Stimulation of sympathetic nervous system causes :-

Options

A. Contriction of blood vessels and high blood pressure
B. Dilation of bronchi & pupil
C. Erection of hair
D. All of these

Answer

**Step-by-Step Solution:**

1. **Understanding the Sympathetic Nervous System (SNS):**
- The sympathetic nervous system is part of the autonomic nervous system that prepares the body for 'fight or flight' responses during stressful situations.

2. **Effects of SNS Stimulation:**
- When the SNS is stimulated, several physiological changes occur in the body to prepare it for action.

3. **Vasoconstriction:**
- One of the primary effects of SNS stimulation is the constriction of blood vessels. This occurs primarily in non-essential organs (like the skin and digestive tract) to redirect blood flow to vital organs and muscles that are essential for immediate survival.

4. **Increased Blood Pressure:**
- Due to the constriction of blood vessels, there is an increase in blood pressure. This is because the same volume of blood is forced through narrower vessels, leading to higher pressure.

5. **Dilation of Bronchi and Pupils:**
- The SNS also causes dilation of the bronchi (air passages in the lungs) and pupils. Dilation of bronchi allows for increased airflow to the lungs, while dilation of pupils enhances vision in low light conditions.

6. **Erection of Hair:**
- The stimulation of the SNS can also lead to the erection of hair (piloerection), which is a reflex response that can make an animal appear larger to potential threats.

7. **Conclusion:**
- Therefore, the stimulation of the sympathetic nervous system causes all of the following: constriction of blood vessels, increased blood pressure, dilation of bronchi and pupils, and erection of hair.

8. **Final Answer:**
- The correct answer to the question is: **All of these.**

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