Question

Dubb Sound originate

• A. Closer of Semilunar valve
• B. Open of Semilunar valve
• C. Closer of AV valve
• D. Open of AV valve

Hint:

Remember the sequence: 'Lubb' occurs with the closure of AV valves at the start of ventricular contraction. 'Dubb' occurs with the closure of semilunar valves at the start of ventricular relaxation. This sequence prevents backflow of blood during the cardiac cycle.

Answer 1

The Correct Option is A

Step 1: Understand Heart Sounds
The human heart produces characteristic sounds, often described as 'lubb-dubb', which correspond to the closing of heart valves. These sounds are important indicators of cardiac health. Step 2: Identify the origin of the 'Lubb' sound
The first heart sound, 'Lubb' (S1), is produced by the simultaneous closure of the atrioventricular (AV) valves. These include the tricuspid valve (between the right atrium and right ventricle) and the bicuspid (mitral) valve (between the left atrium and left ventricle). This occurs at the beginning of ventricular systole (contraction). Step 3: Identify the origin of the 'Dubb' sound
The second heart sound, 'Dubb' (S2), is produced by the simultaneous closure of the semilunar valves. These include the aortic valve (between the left ventricle and the aorta) and the pulmonary valve (between the right ventricle and the pulmonary artery). This occurs at the beginning of ventricular diastole (relaxation), when the ventricles start to relax and the pressure within them falls, causing the semilunar valves to snap shut to prevent backflow of blood from the arteries into the ventricles. Step 4: Analyze each option in relation to the 'Dubb' sound (A) Closer of Semilunar valve
This event directly corresponds to the production of the 'Dubb' sound as blood pushes against the closed valves, creating vibrations. (B) Open of Semilunar valve
The opening of valves is typically a silent event, not associated with the loud 'Dubb' sound. (C) Closer of AV valve
The closure of AV valves produces the 'Lubb' sound, not the 'Dubb' sound. (D) Open of AV valve
The opening of AV valves is also generally a silent event. Step 5: Conclusion
The 'Dubb' sound originates from the closure of the semilunar valves (aortic and pulmonary valves) at the beginning of ventricular diastole. The correct answer is: $$(A) Closer of Semilunar valve$$