Lubb sound is produced when:
Correct answer: C. A.V valves close
- A. A.V valves open
- B. Semilunar valve close
- C. A.V valves close
- D. Semilunar valve open
Explanation
In healthy adults there are two normal heart sounds. often described as a lubb and dubb, that occur in sequence with each heartbeat. These are the first heart sound (S1) and second heart sound (S2), produced by the closing of the atrio-ventricular valves and semilunar valves, respectively.
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The human digestive system covers the organs from mouth to anus, the movement of food, and the mechanical and chemical breakdown of carbohydrates, proteins and fats. It also includes the roles of digestive enzymes, bile, absorption through intestinal villi, and the assimilation of nutrients by body cells.
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