Which of the following is mismatched ?

Options

A. Lubb : First heart sound associated with closure of tricuspid and bicuspid valves
B. Cardiac output : Stroke volume multiplied by heart rate
C. Dub : Second heart sound, due to opening of semilunar valves
D. Duration of cardiac cycle : 0.8 seconds

Answer

To determine which of the following statements is mismatched, we will evaluate each option one by one based on our knowledge of the heart sounds and related concepts.

### Step-by-Step Solution:

1. **Evaluate the First Statement:**
- The first statement claims that the "lub" (first heart sound) is associated with the closure of the tricuspid and bicuspid (mitral) valves.
- **Analysis:** This statement is correct. The "lub" sound is indeed produced by the closure of the atrioventricular valves, which include the tricuspid and bicuspid (mitral) valves.

2. **Evaluate the Second Statement:**
- The second statement claims that the "dub" (second heart sound) is due to the opening of the semilunar valves.
- **Analysis:** This statement is incorrect. The "dub" sound is produced by the closure of the semilunar valves (aortic and pulmonary valves), not their opening. Therefore, this statement is mismatched.

3. **Evaluate the Third Statement:**
- The third statement states that cardiac output is equal to stroke volume multiplied by heart rate.
- **Analysis:** This statement is correct. Cardiac output (CO) is indeed calculated as CO = Stroke Volume (SV) × Heart Rate (HR).

4. **Evaluate the Fourth Statement:**
- The fourth statement mentions that the duration of the cardiac cycle is 0.8 seconds.
- **Analysis:** This statement is also correct. The average duration of the cardiac cycle in a healthy adult at rest is approximately 0.8 seconds.

### Conclusion:
Based on the evaluations:
- The first statement is correct.
- The second statement is mismatched (incorrect).
- The third statement is correct.
- The fourth statement is correct.

Thus, the mismatched statement is the second one.

### Final Answer:
The mismatched statement is: **"dub second heart sound due to opening of semilunar valves."**

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