Time interval between the closure of semilunar valve and closure of AV valve is

Options

A. 0.3 s
B. 0.5 s
C. 0.1 s
D. 0.7 s

Answer

To solve the question regarding the time interval between the closure of the semilunar valve and the closure of the AV valve, we will analyze the cardiac cycle and its phases step by step.

### Step-by-Step Solution:

1. **Understand the Cardiac Cycle**:
- The cardiac cycle consists of two main phases: systole (contraction) and diastole (relaxation).
- During systole, the heart chambers contract, and during diastole, they relax.

2. **Identify the Phases of the Cardiac Cycle**:
- The cardiac cycle can be divided into three main phases:
- Atrial Systole (0.1 seconds): Contraction of the atria, leading to the closure of the AV valves.
- Ventricular Systole (0.3 seconds): Contraction of the ventricles, leading to the closure of the semilunar valves.
- Joint Diastole (0.4 seconds): Both atria and ventricles are relaxed.

3. **Determine the Closure of the Valves**:
- The semilunar valves close at the end of ventricular systole.
- The AV valves close at the beginning of atrial systole.

4. **Calculate the Time Interval**:
- The closure of the semilunar valve occurs at the end of the ventricular systole (0.3 seconds).
- The closure of the AV valve occurs at the beginning of atrial systole (0.1 seconds).
- The time interval between the closure of the semilunar valve and the closure of the AV valve can be calculated as follows:
- Total duration of the cardiac cycle = 0.8 seconds.
- Time from the closure of the semilunar valve to the closure of the AV valve = 0.3 seconds (ventricular systole) + 0.1 seconds (atrial systole) = 0.5 seconds.

5. **Conclusion**:
- Therefore, the time interval between the closure of the semilunar valve and the closure of the AV valve is **0.5 seconds**.

### Final Answer:
The time interval between the closure of the semilunar valve and the closure of the AV valve is **0.5 seconds**.