Which of the following statement is not true?

Options

A. Cardiac output of an athlete is much higher than that of an ordinary man
B. In each minute a single cardiac cycle is performed
C. Cardiac sounds are of clinical diagnostic significances
D. Cardiac cycle includes Auricular systole, ventricular systole and joint diastole / complete diastole

Answer

To determine which statement is not true regarding cardiac output and the cardiac cycle, we need to analyze each statement provided.

### Step-by-Step Solution:

1. **Understanding Cardiac Output**:
- Cardiac output (CO) is defined as the volume of blood the heart pumps per minute. It is calculated as:
\[ \text{Cardiac Output} = \text{Stroke Volume} \times \text{Heart Rate} \]
- An athlete typically has a higher stroke volume and may have a higher heart rate during exercise, leading to a higher cardiac output compared to a non-athlete.

**Hint**: Remember the formula for cardiac output and how it relates to stroke volume and heart rate.

2. **Analyzing the First Statement**:
- The first statement claims that "Cardiac output of an athlete is much higher than that of an ordinary man."
- This statement is true, as athletes generally have a more efficient cardiovascular system.

**Hint**: Consider the physiological adaptations of athletes compared to non-athletes.

3. **Analyzing the Second Statement**:
- The second statement mentions that "In each minute a single cardiac cycle is performed."
- This statement is incorrect because one cardiac cycle consists of multiple heartbeats. In fact, there are about 72 heartbeats in a minute, meaning there are approximately 72 cardiac cycles in one minute.

**Hint**: Recall how many heartbeats occur in a minute and how they relate to cardiac cycles.

4. **Analyzing the Third Statement**:
- The third statement discusses the sounds produced during the cardiac cycle, specifically the closure of the A-V valve and the semilunar valve.
- This statement is true, as these sounds (S1 and S2) are indeed associated with valve closure and can be heard using a stethoscope.

**Hint**: Think about the significance of heart sounds in clinical assessments.

5. **Analyzing the Fourth Statement**:
- The fourth statement describes the phases of the cardiac cycle: auricular systole, ventricular systole, and joint diastole.
- This statement is also true, as it accurately describes the sequence and timing of the cardiac cycle phases.

**Hint**: Familiarize yourself with the phases of the cardiac cycle and their durations.

### Conclusion:
The statement that is not true is: "In each minute a single cardiac cycle is performed."

### Final Answer:
The statement that is not true is the second one regarding the cardiac cycle.