Parasympathetic stimulation causes vasodilatation in penis by release of :-

Options

A. A-Ch
B. Nitric oxide
C. Epinephrine
D. Nor epinephrin

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the mechanism by which parasympathetic stimulation leads to vasodilation in the penis.

2. **Identifying the Options**: The options provided are:
- A) Acetylcholine (ACH)
- B) Nitric oxide
- C) Epinephrine
- D) Norepinephrine

3. **Recalling the Role of the Parasympathetic Nervous System**: The parasympathetic nervous system is responsible for promoting relaxation and vasodilation in various tissues, including the penis.

4. **Analyzing Each Option**:
- **A) Acetylcholine (ACH)**: While acetylcholine is a neurotransmitter involved in the parasympathetic response, it does not directly cause vasodilation in this context.
- **B) Nitric Oxide**: This is a key signaling molecule that promotes vasodilation. It is released in response to parasympathetic stimulation and causes relaxation of the smooth muscle in blood vessels.
- **C) Epinephrine**: This hormone generally causes vasoconstriction and is associated with the sympathetic nervous system, not parasympathetic.
- **D) Norepinephrine**: Similar to epinephrine, norepinephrine is also associated with the sympathetic nervous system and promotes vasoconstriction.

5. **Conclusion**: Based on the analysis, the correct answer is **B) Nitric oxide**. This molecule is released during parasympathetic stimulation and is responsible for causing vasodilation in the penis.

**Final Answer**: Nitric oxide

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