DUP is a long and sharp sound .It is caused by

Options

A. closing of atrio venticular valves
B. opening of atrio ventricular valves
C. closing of semilunar valves
D. opening of semilunar valves

Answer

To answer the question "DUP is a long and sharp sound. It is caused by," we will go through the options step by step.

### Step-by-Step Solution:

1. **Understanding the Heart Sounds**:
- The heart produces two main sounds during each heartbeat, commonly referred to as "LUB" and "DUB."
- "LUB" is the first sound, while "DUB" is the second sound.

2. **Identifying the Cause of "DUB"**:
- The "DUB" sound is associated with the closing of specific heart valves.

3. **Evaluating the Options**:
- **Option 1: Closing of the Atrioventricular valve**:
- This option is incorrect because the closing of the atrioventricular (AV) valves (tricuspid and mitral valves) produces the "LUB" sound, not "DUB."

- **Option 2: Opening of Atrioventricular valve**:
- This option is also incorrect. The opening of the AV valves does not produce a sound that is heard as "DUB."

- **Option 3: Closing of the Semilunar valve**:
- This is the correct option. The "DUB" sound is produced when the semilunar valves (which include the aortic and pulmonic valves) close at the end of ventricular systole.

- **Option 4: Opening of the Semilunar valve**:
- This option is incorrect as well. The opening of the semilunar valves does not produce the "DUB" sound.

4. **Conclusion**:
- Therefore, the correct answer to the question is **Option 3: Closing of the Semilunar valve**.