Cardiac output is determined by

Options

A. heart rate
B. stroke volume
C. blood flow
D. Both (i) and (ii)

Explanation

To determine the factors that influence cardiac output, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition of Cardiac Output**:
- Cardiac output (CO) is defined as the volume of blood pumped by each ventricle of the heart per minute.

2. **Identify the Formula for Cardiac Output**:
- The formula for calculating cardiac output is:
\[ \text{Cardiac Output (CO)} = \text{Heart Rate (HR)} \times \text{Stroke Volume (SV)} \]

3. **Define Heart Rate**:
- Heart rate is the number of times the heart beats in one minute. It is often measured in beats per minute (bpm).

4. **Define Stroke Volume**:
- Stroke volume is the amount of blood pumped by each ventricle with each heartbeat. It is measured in milliliters (mL) per beat.

5. **Establish the Relationship**:
- Cardiac output is directly proportional to both heart rate and stroke volume. This means that if either the heart rate or stroke volume increases, the cardiac output will also increase, assuming the other factor remains constant.

6. **Conclusion**:
- Therefore, cardiac output is determined by both heart rate and stroke volume.

### Final Answer:
Cardiac output is determined by heart rate and stroke volume.

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