A person has 5 litres of blood in his body and his normal heart beat rate is 72 per minute. In fever the duration of cardiac cycle will be _______

Options

A. Higher than normal
B. Less than normal
C. Normal
D. 0.8 seconds

Answer

To solve the question regarding the duration of the cardiac cycle during fever, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Cardiac Cycle**: The cardiac cycle is the sequence of events in one heartbeat, which includes both systole (contraction) and diastole (relaxation) of the heart chambers.

2. **Calculate Normal Duration of Cardiac Cycle**: The normal duration of the cardiac cycle can be calculated using the formula:
\[ \text{Duration of Cardiac Cycle} = \frac{60 \text{ seconds}}{\text{Heart Rate (beats per minute)}} \]
For a heart rate of 72 beats per minute:
\[ \text{Duration of Cardiac Cycle} = \frac{60}{72} \approx 0.833 \text{ seconds} \]
This can be rounded to approximately 0.8 seconds.

3. **Effect of Fever on Heart Rate**: During a fever, the body requires more oxygen and needs to cool down, which leads to an increase in heart rate.

4. **Determine New Duration of Cardiac Cycle**: Since the duration of the cardiac cycle is inversely proportional to the heart rate, if the heart rate increases, the duration of the cardiac cycle will decrease.

5. **Conclusion**: Therefore, in the case of fever, the duration of the cardiac cycle will be less than normal.

### Final Answer:
The duration of the cardiac cycle in fever will be **less than normal**.

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