Which of the following is not an effect produced by parasympathetic stimulation?

Options

A. Dilation of the pupils
B. Increased saliva production
C. Increased stomach activity
D. Constriction of the bronchi

Explanation

To determine which of the following is not an effect produced by parasympathetic stimulation, we will analyze each option based on our understanding of the parasympathetic nervous system.

### Step-by-Step Solution:

1. **Understand the Role of the Parasympathetic Nervous System**:
- The parasympathetic nervous system is part of the autonomic nervous system, which regulates involuntary bodily functions. Its primary role is to promote a "rest and digest" state, counteracting the "fight or flight" response of the sympathetic nervous system.

2. **Evaluate Each Option**:
- **Option 1: Dilation of pupils**:
- The parasympathetic stimulation causes constriction of the pupils (miosis), not dilation. Therefore, this is likely the correct answer.
- **Option 2: Increased saliva production**:
- Parasympathetic stimulation increases saliva production, aiding in digestion.
- **Option 3: Increased stomach activity**:
- It also enhances stomach activity, promoting digestion.
- **Option 4: Constriction of bronchi**:
- The parasympathetic system causes constriction of the bronchi, which reduces airflow, aligning with its calming effects.

3. **Identify the Incorrect Effect**:
- After evaluating all options, we find that dilation of the pupils is not an effect produced by parasympathetic stimulation. Instead, it causes constriction of the pupils.

4. **Conclusion**:
- The correct answer is **dilation of pupils**, as it is not an effect of parasympathetic stimulation.

### Final Answer:
**Dilation of pupils** is not an effect produced by parasympathetic stimulation.

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