Second heart sound is associated with the

Options

A. lub-closure of the Semilunar valves
B. lub-closure of the Tricuspid and Bicuspid valves
C. dub-closure of the Tricuspid and Bicuspid valves
D. dub-closure of the Semilunar valves

Answer

To answer the question "Second heart sound is associated with the:", let's break down the information step by step.

### Step 1: Understanding Heart Sounds
The heart produces two primary sounds during its cycle, commonly referred to as "lub" and "dub." These sounds are generated by the closure of heart valves during the cardiac cycle.

### Step 2: Identifying the Sounds
1. **First Heart Sound (Lub)**: This sound is associated with the closure of the atrioventricular (AV) valves, which include the tricuspid and bicuspid (mitral) valves. This occurs at the beginning of ventricular contraction (systole).

2. **Second Heart Sound (Dub)**: This sound is associated with the closure of the semilunar valves, which include the aortic and pulmonary valves. This occurs at the end of ventricular contraction (systole) when the ventricles relax.

### Step 3: Analyzing the Options
Now, let's analyze the provided options:
- **Option A**: "Lub closure of the semi-lunar valve" - Incorrect, as this describes the first sound.
- **Option B**: "Lub closure of the tricuspid and bicuspid valves" - Incorrect, as this describes the first sound.
- **Option C**: "Dub closure of the tricuspid and bicuspid valves" - Incorrect, as this describes the first sound.
- **Option D**: "Dub closure of the semi-lunar valves" - Correct, as this describes the second heart sound.

### Step 4: Conclusion
The second heart sound is associated with the closure of the semilunar valves. Therefore, the correct answer is **Option D: Dub closure of the semi-lunar valves**.

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