Lub sound produced by heart is caused by

Options

A. ventricular diastole
B. ventricular systole
C. atrial diastole
D. atrial systole

Answer

To determine what causes the "lub" sound produced by the heart, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Heart Sounds**: The heart produces two main sounds known as "lub" and "dub". These sounds are associated with the closing of heart valves during the cardiac cycle.

2. **Identify the Sounds**:
- The "lub" sound is the first heart sound (S1).
- The "dub" sound is the second heart sound (S2).

3. **Determine the Cause of the "Lub" Sound**:
- The "lub" sound occurs due to the closure of the atrioventricular (AV) valves. These valves are located between the atria and the ventricles.
- This closure happens at the beginning of ventricular systole, which is when the ventricles contract to pump blood out of the heart.

4. **Evaluate the Options**:
- The options provided are:
- A) Ventricular diastole
- B) Ventricular systole
- C) Atrial diastole
- D) Atrial systole
- Since the "lub" sound is associated with the closure of the AV valves at the start of ventricular systole, the correct answer is option B.

5. **Conclusion**: The "lub" sound produced by the heart is caused by the closure of the atrioventricular valves at the start of ventricular systole.

### Final Answer:
The "lub" sound produced by the heart is caused by **ventricular systole** (Option B).

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