Cardiac output is defined as

Options

A. (a) heart rate times stroke volume
B. (b) peripheral resistance times heart rate
C. (c) blood pressure minus peripheral resistance
D. (d) blood pressure times peripheral resistance

Answer

**Step-by-Step Solution:**

1. **Understanding Cardiac Output**:
- Cardiac output is a crucial physiological parameter that indicates the efficiency of the heart. It is defined as the volume of blood ejected by the left ventricle of the heart in one minute.

2. **Normal Range**:
- In a healthy adult, the normal range for cardiac output is approximately 4 to 8 liters per minute.

3. **Formula for Cardiac Output**:
- The cardiac output can be calculated using the formula:
\[ \text{Cardiac Output (CO)} = \text{Heart Rate (HR)} \times \text{Stroke Volume (SV)} \]
- Here, HR is the number of heartbeats per minute, and SV is the volume of blood pumped by the heart with each beat.

4. **Defining Heart Rate and Stroke Volume**:
- **Heart Rate (HR)**: This is the frequency of heartbeats in one minute.
- **Stroke Volume (SV)**: This refers to the amount of blood pumped by the heart in one contraction.

5. **Identifying the Correct Option**:
- In the context of the question, the options provided include various definitions of cardiac output. The correct definition is the one that states that cardiac output is the product of heart rate and stroke volume.
- Therefore, if option A states "Heart Rate times Stroke Volume," it correctly defines cardiac output.

6. **Conclusion**:
- Based on the explanation and calculations, the correct answer to the question "Cardiac output is defined as" is option A.