If parasympathetic nerve is cut, then heart beat :

Options

A. Unaffected
B. Decreases
C. Increases
D. Stop

Answer

To solve the question "If parasympathetic nerve is cut, then heart beat:", we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Role of the Parasympathetic Nervous System**:
- The parasympathetic nervous system is part of the autonomic nervous system. Its primary function is to promote the "rest and digest" response, which includes slowing down the heart rate.

2. **Identify the Effect of Cutting the Parasympathetic Nerve**:
- If the parasympathetic nerve is cut, its inhibitory effect on the heart is removed. This means that the heart will no longer receive signals that slow it down.

3. **Consider the Compensatory Mechanism**:
- With the parasympathetic influence gone, the heart is primarily under the control of the sympathetic nervous system, which increases heart rate. Therefore, the heart rate will increase.

4. **Evaluate the Options Given**:
- **Option 1: Unaffected** - This is incorrect because the heart rate will change.
- **Option 2: Decreases** - This is also incorrect since the heart rate will not decrease.
- **Option 3: Increases** - This is the correct answer as the heart rate will increase due to the lack of parasympathetic inhibition.
- **Option 4: Stops** - This is incorrect because the heart will not stop beating; it will continue to beat but at a higher rate.

5. **Conclusion**:
- The correct answer is that the heart rate will **increase** if the parasympathetic nerve is cut.

### Final Answer:
The heart beat will **increase** if the parasympathetic nerve is cut.

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