.
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The circulatory system covers the chambers, valves and conducting pathway of the human heart, along with the cardiac cycle and control of heartbeat. It compares arteries, veins and capillaries by structure and function, and explains how the lymphatic system returns tissue fluid, transports absorbed fats and supports immunity.
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