The duration of the ventricular diastole in a normal cardiac cycle is

Options

A. 0.3 s
B. 0.5 s
C. 0.4 s
D. 0.7 s

Answer

To determine the duration of ventricular diastole in a normal cardiac cycle, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Cardiac Cycle**: The cardiac cycle consists of rhythmic contractions and relaxations of the heart chambers. It includes two main phases: systole (contraction) and diastole (relaxation).

2. **Identify the Phases of the Cardiac Cycle**: The cardiac cycle can be divided into three main phases:
- **Atrial Systole**: This is the contraction of the atria, lasting approximately 0.1 seconds.
- **Ventricular Systole**: This is the contraction of the ventricles, lasting about 0.3 seconds.
- **Joint Diastole**: This phase involves both the atria and ventricles being relaxed, lasting around 0.4 seconds.

3. **Calculate Total Duration of the Cardiac Cycle**: The total duration of the cardiac cycle is the sum of the durations of these phases:
- Atrial Systole (0.1 seconds) + Ventricular Systole (0.3 seconds) + Joint Diastole (0.4 seconds) = 0.8 seconds.

4. **Determine the Duration of Ventricular Diastole**:
- During the joint diastole, both the atria and ventricles are relaxed. This phase lasts for 0.4 seconds.
- However, the ventricular diastole specifically includes the time when the ventricles are relaxing after the ventricular systole and before the next contraction. This means that the duration of ventricular diastole is the total time of joint diastole plus the time during which the atria contract (0.1 seconds).
- Therefore, the duration of ventricular diastole is 0.4 seconds (joint diastole) + 0.1 seconds (during atrial contraction) = 0.5 seconds.

5. **Conclusion**: The duration of ventricular diastole in a normal cardiac cycle is **0.5 seconds**.

### Final Answer:
The duration of the ventricular diastole in a normal cardiac cycle is **0.5 seconds**.